6284 lines
164 KiB
C
6284 lines
164 KiB
C
/*
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* Kernel-based Virtual Machine driver for Linux
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*
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* This module enables machines with Intel VT-x extensions to run virtual
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* machines without emulation or binary translation.
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*
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* MMU support
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*
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* Copyright (C) 2006 Qumranet, Inc.
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* Copyright 2010 Red Hat, Inc. and/or its affiliates.
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*
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* Authors:
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* Yaniv Kamay <yaniv@qumranet.com>
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* Avi Kivity <avi@qumranet.com>
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*
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* This work is licensed under the terms of the GNU GPL, version 2. See
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* the COPYING file in the top-level directory.
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*
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*/
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#include "irq.h"
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#include "mmu.h"
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#include "x86.h"
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#include "kvm_cache_regs.h"
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#include "cpuid.h"
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#include <linux/kvm_host.h>
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#include <linux/types.h>
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#include <linux/string.h>
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#include <linux/mm.h>
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#include <linux/highmem.h>
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#include <linux/moduleparam.h>
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#include <linux/export.h>
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#include <linux/swap.h>
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#include <linux/hugetlb.h>
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#include <linux/compiler.h>
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#include <linux/srcu.h>
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#include <linux/slab.h>
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#include <linux/sched/signal.h>
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#include <linux/uaccess.h>
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#include <linux/hash.h>
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#include <linux/kern_levels.h>
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#include <linux/kthread.h>
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#include <asm/page.h>
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#include <asm/pat.h>
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#include <asm/cmpxchg.h>
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#include <asm/io.h>
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#include <asm/vmx.h>
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#include <asm/kvm_page_track.h>
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#include "trace.h"
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extern bool itlb_multihit_kvm_mitigation;
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static int __read_mostly nx_huge_pages = -1;
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static uint __read_mostly nx_huge_pages_recovery_ratio = 60;
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static int set_nx_huge_pages(const char *val, const struct kernel_param *kp);
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static int set_nx_huge_pages_recovery_ratio(const char *val, const struct kernel_param *kp);
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static struct kernel_param_ops nx_huge_pages_ops = {
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.set = set_nx_huge_pages,
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.get = param_get_bool,
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};
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static struct kernel_param_ops nx_huge_pages_recovery_ratio_ops = {
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.set = set_nx_huge_pages_recovery_ratio,
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.get = param_get_uint,
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};
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module_param_cb(nx_huge_pages, &nx_huge_pages_ops, &nx_huge_pages, 0644);
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__MODULE_PARM_TYPE(nx_huge_pages, "bool");
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module_param_cb(nx_huge_pages_recovery_ratio, &nx_huge_pages_recovery_ratio_ops,
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&nx_huge_pages_recovery_ratio, 0644);
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__MODULE_PARM_TYPE(nx_huge_pages_recovery_ratio, "uint");
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/*
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* When setting this variable to true it enables Two-Dimensional-Paging
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* where the hardware walks 2 page tables:
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* 1. the guest-virtual to guest-physical
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* 2. while doing 1. it walks guest-physical to host-physical
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* If the hardware supports that we don't need to do shadow paging.
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*/
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bool tdp_enabled = false;
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enum {
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AUDIT_PRE_PAGE_FAULT,
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AUDIT_POST_PAGE_FAULT,
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AUDIT_PRE_PTE_WRITE,
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AUDIT_POST_PTE_WRITE,
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AUDIT_PRE_SYNC,
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AUDIT_POST_SYNC
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};
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#undef MMU_DEBUG
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#ifdef MMU_DEBUG
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static bool dbg = 0;
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module_param(dbg, bool, 0644);
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#define pgprintk(x...) do { if (dbg) printk(x); } while (0)
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#define rmap_printk(x...) do { if (dbg) printk(x); } while (0)
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#define MMU_WARN_ON(x) WARN_ON(x)
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#else
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#define pgprintk(x...) do { } while (0)
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#define rmap_printk(x...) do { } while (0)
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#define MMU_WARN_ON(x) do { } while (0)
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#endif
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#define PTE_PREFETCH_NUM 8
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#define PT_FIRST_AVAIL_BITS_SHIFT 10
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#define PT64_SECOND_AVAIL_BITS_SHIFT 52
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#define PT64_LEVEL_BITS 9
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#define PT64_LEVEL_SHIFT(level) \
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(PAGE_SHIFT + (level - 1) * PT64_LEVEL_BITS)
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#define PT64_INDEX(address, level)\
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(((address) >> PT64_LEVEL_SHIFT(level)) & ((1 << PT64_LEVEL_BITS) - 1))
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#define PT32_LEVEL_BITS 10
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#define PT32_LEVEL_SHIFT(level) \
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(PAGE_SHIFT + (level - 1) * PT32_LEVEL_BITS)
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#define PT32_LVL_OFFSET_MASK(level) \
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(PT32_BASE_ADDR_MASK & ((1ULL << (PAGE_SHIFT + (((level) - 1) \
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* PT32_LEVEL_BITS))) - 1))
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#define PT32_INDEX(address, level)\
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(((address) >> PT32_LEVEL_SHIFT(level)) & ((1 << PT32_LEVEL_BITS) - 1))
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#define PT64_BASE_ADDR_MASK __sme_clr((((1ULL << 52) - 1) & ~(u64)(PAGE_SIZE-1)))
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#define PT64_DIR_BASE_ADDR_MASK \
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(PT64_BASE_ADDR_MASK & ~((1ULL << (PAGE_SHIFT + PT64_LEVEL_BITS)) - 1))
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#define PT64_LVL_ADDR_MASK(level) \
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(PT64_BASE_ADDR_MASK & ~((1ULL << (PAGE_SHIFT + (((level) - 1) \
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* PT64_LEVEL_BITS))) - 1))
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#define PT64_LVL_OFFSET_MASK(level) \
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(PT64_BASE_ADDR_MASK & ((1ULL << (PAGE_SHIFT + (((level) - 1) \
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* PT64_LEVEL_BITS))) - 1))
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#define PT32_BASE_ADDR_MASK PAGE_MASK
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#define PT32_DIR_BASE_ADDR_MASK \
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(PAGE_MASK & ~((1ULL << (PAGE_SHIFT + PT32_LEVEL_BITS)) - 1))
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#define PT32_LVL_ADDR_MASK(level) \
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(PAGE_MASK & ~((1ULL << (PAGE_SHIFT + (((level) - 1) \
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* PT32_LEVEL_BITS))) - 1))
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#define PT64_PERM_MASK (PT_PRESENT_MASK | PT_WRITABLE_MASK | shadow_user_mask \
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| shadow_x_mask | shadow_nx_mask | shadow_me_mask)
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#define ACC_EXEC_MASK 1
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#define ACC_WRITE_MASK PT_WRITABLE_MASK
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#define ACC_USER_MASK PT_USER_MASK
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#define ACC_ALL (ACC_EXEC_MASK | ACC_WRITE_MASK | ACC_USER_MASK)
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/* The mask for the R/X bits in EPT PTEs */
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#define PT64_EPT_READABLE_MASK 0x1ull
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#define PT64_EPT_EXECUTABLE_MASK 0x4ull
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#include <trace/events/kvm.h>
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#define SPTE_HOST_WRITEABLE (1ULL << PT_FIRST_AVAIL_BITS_SHIFT)
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#define SPTE_MMU_WRITEABLE (1ULL << (PT_FIRST_AVAIL_BITS_SHIFT + 1))
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#define SHADOW_PT_INDEX(addr, level) PT64_INDEX(addr, level)
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/* make pte_list_desc fit well in cache line */
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#define PTE_LIST_EXT 3
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/*
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* Return values of handle_mmio_page_fault and mmu.page_fault:
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* RET_PF_RETRY: let CPU fault again on the address.
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* RET_PF_EMULATE: mmio page fault, emulate the instruction directly.
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*
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* For handle_mmio_page_fault only:
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* RET_PF_INVALID: the spte is invalid, let the real page fault path update it.
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*/
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enum {
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RET_PF_RETRY = 0,
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RET_PF_EMULATE = 1,
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RET_PF_INVALID = 2,
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};
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struct pte_list_desc {
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u64 *sptes[PTE_LIST_EXT];
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struct pte_list_desc *more;
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};
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struct kvm_shadow_walk_iterator {
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u64 addr;
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hpa_t shadow_addr;
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u64 *sptep;
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int level;
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unsigned index;
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};
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static const union kvm_mmu_page_role mmu_base_role_mask = {
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.cr0_wp = 1,
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.cr4_pae = 1,
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.nxe = 1,
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.smep_andnot_wp = 1,
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.smap_andnot_wp = 1,
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.smm = 1,
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.guest_mode = 1,
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.ad_disabled = 1,
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};
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#define for_each_shadow_entry_using_root(_vcpu, _root, _addr, _walker) \
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for (shadow_walk_init_using_root(&(_walker), (_vcpu), \
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(_root), (_addr)); \
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shadow_walk_okay(&(_walker)); \
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shadow_walk_next(&(_walker)))
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#define for_each_shadow_entry(_vcpu, _addr, _walker) \
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for (shadow_walk_init(&(_walker), _vcpu, _addr); \
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shadow_walk_okay(&(_walker)); \
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shadow_walk_next(&(_walker)))
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#define for_each_shadow_entry_lockless(_vcpu, _addr, _walker, spte) \
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for (shadow_walk_init(&(_walker), _vcpu, _addr); \
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shadow_walk_okay(&(_walker)) && \
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({ spte = mmu_spte_get_lockless(_walker.sptep); 1; }); \
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__shadow_walk_next(&(_walker), spte))
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static struct kmem_cache *pte_list_desc_cache;
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static struct kmem_cache *mmu_page_header_cache;
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static struct percpu_counter kvm_total_used_mmu_pages;
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static u64 __read_mostly shadow_nx_mask;
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static u64 __read_mostly shadow_x_mask; /* mutual exclusive with nx_mask */
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static u64 __read_mostly shadow_user_mask;
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static u64 __read_mostly shadow_accessed_mask;
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static u64 __read_mostly shadow_dirty_mask;
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static u64 __read_mostly shadow_mmio_mask;
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static u64 __read_mostly shadow_mmio_value;
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static u64 __read_mostly shadow_present_mask;
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static u64 __read_mostly shadow_me_mask;
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/*
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* SPTEs used by MMUs without A/D bits are marked with shadow_acc_track_value.
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* Non-present SPTEs with shadow_acc_track_value set are in place for access
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* tracking.
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*/
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static u64 __read_mostly shadow_acc_track_mask;
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static const u64 shadow_acc_track_value = SPTE_SPECIAL_MASK;
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/*
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* The mask/shift to use for saving the original R/X bits when marking the PTE
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* as not-present for access tracking purposes. We do not save the W bit as the
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* PTEs being access tracked also need to be dirty tracked, so the W bit will be
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* restored only when a write is attempted to the page.
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*/
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static const u64 shadow_acc_track_saved_bits_mask = PT64_EPT_READABLE_MASK |
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PT64_EPT_EXECUTABLE_MASK;
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static const u64 shadow_acc_track_saved_bits_shift = PT64_SECOND_AVAIL_BITS_SHIFT;
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/*
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* This mask must be set on all non-zero Non-Present or Reserved SPTEs in order
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* to guard against L1TF attacks.
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*/
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static u64 __read_mostly shadow_nonpresent_or_rsvd_mask;
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/*
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* The number of high-order 1 bits to use in the mask above.
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*/
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static const u64 shadow_nonpresent_or_rsvd_mask_len = 5;
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/*
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* In some cases, we need to preserve the GFN of a non-present or reserved
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* SPTE when we usurp the upper five bits of the physical address space to
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* defend against L1TF, e.g. for MMIO SPTEs. To preserve the GFN, we'll
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* shift bits of the GFN that overlap with shadow_nonpresent_or_rsvd_mask
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* left into the reserved bits, i.e. the GFN in the SPTE will be split into
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* high and low parts. This mask covers the lower bits of the GFN.
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*/
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static u64 __read_mostly shadow_nonpresent_or_rsvd_lower_gfn_mask;
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/*
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* The number of non-reserved physical address bits irrespective of features
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* that repurpose legal bits, e.g. MKTME.
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*/
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static u8 __read_mostly shadow_phys_bits;
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static void mmu_spte_set(u64 *sptep, u64 spte);
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static bool is_executable_pte(u64 spte);
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static union kvm_mmu_page_role
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kvm_mmu_calc_root_page_role(struct kvm_vcpu *vcpu);
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#define CREATE_TRACE_POINTS
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#include "mmutrace.h"
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void kvm_mmu_set_mmio_spte_mask(u64 mmio_mask, u64 mmio_value)
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{
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BUG_ON((mmio_mask & mmio_value) != mmio_value);
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WARN_ON(mmio_value & (shadow_nonpresent_or_rsvd_mask << shadow_nonpresent_or_rsvd_mask_len));
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WARN_ON(mmio_value & shadow_nonpresent_or_rsvd_lower_gfn_mask);
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shadow_mmio_value = mmio_value | SPTE_SPECIAL_MASK;
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shadow_mmio_mask = mmio_mask | SPTE_SPECIAL_MASK;
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}
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EXPORT_SYMBOL_GPL(kvm_mmu_set_mmio_spte_mask);
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static bool is_mmio_spte(u64 spte)
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{
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return (spte & shadow_mmio_mask) == shadow_mmio_value;
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}
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static inline bool sp_ad_disabled(struct kvm_mmu_page *sp)
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{
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return sp->role.ad_disabled;
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}
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static inline bool spte_ad_enabled(u64 spte)
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{
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MMU_WARN_ON(is_mmio_spte(spte));
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return !(spte & shadow_acc_track_value);
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}
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static bool is_nx_huge_page_enabled(void)
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{
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return READ_ONCE(nx_huge_pages);
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}
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static inline u64 spte_shadow_accessed_mask(u64 spte)
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{
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MMU_WARN_ON(is_mmio_spte(spte));
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return spte_ad_enabled(spte) ? shadow_accessed_mask : 0;
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}
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static inline u64 spte_shadow_dirty_mask(u64 spte)
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{
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MMU_WARN_ON(is_mmio_spte(spte));
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return spte_ad_enabled(spte) ? shadow_dirty_mask : 0;
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}
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static inline bool is_access_track_spte(u64 spte)
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{
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return !spte_ad_enabled(spte) && (spte & shadow_acc_track_mask) == 0;
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}
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/*
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* the low bit of the generation number is always presumed to be zero.
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* This disables mmio caching during memslot updates. The concept is
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* similar to a seqcount but instead of retrying the access we just punt
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* and ignore the cache.
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*
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* spte bits 3-11 are used as bits 1-9 of the generation number,
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* the bits 52-61 are used as bits 10-19 of the generation number.
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*/
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#define MMIO_SPTE_GEN_LOW_SHIFT 2
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#define MMIO_SPTE_GEN_HIGH_SHIFT 52
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#define MMIO_GEN_SHIFT 20
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#define MMIO_GEN_LOW_SHIFT 10
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#define MMIO_GEN_LOW_MASK ((1 << MMIO_GEN_LOW_SHIFT) - 2)
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#define MMIO_GEN_MASK ((1 << MMIO_GEN_SHIFT) - 1)
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static u64 generation_mmio_spte_mask(unsigned int gen)
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{
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u64 mask;
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WARN_ON(gen & ~MMIO_GEN_MASK);
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mask = (gen & MMIO_GEN_LOW_MASK) << MMIO_SPTE_GEN_LOW_SHIFT;
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mask |= ((u64)gen >> MMIO_GEN_LOW_SHIFT) << MMIO_SPTE_GEN_HIGH_SHIFT;
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return mask;
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}
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static unsigned int get_mmio_spte_generation(u64 spte)
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{
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unsigned int gen;
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spte &= ~shadow_mmio_mask;
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gen = (spte >> MMIO_SPTE_GEN_LOW_SHIFT) & MMIO_GEN_LOW_MASK;
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gen |= (spte >> MMIO_SPTE_GEN_HIGH_SHIFT) << MMIO_GEN_LOW_SHIFT;
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return gen;
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}
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static unsigned int kvm_current_mmio_generation(struct kvm_vcpu *vcpu)
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{
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return kvm_vcpu_memslots(vcpu)->generation & MMIO_GEN_MASK;
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}
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static void mark_mmio_spte(struct kvm_vcpu *vcpu, u64 *sptep, u64 gfn,
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unsigned access)
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{
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unsigned int gen = kvm_current_mmio_generation(vcpu);
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u64 mask = generation_mmio_spte_mask(gen);
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u64 gpa = gfn << PAGE_SHIFT;
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access &= ACC_WRITE_MASK | ACC_USER_MASK;
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mask |= shadow_mmio_value | access;
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mask |= gpa | shadow_nonpresent_or_rsvd_mask;
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mask |= (gpa & shadow_nonpresent_or_rsvd_mask)
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<< shadow_nonpresent_or_rsvd_mask_len;
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trace_mark_mmio_spte(sptep, gfn, access, gen);
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mmu_spte_set(sptep, mask);
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}
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static gfn_t get_mmio_spte_gfn(u64 spte)
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{
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u64 gpa = spte & shadow_nonpresent_or_rsvd_lower_gfn_mask;
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gpa |= (spte >> shadow_nonpresent_or_rsvd_mask_len)
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& shadow_nonpresent_or_rsvd_mask;
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return gpa >> PAGE_SHIFT;
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}
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static unsigned get_mmio_spte_access(u64 spte)
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{
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u64 mask = generation_mmio_spte_mask(MMIO_GEN_MASK) | shadow_mmio_mask;
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return (spte & ~mask) & ~PAGE_MASK;
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}
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static bool set_mmio_spte(struct kvm_vcpu *vcpu, u64 *sptep, gfn_t gfn,
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kvm_pfn_t pfn, unsigned access)
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{
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if (unlikely(is_noslot_pfn(pfn))) {
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mark_mmio_spte(vcpu, sptep, gfn, access);
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return true;
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}
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return false;
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}
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static bool check_mmio_spte(struct kvm_vcpu *vcpu, u64 spte)
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{
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unsigned int kvm_gen, spte_gen;
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kvm_gen = kvm_current_mmio_generation(vcpu);
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spte_gen = get_mmio_spte_generation(spte);
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trace_check_mmio_spte(spte, kvm_gen, spte_gen);
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return likely(kvm_gen == spte_gen);
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}
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/*
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* Sets the shadow PTE masks used by the MMU.
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*
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* Assumptions:
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* - Setting either @accessed_mask or @dirty_mask requires setting both
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* - At least one of @accessed_mask or @acc_track_mask must be set
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*/
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void kvm_mmu_set_mask_ptes(u64 user_mask, u64 accessed_mask,
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u64 dirty_mask, u64 nx_mask, u64 x_mask, u64 p_mask,
|
|
u64 acc_track_mask, u64 me_mask)
|
|
{
|
|
BUG_ON(!dirty_mask != !accessed_mask);
|
|
BUG_ON(!accessed_mask && !acc_track_mask);
|
|
BUG_ON(acc_track_mask & shadow_acc_track_value);
|
|
|
|
shadow_user_mask = user_mask;
|
|
shadow_accessed_mask = accessed_mask;
|
|
shadow_dirty_mask = dirty_mask;
|
|
shadow_nx_mask = nx_mask;
|
|
shadow_x_mask = x_mask;
|
|
shadow_present_mask = p_mask;
|
|
shadow_acc_track_mask = acc_track_mask;
|
|
shadow_me_mask = me_mask;
|
|
}
|
|
EXPORT_SYMBOL_GPL(kvm_mmu_set_mask_ptes);
|
|
|
|
static u8 kvm_get_shadow_phys_bits(void)
|
|
{
|
|
/*
|
|
* boot_cpu_data.x86_phys_bits is reduced when MKTME is detected
|
|
* in CPU detection code, but MKTME treats those reduced bits as
|
|
* 'keyID' thus they are not reserved bits. Therefore for MKTME
|
|
* we should still return physical address bits reported by CPUID.
|
|
*/
|
|
if (!boot_cpu_has(X86_FEATURE_TME) ||
|
|
WARN_ON_ONCE(boot_cpu_data.extended_cpuid_level < 0x80000008))
|
|
return boot_cpu_data.x86_phys_bits;
|
|
|
|
return cpuid_eax(0x80000008) & 0xff;
|
|
}
|
|
|
|
static void kvm_mmu_reset_all_pte_masks(void)
|
|
{
|
|
u8 low_phys_bits;
|
|
|
|
shadow_user_mask = 0;
|
|
shadow_accessed_mask = 0;
|
|
shadow_dirty_mask = 0;
|
|
shadow_nx_mask = 0;
|
|
shadow_x_mask = 0;
|
|
shadow_mmio_mask = 0;
|
|
shadow_present_mask = 0;
|
|
shadow_acc_track_mask = 0;
|
|
|
|
shadow_phys_bits = kvm_get_shadow_phys_bits();
|
|
|
|
/*
|
|
* If the CPU has 46 or less physical address bits, then set an
|
|
* appropriate mask to guard against L1TF attacks. Otherwise, it is
|
|
* assumed that the CPU is not vulnerable to L1TF.
|
|
*
|
|
* Some Intel CPUs address the L1 cache using more PA bits than are
|
|
* reported by CPUID. Use the PA width of the L1 cache when possible
|
|
* to achieve more effective mitigation, e.g. if system RAM overlaps
|
|
* the most significant bits of legal physical address space.
|
|
*/
|
|
shadow_nonpresent_or_rsvd_mask = 0;
|
|
low_phys_bits = boot_cpu_data.x86_phys_bits;
|
|
if (boot_cpu_has_bug(X86_BUG_L1TF) &&
|
|
!WARN_ON_ONCE(boot_cpu_data.x86_cache_bits >=
|
|
52 - shadow_nonpresent_or_rsvd_mask_len)) {
|
|
low_phys_bits = boot_cpu_data.x86_cache_bits
|
|
- shadow_nonpresent_or_rsvd_mask_len;
|
|
shadow_nonpresent_or_rsvd_mask =
|
|
rsvd_bits(low_phys_bits, boot_cpu_data.x86_cache_bits - 1);
|
|
}
|
|
|
|
shadow_nonpresent_or_rsvd_lower_gfn_mask =
|
|
GENMASK_ULL(low_phys_bits - 1, PAGE_SHIFT);
|
|
}
|
|
|
|
static int is_cpuid_PSE36(void)
|
|
{
|
|
return 1;
|
|
}
|
|
|
|
static int is_nx(struct kvm_vcpu *vcpu)
|
|
{
|
|
return vcpu->arch.efer & EFER_NX;
|
|
}
|
|
|
|
static int is_shadow_present_pte(u64 pte)
|
|
{
|
|
return (pte != 0) && !is_mmio_spte(pte);
|
|
}
|
|
|
|
static int is_large_pte(u64 pte)
|
|
{
|
|
return pte & PT_PAGE_SIZE_MASK;
|
|
}
|
|
|
|
static int is_last_spte(u64 pte, int level)
|
|
{
|
|
if (level == PT_PAGE_TABLE_LEVEL)
|
|
return 1;
|
|
if (is_large_pte(pte))
|
|
return 1;
|
|
return 0;
|
|
}
|
|
|
|
static bool is_executable_pte(u64 spte)
|
|
{
|
|
return (spte & (shadow_x_mask | shadow_nx_mask)) == shadow_x_mask;
|
|
}
|
|
|
|
static kvm_pfn_t spte_to_pfn(u64 pte)
|
|
{
|
|
return (pte & PT64_BASE_ADDR_MASK) >> PAGE_SHIFT;
|
|
}
|
|
|
|
static gfn_t pse36_gfn_delta(u32 gpte)
|
|
{
|
|
int shift = 32 - PT32_DIR_PSE36_SHIFT - PAGE_SHIFT;
|
|
|
|
return (gpte & PT32_DIR_PSE36_MASK) << shift;
|
|
}
|
|
|
|
#ifdef CONFIG_X86_64
|
|
static void __set_spte(u64 *sptep, u64 spte)
|
|
{
|
|
WRITE_ONCE(*sptep, spte);
|
|
}
|
|
|
|
static void __update_clear_spte_fast(u64 *sptep, u64 spte)
|
|
{
|
|
WRITE_ONCE(*sptep, spte);
|
|
}
|
|
|
|
static u64 __update_clear_spte_slow(u64 *sptep, u64 spte)
|
|
{
|
|
return xchg(sptep, spte);
|
|
}
|
|
|
|
static u64 __get_spte_lockless(u64 *sptep)
|
|
{
|
|
return READ_ONCE(*sptep);
|
|
}
|
|
#else
|
|
union split_spte {
|
|
struct {
|
|
u32 spte_low;
|
|
u32 spte_high;
|
|
};
|
|
u64 spte;
|
|
};
|
|
|
|
static void count_spte_clear(u64 *sptep, u64 spte)
|
|
{
|
|
struct kvm_mmu_page *sp = page_header(__pa(sptep));
|
|
|
|
if (is_shadow_present_pte(spte))
|
|
return;
|
|
|
|
/* Ensure the spte is completely set before we increase the count */
|
|
smp_wmb();
|
|
sp->clear_spte_count++;
|
|
}
|
|
|
|
static void __set_spte(u64 *sptep, u64 spte)
|
|
{
|
|
union split_spte *ssptep, sspte;
|
|
|
|
ssptep = (union split_spte *)sptep;
|
|
sspte = (union split_spte)spte;
|
|
|
|
ssptep->spte_high = sspte.spte_high;
|
|
|
|
/*
|
|
* If we map the spte from nonpresent to present, We should store
|
|
* the high bits firstly, then set present bit, so cpu can not
|
|
* fetch this spte while we are setting the spte.
|
|
*/
|
|
smp_wmb();
|
|
|
|
WRITE_ONCE(ssptep->spte_low, sspte.spte_low);
|
|
}
|
|
|
|
static void __update_clear_spte_fast(u64 *sptep, u64 spte)
|
|
{
|
|
union split_spte *ssptep, sspte;
|
|
|
|
ssptep = (union split_spte *)sptep;
|
|
sspte = (union split_spte)spte;
|
|
|
|
WRITE_ONCE(ssptep->spte_low, sspte.spte_low);
|
|
|
|
/*
|
|
* If we map the spte from present to nonpresent, we should clear
|
|
* present bit firstly to avoid vcpu fetch the old high bits.
|
|
*/
|
|
smp_wmb();
|
|
|
|
ssptep->spte_high = sspte.spte_high;
|
|
count_spte_clear(sptep, spte);
|
|
}
|
|
|
|
static u64 __update_clear_spte_slow(u64 *sptep, u64 spte)
|
|
{
|
|
union split_spte *ssptep, sspte, orig;
|
|
|
|
ssptep = (union split_spte *)sptep;
|
|
sspte = (union split_spte)spte;
|
|
|
|
/* xchg acts as a barrier before the setting of the high bits */
|
|
orig.spte_low = xchg(&ssptep->spte_low, sspte.spte_low);
|
|
orig.spte_high = ssptep->spte_high;
|
|
ssptep->spte_high = sspte.spte_high;
|
|
count_spte_clear(sptep, spte);
|
|
|
|
return orig.spte;
|
|
}
|
|
|
|
/*
|
|
* The idea using the light way get the spte on x86_32 guest is from
|
|
* gup_get_pte(arch/x86/mm/gup.c).
|
|
*
|
|
* An spte tlb flush may be pending, because kvm_set_pte_rmapp
|
|
* coalesces them and we are running out of the MMU lock. Therefore
|
|
* we need to protect against in-progress updates of the spte.
|
|
*
|
|
* Reading the spte while an update is in progress may get the old value
|
|
* for the high part of the spte. The race is fine for a present->non-present
|
|
* change (because the high part of the spte is ignored for non-present spte),
|
|
* but for a present->present change we must reread the spte.
|
|
*
|
|
* All such changes are done in two steps (present->non-present and
|
|
* non-present->present), hence it is enough to count the number of
|
|
* present->non-present updates: if it changed while reading the spte,
|
|
* we might have hit the race. This is done using clear_spte_count.
|
|
*/
|
|
static u64 __get_spte_lockless(u64 *sptep)
|
|
{
|
|
struct kvm_mmu_page *sp = page_header(__pa(sptep));
|
|
union split_spte spte, *orig = (union split_spte *)sptep;
|
|
int count;
|
|
|
|
retry:
|
|
count = sp->clear_spte_count;
|
|
smp_rmb();
|
|
|
|
spte.spte_low = orig->spte_low;
|
|
smp_rmb();
|
|
|
|
spte.spte_high = orig->spte_high;
|
|
smp_rmb();
|
|
|
|
if (unlikely(spte.spte_low != orig->spte_low ||
|
|
count != sp->clear_spte_count))
|
|
goto retry;
|
|
|
|
return spte.spte;
|
|
}
|
|
#endif
|
|
|
|
static bool spte_can_locklessly_be_made_writable(u64 spte)
|
|
{
|
|
return (spte & (SPTE_HOST_WRITEABLE | SPTE_MMU_WRITEABLE)) ==
|
|
(SPTE_HOST_WRITEABLE | SPTE_MMU_WRITEABLE);
|
|
}
|
|
|
|
static bool spte_has_volatile_bits(u64 spte)
|
|
{
|
|
if (!is_shadow_present_pte(spte))
|
|
return false;
|
|
|
|
/*
|
|
* Always atomically update spte if it can be updated
|
|
* out of mmu-lock, it can ensure dirty bit is not lost,
|
|
* also, it can help us to get a stable is_writable_pte()
|
|
* to ensure tlb flush is not missed.
|
|
*/
|
|
if (spte_can_locklessly_be_made_writable(spte) ||
|
|
is_access_track_spte(spte))
|
|
return true;
|
|
|
|
if (spte_ad_enabled(spte)) {
|
|
if ((spte & shadow_accessed_mask) == 0 ||
|
|
(is_writable_pte(spte) && (spte & shadow_dirty_mask) == 0))
|
|
return true;
|
|
}
|
|
|
|
return false;
|
|
}
|
|
|
|
static bool is_accessed_spte(u64 spte)
|
|
{
|
|
u64 accessed_mask = spte_shadow_accessed_mask(spte);
|
|
|
|
return accessed_mask ? spte & accessed_mask
|
|
: !is_access_track_spte(spte);
|
|
}
|
|
|
|
static bool is_dirty_spte(u64 spte)
|
|
{
|
|
u64 dirty_mask = spte_shadow_dirty_mask(spte);
|
|
|
|
return dirty_mask ? spte & dirty_mask : spte & PT_WRITABLE_MASK;
|
|
}
|
|
|
|
/* Rules for using mmu_spte_set:
|
|
* Set the sptep from nonpresent to present.
|
|
* Note: the sptep being assigned *must* be either not present
|
|
* or in a state where the hardware will not attempt to update
|
|
* the spte.
|
|
*/
|
|
static void mmu_spte_set(u64 *sptep, u64 new_spte)
|
|
{
|
|
WARN_ON(is_shadow_present_pte(*sptep));
|
|
__set_spte(sptep, new_spte);
|
|
}
|
|
|
|
/*
|
|
* Update the SPTE (excluding the PFN), but do not track changes in its
|
|
* accessed/dirty status.
|
|
*/
|
|
static u64 mmu_spte_update_no_track(u64 *sptep, u64 new_spte)
|
|
{
|
|
u64 old_spte = *sptep;
|
|
|
|
WARN_ON(!is_shadow_present_pte(new_spte));
|
|
|
|
if (!is_shadow_present_pte(old_spte)) {
|
|
mmu_spte_set(sptep, new_spte);
|
|
return old_spte;
|
|
}
|
|
|
|
if (!spte_has_volatile_bits(old_spte))
|
|
__update_clear_spte_fast(sptep, new_spte);
|
|
else
|
|
old_spte = __update_clear_spte_slow(sptep, new_spte);
|
|
|
|
WARN_ON(spte_to_pfn(old_spte) != spte_to_pfn(new_spte));
|
|
|
|
return old_spte;
|
|
}
|
|
|
|
/* Rules for using mmu_spte_update:
|
|
* Update the state bits, it means the mapped pfn is not changed.
|
|
*
|
|
* Whenever we overwrite a writable spte with a read-only one we
|
|
* should flush remote TLBs. Otherwise rmap_write_protect
|
|
* will find a read-only spte, even though the writable spte
|
|
* might be cached on a CPU's TLB, the return value indicates this
|
|
* case.
|
|
*
|
|
* Returns true if the TLB needs to be flushed
|
|
*/
|
|
static bool mmu_spte_update(u64 *sptep, u64 new_spte)
|
|
{
|
|
bool flush = false;
|
|
u64 old_spte = mmu_spte_update_no_track(sptep, new_spte);
|
|
|
|
if (!is_shadow_present_pte(old_spte))
|
|
return false;
|
|
|
|
/*
|
|
* For the spte updated out of mmu-lock is safe, since
|
|
* we always atomically update it, see the comments in
|
|
* spte_has_volatile_bits().
|
|
*/
|
|
if (spte_can_locklessly_be_made_writable(old_spte) &&
|
|
!is_writable_pte(new_spte))
|
|
flush = true;
|
|
|
|
/*
|
|
* Flush TLB when accessed/dirty states are changed in the page tables,
|
|
* to guarantee consistency between TLB and page tables.
|
|
*/
|
|
|
|
if (is_accessed_spte(old_spte) && !is_accessed_spte(new_spte)) {
|
|
flush = true;
|
|
kvm_set_pfn_accessed(spte_to_pfn(old_spte));
|
|
}
|
|
|
|
if (is_dirty_spte(old_spte) && !is_dirty_spte(new_spte)) {
|
|
flush = true;
|
|
kvm_set_pfn_dirty(spte_to_pfn(old_spte));
|
|
}
|
|
|
|
return flush;
|
|
}
|
|
|
|
/*
|
|
* Rules for using mmu_spte_clear_track_bits:
|
|
* It sets the sptep from present to nonpresent, and track the
|
|
* state bits, it is used to clear the last level sptep.
|
|
* Returns non-zero if the PTE was previously valid.
|
|
*/
|
|
static int mmu_spte_clear_track_bits(u64 *sptep)
|
|
{
|
|
kvm_pfn_t pfn;
|
|
u64 old_spte = *sptep;
|
|
|
|
if (!spte_has_volatile_bits(old_spte))
|
|
__update_clear_spte_fast(sptep, 0ull);
|
|
else
|
|
old_spte = __update_clear_spte_slow(sptep, 0ull);
|
|
|
|
if (!is_shadow_present_pte(old_spte))
|
|
return 0;
|
|
|
|
pfn = spte_to_pfn(old_spte);
|
|
|
|
/*
|
|
* KVM does not hold the refcount of the page used by
|
|
* kvm mmu, before reclaiming the page, we should
|
|
* unmap it from mmu first.
|
|
*/
|
|
WARN_ON(!kvm_is_reserved_pfn(pfn) && !page_count(pfn_to_page(pfn)));
|
|
|
|
if (is_accessed_spte(old_spte))
|
|
kvm_set_pfn_accessed(pfn);
|
|
|
|
if (is_dirty_spte(old_spte))
|
|
kvm_set_pfn_dirty(pfn);
|
|
|
|
return 1;
|
|
}
|
|
|
|
/*
|
|
* Rules for using mmu_spte_clear_no_track:
|
|
* Directly clear spte without caring the state bits of sptep,
|
|
* it is used to set the upper level spte.
|
|
*/
|
|
static void mmu_spte_clear_no_track(u64 *sptep)
|
|
{
|
|
__update_clear_spte_fast(sptep, 0ull);
|
|
}
|
|
|
|
static u64 mmu_spte_get_lockless(u64 *sptep)
|
|
{
|
|
return __get_spte_lockless(sptep);
|
|
}
|
|
|
|
static u64 mark_spte_for_access_track(u64 spte)
|
|
{
|
|
if (spte_ad_enabled(spte))
|
|
return spte & ~shadow_accessed_mask;
|
|
|
|
if (is_access_track_spte(spte))
|
|
return spte;
|
|
|
|
/*
|
|
* Making an Access Tracking PTE will result in removal of write access
|
|
* from the PTE. So, verify that we will be able to restore the write
|
|
* access in the fast page fault path later on.
|
|
*/
|
|
WARN_ONCE((spte & PT_WRITABLE_MASK) &&
|
|
!spte_can_locklessly_be_made_writable(spte),
|
|
"kvm: Writable SPTE is not locklessly dirty-trackable\n");
|
|
|
|
WARN_ONCE(spte & (shadow_acc_track_saved_bits_mask <<
|
|
shadow_acc_track_saved_bits_shift),
|
|
"kvm: Access Tracking saved bit locations are not zero\n");
|
|
|
|
spte |= (spte & shadow_acc_track_saved_bits_mask) <<
|
|
shadow_acc_track_saved_bits_shift;
|
|
spte &= ~shadow_acc_track_mask;
|
|
|
|
return spte;
|
|
}
|
|
|
|
/* Restore an acc-track PTE back to a regular PTE */
|
|
static u64 restore_acc_track_spte(u64 spte)
|
|
{
|
|
u64 new_spte = spte;
|
|
u64 saved_bits = (spte >> shadow_acc_track_saved_bits_shift)
|
|
& shadow_acc_track_saved_bits_mask;
|
|
|
|
WARN_ON_ONCE(spte_ad_enabled(spte));
|
|
WARN_ON_ONCE(!is_access_track_spte(spte));
|
|
|
|
new_spte &= ~shadow_acc_track_mask;
|
|
new_spte &= ~(shadow_acc_track_saved_bits_mask <<
|
|
shadow_acc_track_saved_bits_shift);
|
|
new_spte |= saved_bits;
|
|
|
|
return new_spte;
|
|
}
|
|
|
|
/* Returns the Accessed status of the PTE and resets it at the same time. */
|
|
static bool mmu_spte_age(u64 *sptep)
|
|
{
|
|
u64 spte = mmu_spte_get_lockless(sptep);
|
|
|
|
if (!is_accessed_spte(spte))
|
|
return false;
|
|
|
|
if (spte_ad_enabled(spte)) {
|
|
clear_bit((ffs(shadow_accessed_mask) - 1),
|
|
(unsigned long *)sptep);
|
|
} else {
|
|
/*
|
|
* Capture the dirty status of the page, so that it doesn't get
|
|
* lost when the SPTE is marked for access tracking.
|
|
*/
|
|
if (is_writable_pte(spte))
|
|
kvm_set_pfn_dirty(spte_to_pfn(spte));
|
|
|
|
spte = mark_spte_for_access_track(spte);
|
|
mmu_spte_update_no_track(sptep, spte);
|
|
}
|
|
|
|
return true;
|
|
}
|
|
|
|
static void walk_shadow_page_lockless_begin(struct kvm_vcpu *vcpu)
|
|
{
|
|
/*
|
|
* Prevent page table teardown by making any free-er wait during
|
|
* kvm_flush_remote_tlbs() IPI to all active vcpus.
|
|
*/
|
|
local_irq_disable();
|
|
|
|
/*
|
|
* Make sure a following spte read is not reordered ahead of the write
|
|
* to vcpu->mode.
|
|
*/
|
|
smp_store_mb(vcpu->mode, READING_SHADOW_PAGE_TABLES);
|
|
}
|
|
|
|
static void walk_shadow_page_lockless_end(struct kvm_vcpu *vcpu)
|
|
{
|
|
/*
|
|
* Make sure the write to vcpu->mode is not reordered in front of
|
|
* reads to sptes. If it does, kvm_mmu_commit_zap_page() can see us
|
|
* OUTSIDE_GUEST_MODE and proceed to free the shadow page table.
|
|
*/
|
|
smp_store_release(&vcpu->mode, OUTSIDE_GUEST_MODE);
|
|
local_irq_enable();
|
|
}
|
|
|
|
static int mmu_topup_memory_cache(struct kvm_mmu_memory_cache *cache,
|
|
struct kmem_cache *base_cache, int min)
|
|
{
|
|
void *obj;
|
|
|
|
if (cache->nobjs >= min)
|
|
return 0;
|
|
while (cache->nobjs < ARRAY_SIZE(cache->objects)) {
|
|
obj = kmem_cache_zalloc(base_cache, GFP_KERNEL);
|
|
if (!obj)
|
|
return -ENOMEM;
|
|
cache->objects[cache->nobjs++] = obj;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
static int mmu_memory_cache_free_objects(struct kvm_mmu_memory_cache *cache)
|
|
{
|
|
return cache->nobjs;
|
|
}
|
|
|
|
static void mmu_free_memory_cache(struct kvm_mmu_memory_cache *mc,
|
|
struct kmem_cache *cache)
|
|
{
|
|
while (mc->nobjs)
|
|
kmem_cache_free(cache, mc->objects[--mc->nobjs]);
|
|
}
|
|
|
|
static int mmu_topup_memory_cache_page(struct kvm_mmu_memory_cache *cache,
|
|
int min)
|
|
{
|
|
void *page;
|
|
|
|
if (cache->nobjs >= min)
|
|
return 0;
|
|
while (cache->nobjs < ARRAY_SIZE(cache->objects)) {
|
|
page = (void *)__get_free_page(GFP_KERNEL_ACCOUNT);
|
|
if (!page)
|
|
return -ENOMEM;
|
|
cache->objects[cache->nobjs++] = page;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
static void mmu_free_memory_cache_page(struct kvm_mmu_memory_cache *mc)
|
|
{
|
|
while (mc->nobjs)
|
|
free_page((unsigned long)mc->objects[--mc->nobjs]);
|
|
}
|
|
|
|
static int mmu_topup_memory_caches(struct kvm_vcpu *vcpu)
|
|
{
|
|
int r;
|
|
|
|
r = mmu_topup_memory_cache(&vcpu->arch.mmu_pte_list_desc_cache,
|
|
pte_list_desc_cache, 8 + PTE_PREFETCH_NUM);
|
|
if (r)
|
|
goto out;
|
|
r = mmu_topup_memory_cache_page(&vcpu->arch.mmu_page_cache, 8);
|
|
if (r)
|
|
goto out;
|
|
r = mmu_topup_memory_cache(&vcpu->arch.mmu_page_header_cache,
|
|
mmu_page_header_cache, 4);
|
|
out:
|
|
return r;
|
|
}
|
|
|
|
static void mmu_free_memory_caches(struct kvm_vcpu *vcpu)
|
|
{
|
|
mmu_free_memory_cache(&vcpu->arch.mmu_pte_list_desc_cache,
|
|
pte_list_desc_cache);
|
|
mmu_free_memory_cache_page(&vcpu->arch.mmu_page_cache);
|
|
mmu_free_memory_cache(&vcpu->arch.mmu_page_header_cache,
|
|
mmu_page_header_cache);
|
|
}
|
|
|
|
static void *mmu_memory_cache_alloc(struct kvm_mmu_memory_cache *mc)
|
|
{
|
|
void *p;
|
|
|
|
BUG_ON(!mc->nobjs);
|
|
p = mc->objects[--mc->nobjs];
|
|
return p;
|
|
}
|
|
|
|
static struct pte_list_desc *mmu_alloc_pte_list_desc(struct kvm_vcpu *vcpu)
|
|
{
|
|
return mmu_memory_cache_alloc(&vcpu->arch.mmu_pte_list_desc_cache);
|
|
}
|
|
|
|
static void mmu_free_pte_list_desc(struct pte_list_desc *pte_list_desc)
|
|
{
|
|
kmem_cache_free(pte_list_desc_cache, pte_list_desc);
|
|
}
|
|
|
|
static gfn_t kvm_mmu_page_get_gfn(struct kvm_mmu_page *sp, int index)
|
|
{
|
|
if (!sp->role.direct)
|
|
return sp->gfns[index];
|
|
|
|
return sp->gfn + (index << ((sp->role.level - 1) * PT64_LEVEL_BITS));
|
|
}
|
|
|
|
static void kvm_mmu_page_set_gfn(struct kvm_mmu_page *sp, int index, gfn_t gfn)
|
|
{
|
|
if (!sp->role.direct) {
|
|
sp->gfns[index] = gfn;
|
|
return;
|
|
}
|
|
|
|
if (WARN_ON(gfn != kvm_mmu_page_get_gfn(sp, index)))
|
|
pr_err_ratelimited("gfn mismatch under direct page %llx "
|
|
"(expected %llx, got %llx)\n",
|
|
sp->gfn,
|
|
kvm_mmu_page_get_gfn(sp, index), gfn);
|
|
}
|
|
|
|
/*
|
|
* Return the pointer to the large page information for a given gfn,
|
|
* handling slots that are not large page aligned.
|
|
*/
|
|
static struct kvm_lpage_info *lpage_info_slot(gfn_t gfn,
|
|
struct kvm_memory_slot *slot,
|
|
int level)
|
|
{
|
|
unsigned long idx;
|
|
|
|
idx = gfn_to_index(gfn, slot->base_gfn, level);
|
|
return &slot->arch.lpage_info[level - 2][idx];
|
|
}
|
|
|
|
static void update_gfn_disallow_lpage_count(struct kvm_memory_slot *slot,
|
|
gfn_t gfn, int count)
|
|
{
|
|
struct kvm_lpage_info *linfo;
|
|
int i;
|
|
|
|
for (i = PT_DIRECTORY_LEVEL; i <= PT_MAX_HUGEPAGE_LEVEL; ++i) {
|
|
linfo = lpage_info_slot(gfn, slot, i);
|
|
linfo->disallow_lpage += count;
|
|
WARN_ON(linfo->disallow_lpage < 0);
|
|
}
|
|
}
|
|
|
|
void kvm_mmu_gfn_disallow_lpage(struct kvm_memory_slot *slot, gfn_t gfn)
|
|
{
|
|
update_gfn_disallow_lpage_count(slot, gfn, 1);
|
|
}
|
|
|
|
void kvm_mmu_gfn_allow_lpage(struct kvm_memory_slot *slot, gfn_t gfn)
|
|
{
|
|
update_gfn_disallow_lpage_count(slot, gfn, -1);
|
|
}
|
|
|
|
static void account_shadowed(struct kvm *kvm, struct kvm_mmu_page *sp)
|
|
{
|
|
struct kvm_memslots *slots;
|
|
struct kvm_memory_slot *slot;
|
|
gfn_t gfn;
|
|
|
|
kvm->arch.indirect_shadow_pages++;
|
|
gfn = sp->gfn;
|
|
slots = kvm_memslots_for_spte_role(kvm, sp->role);
|
|
slot = __gfn_to_memslot(slots, gfn);
|
|
|
|
/* the non-leaf shadow pages are keeping readonly. */
|
|
if (sp->role.level > PT_PAGE_TABLE_LEVEL)
|
|
return kvm_slot_page_track_add_page(kvm, slot, gfn,
|
|
KVM_PAGE_TRACK_WRITE);
|
|
|
|
kvm_mmu_gfn_disallow_lpage(slot, gfn);
|
|
}
|
|
|
|
static void account_huge_nx_page(struct kvm *kvm, struct kvm_mmu_page *sp)
|
|
{
|
|
if (sp->lpage_disallowed)
|
|
return;
|
|
|
|
++kvm->stat.nx_lpage_splits;
|
|
list_add_tail(&sp->lpage_disallowed_link,
|
|
&kvm->arch.lpage_disallowed_mmu_pages);
|
|
sp->lpage_disallowed = true;
|
|
}
|
|
|
|
static void unaccount_shadowed(struct kvm *kvm, struct kvm_mmu_page *sp)
|
|
{
|
|
struct kvm_memslots *slots;
|
|
struct kvm_memory_slot *slot;
|
|
gfn_t gfn;
|
|
|
|
kvm->arch.indirect_shadow_pages--;
|
|
gfn = sp->gfn;
|
|
slots = kvm_memslots_for_spte_role(kvm, sp->role);
|
|
slot = __gfn_to_memslot(slots, gfn);
|
|
if (sp->role.level > PT_PAGE_TABLE_LEVEL)
|
|
return kvm_slot_page_track_remove_page(kvm, slot, gfn,
|
|
KVM_PAGE_TRACK_WRITE);
|
|
|
|
kvm_mmu_gfn_allow_lpage(slot, gfn);
|
|
}
|
|
|
|
static void unaccount_huge_nx_page(struct kvm *kvm, struct kvm_mmu_page *sp)
|
|
{
|
|
--kvm->stat.nx_lpage_splits;
|
|
sp->lpage_disallowed = false;
|
|
list_del(&sp->lpage_disallowed_link);
|
|
}
|
|
|
|
static bool __mmu_gfn_lpage_is_disallowed(gfn_t gfn, int level,
|
|
struct kvm_memory_slot *slot)
|
|
{
|
|
struct kvm_lpage_info *linfo;
|
|
|
|
if (slot) {
|
|
linfo = lpage_info_slot(gfn, slot, level);
|
|
return !!linfo->disallow_lpage;
|
|
}
|
|
|
|
return true;
|
|
}
|
|
|
|
static bool mmu_gfn_lpage_is_disallowed(struct kvm_vcpu *vcpu, gfn_t gfn,
|
|
int level)
|
|
{
|
|
struct kvm_memory_slot *slot;
|
|
|
|
slot = kvm_vcpu_gfn_to_memslot(vcpu, gfn);
|
|
return __mmu_gfn_lpage_is_disallowed(gfn, level, slot);
|
|
}
|
|
|
|
static int host_mapping_level(struct kvm_vcpu *vcpu, gfn_t gfn)
|
|
{
|
|
unsigned long page_size;
|
|
int i, ret = 0;
|
|
|
|
page_size = kvm_host_page_size(vcpu, gfn);
|
|
|
|
for (i = PT_PAGE_TABLE_LEVEL; i <= PT_MAX_HUGEPAGE_LEVEL; ++i) {
|
|
if (page_size >= KVM_HPAGE_SIZE(i))
|
|
ret = i;
|
|
else
|
|
break;
|
|
}
|
|
|
|
return ret;
|
|
}
|
|
|
|
static inline bool memslot_valid_for_gpte(struct kvm_memory_slot *slot,
|
|
bool no_dirty_log)
|
|
{
|
|
if (!slot || slot->flags & KVM_MEMSLOT_INVALID)
|
|
return false;
|
|
if (no_dirty_log && slot->dirty_bitmap)
|
|
return false;
|
|
|
|
return true;
|
|
}
|
|
|
|
static struct kvm_memory_slot *
|
|
gfn_to_memslot_dirty_bitmap(struct kvm_vcpu *vcpu, gfn_t gfn,
|
|
bool no_dirty_log)
|
|
{
|
|
struct kvm_memory_slot *slot;
|
|
|
|
slot = kvm_vcpu_gfn_to_memslot(vcpu, gfn);
|
|
if (!memslot_valid_for_gpte(slot, no_dirty_log))
|
|
slot = NULL;
|
|
|
|
return slot;
|
|
}
|
|
|
|
static int mapping_level(struct kvm_vcpu *vcpu, gfn_t large_gfn,
|
|
bool *force_pt_level)
|
|
{
|
|
int host_level, level, max_level;
|
|
struct kvm_memory_slot *slot;
|
|
|
|
if (unlikely(*force_pt_level))
|
|
return PT_PAGE_TABLE_LEVEL;
|
|
|
|
slot = kvm_vcpu_gfn_to_memslot(vcpu, large_gfn);
|
|
*force_pt_level = !memslot_valid_for_gpte(slot, true);
|
|
if (unlikely(*force_pt_level))
|
|
return PT_PAGE_TABLE_LEVEL;
|
|
|
|
host_level = host_mapping_level(vcpu, large_gfn);
|
|
|
|
if (host_level == PT_PAGE_TABLE_LEVEL)
|
|
return host_level;
|
|
|
|
max_level = min(kvm_x86_ops->get_lpage_level(), host_level);
|
|
|
|
for (level = PT_DIRECTORY_LEVEL; level <= max_level; ++level)
|
|
if (__mmu_gfn_lpage_is_disallowed(large_gfn, level, slot))
|
|
break;
|
|
|
|
return level - 1;
|
|
}
|
|
|
|
/*
|
|
* About rmap_head encoding:
|
|
*
|
|
* If the bit zero of rmap_head->val is clear, then it points to the only spte
|
|
* in this rmap chain. Otherwise, (rmap_head->val & ~1) points to a struct
|
|
* pte_list_desc containing more mappings.
|
|
*/
|
|
|
|
/*
|
|
* Returns the number of pointers in the rmap chain, not counting the new one.
|
|
*/
|
|
static int pte_list_add(struct kvm_vcpu *vcpu, u64 *spte,
|
|
struct kvm_rmap_head *rmap_head)
|
|
{
|
|
struct pte_list_desc *desc;
|
|
int i, count = 0;
|
|
|
|
if (!rmap_head->val) {
|
|
rmap_printk("pte_list_add: %p %llx 0->1\n", spte, *spte);
|
|
rmap_head->val = (unsigned long)spte;
|
|
} else if (!(rmap_head->val & 1)) {
|
|
rmap_printk("pte_list_add: %p %llx 1->many\n", spte, *spte);
|
|
desc = mmu_alloc_pte_list_desc(vcpu);
|
|
desc->sptes[0] = (u64 *)rmap_head->val;
|
|
desc->sptes[1] = spte;
|
|
rmap_head->val = (unsigned long)desc | 1;
|
|
++count;
|
|
} else {
|
|
rmap_printk("pte_list_add: %p %llx many->many\n", spte, *spte);
|
|
desc = (struct pte_list_desc *)(rmap_head->val & ~1ul);
|
|
while (desc->sptes[PTE_LIST_EXT-1] && desc->more) {
|
|
desc = desc->more;
|
|
count += PTE_LIST_EXT;
|
|
}
|
|
if (desc->sptes[PTE_LIST_EXT-1]) {
|
|
desc->more = mmu_alloc_pte_list_desc(vcpu);
|
|
desc = desc->more;
|
|
}
|
|
for (i = 0; desc->sptes[i]; ++i)
|
|
++count;
|
|
desc->sptes[i] = spte;
|
|
}
|
|
return count;
|
|
}
|
|
|
|
static void
|
|
pte_list_desc_remove_entry(struct kvm_rmap_head *rmap_head,
|
|
struct pte_list_desc *desc, int i,
|
|
struct pte_list_desc *prev_desc)
|
|
{
|
|
int j;
|
|
|
|
for (j = PTE_LIST_EXT - 1; !desc->sptes[j] && j > i; --j)
|
|
;
|
|
desc->sptes[i] = desc->sptes[j];
|
|
desc->sptes[j] = NULL;
|
|
if (j != 0)
|
|
return;
|
|
if (!prev_desc && !desc->more)
|
|
rmap_head->val = (unsigned long)desc->sptes[0];
|
|
else
|
|
if (prev_desc)
|
|
prev_desc->more = desc->more;
|
|
else
|
|
rmap_head->val = (unsigned long)desc->more | 1;
|
|
mmu_free_pte_list_desc(desc);
|
|
}
|
|
|
|
static void pte_list_remove(u64 *spte, struct kvm_rmap_head *rmap_head)
|
|
{
|
|
struct pte_list_desc *desc;
|
|
struct pte_list_desc *prev_desc;
|
|
int i;
|
|
|
|
if (!rmap_head->val) {
|
|
printk(KERN_ERR "pte_list_remove: %p 0->BUG\n", spte);
|
|
BUG();
|
|
} else if (!(rmap_head->val & 1)) {
|
|
rmap_printk("pte_list_remove: %p 1->0\n", spte);
|
|
if ((u64 *)rmap_head->val != spte) {
|
|
printk(KERN_ERR "pte_list_remove: %p 1->BUG\n", spte);
|
|
BUG();
|
|
}
|
|
rmap_head->val = 0;
|
|
} else {
|
|
rmap_printk("pte_list_remove: %p many->many\n", spte);
|
|
desc = (struct pte_list_desc *)(rmap_head->val & ~1ul);
|
|
prev_desc = NULL;
|
|
while (desc) {
|
|
for (i = 0; i < PTE_LIST_EXT && desc->sptes[i]; ++i) {
|
|
if (desc->sptes[i] == spte) {
|
|
pte_list_desc_remove_entry(rmap_head,
|
|
desc, i, prev_desc);
|
|
return;
|
|
}
|
|
}
|
|
prev_desc = desc;
|
|
desc = desc->more;
|
|
}
|
|
pr_err("pte_list_remove: %p many->many\n", spte);
|
|
BUG();
|
|
}
|
|
}
|
|
|
|
static struct kvm_rmap_head *__gfn_to_rmap(gfn_t gfn, int level,
|
|
struct kvm_memory_slot *slot)
|
|
{
|
|
unsigned long idx;
|
|
|
|
idx = gfn_to_index(gfn, slot->base_gfn, level);
|
|
return &slot->arch.rmap[level - PT_PAGE_TABLE_LEVEL][idx];
|
|
}
|
|
|
|
static struct kvm_rmap_head *gfn_to_rmap(struct kvm *kvm, gfn_t gfn,
|
|
struct kvm_mmu_page *sp)
|
|
{
|
|
struct kvm_memslots *slots;
|
|
struct kvm_memory_slot *slot;
|
|
|
|
slots = kvm_memslots_for_spte_role(kvm, sp->role);
|
|
slot = __gfn_to_memslot(slots, gfn);
|
|
return __gfn_to_rmap(gfn, sp->role.level, slot);
|
|
}
|
|
|
|
static bool rmap_can_add(struct kvm_vcpu *vcpu)
|
|
{
|
|
struct kvm_mmu_memory_cache *cache;
|
|
|
|
cache = &vcpu->arch.mmu_pte_list_desc_cache;
|
|
return mmu_memory_cache_free_objects(cache);
|
|
}
|
|
|
|
static int rmap_add(struct kvm_vcpu *vcpu, u64 *spte, gfn_t gfn)
|
|
{
|
|
struct kvm_mmu_page *sp;
|
|
struct kvm_rmap_head *rmap_head;
|
|
|
|
sp = page_header(__pa(spte));
|
|
kvm_mmu_page_set_gfn(sp, spte - sp->spt, gfn);
|
|
rmap_head = gfn_to_rmap(vcpu->kvm, gfn, sp);
|
|
return pte_list_add(vcpu, spte, rmap_head);
|
|
}
|
|
|
|
static void rmap_remove(struct kvm *kvm, u64 *spte)
|
|
{
|
|
struct kvm_mmu_page *sp;
|
|
gfn_t gfn;
|
|
struct kvm_rmap_head *rmap_head;
|
|
|
|
sp = page_header(__pa(spte));
|
|
gfn = kvm_mmu_page_get_gfn(sp, spte - sp->spt);
|
|
rmap_head = gfn_to_rmap(kvm, gfn, sp);
|
|
pte_list_remove(spte, rmap_head);
|
|
}
|
|
|
|
/*
|
|
* Used by the following functions to iterate through the sptes linked by a
|
|
* rmap. All fields are private and not assumed to be used outside.
|
|
*/
|
|
struct rmap_iterator {
|
|
/* private fields */
|
|
struct pte_list_desc *desc; /* holds the sptep if not NULL */
|
|
int pos; /* index of the sptep */
|
|
};
|
|
|
|
/*
|
|
* Iteration must be started by this function. This should also be used after
|
|
* removing/dropping sptes from the rmap link because in such cases the
|
|
* information in the itererator may not be valid.
|
|
*
|
|
* Returns sptep if found, NULL otherwise.
|
|
*/
|
|
static u64 *rmap_get_first(struct kvm_rmap_head *rmap_head,
|
|
struct rmap_iterator *iter)
|
|
{
|
|
u64 *sptep;
|
|
|
|
if (!rmap_head->val)
|
|
return NULL;
|
|
|
|
if (!(rmap_head->val & 1)) {
|
|
iter->desc = NULL;
|
|
sptep = (u64 *)rmap_head->val;
|
|
goto out;
|
|
}
|
|
|
|
iter->desc = (struct pte_list_desc *)(rmap_head->val & ~1ul);
|
|
iter->pos = 0;
|
|
sptep = iter->desc->sptes[iter->pos];
|
|
out:
|
|
BUG_ON(!is_shadow_present_pte(*sptep));
|
|
return sptep;
|
|
}
|
|
|
|
/*
|
|
* Must be used with a valid iterator: e.g. after rmap_get_first().
|
|
*
|
|
* Returns sptep if found, NULL otherwise.
|
|
*/
|
|
static u64 *rmap_get_next(struct rmap_iterator *iter)
|
|
{
|
|
u64 *sptep;
|
|
|
|
if (iter->desc) {
|
|
if (iter->pos < PTE_LIST_EXT - 1) {
|
|
++iter->pos;
|
|
sptep = iter->desc->sptes[iter->pos];
|
|
if (sptep)
|
|
goto out;
|
|
}
|
|
|
|
iter->desc = iter->desc->more;
|
|
|
|
if (iter->desc) {
|
|
iter->pos = 0;
|
|
/* desc->sptes[0] cannot be NULL */
|
|
sptep = iter->desc->sptes[iter->pos];
|
|
goto out;
|
|
}
|
|
}
|
|
|
|
return NULL;
|
|
out:
|
|
BUG_ON(!is_shadow_present_pte(*sptep));
|
|
return sptep;
|
|
}
|
|
|
|
#define for_each_rmap_spte(_rmap_head_, _iter_, _spte_) \
|
|
for (_spte_ = rmap_get_first(_rmap_head_, _iter_); \
|
|
_spte_; _spte_ = rmap_get_next(_iter_))
|
|
|
|
static void drop_spte(struct kvm *kvm, u64 *sptep)
|
|
{
|
|
if (mmu_spte_clear_track_bits(sptep))
|
|
rmap_remove(kvm, sptep);
|
|
}
|
|
|
|
|
|
static bool __drop_large_spte(struct kvm *kvm, u64 *sptep)
|
|
{
|
|
if (is_large_pte(*sptep)) {
|
|
WARN_ON(page_header(__pa(sptep))->role.level ==
|
|
PT_PAGE_TABLE_LEVEL);
|
|
drop_spte(kvm, sptep);
|
|
--kvm->stat.lpages;
|
|
return true;
|
|
}
|
|
|
|
return false;
|
|
}
|
|
|
|
static void drop_large_spte(struct kvm_vcpu *vcpu, u64 *sptep)
|
|
{
|
|
if (__drop_large_spte(vcpu->kvm, sptep))
|
|
kvm_flush_remote_tlbs(vcpu->kvm);
|
|
}
|
|
|
|
/*
|
|
* Write-protect on the specified @sptep, @pt_protect indicates whether
|
|
* spte write-protection is caused by protecting shadow page table.
|
|
*
|
|
* Note: write protection is difference between dirty logging and spte
|
|
* protection:
|
|
* - for dirty logging, the spte can be set to writable at anytime if
|
|
* its dirty bitmap is properly set.
|
|
* - for spte protection, the spte can be writable only after unsync-ing
|
|
* shadow page.
|
|
*
|
|
* Return true if tlb need be flushed.
|
|
*/
|
|
static bool spte_write_protect(u64 *sptep, bool pt_protect)
|
|
{
|
|
u64 spte = *sptep;
|
|
|
|
if (!is_writable_pte(spte) &&
|
|
!(pt_protect && spte_can_locklessly_be_made_writable(spte)))
|
|
return false;
|
|
|
|
rmap_printk("rmap_write_protect: spte %p %llx\n", sptep, *sptep);
|
|
|
|
if (pt_protect)
|
|
spte &= ~SPTE_MMU_WRITEABLE;
|
|
spte = spte & ~PT_WRITABLE_MASK;
|
|
|
|
return mmu_spte_update(sptep, spte);
|
|
}
|
|
|
|
static bool __rmap_write_protect(struct kvm *kvm,
|
|
struct kvm_rmap_head *rmap_head,
|
|
bool pt_protect)
|
|
{
|
|
u64 *sptep;
|
|
struct rmap_iterator iter;
|
|
bool flush = false;
|
|
|
|
for_each_rmap_spte(rmap_head, &iter, sptep)
|
|
flush |= spte_write_protect(sptep, pt_protect);
|
|
|
|
return flush;
|
|
}
|
|
|
|
static bool spte_clear_dirty(u64 *sptep)
|
|
{
|
|
u64 spte = *sptep;
|
|
|
|
rmap_printk("rmap_clear_dirty: spte %p %llx\n", sptep, *sptep);
|
|
|
|
spte &= ~shadow_dirty_mask;
|
|
|
|
return mmu_spte_update(sptep, spte);
|
|
}
|
|
|
|
static bool wrprot_ad_disabled_spte(u64 *sptep)
|
|
{
|
|
bool was_writable = test_and_clear_bit(PT_WRITABLE_SHIFT,
|
|
(unsigned long *)sptep);
|
|
if (was_writable)
|
|
kvm_set_pfn_dirty(spte_to_pfn(*sptep));
|
|
|
|
return was_writable;
|
|
}
|
|
|
|
/*
|
|
* Gets the GFN ready for another round of dirty logging by clearing the
|
|
* - D bit on ad-enabled SPTEs, and
|
|
* - W bit on ad-disabled SPTEs.
|
|
* Returns true iff any D or W bits were cleared.
|
|
*/
|
|
static bool __rmap_clear_dirty(struct kvm *kvm, struct kvm_rmap_head *rmap_head)
|
|
{
|
|
u64 *sptep;
|
|
struct rmap_iterator iter;
|
|
bool flush = false;
|
|
|
|
for_each_rmap_spte(rmap_head, &iter, sptep)
|
|
if (spte_ad_enabled(*sptep))
|
|
flush |= spte_clear_dirty(sptep);
|
|
else
|
|
flush |= wrprot_ad_disabled_spte(sptep);
|
|
|
|
return flush;
|
|
}
|
|
|
|
static bool spte_set_dirty(u64 *sptep)
|
|
{
|
|
u64 spte = *sptep;
|
|
|
|
rmap_printk("rmap_set_dirty: spte %p %llx\n", sptep, *sptep);
|
|
|
|
spte |= shadow_dirty_mask;
|
|
|
|
return mmu_spte_update(sptep, spte);
|
|
}
|
|
|
|
static bool __rmap_set_dirty(struct kvm *kvm, struct kvm_rmap_head *rmap_head)
|
|
{
|
|
u64 *sptep;
|
|
struct rmap_iterator iter;
|
|
bool flush = false;
|
|
|
|
for_each_rmap_spte(rmap_head, &iter, sptep)
|
|
if (spte_ad_enabled(*sptep))
|
|
flush |= spte_set_dirty(sptep);
|
|
|
|
return flush;
|
|
}
|
|
|
|
/**
|
|
* kvm_mmu_write_protect_pt_masked - write protect selected PT level pages
|
|
* @kvm: kvm instance
|
|
* @slot: slot to protect
|
|
* @gfn_offset: start of the BITS_PER_LONG pages we care about
|
|
* @mask: indicates which pages we should protect
|
|
*
|
|
* Used when we do not need to care about huge page mappings: e.g. during dirty
|
|
* logging we do not have any such mappings.
|
|
*/
|
|
static void kvm_mmu_write_protect_pt_masked(struct kvm *kvm,
|
|
struct kvm_memory_slot *slot,
|
|
gfn_t gfn_offset, unsigned long mask)
|
|
{
|
|
struct kvm_rmap_head *rmap_head;
|
|
|
|
while (mask) {
|
|
rmap_head = __gfn_to_rmap(slot->base_gfn + gfn_offset + __ffs(mask),
|
|
PT_PAGE_TABLE_LEVEL, slot);
|
|
__rmap_write_protect(kvm, rmap_head, false);
|
|
|
|
/* clear the first set bit */
|
|
mask &= mask - 1;
|
|
}
|
|
}
|
|
|
|
/**
|
|
* kvm_mmu_clear_dirty_pt_masked - clear MMU D-bit for PT level pages, or write
|
|
* protect the page if the D-bit isn't supported.
|
|
* @kvm: kvm instance
|
|
* @slot: slot to clear D-bit
|
|
* @gfn_offset: start of the BITS_PER_LONG pages we care about
|
|
* @mask: indicates which pages we should clear D-bit
|
|
*
|
|
* Used for PML to re-log the dirty GPAs after userspace querying dirty_bitmap.
|
|
*/
|
|
void kvm_mmu_clear_dirty_pt_masked(struct kvm *kvm,
|
|
struct kvm_memory_slot *slot,
|
|
gfn_t gfn_offset, unsigned long mask)
|
|
{
|
|
struct kvm_rmap_head *rmap_head;
|
|
|
|
while (mask) {
|
|
rmap_head = __gfn_to_rmap(slot->base_gfn + gfn_offset + __ffs(mask),
|
|
PT_PAGE_TABLE_LEVEL, slot);
|
|
__rmap_clear_dirty(kvm, rmap_head);
|
|
|
|
/* clear the first set bit */
|
|
mask &= mask - 1;
|
|
}
|
|
}
|
|
EXPORT_SYMBOL_GPL(kvm_mmu_clear_dirty_pt_masked);
|
|
|
|
/**
|
|
* kvm_arch_mmu_enable_log_dirty_pt_masked - enable dirty logging for selected
|
|
* PT level pages.
|
|
*
|
|
* It calls kvm_mmu_write_protect_pt_masked to write protect selected pages to
|
|
* enable dirty logging for them.
|
|
*
|
|
* Used when we do not need to care about huge page mappings: e.g. during dirty
|
|
* logging we do not have any such mappings.
|
|
*/
|
|
void kvm_arch_mmu_enable_log_dirty_pt_masked(struct kvm *kvm,
|
|
struct kvm_memory_slot *slot,
|
|
gfn_t gfn_offset, unsigned long mask)
|
|
{
|
|
if (kvm_x86_ops->enable_log_dirty_pt_masked)
|
|
kvm_x86_ops->enable_log_dirty_pt_masked(kvm, slot, gfn_offset,
|
|
mask);
|
|
else
|
|
kvm_mmu_write_protect_pt_masked(kvm, slot, gfn_offset, mask);
|
|
}
|
|
|
|
/**
|
|
* kvm_arch_write_log_dirty - emulate dirty page logging
|
|
* @vcpu: Guest mode vcpu
|
|
*
|
|
* Emulate arch specific page modification logging for the
|
|
* nested hypervisor
|
|
*/
|
|
int kvm_arch_write_log_dirty(struct kvm_vcpu *vcpu, gpa_t l2_gpa)
|
|
{
|
|
if (kvm_x86_ops->write_log_dirty)
|
|
return kvm_x86_ops->write_log_dirty(vcpu, l2_gpa);
|
|
|
|
return 0;
|
|
}
|
|
|
|
bool kvm_mmu_slot_gfn_write_protect(struct kvm *kvm,
|
|
struct kvm_memory_slot *slot, u64 gfn)
|
|
{
|
|
struct kvm_rmap_head *rmap_head;
|
|
int i;
|
|
bool write_protected = false;
|
|
|
|
for (i = PT_PAGE_TABLE_LEVEL; i <= PT_MAX_HUGEPAGE_LEVEL; ++i) {
|
|
rmap_head = __gfn_to_rmap(gfn, i, slot);
|
|
write_protected |= __rmap_write_protect(kvm, rmap_head, true);
|
|
}
|
|
|
|
return write_protected;
|
|
}
|
|
|
|
static bool rmap_write_protect(struct kvm_vcpu *vcpu, u64 gfn)
|
|
{
|
|
struct kvm_memory_slot *slot;
|
|
|
|
slot = kvm_vcpu_gfn_to_memslot(vcpu, gfn);
|
|
return kvm_mmu_slot_gfn_write_protect(vcpu->kvm, slot, gfn);
|
|
}
|
|
|
|
static bool kvm_zap_rmapp(struct kvm *kvm, struct kvm_rmap_head *rmap_head)
|
|
{
|
|
u64 *sptep;
|
|
struct rmap_iterator iter;
|
|
bool flush = false;
|
|
|
|
while ((sptep = rmap_get_first(rmap_head, &iter))) {
|
|
rmap_printk("%s: spte %p %llx.\n", __func__, sptep, *sptep);
|
|
|
|
drop_spte(kvm, sptep);
|
|
flush = true;
|
|
}
|
|
|
|
return flush;
|
|
}
|
|
|
|
static int kvm_unmap_rmapp(struct kvm *kvm, struct kvm_rmap_head *rmap_head,
|
|
struct kvm_memory_slot *slot, gfn_t gfn, int level,
|
|
unsigned long data)
|
|
{
|
|
return kvm_zap_rmapp(kvm, rmap_head);
|
|
}
|
|
|
|
static int kvm_set_pte_rmapp(struct kvm *kvm, struct kvm_rmap_head *rmap_head,
|
|
struct kvm_memory_slot *slot, gfn_t gfn, int level,
|
|
unsigned long data)
|
|
{
|
|
u64 *sptep;
|
|
struct rmap_iterator iter;
|
|
int need_flush = 0;
|
|
u64 new_spte;
|
|
pte_t *ptep = (pte_t *)data;
|
|
kvm_pfn_t new_pfn;
|
|
|
|
WARN_ON(pte_huge(*ptep));
|
|
new_pfn = pte_pfn(*ptep);
|
|
|
|
restart:
|
|
for_each_rmap_spte(rmap_head, &iter, sptep) {
|
|
rmap_printk("kvm_set_pte_rmapp: spte %p %llx gfn %llx (%d)\n",
|
|
sptep, *sptep, gfn, level);
|
|
|
|
need_flush = 1;
|
|
|
|
if (pte_write(*ptep)) {
|
|
drop_spte(kvm, sptep);
|
|
goto restart;
|
|
} else {
|
|
new_spte = *sptep & ~PT64_BASE_ADDR_MASK;
|
|
new_spte |= (u64)new_pfn << PAGE_SHIFT;
|
|
|
|
new_spte &= ~PT_WRITABLE_MASK;
|
|
new_spte &= ~SPTE_HOST_WRITEABLE;
|
|
|
|
new_spte = mark_spte_for_access_track(new_spte);
|
|
|
|
mmu_spte_clear_track_bits(sptep);
|
|
mmu_spte_set(sptep, new_spte);
|
|
}
|
|
}
|
|
|
|
if (need_flush)
|
|
kvm_flush_remote_tlbs(kvm);
|
|
|
|
return 0;
|
|
}
|
|
|
|
struct slot_rmap_walk_iterator {
|
|
/* input fields. */
|
|
struct kvm_memory_slot *slot;
|
|
gfn_t start_gfn;
|
|
gfn_t end_gfn;
|
|
int start_level;
|
|
int end_level;
|
|
|
|
/* output fields. */
|
|
gfn_t gfn;
|
|
struct kvm_rmap_head *rmap;
|
|
int level;
|
|
|
|
/* private field. */
|
|
struct kvm_rmap_head *end_rmap;
|
|
};
|
|
|
|
static void
|
|
rmap_walk_init_level(struct slot_rmap_walk_iterator *iterator, int level)
|
|
{
|
|
iterator->level = level;
|
|
iterator->gfn = iterator->start_gfn;
|
|
iterator->rmap = __gfn_to_rmap(iterator->gfn, level, iterator->slot);
|
|
iterator->end_rmap = __gfn_to_rmap(iterator->end_gfn, level,
|
|
iterator->slot);
|
|
}
|
|
|
|
static void
|
|
slot_rmap_walk_init(struct slot_rmap_walk_iterator *iterator,
|
|
struct kvm_memory_slot *slot, int start_level,
|
|
int end_level, gfn_t start_gfn, gfn_t end_gfn)
|
|
{
|
|
iterator->slot = slot;
|
|
iterator->start_level = start_level;
|
|
iterator->end_level = end_level;
|
|
iterator->start_gfn = start_gfn;
|
|
iterator->end_gfn = end_gfn;
|
|
|
|
rmap_walk_init_level(iterator, iterator->start_level);
|
|
}
|
|
|
|
static bool slot_rmap_walk_okay(struct slot_rmap_walk_iterator *iterator)
|
|
{
|
|
return !!iterator->rmap;
|
|
}
|
|
|
|
static void slot_rmap_walk_next(struct slot_rmap_walk_iterator *iterator)
|
|
{
|
|
if (++iterator->rmap <= iterator->end_rmap) {
|
|
iterator->gfn += (1UL << KVM_HPAGE_GFN_SHIFT(iterator->level));
|
|
return;
|
|
}
|
|
|
|
if (++iterator->level > iterator->end_level) {
|
|
iterator->rmap = NULL;
|
|
return;
|
|
}
|
|
|
|
rmap_walk_init_level(iterator, iterator->level);
|
|
}
|
|
|
|
#define for_each_slot_rmap_range(_slot_, _start_level_, _end_level_, \
|
|
_start_gfn, _end_gfn, _iter_) \
|
|
for (slot_rmap_walk_init(_iter_, _slot_, _start_level_, \
|
|
_end_level_, _start_gfn, _end_gfn); \
|
|
slot_rmap_walk_okay(_iter_); \
|
|
slot_rmap_walk_next(_iter_))
|
|
|
|
static int kvm_handle_hva_range(struct kvm *kvm,
|
|
unsigned long start,
|
|
unsigned long end,
|
|
unsigned long data,
|
|
int (*handler)(struct kvm *kvm,
|
|
struct kvm_rmap_head *rmap_head,
|
|
struct kvm_memory_slot *slot,
|
|
gfn_t gfn,
|
|
int level,
|
|
unsigned long data))
|
|
{
|
|
struct kvm_memslots *slots;
|
|
struct kvm_memory_slot *memslot;
|
|
struct slot_rmap_walk_iterator iterator;
|
|
int ret = 0;
|
|
int i;
|
|
|
|
for (i = 0; i < KVM_ADDRESS_SPACE_NUM; i++) {
|
|
slots = __kvm_memslots(kvm, i);
|
|
kvm_for_each_memslot(memslot, slots) {
|
|
unsigned long hva_start, hva_end;
|
|
gfn_t gfn_start, gfn_end;
|
|
|
|
hva_start = max(start, memslot->userspace_addr);
|
|
hva_end = min(end, memslot->userspace_addr +
|
|
(memslot->npages << PAGE_SHIFT));
|
|
if (hva_start >= hva_end)
|
|
continue;
|
|
/*
|
|
* {gfn(page) | page intersects with [hva_start, hva_end)} =
|
|
* {gfn_start, gfn_start+1, ..., gfn_end-1}.
|
|
*/
|
|
gfn_start = hva_to_gfn_memslot(hva_start, memslot);
|
|
gfn_end = hva_to_gfn_memslot(hva_end + PAGE_SIZE - 1, memslot);
|
|
|
|
for_each_slot_rmap_range(memslot, PT_PAGE_TABLE_LEVEL,
|
|
PT_MAX_HUGEPAGE_LEVEL,
|
|
gfn_start, gfn_end - 1,
|
|
&iterator)
|
|
ret |= handler(kvm, iterator.rmap, memslot,
|
|
iterator.gfn, iterator.level, data);
|
|
}
|
|
}
|
|
|
|
return ret;
|
|
}
|
|
|
|
static int kvm_handle_hva(struct kvm *kvm, unsigned long hva,
|
|
unsigned long data,
|
|
int (*handler)(struct kvm *kvm,
|
|
struct kvm_rmap_head *rmap_head,
|
|
struct kvm_memory_slot *slot,
|
|
gfn_t gfn, int level,
|
|
unsigned long data))
|
|
{
|
|
return kvm_handle_hva_range(kvm, hva, hva + 1, data, handler);
|
|
}
|
|
|
|
int kvm_unmap_hva_range(struct kvm *kvm, unsigned long start, unsigned long end,
|
|
bool blockable)
|
|
{
|
|
return kvm_handle_hva_range(kvm, start, end, 0, kvm_unmap_rmapp);
|
|
}
|
|
|
|
void kvm_set_spte_hva(struct kvm *kvm, unsigned long hva, pte_t pte)
|
|
{
|
|
kvm_handle_hva(kvm, hva, (unsigned long)&pte, kvm_set_pte_rmapp);
|
|
}
|
|
|
|
static int kvm_age_rmapp(struct kvm *kvm, struct kvm_rmap_head *rmap_head,
|
|
struct kvm_memory_slot *slot, gfn_t gfn, int level,
|
|
unsigned long data)
|
|
{
|
|
u64 *sptep;
|
|
struct rmap_iterator uninitialized_var(iter);
|
|
int young = 0;
|
|
|
|
for_each_rmap_spte(rmap_head, &iter, sptep)
|
|
young |= mmu_spte_age(sptep);
|
|
|
|
trace_kvm_age_page(gfn, level, slot, young);
|
|
return young;
|
|
}
|
|
|
|
static int kvm_test_age_rmapp(struct kvm *kvm, struct kvm_rmap_head *rmap_head,
|
|
struct kvm_memory_slot *slot, gfn_t gfn,
|
|
int level, unsigned long data)
|
|
{
|
|
u64 *sptep;
|
|
struct rmap_iterator iter;
|
|
|
|
for_each_rmap_spte(rmap_head, &iter, sptep)
|
|
if (is_accessed_spte(*sptep))
|
|
return 1;
|
|
return 0;
|
|
}
|
|
|
|
#define RMAP_RECYCLE_THRESHOLD 1000
|
|
|
|
static void rmap_recycle(struct kvm_vcpu *vcpu, u64 *spte, gfn_t gfn)
|
|
{
|
|
struct kvm_rmap_head *rmap_head;
|
|
struct kvm_mmu_page *sp;
|
|
|
|
sp = page_header(__pa(spte));
|
|
|
|
rmap_head = gfn_to_rmap(vcpu->kvm, gfn, sp);
|
|
|
|
kvm_unmap_rmapp(vcpu->kvm, rmap_head, NULL, gfn, sp->role.level, 0);
|
|
kvm_flush_remote_tlbs(vcpu->kvm);
|
|
}
|
|
|
|
int kvm_age_hva(struct kvm *kvm, unsigned long start, unsigned long end)
|
|
{
|
|
return kvm_handle_hva_range(kvm, start, end, 0, kvm_age_rmapp);
|
|
}
|
|
|
|
int kvm_test_age_hva(struct kvm *kvm, unsigned long hva)
|
|
{
|
|
return kvm_handle_hva(kvm, hva, 0, kvm_test_age_rmapp);
|
|
}
|
|
|
|
#ifdef MMU_DEBUG
|
|
static int is_empty_shadow_page(u64 *spt)
|
|
{
|
|
u64 *pos;
|
|
u64 *end;
|
|
|
|
for (pos = spt, end = pos + PAGE_SIZE / sizeof(u64); pos != end; pos++)
|
|
if (is_shadow_present_pte(*pos)) {
|
|
printk(KERN_ERR "%s: %p %llx\n", __func__,
|
|
pos, *pos);
|
|
return 0;
|
|
}
|
|
return 1;
|
|
}
|
|
#endif
|
|
|
|
/*
|
|
* This value is the sum of all of the kvm instances's
|
|
* kvm->arch.n_used_mmu_pages values. We need a global,
|
|
* aggregate version in order to make the slab shrinker
|
|
* faster
|
|
*/
|
|
static inline void kvm_mod_used_mmu_pages(struct kvm *kvm, unsigned long nr)
|
|
{
|
|
kvm->arch.n_used_mmu_pages += nr;
|
|
percpu_counter_add(&kvm_total_used_mmu_pages, nr);
|
|
}
|
|
|
|
static void kvm_mmu_free_page(struct kvm_mmu_page *sp)
|
|
{
|
|
MMU_WARN_ON(!is_empty_shadow_page(sp->spt));
|
|
hlist_del(&sp->hash_link);
|
|
list_del(&sp->link);
|
|
free_page((unsigned long)sp->spt);
|
|
if (!sp->role.direct)
|
|
free_page((unsigned long)sp->gfns);
|
|
kmem_cache_free(mmu_page_header_cache, sp);
|
|
}
|
|
|
|
static unsigned kvm_page_table_hashfn(gfn_t gfn)
|
|
{
|
|
return hash_64(gfn, KVM_MMU_HASH_SHIFT);
|
|
}
|
|
|
|
static void mmu_page_add_parent_pte(struct kvm_vcpu *vcpu,
|
|
struct kvm_mmu_page *sp, u64 *parent_pte)
|
|
{
|
|
if (!parent_pte)
|
|
return;
|
|
|
|
pte_list_add(vcpu, parent_pte, &sp->parent_ptes);
|
|
}
|
|
|
|
static void mmu_page_remove_parent_pte(struct kvm_mmu_page *sp,
|
|
u64 *parent_pte)
|
|
{
|
|
pte_list_remove(parent_pte, &sp->parent_ptes);
|
|
}
|
|
|
|
static void drop_parent_pte(struct kvm_mmu_page *sp,
|
|
u64 *parent_pte)
|
|
{
|
|
mmu_page_remove_parent_pte(sp, parent_pte);
|
|
mmu_spte_clear_no_track(parent_pte);
|
|
}
|
|
|
|
static struct kvm_mmu_page *kvm_mmu_alloc_page(struct kvm_vcpu *vcpu, int direct)
|
|
{
|
|
struct kvm_mmu_page *sp;
|
|
|
|
sp = mmu_memory_cache_alloc(&vcpu->arch.mmu_page_header_cache);
|
|
sp->spt = mmu_memory_cache_alloc(&vcpu->arch.mmu_page_cache);
|
|
if (!direct)
|
|
sp->gfns = mmu_memory_cache_alloc(&vcpu->arch.mmu_page_cache);
|
|
set_page_private(virt_to_page(sp->spt), (unsigned long)sp);
|
|
|
|
/*
|
|
* The active_mmu_pages list is the FIFO list, do not move the
|
|
* page until it is zapped. kvm_zap_obsolete_pages depends on
|
|
* this feature. See the comments in kvm_zap_obsolete_pages().
|
|
*/
|
|
list_add(&sp->link, &vcpu->kvm->arch.active_mmu_pages);
|
|
kvm_mod_used_mmu_pages(vcpu->kvm, +1);
|
|
return sp;
|
|
}
|
|
|
|
static void mark_unsync(u64 *spte);
|
|
static void kvm_mmu_mark_parents_unsync(struct kvm_mmu_page *sp)
|
|
{
|
|
u64 *sptep;
|
|
struct rmap_iterator iter;
|
|
|
|
for_each_rmap_spte(&sp->parent_ptes, &iter, sptep) {
|
|
mark_unsync(sptep);
|
|
}
|
|
}
|
|
|
|
static void mark_unsync(u64 *spte)
|
|
{
|
|
struct kvm_mmu_page *sp;
|
|
unsigned int index;
|
|
|
|
sp = page_header(__pa(spte));
|
|
index = spte - sp->spt;
|
|
if (__test_and_set_bit(index, sp->unsync_child_bitmap))
|
|
return;
|
|
if (sp->unsync_children++)
|
|
return;
|
|
kvm_mmu_mark_parents_unsync(sp);
|
|
}
|
|
|
|
static int nonpaging_sync_page(struct kvm_vcpu *vcpu,
|
|
struct kvm_mmu_page *sp)
|
|
{
|
|
return 0;
|
|
}
|
|
|
|
static void nonpaging_invlpg(struct kvm_vcpu *vcpu, gva_t gva, hpa_t root)
|
|
{
|
|
}
|
|
|
|
static void nonpaging_update_pte(struct kvm_vcpu *vcpu,
|
|
struct kvm_mmu_page *sp, u64 *spte,
|
|
const void *pte)
|
|
{
|
|
WARN_ON(1);
|
|
}
|
|
|
|
#define KVM_PAGE_ARRAY_NR 16
|
|
|
|
struct kvm_mmu_pages {
|
|
struct mmu_page_and_offset {
|
|
struct kvm_mmu_page *sp;
|
|
unsigned int idx;
|
|
} page[KVM_PAGE_ARRAY_NR];
|
|
unsigned int nr;
|
|
};
|
|
|
|
static int mmu_pages_add(struct kvm_mmu_pages *pvec, struct kvm_mmu_page *sp,
|
|
int idx)
|
|
{
|
|
int i;
|
|
|
|
if (sp->unsync)
|
|
for (i=0; i < pvec->nr; i++)
|
|
if (pvec->page[i].sp == sp)
|
|
return 0;
|
|
|
|
pvec->page[pvec->nr].sp = sp;
|
|
pvec->page[pvec->nr].idx = idx;
|
|
pvec->nr++;
|
|
return (pvec->nr == KVM_PAGE_ARRAY_NR);
|
|
}
|
|
|
|
static inline void clear_unsync_child_bit(struct kvm_mmu_page *sp, int idx)
|
|
{
|
|
--sp->unsync_children;
|
|
WARN_ON((int)sp->unsync_children < 0);
|
|
__clear_bit(idx, sp->unsync_child_bitmap);
|
|
}
|
|
|
|
static int __mmu_unsync_walk(struct kvm_mmu_page *sp,
|
|
struct kvm_mmu_pages *pvec)
|
|
{
|
|
int i, ret, nr_unsync_leaf = 0;
|
|
|
|
for_each_set_bit(i, sp->unsync_child_bitmap, 512) {
|
|
struct kvm_mmu_page *child;
|
|
u64 ent = sp->spt[i];
|
|
|
|
if (!is_shadow_present_pte(ent) || is_large_pte(ent)) {
|
|
clear_unsync_child_bit(sp, i);
|
|
continue;
|
|
}
|
|
|
|
child = page_header(ent & PT64_BASE_ADDR_MASK);
|
|
|
|
if (child->unsync_children) {
|
|
if (mmu_pages_add(pvec, child, i))
|
|
return -ENOSPC;
|
|
|
|
ret = __mmu_unsync_walk(child, pvec);
|
|
if (!ret) {
|
|
clear_unsync_child_bit(sp, i);
|
|
continue;
|
|
} else if (ret > 0) {
|
|
nr_unsync_leaf += ret;
|
|
} else
|
|
return ret;
|
|
} else if (child->unsync) {
|
|
nr_unsync_leaf++;
|
|
if (mmu_pages_add(pvec, child, i))
|
|
return -ENOSPC;
|
|
} else
|
|
clear_unsync_child_bit(sp, i);
|
|
}
|
|
|
|
return nr_unsync_leaf;
|
|
}
|
|
|
|
#define INVALID_INDEX (-1)
|
|
|
|
static int mmu_unsync_walk(struct kvm_mmu_page *sp,
|
|
struct kvm_mmu_pages *pvec)
|
|
{
|
|
pvec->nr = 0;
|
|
if (!sp->unsync_children)
|
|
return 0;
|
|
|
|
mmu_pages_add(pvec, sp, INVALID_INDEX);
|
|
return __mmu_unsync_walk(sp, pvec);
|
|
}
|
|
|
|
static void kvm_unlink_unsync_page(struct kvm *kvm, struct kvm_mmu_page *sp)
|
|
{
|
|
WARN_ON(!sp->unsync);
|
|
trace_kvm_mmu_sync_page(sp);
|
|
sp->unsync = 0;
|
|
--kvm->stat.mmu_unsync;
|
|
}
|
|
|
|
static int kvm_mmu_prepare_zap_page(struct kvm *kvm, struct kvm_mmu_page *sp,
|
|
struct list_head *invalid_list);
|
|
static void kvm_mmu_commit_zap_page(struct kvm *kvm,
|
|
struct list_head *invalid_list);
|
|
|
|
/*
|
|
* NOTE: we should pay more attention on the zapped-obsolete page
|
|
* (is_obsolete_sp(sp) && sp->role.invalid) when you do hash list walk
|
|
* since it has been deleted from active_mmu_pages but still can be found
|
|
* at hast list.
|
|
*
|
|
* for_each_valid_sp() has skipped that kind of pages.
|
|
*/
|
|
#define for_each_valid_sp(_kvm, _sp, _gfn) \
|
|
hlist_for_each_entry(_sp, \
|
|
&(_kvm)->arch.mmu_page_hash[kvm_page_table_hashfn(_gfn)], hash_link) \
|
|
if (is_obsolete_sp((_kvm), (_sp)) || (_sp)->role.invalid) { \
|
|
} else
|
|
|
|
#define for_each_gfn_indirect_valid_sp(_kvm, _sp, _gfn) \
|
|
for_each_valid_sp(_kvm, _sp, _gfn) \
|
|
if ((_sp)->gfn != (_gfn) || (_sp)->role.direct) {} else
|
|
|
|
/* @sp->gfn should be write-protected at the call site */
|
|
static bool __kvm_sync_page(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp,
|
|
struct list_head *invalid_list)
|
|
{
|
|
if (sp->role.cr4_pae != !!is_pae(vcpu)
|
|
|| vcpu->arch.mmu.sync_page(vcpu, sp) == 0) {
|
|
kvm_mmu_prepare_zap_page(vcpu->kvm, sp, invalid_list);
|
|
return false;
|
|
}
|
|
|
|
return true;
|
|
}
|
|
|
|
static void kvm_mmu_flush_or_zap(struct kvm_vcpu *vcpu,
|
|
struct list_head *invalid_list,
|
|
bool remote_flush, bool local_flush)
|
|
{
|
|
if (!list_empty(invalid_list)) {
|
|
kvm_mmu_commit_zap_page(vcpu->kvm, invalid_list);
|
|
return;
|
|
}
|
|
|
|
if (remote_flush)
|
|
kvm_flush_remote_tlbs(vcpu->kvm);
|
|
else if (local_flush)
|
|
kvm_make_request(KVM_REQ_TLB_FLUSH, vcpu);
|
|
}
|
|
|
|
#ifdef CONFIG_KVM_MMU_AUDIT
|
|
#include "mmu_audit.c"
|
|
#else
|
|
static void kvm_mmu_audit(struct kvm_vcpu *vcpu, int point) { }
|
|
static void mmu_audit_disable(void) { }
|
|
#endif
|
|
|
|
static bool is_obsolete_sp(struct kvm *kvm, struct kvm_mmu_page *sp)
|
|
{
|
|
return unlikely(sp->mmu_valid_gen != kvm->arch.mmu_valid_gen);
|
|
}
|
|
|
|
static bool kvm_sync_page(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp,
|
|
struct list_head *invalid_list)
|
|
{
|
|
kvm_unlink_unsync_page(vcpu->kvm, sp);
|
|
return __kvm_sync_page(vcpu, sp, invalid_list);
|
|
}
|
|
|
|
/* @gfn should be write-protected at the call site */
|
|
static bool kvm_sync_pages(struct kvm_vcpu *vcpu, gfn_t gfn,
|
|
struct list_head *invalid_list)
|
|
{
|
|
struct kvm_mmu_page *s;
|
|
bool ret = false;
|
|
|
|
for_each_gfn_indirect_valid_sp(vcpu->kvm, s, gfn) {
|
|
if (!s->unsync)
|
|
continue;
|
|
|
|
WARN_ON(s->role.level != PT_PAGE_TABLE_LEVEL);
|
|
ret |= kvm_sync_page(vcpu, s, invalid_list);
|
|
}
|
|
|
|
return ret;
|
|
}
|
|
|
|
struct mmu_page_path {
|
|
struct kvm_mmu_page *parent[PT64_ROOT_MAX_LEVEL];
|
|
unsigned int idx[PT64_ROOT_MAX_LEVEL];
|
|
};
|
|
|
|
#define for_each_sp(pvec, sp, parents, i) \
|
|
for (i = mmu_pages_first(&pvec, &parents); \
|
|
i < pvec.nr && ({ sp = pvec.page[i].sp; 1;}); \
|
|
i = mmu_pages_next(&pvec, &parents, i))
|
|
|
|
static int mmu_pages_next(struct kvm_mmu_pages *pvec,
|
|
struct mmu_page_path *parents,
|
|
int i)
|
|
{
|
|
int n;
|
|
|
|
for (n = i+1; n < pvec->nr; n++) {
|
|
struct kvm_mmu_page *sp = pvec->page[n].sp;
|
|
unsigned idx = pvec->page[n].idx;
|
|
int level = sp->role.level;
|
|
|
|
parents->idx[level-1] = idx;
|
|
if (level == PT_PAGE_TABLE_LEVEL)
|
|
break;
|
|
|
|
parents->parent[level-2] = sp;
|
|
}
|
|
|
|
return n;
|
|
}
|
|
|
|
static int mmu_pages_first(struct kvm_mmu_pages *pvec,
|
|
struct mmu_page_path *parents)
|
|
{
|
|
struct kvm_mmu_page *sp;
|
|
int level;
|
|
|
|
if (pvec->nr == 0)
|
|
return 0;
|
|
|
|
WARN_ON(pvec->page[0].idx != INVALID_INDEX);
|
|
|
|
sp = pvec->page[0].sp;
|
|
level = sp->role.level;
|
|
WARN_ON(level == PT_PAGE_TABLE_LEVEL);
|
|
|
|
parents->parent[level-2] = sp;
|
|
|
|
/* Also set up a sentinel. Further entries in pvec are all
|
|
* children of sp, so this element is never overwritten.
|
|
*/
|
|
parents->parent[level-1] = NULL;
|
|
return mmu_pages_next(pvec, parents, 0);
|
|
}
|
|
|
|
static void mmu_pages_clear_parents(struct mmu_page_path *parents)
|
|
{
|
|
struct kvm_mmu_page *sp;
|
|
unsigned int level = 0;
|
|
|
|
do {
|
|
unsigned int idx = parents->idx[level];
|
|
sp = parents->parent[level];
|
|
if (!sp)
|
|
return;
|
|
|
|
WARN_ON(idx == INVALID_INDEX);
|
|
clear_unsync_child_bit(sp, idx);
|
|
level++;
|
|
} while (!sp->unsync_children);
|
|
}
|
|
|
|
static void mmu_sync_children(struct kvm_vcpu *vcpu,
|
|
struct kvm_mmu_page *parent)
|
|
{
|
|
int i;
|
|
struct kvm_mmu_page *sp;
|
|
struct mmu_page_path parents;
|
|
struct kvm_mmu_pages pages;
|
|
LIST_HEAD(invalid_list);
|
|
bool flush = false;
|
|
|
|
while (mmu_unsync_walk(parent, &pages)) {
|
|
bool protected = false;
|
|
|
|
for_each_sp(pages, sp, parents, i)
|
|
protected |= rmap_write_protect(vcpu, sp->gfn);
|
|
|
|
if (protected) {
|
|
kvm_flush_remote_tlbs(vcpu->kvm);
|
|
flush = false;
|
|
}
|
|
|
|
for_each_sp(pages, sp, parents, i) {
|
|
flush |= kvm_sync_page(vcpu, sp, &invalid_list);
|
|
mmu_pages_clear_parents(&parents);
|
|
}
|
|
if (need_resched() || spin_needbreak(&vcpu->kvm->mmu_lock)) {
|
|
kvm_mmu_flush_or_zap(vcpu, &invalid_list, false, flush);
|
|
cond_resched_lock(&vcpu->kvm->mmu_lock);
|
|
flush = false;
|
|
}
|
|
}
|
|
|
|
kvm_mmu_flush_or_zap(vcpu, &invalid_list, false, flush);
|
|
}
|
|
|
|
static void __clear_sp_write_flooding_count(struct kvm_mmu_page *sp)
|
|
{
|
|
atomic_set(&sp->write_flooding_count, 0);
|
|
}
|
|
|
|
static void clear_sp_write_flooding_count(u64 *spte)
|
|
{
|
|
struct kvm_mmu_page *sp = page_header(__pa(spte));
|
|
|
|
__clear_sp_write_flooding_count(sp);
|
|
}
|
|
|
|
static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu,
|
|
gfn_t gfn,
|
|
gva_t gaddr,
|
|
unsigned level,
|
|
int direct,
|
|
unsigned access)
|
|
{
|
|
union kvm_mmu_page_role role;
|
|
unsigned quadrant;
|
|
struct kvm_mmu_page *sp;
|
|
bool need_sync = false;
|
|
bool flush = false;
|
|
int collisions = 0;
|
|
LIST_HEAD(invalid_list);
|
|
|
|
role = vcpu->arch.mmu.base_role;
|
|
role.level = level;
|
|
role.direct = direct;
|
|
if (role.direct)
|
|
role.cr4_pae = 0;
|
|
role.access = access;
|
|
if (!vcpu->arch.mmu.direct_map
|
|
&& vcpu->arch.mmu.root_level <= PT32_ROOT_LEVEL) {
|
|
quadrant = gaddr >> (PAGE_SHIFT + (PT64_PT_BITS * level));
|
|
quadrant &= (1 << ((PT32_PT_BITS - PT64_PT_BITS) * level)) - 1;
|
|
role.quadrant = quadrant;
|
|
}
|
|
for_each_valid_sp(vcpu->kvm, sp, gfn) {
|
|
if (sp->gfn != gfn) {
|
|
collisions++;
|
|
continue;
|
|
}
|
|
|
|
if (!need_sync && sp->unsync)
|
|
need_sync = true;
|
|
|
|
if (sp->role.word != role.word)
|
|
continue;
|
|
|
|
if (sp->unsync) {
|
|
/* The page is good, but __kvm_sync_page might still end
|
|
* up zapping it. If so, break in order to rebuild it.
|
|
*/
|
|
if (!__kvm_sync_page(vcpu, sp, &invalid_list))
|
|
break;
|
|
|
|
WARN_ON(!list_empty(&invalid_list));
|
|
kvm_make_request(KVM_REQ_TLB_FLUSH, vcpu);
|
|
}
|
|
|
|
if (sp->unsync_children)
|
|
kvm_make_request(KVM_REQ_MMU_SYNC, vcpu);
|
|
|
|
__clear_sp_write_flooding_count(sp);
|
|
trace_kvm_mmu_get_page(sp, false);
|
|
goto out;
|
|
}
|
|
|
|
++vcpu->kvm->stat.mmu_cache_miss;
|
|
|
|
sp = kvm_mmu_alloc_page(vcpu, direct);
|
|
|
|
sp->gfn = gfn;
|
|
sp->role = role;
|
|
hlist_add_head(&sp->hash_link,
|
|
&vcpu->kvm->arch.mmu_page_hash[kvm_page_table_hashfn(gfn)]);
|
|
if (!direct) {
|
|
/*
|
|
* we should do write protection before syncing pages
|
|
* otherwise the content of the synced shadow page may
|
|
* be inconsistent with guest page table.
|
|
*/
|
|
account_shadowed(vcpu->kvm, sp);
|
|
if (level == PT_PAGE_TABLE_LEVEL &&
|
|
rmap_write_protect(vcpu, gfn))
|
|
kvm_flush_remote_tlbs(vcpu->kvm);
|
|
|
|
if (level > PT_PAGE_TABLE_LEVEL && need_sync)
|
|
flush |= kvm_sync_pages(vcpu, gfn, &invalid_list);
|
|
}
|
|
sp->mmu_valid_gen = vcpu->kvm->arch.mmu_valid_gen;
|
|
clear_page(sp->spt);
|
|
trace_kvm_mmu_get_page(sp, true);
|
|
|
|
kvm_mmu_flush_or_zap(vcpu, &invalid_list, false, flush);
|
|
out:
|
|
if (collisions > vcpu->kvm->stat.max_mmu_page_hash_collisions)
|
|
vcpu->kvm->stat.max_mmu_page_hash_collisions = collisions;
|
|
return sp;
|
|
}
|
|
|
|
static void shadow_walk_init_using_root(struct kvm_shadow_walk_iterator *iterator,
|
|
struct kvm_vcpu *vcpu, hpa_t root,
|
|
u64 addr)
|
|
{
|
|
iterator->addr = addr;
|
|
iterator->shadow_addr = root;
|
|
iterator->level = vcpu->arch.mmu.shadow_root_level;
|
|
|
|
if (iterator->level == PT64_ROOT_4LEVEL &&
|
|
vcpu->arch.mmu.root_level < PT64_ROOT_4LEVEL &&
|
|
!vcpu->arch.mmu.direct_map)
|
|
--iterator->level;
|
|
|
|
if (iterator->level == PT32E_ROOT_LEVEL) {
|
|
/*
|
|
* prev_root is currently only used for 64-bit hosts. So only
|
|
* the active root_hpa is valid here.
|
|
*/
|
|
BUG_ON(root != vcpu->arch.mmu.root_hpa);
|
|
|
|
iterator->shadow_addr
|
|
= vcpu->arch.mmu.pae_root[(addr >> 30) & 3];
|
|
iterator->shadow_addr &= PT64_BASE_ADDR_MASK;
|
|
--iterator->level;
|
|
if (!iterator->shadow_addr)
|
|
iterator->level = 0;
|
|
}
|
|
}
|
|
|
|
static void shadow_walk_init(struct kvm_shadow_walk_iterator *iterator,
|
|
struct kvm_vcpu *vcpu, u64 addr)
|
|
{
|
|
shadow_walk_init_using_root(iterator, vcpu, vcpu->arch.mmu.root_hpa,
|
|
addr);
|
|
}
|
|
|
|
static bool shadow_walk_okay(struct kvm_shadow_walk_iterator *iterator)
|
|
{
|
|
if (iterator->level < PT_PAGE_TABLE_LEVEL)
|
|
return false;
|
|
|
|
iterator->index = SHADOW_PT_INDEX(iterator->addr, iterator->level);
|
|
iterator->sptep = ((u64 *)__va(iterator->shadow_addr)) + iterator->index;
|
|
return true;
|
|
}
|
|
|
|
static void __shadow_walk_next(struct kvm_shadow_walk_iterator *iterator,
|
|
u64 spte)
|
|
{
|
|
if (is_last_spte(spte, iterator->level)) {
|
|
iterator->level = 0;
|
|
return;
|
|
}
|
|
|
|
iterator->shadow_addr = spte & PT64_BASE_ADDR_MASK;
|
|
--iterator->level;
|
|
}
|
|
|
|
static void shadow_walk_next(struct kvm_shadow_walk_iterator *iterator)
|
|
{
|
|
__shadow_walk_next(iterator, *iterator->sptep);
|
|
}
|
|
|
|
static void link_shadow_page(struct kvm_vcpu *vcpu, u64 *sptep,
|
|
struct kvm_mmu_page *sp)
|
|
{
|
|
u64 spte;
|
|
|
|
BUILD_BUG_ON(VMX_EPT_WRITABLE_MASK != PT_WRITABLE_MASK);
|
|
|
|
spte = __pa(sp->spt) | shadow_present_mask | PT_WRITABLE_MASK |
|
|
shadow_user_mask | shadow_x_mask | shadow_me_mask;
|
|
|
|
if (sp_ad_disabled(sp))
|
|
spte |= shadow_acc_track_value;
|
|
else
|
|
spte |= shadow_accessed_mask;
|
|
|
|
mmu_spte_set(sptep, spte);
|
|
|
|
mmu_page_add_parent_pte(vcpu, sp, sptep);
|
|
|
|
if (sp->unsync_children || sp->unsync)
|
|
mark_unsync(sptep);
|
|
}
|
|
|
|
static void validate_direct_spte(struct kvm_vcpu *vcpu, u64 *sptep,
|
|
unsigned direct_access)
|
|
{
|
|
if (is_shadow_present_pte(*sptep) && !is_large_pte(*sptep)) {
|
|
struct kvm_mmu_page *child;
|
|
|
|
/*
|
|
* For the direct sp, if the guest pte's dirty bit
|
|
* changed form clean to dirty, it will corrupt the
|
|
* sp's access: allow writable in the read-only sp,
|
|
* so we should update the spte at this point to get
|
|
* a new sp with the correct access.
|
|
*/
|
|
child = page_header(*sptep & PT64_BASE_ADDR_MASK);
|
|
if (child->role.access == direct_access)
|
|
return;
|
|
|
|
drop_parent_pte(child, sptep);
|
|
kvm_flush_remote_tlbs(vcpu->kvm);
|
|
}
|
|
}
|
|
|
|
static bool mmu_page_zap_pte(struct kvm *kvm, struct kvm_mmu_page *sp,
|
|
u64 *spte)
|
|
{
|
|
u64 pte;
|
|
struct kvm_mmu_page *child;
|
|
|
|
pte = *spte;
|
|
if (is_shadow_present_pte(pte)) {
|
|
if (is_last_spte(pte, sp->role.level)) {
|
|
drop_spte(kvm, spte);
|
|
if (is_large_pte(pte))
|
|
--kvm->stat.lpages;
|
|
} else {
|
|
child = page_header(pte & PT64_BASE_ADDR_MASK);
|
|
drop_parent_pte(child, spte);
|
|
}
|
|
return true;
|
|
}
|
|
|
|
if (is_mmio_spte(pte))
|
|
mmu_spte_clear_no_track(spte);
|
|
|
|
return false;
|
|
}
|
|
|
|
static void kvm_mmu_page_unlink_children(struct kvm *kvm,
|
|
struct kvm_mmu_page *sp)
|
|
{
|
|
unsigned i;
|
|
|
|
for (i = 0; i < PT64_ENT_PER_PAGE; ++i)
|
|
mmu_page_zap_pte(kvm, sp, sp->spt + i);
|
|
}
|
|
|
|
static void kvm_mmu_unlink_parents(struct kvm *kvm, struct kvm_mmu_page *sp)
|
|
{
|
|
u64 *sptep;
|
|
struct rmap_iterator iter;
|
|
|
|
while ((sptep = rmap_get_first(&sp->parent_ptes, &iter)))
|
|
drop_parent_pte(sp, sptep);
|
|
}
|
|
|
|
static int mmu_zap_unsync_children(struct kvm *kvm,
|
|
struct kvm_mmu_page *parent,
|
|
struct list_head *invalid_list)
|
|
{
|
|
int i, zapped = 0;
|
|
struct mmu_page_path parents;
|
|
struct kvm_mmu_pages pages;
|
|
|
|
if (parent->role.level == PT_PAGE_TABLE_LEVEL)
|
|
return 0;
|
|
|
|
while (mmu_unsync_walk(parent, &pages)) {
|
|
struct kvm_mmu_page *sp;
|
|
|
|
for_each_sp(pages, sp, parents, i) {
|
|
kvm_mmu_prepare_zap_page(kvm, sp, invalid_list);
|
|
mmu_pages_clear_parents(&parents);
|
|
zapped++;
|
|
}
|
|
}
|
|
|
|
return zapped;
|
|
}
|
|
|
|
static int kvm_mmu_prepare_zap_page(struct kvm *kvm, struct kvm_mmu_page *sp,
|
|
struct list_head *invalid_list)
|
|
{
|
|
int ret;
|
|
|
|
trace_kvm_mmu_prepare_zap_page(sp);
|
|
++kvm->stat.mmu_shadow_zapped;
|
|
ret = mmu_zap_unsync_children(kvm, sp, invalid_list);
|
|
kvm_mmu_page_unlink_children(kvm, sp);
|
|
kvm_mmu_unlink_parents(kvm, sp);
|
|
|
|
if (!sp->role.invalid && !sp->role.direct)
|
|
unaccount_shadowed(kvm, sp);
|
|
|
|
if (sp->unsync)
|
|
kvm_unlink_unsync_page(kvm, sp);
|
|
if (!sp->root_count) {
|
|
/* Count self */
|
|
ret++;
|
|
list_move(&sp->link, invalid_list);
|
|
kvm_mod_used_mmu_pages(kvm, -1);
|
|
} else {
|
|
list_move(&sp->link, &kvm->arch.active_mmu_pages);
|
|
|
|
/*
|
|
* The obsolete pages can not be used on any vcpus.
|
|
* See the comments in kvm_mmu_invalidate_zap_all_pages().
|
|
*/
|
|
if (!sp->role.invalid && !is_obsolete_sp(kvm, sp))
|
|
kvm_reload_remote_mmus(kvm);
|
|
}
|
|
|
|
if (sp->lpage_disallowed)
|
|
unaccount_huge_nx_page(kvm, sp);
|
|
|
|
sp->role.invalid = 1;
|
|
return ret;
|
|
}
|
|
|
|
static void kvm_mmu_commit_zap_page(struct kvm *kvm,
|
|
struct list_head *invalid_list)
|
|
{
|
|
struct kvm_mmu_page *sp, *nsp;
|
|
|
|
if (list_empty(invalid_list))
|
|
return;
|
|
|
|
/*
|
|
* We need to make sure everyone sees our modifications to
|
|
* the page tables and see changes to vcpu->mode here. The barrier
|
|
* in the kvm_flush_remote_tlbs() achieves this. This pairs
|
|
* with vcpu_enter_guest and walk_shadow_page_lockless_begin/end.
|
|
*
|
|
* In addition, kvm_flush_remote_tlbs waits for all vcpus to exit
|
|
* guest mode and/or lockless shadow page table walks.
|
|
*/
|
|
kvm_flush_remote_tlbs(kvm);
|
|
|
|
list_for_each_entry_safe(sp, nsp, invalid_list, link) {
|
|
WARN_ON(!sp->role.invalid || sp->root_count);
|
|
kvm_mmu_free_page(sp);
|
|
}
|
|
}
|
|
|
|
static bool prepare_zap_oldest_mmu_page(struct kvm *kvm,
|
|
struct list_head *invalid_list)
|
|
{
|
|
struct kvm_mmu_page *sp;
|
|
|
|
if (list_empty(&kvm->arch.active_mmu_pages))
|
|
return false;
|
|
|
|
sp = list_last_entry(&kvm->arch.active_mmu_pages,
|
|
struct kvm_mmu_page, link);
|
|
return kvm_mmu_prepare_zap_page(kvm, sp, invalid_list);
|
|
}
|
|
|
|
/*
|
|
* Changing the number of mmu pages allocated to the vm
|
|
* Note: if goal_nr_mmu_pages is too small, you will get dead lock
|
|
*/
|
|
void kvm_mmu_change_mmu_pages(struct kvm *kvm, unsigned long goal_nr_mmu_pages)
|
|
{
|
|
LIST_HEAD(invalid_list);
|
|
|
|
spin_lock(&kvm->mmu_lock);
|
|
|
|
if (kvm->arch.n_used_mmu_pages > goal_nr_mmu_pages) {
|
|
/* Need to free some mmu pages to achieve the goal. */
|
|
while (kvm->arch.n_used_mmu_pages > goal_nr_mmu_pages)
|
|
if (!prepare_zap_oldest_mmu_page(kvm, &invalid_list))
|
|
break;
|
|
|
|
kvm_mmu_commit_zap_page(kvm, &invalid_list);
|
|
goal_nr_mmu_pages = kvm->arch.n_used_mmu_pages;
|
|
}
|
|
|
|
kvm->arch.n_max_mmu_pages = goal_nr_mmu_pages;
|
|
|
|
spin_unlock(&kvm->mmu_lock);
|
|
}
|
|
|
|
int kvm_mmu_unprotect_page(struct kvm *kvm, gfn_t gfn)
|
|
{
|
|
struct kvm_mmu_page *sp;
|
|
LIST_HEAD(invalid_list);
|
|
int r;
|
|
|
|
pgprintk("%s: looking for gfn %llx\n", __func__, gfn);
|
|
r = 0;
|
|
spin_lock(&kvm->mmu_lock);
|
|
for_each_gfn_indirect_valid_sp(kvm, sp, gfn) {
|
|
pgprintk("%s: gfn %llx role %x\n", __func__, gfn,
|
|
sp->role.word);
|
|
r = 1;
|
|
kvm_mmu_prepare_zap_page(kvm, sp, &invalid_list);
|
|
}
|
|
kvm_mmu_commit_zap_page(kvm, &invalid_list);
|
|
spin_unlock(&kvm->mmu_lock);
|
|
|
|
return r;
|
|
}
|
|
EXPORT_SYMBOL_GPL(kvm_mmu_unprotect_page);
|
|
|
|
static void kvm_unsync_page(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp)
|
|
{
|
|
trace_kvm_mmu_unsync_page(sp);
|
|
++vcpu->kvm->stat.mmu_unsync;
|
|
sp->unsync = 1;
|
|
|
|
kvm_mmu_mark_parents_unsync(sp);
|
|
}
|
|
|
|
static bool mmu_need_write_protect(struct kvm_vcpu *vcpu, gfn_t gfn,
|
|
bool can_unsync)
|
|
{
|
|
struct kvm_mmu_page *sp;
|
|
|
|
if (kvm_page_track_is_active(vcpu, gfn, KVM_PAGE_TRACK_WRITE))
|
|
return true;
|
|
|
|
for_each_gfn_indirect_valid_sp(vcpu->kvm, sp, gfn) {
|
|
if (!can_unsync)
|
|
return true;
|
|
|
|
if (sp->unsync)
|
|
continue;
|
|
|
|
WARN_ON(sp->role.level != PT_PAGE_TABLE_LEVEL);
|
|
kvm_unsync_page(vcpu, sp);
|
|
}
|
|
|
|
/*
|
|
* We need to ensure that the marking of unsync pages is visible
|
|
* before the SPTE is updated to allow writes because
|
|
* kvm_mmu_sync_roots() checks the unsync flags without holding
|
|
* the MMU lock and so can race with this. If the SPTE was updated
|
|
* before the page had been marked as unsync-ed, something like the
|
|
* following could happen:
|
|
*
|
|
* CPU 1 CPU 2
|
|
* ---------------------------------------------------------------------
|
|
* 1.2 Host updates SPTE
|
|
* to be writable
|
|
* 2.1 Guest writes a GPTE for GVA X.
|
|
* (GPTE being in the guest page table shadowed
|
|
* by the SP from CPU 1.)
|
|
* This reads SPTE during the page table walk.
|
|
* Since SPTE.W is read as 1, there is no
|
|
* fault.
|
|
*
|
|
* 2.2 Guest issues TLB flush.
|
|
* That causes a VM Exit.
|
|
*
|
|
* 2.3 kvm_mmu_sync_pages() reads sp->unsync.
|
|
* Since it is false, so it just returns.
|
|
*
|
|
* 2.4 Guest accesses GVA X.
|
|
* Since the mapping in the SP was not updated,
|
|
* so the old mapping for GVA X incorrectly
|
|
* gets used.
|
|
* 1.1 Host marks SP
|
|
* as unsync
|
|
* (sp->unsync = true)
|
|
*
|
|
* The write barrier below ensures that 1.1 happens before 1.2 and thus
|
|
* the situation in 2.4 does not arise. The implicit barrier in 2.2
|
|
* pairs with this write barrier.
|
|
*/
|
|
smp_wmb();
|
|
|
|
return false;
|
|
}
|
|
|
|
static bool kvm_is_mmio_pfn(kvm_pfn_t pfn)
|
|
{
|
|
if (pfn_valid(pfn))
|
|
return !is_zero_pfn(pfn) && PageReserved(pfn_to_page(pfn)) &&
|
|
/*
|
|
* Some reserved pages, such as those from NVDIMM
|
|
* DAX devices, are not for MMIO, and can be mapped
|
|
* with cached memory type for better performance.
|
|
* However, the above check misconceives those pages
|
|
* as MMIO, and results in KVM mapping them with UC
|
|
* memory type, which would hurt the performance.
|
|
* Therefore, we check the host memory type in addition
|
|
* and only treat UC/UC-/WC pages as MMIO.
|
|
*/
|
|
(!pat_enabled() || pat_pfn_immune_to_uc_mtrr(pfn));
|
|
|
|
return true;
|
|
}
|
|
|
|
/* Bits which may be returned by set_spte() */
|
|
#define SET_SPTE_WRITE_PROTECTED_PT BIT(0)
|
|
#define SET_SPTE_NEED_REMOTE_TLB_FLUSH BIT(1)
|
|
|
|
static int set_spte(struct kvm_vcpu *vcpu, u64 *sptep,
|
|
unsigned pte_access, int level,
|
|
gfn_t gfn, kvm_pfn_t pfn, bool speculative,
|
|
bool can_unsync, bool host_writable)
|
|
{
|
|
u64 spte = 0;
|
|
int ret = 0;
|
|
struct kvm_mmu_page *sp;
|
|
|
|
if (set_mmio_spte(vcpu, sptep, gfn, pfn, pte_access))
|
|
return 0;
|
|
|
|
sp = page_header(__pa(sptep));
|
|
if (sp_ad_disabled(sp))
|
|
spte |= shadow_acc_track_value;
|
|
|
|
/*
|
|
* For the EPT case, shadow_present_mask is 0 if hardware
|
|
* supports exec-only page table entries. In that case,
|
|
* ACC_USER_MASK and shadow_user_mask are used to represent
|
|
* read access. See FNAME(gpte_access) in paging_tmpl.h.
|
|
*/
|
|
spte |= shadow_present_mask;
|
|
if (!speculative)
|
|
spte |= spte_shadow_accessed_mask(spte);
|
|
|
|
if (level > PT_PAGE_TABLE_LEVEL && (pte_access & ACC_EXEC_MASK) &&
|
|
is_nx_huge_page_enabled()) {
|
|
pte_access &= ~ACC_EXEC_MASK;
|
|
}
|
|
|
|
if (pte_access & ACC_EXEC_MASK)
|
|
spte |= shadow_x_mask;
|
|
else
|
|
spte |= shadow_nx_mask;
|
|
|
|
if (pte_access & ACC_USER_MASK)
|
|
spte |= shadow_user_mask;
|
|
|
|
if (level > PT_PAGE_TABLE_LEVEL)
|
|
spte |= PT_PAGE_SIZE_MASK;
|
|
if (tdp_enabled)
|
|
spte |= kvm_x86_ops->get_mt_mask(vcpu, gfn,
|
|
kvm_is_mmio_pfn(pfn));
|
|
|
|
if (host_writable)
|
|
spte |= SPTE_HOST_WRITEABLE;
|
|
else
|
|
pte_access &= ~ACC_WRITE_MASK;
|
|
|
|
if (!kvm_is_mmio_pfn(pfn))
|
|
spte |= shadow_me_mask;
|
|
|
|
spte |= (u64)pfn << PAGE_SHIFT;
|
|
|
|
if (pte_access & ACC_WRITE_MASK) {
|
|
|
|
/*
|
|
* Other vcpu creates new sp in the window between
|
|
* mapping_level() and acquiring mmu-lock. We can
|
|
* allow guest to retry the access, the mapping can
|
|
* be fixed if guest refault.
|
|
*/
|
|
if (level > PT_PAGE_TABLE_LEVEL &&
|
|
mmu_gfn_lpage_is_disallowed(vcpu, gfn, level))
|
|
goto done;
|
|
|
|
spte |= PT_WRITABLE_MASK | SPTE_MMU_WRITEABLE;
|
|
|
|
/*
|
|
* Optimization: for pte sync, if spte was writable the hash
|
|
* lookup is unnecessary (and expensive). Write protection
|
|
* is responsibility of mmu_get_page / kvm_sync_page.
|
|
* Same reasoning can be applied to dirty page accounting.
|
|
*/
|
|
if (!can_unsync && is_writable_pte(*sptep))
|
|
goto set_pte;
|
|
|
|
if (mmu_need_write_protect(vcpu, gfn, can_unsync)) {
|
|
pgprintk("%s: found shadow page for %llx, marking ro\n",
|
|
__func__, gfn);
|
|
ret |= SET_SPTE_WRITE_PROTECTED_PT;
|
|
pte_access &= ~ACC_WRITE_MASK;
|
|
spte &= ~(PT_WRITABLE_MASK | SPTE_MMU_WRITEABLE);
|
|
}
|
|
}
|
|
|
|
if (pte_access & ACC_WRITE_MASK) {
|
|
kvm_vcpu_mark_page_dirty(vcpu, gfn);
|
|
spte |= spte_shadow_dirty_mask(spte);
|
|
}
|
|
|
|
if (speculative)
|
|
spte = mark_spte_for_access_track(spte);
|
|
|
|
set_pte:
|
|
if (mmu_spte_update(sptep, spte))
|
|
ret |= SET_SPTE_NEED_REMOTE_TLB_FLUSH;
|
|
done:
|
|
return ret;
|
|
}
|
|
|
|
static int mmu_set_spte(struct kvm_vcpu *vcpu, u64 *sptep, unsigned pte_access,
|
|
int write_fault, int level, gfn_t gfn, kvm_pfn_t pfn,
|
|
bool speculative, bool host_writable)
|
|
{
|
|
int was_rmapped = 0;
|
|
int rmap_count;
|
|
int set_spte_ret;
|
|
int ret = RET_PF_RETRY;
|
|
bool flush = false;
|
|
|
|
pgprintk("%s: spte %llx write_fault %d gfn %llx\n", __func__,
|
|
*sptep, write_fault, gfn);
|
|
|
|
if (is_shadow_present_pte(*sptep)) {
|
|
/*
|
|
* If we overwrite a PTE page pointer with a 2MB PMD, unlink
|
|
* the parent of the now unreachable PTE.
|
|
*/
|
|
if (level > PT_PAGE_TABLE_LEVEL &&
|
|
!is_large_pte(*sptep)) {
|
|
struct kvm_mmu_page *child;
|
|
u64 pte = *sptep;
|
|
|
|
child = page_header(pte & PT64_BASE_ADDR_MASK);
|
|
drop_parent_pte(child, sptep);
|
|
flush = true;
|
|
} else if (pfn != spte_to_pfn(*sptep)) {
|
|
pgprintk("hfn old %llx new %llx\n",
|
|
spte_to_pfn(*sptep), pfn);
|
|
drop_spte(vcpu->kvm, sptep);
|
|
flush = true;
|
|
} else
|
|
was_rmapped = 1;
|
|
}
|
|
|
|
set_spte_ret = set_spte(vcpu, sptep, pte_access, level, gfn, pfn,
|
|
speculative, true, host_writable);
|
|
if (set_spte_ret & SET_SPTE_WRITE_PROTECTED_PT) {
|
|
if (write_fault)
|
|
ret = RET_PF_EMULATE;
|
|
kvm_make_request(KVM_REQ_TLB_FLUSH, vcpu);
|
|
}
|
|
if (set_spte_ret & SET_SPTE_NEED_REMOTE_TLB_FLUSH || flush)
|
|
kvm_flush_remote_tlbs(vcpu->kvm);
|
|
|
|
if (unlikely(is_mmio_spte(*sptep)))
|
|
ret = RET_PF_EMULATE;
|
|
|
|
pgprintk("%s: setting spte %llx\n", __func__, *sptep);
|
|
trace_kvm_mmu_set_spte(level, gfn, sptep);
|
|
if (!was_rmapped && is_large_pte(*sptep))
|
|
++vcpu->kvm->stat.lpages;
|
|
|
|
if (is_shadow_present_pte(*sptep)) {
|
|
if (!was_rmapped) {
|
|
rmap_count = rmap_add(vcpu, sptep, gfn);
|
|
if (rmap_count > RMAP_RECYCLE_THRESHOLD)
|
|
rmap_recycle(vcpu, sptep, gfn);
|
|
}
|
|
}
|
|
|
|
return ret;
|
|
}
|
|
|
|
static kvm_pfn_t pte_prefetch_gfn_to_pfn(struct kvm_vcpu *vcpu, gfn_t gfn,
|
|
bool no_dirty_log)
|
|
{
|
|
struct kvm_memory_slot *slot;
|
|
|
|
slot = gfn_to_memslot_dirty_bitmap(vcpu, gfn, no_dirty_log);
|
|
if (!slot)
|
|
return KVM_PFN_ERR_FAULT;
|
|
|
|
return gfn_to_pfn_memslot_atomic(slot, gfn);
|
|
}
|
|
|
|
static int direct_pte_prefetch_many(struct kvm_vcpu *vcpu,
|
|
struct kvm_mmu_page *sp,
|
|
u64 *start, u64 *end)
|
|
{
|
|
struct page *pages[PTE_PREFETCH_NUM];
|
|
struct kvm_memory_slot *slot;
|
|
unsigned access = sp->role.access;
|
|
int i, ret;
|
|
gfn_t gfn;
|
|
|
|
gfn = kvm_mmu_page_get_gfn(sp, start - sp->spt);
|
|
slot = gfn_to_memslot_dirty_bitmap(vcpu, gfn, access & ACC_WRITE_MASK);
|
|
if (!slot)
|
|
return -1;
|
|
|
|
ret = gfn_to_page_many_atomic(slot, gfn, pages, end - start);
|
|
if (ret <= 0)
|
|
return -1;
|
|
|
|
for (i = 0; i < ret; i++, gfn++, start++) {
|
|
mmu_set_spte(vcpu, start, access, 0, sp->role.level, gfn,
|
|
page_to_pfn(pages[i]), true, true);
|
|
put_page(pages[i]);
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
static void __direct_pte_prefetch(struct kvm_vcpu *vcpu,
|
|
struct kvm_mmu_page *sp, u64 *sptep)
|
|
{
|
|
u64 *spte, *start = NULL;
|
|
int i;
|
|
|
|
WARN_ON(!sp->role.direct);
|
|
|
|
i = (sptep - sp->spt) & ~(PTE_PREFETCH_NUM - 1);
|
|
spte = sp->spt + i;
|
|
|
|
for (i = 0; i < PTE_PREFETCH_NUM; i++, spte++) {
|
|
if (is_shadow_present_pte(*spte) || spte == sptep) {
|
|
if (!start)
|
|
continue;
|
|
if (direct_pte_prefetch_many(vcpu, sp, start, spte) < 0)
|
|
break;
|
|
start = NULL;
|
|
} else if (!start)
|
|
start = spte;
|
|
}
|
|
}
|
|
|
|
static void direct_pte_prefetch(struct kvm_vcpu *vcpu, u64 *sptep)
|
|
{
|
|
struct kvm_mmu_page *sp;
|
|
|
|
sp = page_header(__pa(sptep));
|
|
|
|
/*
|
|
* Without accessed bits, there's no way to distinguish between
|
|
* actually accessed translations and prefetched, so disable pte
|
|
* prefetch if accessed bits aren't available.
|
|
*/
|
|
if (sp_ad_disabled(sp))
|
|
return;
|
|
|
|
if (sp->role.level > PT_PAGE_TABLE_LEVEL)
|
|
return;
|
|
|
|
__direct_pte_prefetch(vcpu, sp, sptep);
|
|
}
|
|
|
|
static void disallowed_hugepage_adjust(struct kvm_shadow_walk_iterator it,
|
|
gfn_t gfn, kvm_pfn_t *pfnp, int *levelp)
|
|
{
|
|
int level = *levelp;
|
|
u64 spte = *it.sptep;
|
|
|
|
if (it.level == level && level > PT_PAGE_TABLE_LEVEL &&
|
|
is_nx_huge_page_enabled() &&
|
|
is_shadow_present_pte(spte) &&
|
|
!is_large_pte(spte)) {
|
|
/*
|
|
* A small SPTE exists for this pfn, but FNAME(fetch)
|
|
* and __direct_map would like to create a large PTE
|
|
* instead: just force them to go down another level,
|
|
* patching back for them into pfn the next 9 bits of
|
|
* the address.
|
|
*/
|
|
u64 page_mask = KVM_PAGES_PER_HPAGE(level) - KVM_PAGES_PER_HPAGE(level - 1);
|
|
*pfnp |= gfn & page_mask;
|
|
(*levelp)--;
|
|
}
|
|
}
|
|
|
|
static int __direct_map(struct kvm_vcpu *vcpu, gpa_t gpa, int write,
|
|
int map_writable, int level, kvm_pfn_t pfn,
|
|
bool prefault, bool lpage_disallowed)
|
|
{
|
|
struct kvm_shadow_walk_iterator it;
|
|
struct kvm_mmu_page *sp;
|
|
int ret;
|
|
gfn_t gfn = gpa >> PAGE_SHIFT;
|
|
gfn_t base_gfn = gfn;
|
|
|
|
if (!VALID_PAGE(vcpu->arch.mmu.root_hpa))
|
|
return RET_PF_RETRY;
|
|
|
|
trace_kvm_mmu_spte_requested(gpa, level, pfn);
|
|
for_each_shadow_entry(vcpu, gpa, it) {
|
|
/*
|
|
* We cannot overwrite existing page tables with an NX
|
|
* large page, as the leaf could be executable.
|
|
*/
|
|
disallowed_hugepage_adjust(it, gfn, &pfn, &level);
|
|
|
|
base_gfn = gfn & ~(KVM_PAGES_PER_HPAGE(it.level) - 1);
|
|
if (it.level == level)
|
|
break;
|
|
|
|
drop_large_spte(vcpu, it.sptep);
|
|
if (!is_shadow_present_pte(*it.sptep)) {
|
|
sp = kvm_mmu_get_page(vcpu, base_gfn, it.addr,
|
|
it.level - 1, true, ACC_ALL);
|
|
|
|
link_shadow_page(vcpu, it.sptep, sp);
|
|
if (lpage_disallowed)
|
|
account_huge_nx_page(vcpu->kvm, sp);
|
|
}
|
|
}
|
|
|
|
ret = mmu_set_spte(vcpu, it.sptep, ACC_ALL,
|
|
write, level, base_gfn, pfn, prefault,
|
|
map_writable);
|
|
direct_pte_prefetch(vcpu, it.sptep);
|
|
++vcpu->stat.pf_fixed;
|
|
return ret;
|
|
}
|
|
|
|
static void kvm_send_hwpoison_signal(unsigned long address, struct task_struct *tsk)
|
|
{
|
|
siginfo_t info;
|
|
|
|
clear_siginfo(&info);
|
|
info.si_signo = SIGBUS;
|
|
info.si_errno = 0;
|
|
info.si_code = BUS_MCEERR_AR;
|
|
info.si_addr = (void __user *)address;
|
|
info.si_addr_lsb = PAGE_SHIFT;
|
|
|
|
send_sig_info(SIGBUS, &info, tsk);
|
|
}
|
|
|
|
static int kvm_handle_bad_page(struct kvm_vcpu *vcpu, gfn_t gfn, kvm_pfn_t pfn)
|
|
{
|
|
/*
|
|
* Do not cache the mmio info caused by writing the readonly gfn
|
|
* into the spte otherwise read access on readonly gfn also can
|
|
* caused mmio page fault and treat it as mmio access.
|
|
*/
|
|
if (pfn == KVM_PFN_ERR_RO_FAULT)
|
|
return RET_PF_EMULATE;
|
|
|
|
if (pfn == KVM_PFN_ERR_HWPOISON) {
|
|
kvm_send_hwpoison_signal(kvm_vcpu_gfn_to_hva(vcpu, gfn), current);
|
|
return RET_PF_RETRY;
|
|
}
|
|
|
|
return -EFAULT;
|
|
}
|
|
|
|
static void transparent_hugepage_adjust(struct kvm_vcpu *vcpu,
|
|
gfn_t gfn, kvm_pfn_t *pfnp,
|
|
int *levelp)
|
|
{
|
|
kvm_pfn_t pfn = *pfnp;
|
|
int level = *levelp;
|
|
|
|
/*
|
|
* Check if it's a transparent hugepage. If this would be an
|
|
* hugetlbfs page, level wouldn't be set to
|
|
* PT_PAGE_TABLE_LEVEL and there would be no adjustment done
|
|
* here.
|
|
*/
|
|
if (!is_error_noslot_pfn(pfn) && !kvm_is_reserved_pfn(pfn) &&
|
|
!kvm_is_zone_device_pfn(pfn) && level == PT_PAGE_TABLE_LEVEL &&
|
|
PageTransCompoundMap(pfn_to_page(pfn)) &&
|
|
!mmu_gfn_lpage_is_disallowed(vcpu, gfn, PT_DIRECTORY_LEVEL)) {
|
|
unsigned long mask;
|
|
/*
|
|
* mmu_notifier_retry was successful and we hold the
|
|
* mmu_lock here, so the pmd can't become splitting
|
|
* from under us, and in turn
|
|
* __split_huge_page_refcount() can't run from under
|
|
* us and we can safely transfer the refcount from
|
|
* PG_tail to PG_head as we switch the pfn to tail to
|
|
* head.
|
|
*/
|
|
*levelp = level = PT_DIRECTORY_LEVEL;
|
|
mask = KVM_PAGES_PER_HPAGE(level) - 1;
|
|
VM_BUG_ON((gfn & mask) != (pfn & mask));
|
|
if (pfn & mask) {
|
|
kvm_release_pfn_clean(pfn);
|
|
pfn &= ~mask;
|
|
kvm_get_pfn(pfn);
|
|
*pfnp = pfn;
|
|
}
|
|
}
|
|
}
|
|
|
|
static bool handle_abnormal_pfn(struct kvm_vcpu *vcpu, gva_t gva, gfn_t gfn,
|
|
kvm_pfn_t pfn, unsigned access, int *ret_val)
|
|
{
|
|
/* The pfn is invalid, report the error! */
|
|
if (unlikely(is_error_pfn(pfn))) {
|
|
*ret_val = kvm_handle_bad_page(vcpu, gfn, pfn);
|
|
return true;
|
|
}
|
|
|
|
if (unlikely(is_noslot_pfn(pfn)))
|
|
vcpu_cache_mmio_info(vcpu, gva, gfn, access);
|
|
|
|
return false;
|
|
}
|
|
|
|
static bool page_fault_can_be_fast(u32 error_code)
|
|
{
|
|
/*
|
|
* Do not fix the mmio spte with invalid generation number which
|
|
* need to be updated by slow page fault path.
|
|
*/
|
|
if (unlikely(error_code & PFERR_RSVD_MASK))
|
|
return false;
|
|
|
|
/* See if the page fault is due to an NX violation */
|
|
if (unlikely(((error_code & (PFERR_FETCH_MASK | PFERR_PRESENT_MASK))
|
|
== (PFERR_FETCH_MASK | PFERR_PRESENT_MASK))))
|
|
return false;
|
|
|
|
/*
|
|
* #PF can be fast if:
|
|
* 1. The shadow page table entry is not present, which could mean that
|
|
* the fault is potentially caused by access tracking (if enabled).
|
|
* 2. The shadow page table entry is present and the fault
|
|
* is caused by write-protect, that means we just need change the W
|
|
* bit of the spte which can be done out of mmu-lock.
|
|
*
|
|
* However, if access tracking is disabled we know that a non-present
|
|
* page must be a genuine page fault where we have to create a new SPTE.
|
|
* So, if access tracking is disabled, we return true only for write
|
|
* accesses to a present page.
|
|
*/
|
|
|
|
return shadow_acc_track_mask != 0 ||
|
|
((error_code & (PFERR_WRITE_MASK | PFERR_PRESENT_MASK))
|
|
== (PFERR_WRITE_MASK | PFERR_PRESENT_MASK));
|
|
}
|
|
|
|
/*
|
|
* Returns true if the SPTE was fixed successfully. Otherwise,
|
|
* someone else modified the SPTE from its original value.
|
|
*/
|
|
static bool
|
|
fast_pf_fix_direct_spte(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp,
|
|
u64 *sptep, u64 old_spte, u64 new_spte)
|
|
{
|
|
gfn_t gfn;
|
|
|
|
WARN_ON(!sp->role.direct);
|
|
|
|
/*
|
|
* Theoretically we could also set dirty bit (and flush TLB) here in
|
|
* order to eliminate unnecessary PML logging. See comments in
|
|
* set_spte. But fast_page_fault is very unlikely to happen with PML
|
|
* enabled, so we do not do this. This might result in the same GPA
|
|
* to be logged in PML buffer again when the write really happens, and
|
|
* eventually to be called by mark_page_dirty twice. But it's also no
|
|
* harm. This also avoids the TLB flush needed after setting dirty bit
|
|
* so non-PML cases won't be impacted.
|
|
*
|
|
* Compare with set_spte where instead shadow_dirty_mask is set.
|
|
*/
|
|
if (cmpxchg64(sptep, old_spte, new_spte) != old_spte)
|
|
return false;
|
|
|
|
if (is_writable_pte(new_spte) && !is_writable_pte(old_spte)) {
|
|
/*
|
|
* The gfn of direct spte is stable since it is
|
|
* calculated by sp->gfn.
|
|
*/
|
|
gfn = kvm_mmu_page_get_gfn(sp, sptep - sp->spt);
|
|
kvm_vcpu_mark_page_dirty(vcpu, gfn);
|
|
}
|
|
|
|
return true;
|
|
}
|
|
|
|
static bool is_access_allowed(u32 fault_err_code, u64 spte)
|
|
{
|
|
if (fault_err_code & PFERR_FETCH_MASK)
|
|
return is_executable_pte(spte);
|
|
|
|
if (fault_err_code & PFERR_WRITE_MASK)
|
|
return is_writable_pte(spte);
|
|
|
|
/* Fault was on Read access */
|
|
return spte & PT_PRESENT_MASK;
|
|
}
|
|
|
|
/*
|
|
* Return value:
|
|
* - true: let the vcpu to access on the same address again.
|
|
* - false: let the real page fault path to fix it.
|
|
*/
|
|
static bool fast_page_fault(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa, int level,
|
|
u32 error_code)
|
|
{
|
|
struct kvm_shadow_walk_iterator iterator;
|
|
struct kvm_mmu_page *sp;
|
|
bool fault_handled = false;
|
|
u64 spte = 0ull;
|
|
uint retry_count = 0;
|
|
|
|
if (!VALID_PAGE(vcpu->arch.mmu.root_hpa))
|
|
return false;
|
|
|
|
if (!page_fault_can_be_fast(error_code))
|
|
return false;
|
|
|
|
walk_shadow_page_lockless_begin(vcpu);
|
|
|
|
do {
|
|
u64 new_spte;
|
|
|
|
for_each_shadow_entry_lockless(vcpu, cr2_or_gpa, iterator, spte)
|
|
if (!is_shadow_present_pte(spte) ||
|
|
iterator.level < level)
|
|
break;
|
|
|
|
sp = page_header(__pa(iterator.sptep));
|
|
if (!is_last_spte(spte, sp->role.level))
|
|
break;
|
|
|
|
/*
|
|
* Check whether the memory access that caused the fault would
|
|
* still cause it if it were to be performed right now. If not,
|
|
* then this is a spurious fault caused by TLB lazily flushed,
|
|
* or some other CPU has already fixed the PTE after the
|
|
* current CPU took the fault.
|
|
*
|
|
* Need not check the access of upper level table entries since
|
|
* they are always ACC_ALL.
|
|
*/
|
|
if (is_access_allowed(error_code, spte)) {
|
|
fault_handled = true;
|
|
break;
|
|
}
|
|
|
|
new_spte = spte;
|
|
|
|
if (is_access_track_spte(spte))
|
|
new_spte = restore_acc_track_spte(new_spte);
|
|
|
|
/*
|
|
* Currently, to simplify the code, write-protection can
|
|
* be removed in the fast path only if the SPTE was
|
|
* write-protected for dirty-logging or access tracking.
|
|
*/
|
|
if ((error_code & PFERR_WRITE_MASK) &&
|
|
spte_can_locklessly_be_made_writable(spte))
|
|
{
|
|
new_spte |= PT_WRITABLE_MASK;
|
|
|
|
/*
|
|
* Do not fix write-permission on the large spte. Since
|
|
* we only dirty the first page into the dirty-bitmap in
|
|
* fast_pf_fix_direct_spte(), other pages are missed
|
|
* if its slot has dirty logging enabled.
|
|
*
|
|
* Instead, we let the slow page fault path create a
|
|
* normal spte to fix the access.
|
|
*
|
|
* See the comments in kvm_arch_commit_memory_region().
|
|
*/
|
|
if (sp->role.level > PT_PAGE_TABLE_LEVEL)
|
|
break;
|
|
}
|
|
|
|
/* Verify that the fault can be handled in the fast path */
|
|
if (new_spte == spte ||
|
|
!is_access_allowed(error_code, new_spte))
|
|
break;
|
|
|
|
/*
|
|
* Currently, fast page fault only works for direct mapping
|
|
* since the gfn is not stable for indirect shadow page. See
|
|
* Documentation/virtual/kvm/locking.txt to get more detail.
|
|
*/
|
|
fault_handled = fast_pf_fix_direct_spte(vcpu, sp,
|
|
iterator.sptep, spte,
|
|
new_spte);
|
|
if (fault_handled)
|
|
break;
|
|
|
|
if (++retry_count > 4) {
|
|
printk_once(KERN_WARNING
|
|
"kvm: Fast #PF retrying more than 4 times.\n");
|
|
break;
|
|
}
|
|
|
|
} while (true);
|
|
|
|
trace_fast_page_fault(vcpu, cr2_or_gpa, error_code, iterator.sptep,
|
|
spte, fault_handled);
|
|
walk_shadow_page_lockless_end(vcpu);
|
|
|
|
return fault_handled;
|
|
}
|
|
|
|
static bool try_async_pf(struct kvm_vcpu *vcpu, bool prefault, gfn_t gfn,
|
|
gpa_t cr2_or_gpa, kvm_pfn_t *pfn, bool write,
|
|
bool *writable);
|
|
static int make_mmu_pages_available(struct kvm_vcpu *vcpu);
|
|
|
|
static int nonpaging_map(struct kvm_vcpu *vcpu, gpa_t gpa, u32 error_code,
|
|
gfn_t gfn, bool prefault)
|
|
{
|
|
int r;
|
|
int level;
|
|
bool force_pt_level;
|
|
kvm_pfn_t pfn;
|
|
unsigned long mmu_seq;
|
|
bool map_writable, write = error_code & PFERR_WRITE_MASK;
|
|
bool lpage_disallowed = (error_code & PFERR_FETCH_MASK) &&
|
|
is_nx_huge_page_enabled();
|
|
|
|
force_pt_level = lpage_disallowed;
|
|
level = mapping_level(vcpu, gfn, &force_pt_level);
|
|
if (likely(!force_pt_level)) {
|
|
/*
|
|
* This path builds a PAE pagetable - so we can map
|
|
* 2mb pages at maximum. Therefore check if the level
|
|
* is larger than that.
|
|
*/
|
|
if (level > PT_DIRECTORY_LEVEL)
|
|
level = PT_DIRECTORY_LEVEL;
|
|
|
|
gfn &= ~(KVM_PAGES_PER_HPAGE(level) - 1);
|
|
}
|
|
|
|
if (fast_page_fault(vcpu, gpa, level, error_code))
|
|
return RET_PF_RETRY;
|
|
|
|
mmu_seq = vcpu->kvm->mmu_notifier_seq;
|
|
smp_rmb();
|
|
|
|
if (try_async_pf(vcpu, prefault, gfn, gpa, &pfn, write, &map_writable))
|
|
return RET_PF_RETRY;
|
|
|
|
if (handle_abnormal_pfn(vcpu, gpa, gfn, pfn, ACC_ALL, &r))
|
|
return r;
|
|
|
|
r = RET_PF_RETRY;
|
|
spin_lock(&vcpu->kvm->mmu_lock);
|
|
if (mmu_notifier_retry(vcpu->kvm, mmu_seq))
|
|
goto out_unlock;
|
|
if (make_mmu_pages_available(vcpu) < 0)
|
|
goto out_unlock;
|
|
if (likely(!force_pt_level))
|
|
transparent_hugepage_adjust(vcpu, gfn, &pfn, &level);
|
|
r = __direct_map(vcpu, gpa, write, map_writable, level, pfn,
|
|
prefault, false);
|
|
out_unlock:
|
|
spin_unlock(&vcpu->kvm->mmu_lock);
|
|
kvm_release_pfn_clean(pfn);
|
|
return r;
|
|
}
|
|
|
|
static void mmu_free_root_page(struct kvm *kvm, hpa_t *root_hpa,
|
|
struct list_head *invalid_list)
|
|
{
|
|
struct kvm_mmu_page *sp;
|
|
|
|
if (!VALID_PAGE(*root_hpa))
|
|
return;
|
|
|
|
sp = page_header(*root_hpa & PT64_BASE_ADDR_MASK);
|
|
--sp->root_count;
|
|
if (!sp->root_count && sp->role.invalid)
|
|
kvm_mmu_prepare_zap_page(kvm, sp, invalid_list);
|
|
|
|
*root_hpa = INVALID_PAGE;
|
|
}
|
|
|
|
/* roots_to_free must be some combination of the KVM_MMU_ROOT_* flags */
|
|
void kvm_mmu_free_roots(struct kvm_vcpu *vcpu, ulong roots_to_free)
|
|
{
|
|
int i;
|
|
LIST_HEAD(invalid_list);
|
|
struct kvm_mmu *mmu = &vcpu->arch.mmu;
|
|
bool free_active_root = roots_to_free & KVM_MMU_ROOT_CURRENT;
|
|
|
|
BUILD_BUG_ON(KVM_MMU_NUM_PREV_ROOTS >= BITS_PER_LONG);
|
|
|
|
/* Before acquiring the MMU lock, see if we need to do any real work. */
|
|
if (!(free_active_root && VALID_PAGE(mmu->root_hpa))) {
|
|
for (i = 0; i < KVM_MMU_NUM_PREV_ROOTS; i++)
|
|
if ((roots_to_free & KVM_MMU_ROOT_PREVIOUS(i)) &&
|
|
VALID_PAGE(mmu->prev_roots[i].hpa))
|
|
break;
|
|
|
|
if (i == KVM_MMU_NUM_PREV_ROOTS)
|
|
return;
|
|
}
|
|
|
|
spin_lock(&vcpu->kvm->mmu_lock);
|
|
|
|
for (i = 0; i < KVM_MMU_NUM_PREV_ROOTS; i++)
|
|
if (roots_to_free & KVM_MMU_ROOT_PREVIOUS(i))
|
|
mmu_free_root_page(vcpu->kvm, &mmu->prev_roots[i].hpa,
|
|
&invalid_list);
|
|
|
|
if (free_active_root) {
|
|
if (mmu->shadow_root_level >= PT64_ROOT_4LEVEL &&
|
|
(mmu->root_level >= PT64_ROOT_4LEVEL || mmu->direct_map)) {
|
|
mmu_free_root_page(vcpu->kvm, &mmu->root_hpa,
|
|
&invalid_list);
|
|
} else {
|
|
for (i = 0; i < 4; ++i)
|
|
if (mmu->pae_root[i] != 0)
|
|
mmu_free_root_page(vcpu->kvm,
|
|
&mmu->pae_root[i],
|
|
&invalid_list);
|
|
mmu->root_hpa = INVALID_PAGE;
|
|
}
|
|
}
|
|
|
|
kvm_mmu_commit_zap_page(vcpu->kvm, &invalid_list);
|
|
spin_unlock(&vcpu->kvm->mmu_lock);
|
|
}
|
|
EXPORT_SYMBOL_GPL(kvm_mmu_free_roots);
|
|
|
|
static int mmu_check_root(struct kvm_vcpu *vcpu, gfn_t root_gfn)
|
|
{
|
|
int ret = 0;
|
|
|
|
if (!kvm_is_visible_gfn(vcpu->kvm, root_gfn)) {
|
|
kvm_make_request(KVM_REQ_TRIPLE_FAULT, vcpu);
|
|
ret = 1;
|
|
}
|
|
|
|
return ret;
|
|
}
|
|
|
|
static int mmu_alloc_direct_roots(struct kvm_vcpu *vcpu)
|
|
{
|
|
struct kvm_mmu_page *sp;
|
|
unsigned i;
|
|
|
|
if (vcpu->arch.mmu.shadow_root_level >= PT64_ROOT_4LEVEL) {
|
|
spin_lock(&vcpu->kvm->mmu_lock);
|
|
if(make_mmu_pages_available(vcpu) < 0) {
|
|
spin_unlock(&vcpu->kvm->mmu_lock);
|
|
return -ENOSPC;
|
|
}
|
|
sp = kvm_mmu_get_page(vcpu, 0, 0,
|
|
vcpu->arch.mmu.shadow_root_level, 1, ACC_ALL);
|
|
++sp->root_count;
|
|
spin_unlock(&vcpu->kvm->mmu_lock);
|
|
vcpu->arch.mmu.root_hpa = __pa(sp->spt);
|
|
} else if (vcpu->arch.mmu.shadow_root_level == PT32E_ROOT_LEVEL) {
|
|
for (i = 0; i < 4; ++i) {
|
|
hpa_t root = vcpu->arch.mmu.pae_root[i];
|
|
|
|
MMU_WARN_ON(VALID_PAGE(root));
|
|
spin_lock(&vcpu->kvm->mmu_lock);
|
|
if (make_mmu_pages_available(vcpu) < 0) {
|
|
spin_unlock(&vcpu->kvm->mmu_lock);
|
|
return -ENOSPC;
|
|
}
|
|
sp = kvm_mmu_get_page(vcpu, i << (30 - PAGE_SHIFT),
|
|
i << 30, PT32_ROOT_LEVEL, 1, ACC_ALL);
|
|
root = __pa(sp->spt);
|
|
++sp->root_count;
|
|
spin_unlock(&vcpu->kvm->mmu_lock);
|
|
vcpu->arch.mmu.pae_root[i] = root | PT_PRESENT_MASK;
|
|
}
|
|
vcpu->arch.mmu.root_hpa = __pa(vcpu->arch.mmu.pae_root);
|
|
} else
|
|
BUG();
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int mmu_alloc_shadow_roots(struct kvm_vcpu *vcpu)
|
|
{
|
|
struct kvm_mmu_page *sp;
|
|
u64 pdptr, pm_mask;
|
|
gfn_t root_gfn;
|
|
int i;
|
|
|
|
root_gfn = vcpu->arch.mmu.get_cr3(vcpu) >> PAGE_SHIFT;
|
|
|
|
if (mmu_check_root(vcpu, root_gfn))
|
|
return 1;
|
|
|
|
/*
|
|
* Do we shadow a long mode page table? If so we need to
|
|
* write-protect the guests page table root.
|
|
*/
|
|
if (vcpu->arch.mmu.root_level >= PT64_ROOT_4LEVEL) {
|
|
hpa_t root = vcpu->arch.mmu.root_hpa;
|
|
|
|
MMU_WARN_ON(VALID_PAGE(root));
|
|
|
|
spin_lock(&vcpu->kvm->mmu_lock);
|
|
if (make_mmu_pages_available(vcpu) < 0) {
|
|
spin_unlock(&vcpu->kvm->mmu_lock);
|
|
return -ENOSPC;
|
|
}
|
|
sp = kvm_mmu_get_page(vcpu, root_gfn, 0,
|
|
vcpu->arch.mmu.shadow_root_level, 0, ACC_ALL);
|
|
root = __pa(sp->spt);
|
|
++sp->root_count;
|
|
spin_unlock(&vcpu->kvm->mmu_lock);
|
|
vcpu->arch.mmu.root_hpa = root;
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* We shadow a 32 bit page table. This may be a legacy 2-level
|
|
* or a PAE 3-level page table. In either case we need to be aware that
|
|
* the shadow page table may be a PAE or a long mode page table.
|
|
*/
|
|
pm_mask = PT_PRESENT_MASK;
|
|
if (vcpu->arch.mmu.shadow_root_level == PT64_ROOT_4LEVEL)
|
|
pm_mask |= PT_ACCESSED_MASK | PT_WRITABLE_MASK | PT_USER_MASK;
|
|
|
|
for (i = 0; i < 4; ++i) {
|
|
hpa_t root = vcpu->arch.mmu.pae_root[i];
|
|
|
|
MMU_WARN_ON(VALID_PAGE(root));
|
|
if (vcpu->arch.mmu.root_level == PT32E_ROOT_LEVEL) {
|
|
pdptr = vcpu->arch.mmu.get_pdptr(vcpu, i);
|
|
if (!(pdptr & PT_PRESENT_MASK)) {
|
|
vcpu->arch.mmu.pae_root[i] = 0;
|
|
continue;
|
|
}
|
|
root_gfn = pdptr >> PAGE_SHIFT;
|
|
if (mmu_check_root(vcpu, root_gfn))
|
|
return 1;
|
|
}
|
|
spin_lock(&vcpu->kvm->mmu_lock);
|
|
if (make_mmu_pages_available(vcpu) < 0) {
|
|
spin_unlock(&vcpu->kvm->mmu_lock);
|
|
return -ENOSPC;
|
|
}
|
|
sp = kvm_mmu_get_page(vcpu, root_gfn, i << 30, PT32_ROOT_LEVEL,
|
|
0, ACC_ALL);
|
|
root = __pa(sp->spt);
|
|
++sp->root_count;
|
|
spin_unlock(&vcpu->kvm->mmu_lock);
|
|
|
|
vcpu->arch.mmu.pae_root[i] = root | pm_mask;
|
|
}
|
|
vcpu->arch.mmu.root_hpa = __pa(vcpu->arch.mmu.pae_root);
|
|
|
|
/*
|
|
* If we shadow a 32 bit page table with a long mode page
|
|
* table we enter this path.
|
|
*/
|
|
if (vcpu->arch.mmu.shadow_root_level == PT64_ROOT_4LEVEL) {
|
|
if (vcpu->arch.mmu.lm_root == NULL) {
|
|
/*
|
|
* The additional page necessary for this is only
|
|
* allocated on demand.
|
|
*/
|
|
|
|
u64 *lm_root;
|
|
|
|
lm_root = (void*)get_zeroed_page(GFP_KERNEL);
|
|
if (lm_root == NULL)
|
|
return 1;
|
|
|
|
lm_root[0] = __pa(vcpu->arch.mmu.pae_root) | pm_mask;
|
|
|
|
vcpu->arch.mmu.lm_root = lm_root;
|
|
}
|
|
|
|
vcpu->arch.mmu.root_hpa = __pa(vcpu->arch.mmu.lm_root);
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int mmu_alloc_roots(struct kvm_vcpu *vcpu)
|
|
{
|
|
if (vcpu->arch.mmu.direct_map)
|
|
return mmu_alloc_direct_roots(vcpu);
|
|
else
|
|
return mmu_alloc_shadow_roots(vcpu);
|
|
}
|
|
|
|
void kvm_mmu_sync_roots(struct kvm_vcpu *vcpu)
|
|
{
|
|
int i;
|
|
struct kvm_mmu_page *sp;
|
|
|
|
if (vcpu->arch.mmu.direct_map)
|
|
return;
|
|
|
|
if (!VALID_PAGE(vcpu->arch.mmu.root_hpa))
|
|
return;
|
|
|
|
vcpu_clear_mmio_info(vcpu, MMIO_GVA_ANY);
|
|
|
|
if (vcpu->arch.mmu.root_level >= PT64_ROOT_4LEVEL) {
|
|
hpa_t root = vcpu->arch.mmu.root_hpa;
|
|
|
|
sp = page_header(root);
|
|
|
|
/*
|
|
* Even if another CPU was marking the SP as unsync-ed
|
|
* simultaneously, any guest page table changes are not
|
|
* guaranteed to be visible anyway until this VCPU issues a TLB
|
|
* flush strictly after those changes are made. We only need to
|
|
* ensure that the other CPU sets these flags before any actual
|
|
* changes to the page tables are made. The comments in
|
|
* mmu_need_write_protect() describe what could go wrong if this
|
|
* requirement isn't satisfied.
|
|
*/
|
|
if (!smp_load_acquire(&sp->unsync) &&
|
|
!smp_load_acquire(&sp->unsync_children))
|
|
return;
|
|
|
|
spin_lock(&vcpu->kvm->mmu_lock);
|
|
kvm_mmu_audit(vcpu, AUDIT_PRE_SYNC);
|
|
|
|
mmu_sync_children(vcpu, sp);
|
|
|
|
kvm_mmu_audit(vcpu, AUDIT_POST_SYNC);
|
|
spin_unlock(&vcpu->kvm->mmu_lock);
|
|
return;
|
|
}
|
|
|
|
spin_lock(&vcpu->kvm->mmu_lock);
|
|
kvm_mmu_audit(vcpu, AUDIT_PRE_SYNC);
|
|
|
|
for (i = 0; i < 4; ++i) {
|
|
hpa_t root = vcpu->arch.mmu.pae_root[i];
|
|
|
|
if (root && VALID_PAGE(root)) {
|
|
root &= PT64_BASE_ADDR_MASK;
|
|
sp = page_header(root);
|
|
mmu_sync_children(vcpu, sp);
|
|
}
|
|
}
|
|
|
|
kvm_mmu_audit(vcpu, AUDIT_POST_SYNC);
|
|
spin_unlock(&vcpu->kvm->mmu_lock);
|
|
}
|
|
EXPORT_SYMBOL_GPL(kvm_mmu_sync_roots);
|
|
|
|
static gpa_t nonpaging_gva_to_gpa(struct kvm_vcpu *vcpu, gpa_t vaddr,
|
|
u32 access, struct x86_exception *exception)
|
|
{
|
|
if (exception)
|
|
exception->error_code = 0;
|
|
return vaddr;
|
|
}
|
|
|
|
static gpa_t nonpaging_gva_to_gpa_nested(struct kvm_vcpu *vcpu, gpa_t vaddr,
|
|
u32 access,
|
|
struct x86_exception *exception)
|
|
{
|
|
if (exception)
|
|
exception->error_code = 0;
|
|
return vcpu->arch.nested_mmu.translate_gpa(vcpu, vaddr, access, exception);
|
|
}
|
|
|
|
static bool
|
|
__is_rsvd_bits_set(struct rsvd_bits_validate *rsvd_check, u64 pte, int level)
|
|
{
|
|
int bit7 = (pte >> 7) & 1, low6 = pte & 0x3f;
|
|
|
|
return (pte & rsvd_check->rsvd_bits_mask[bit7][level-1]) |
|
|
((rsvd_check->bad_mt_xwr & (1ull << low6)) != 0);
|
|
}
|
|
|
|
static bool is_rsvd_bits_set(struct kvm_mmu *mmu, u64 gpte, int level)
|
|
{
|
|
return __is_rsvd_bits_set(&mmu->guest_rsvd_check, gpte, level);
|
|
}
|
|
|
|
static bool is_shadow_zero_bits_set(struct kvm_mmu *mmu, u64 spte, int level)
|
|
{
|
|
return __is_rsvd_bits_set(&mmu->shadow_zero_check, spte, level);
|
|
}
|
|
|
|
static bool mmio_info_in_cache(struct kvm_vcpu *vcpu, u64 addr, bool direct)
|
|
{
|
|
/*
|
|
* A nested guest cannot use the MMIO cache if it is using nested
|
|
* page tables, because cr2 is a nGPA while the cache stores GPAs.
|
|
*/
|
|
if (mmu_is_nested(vcpu))
|
|
return false;
|
|
|
|
if (direct)
|
|
return vcpu_match_mmio_gpa(vcpu, addr);
|
|
|
|
return vcpu_match_mmio_gva(vcpu, addr);
|
|
}
|
|
|
|
/* return true if reserved bit is detected on spte. */
|
|
static bool
|
|
walk_shadow_page_get_mmio_spte(struct kvm_vcpu *vcpu, u64 addr, u64 *sptep)
|
|
{
|
|
struct kvm_shadow_walk_iterator iterator;
|
|
u64 sptes[PT64_ROOT_MAX_LEVEL], spte = 0ull;
|
|
int root, leaf;
|
|
bool reserved = false;
|
|
|
|
if (!VALID_PAGE(vcpu->arch.mmu.root_hpa))
|
|
goto exit;
|
|
|
|
walk_shadow_page_lockless_begin(vcpu);
|
|
|
|
for (shadow_walk_init(&iterator, vcpu, addr),
|
|
leaf = root = iterator.level;
|
|
shadow_walk_okay(&iterator);
|
|
__shadow_walk_next(&iterator, spte)) {
|
|
spte = mmu_spte_get_lockless(iterator.sptep);
|
|
|
|
sptes[leaf - 1] = spte;
|
|
leaf--;
|
|
|
|
if (!is_shadow_present_pte(spte))
|
|
break;
|
|
|
|
reserved |= is_shadow_zero_bits_set(&vcpu->arch.mmu, spte,
|
|
iterator.level);
|
|
}
|
|
|
|
walk_shadow_page_lockless_end(vcpu);
|
|
|
|
if (reserved) {
|
|
pr_err("%s: detect reserved bits on spte, addr 0x%llx, dump hierarchy:\n",
|
|
__func__, addr);
|
|
while (root > leaf) {
|
|
pr_err("------ spte 0x%llx level %d.\n",
|
|
sptes[root - 1], root);
|
|
root--;
|
|
}
|
|
}
|
|
exit:
|
|
*sptep = spte;
|
|
return reserved;
|
|
}
|
|
|
|
static int handle_mmio_page_fault(struct kvm_vcpu *vcpu, u64 addr, bool direct)
|
|
{
|
|
u64 spte;
|
|
bool reserved;
|
|
|
|
if (mmio_info_in_cache(vcpu, addr, direct))
|
|
return RET_PF_EMULATE;
|
|
|
|
reserved = walk_shadow_page_get_mmio_spte(vcpu, addr, &spte);
|
|
if (WARN_ON(reserved))
|
|
return -EINVAL;
|
|
|
|
if (is_mmio_spte(spte)) {
|
|
gfn_t gfn = get_mmio_spte_gfn(spte);
|
|
unsigned access = get_mmio_spte_access(spte);
|
|
|
|
if (!check_mmio_spte(vcpu, spte))
|
|
return RET_PF_INVALID;
|
|
|
|
if (direct)
|
|
addr = 0;
|
|
|
|
trace_handle_mmio_page_fault(addr, gfn, access);
|
|
vcpu_cache_mmio_info(vcpu, addr, gfn, access);
|
|
return RET_PF_EMULATE;
|
|
}
|
|
|
|
/*
|
|
* If the page table is zapped by other cpus, let CPU fault again on
|
|
* the address.
|
|
*/
|
|
return RET_PF_RETRY;
|
|
}
|
|
|
|
static bool page_fault_handle_page_track(struct kvm_vcpu *vcpu,
|
|
u32 error_code, gfn_t gfn)
|
|
{
|
|
if (unlikely(error_code & PFERR_RSVD_MASK))
|
|
return false;
|
|
|
|
if (!(error_code & PFERR_PRESENT_MASK) ||
|
|
!(error_code & PFERR_WRITE_MASK))
|
|
return false;
|
|
|
|
/*
|
|
* guest is writing the page which is write tracked which can
|
|
* not be fixed by page fault handler.
|
|
*/
|
|
if (kvm_page_track_is_active(vcpu, gfn, KVM_PAGE_TRACK_WRITE))
|
|
return true;
|
|
|
|
return false;
|
|
}
|
|
|
|
static void shadow_page_table_clear_flood(struct kvm_vcpu *vcpu, gva_t addr)
|
|
{
|
|
struct kvm_shadow_walk_iterator iterator;
|
|
u64 spte;
|
|
|
|
if (!VALID_PAGE(vcpu->arch.mmu.root_hpa))
|
|
return;
|
|
|
|
walk_shadow_page_lockless_begin(vcpu);
|
|
for_each_shadow_entry_lockless(vcpu, addr, iterator, spte) {
|
|
clear_sp_write_flooding_count(iterator.sptep);
|
|
if (!is_shadow_present_pte(spte))
|
|
break;
|
|
}
|
|
walk_shadow_page_lockless_end(vcpu);
|
|
}
|
|
|
|
static int nonpaging_page_fault(struct kvm_vcpu *vcpu, gpa_t gpa,
|
|
u32 error_code, bool prefault)
|
|
{
|
|
gfn_t gfn = gpa >> PAGE_SHIFT;
|
|
int r;
|
|
|
|
/* Note, paging is disabled, ergo gva == gpa. */
|
|
pgprintk("%s: gva %lx error %x\n", __func__, gpa, error_code);
|
|
|
|
if (page_fault_handle_page_track(vcpu, error_code, gfn))
|
|
return RET_PF_EMULATE;
|
|
|
|
r = mmu_topup_memory_caches(vcpu);
|
|
if (r)
|
|
return r;
|
|
|
|
MMU_WARN_ON(!VALID_PAGE(vcpu->arch.mmu.root_hpa));
|
|
|
|
|
|
return nonpaging_map(vcpu, gpa & PAGE_MASK,
|
|
error_code, gfn, prefault);
|
|
}
|
|
|
|
static int kvm_arch_setup_async_pf(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa,
|
|
gfn_t gfn)
|
|
{
|
|
struct kvm_arch_async_pf arch;
|
|
|
|
arch.token = (vcpu->arch.apf.id++ << 12) | vcpu->vcpu_id;
|
|
arch.gfn = gfn;
|
|
arch.direct_map = vcpu->arch.mmu.direct_map;
|
|
arch.cr3 = vcpu->arch.mmu.get_cr3(vcpu);
|
|
|
|
return kvm_setup_async_pf(vcpu, cr2_or_gpa,
|
|
kvm_vcpu_gfn_to_hva(vcpu, gfn), &arch);
|
|
}
|
|
|
|
bool kvm_can_do_async_pf(struct kvm_vcpu *vcpu)
|
|
{
|
|
if (unlikely(!lapic_in_kernel(vcpu) ||
|
|
kvm_event_needs_reinjection(vcpu) ||
|
|
vcpu->arch.exception.pending))
|
|
return false;
|
|
|
|
if (!vcpu->arch.apf.delivery_as_pf_vmexit && is_guest_mode(vcpu))
|
|
return false;
|
|
|
|
return kvm_x86_ops->interrupt_allowed(vcpu);
|
|
}
|
|
|
|
static bool try_async_pf(struct kvm_vcpu *vcpu, bool prefault, gfn_t gfn,
|
|
gpa_t cr2_or_gpa, kvm_pfn_t *pfn, bool write,
|
|
bool *writable)
|
|
{
|
|
struct kvm_memory_slot *slot;
|
|
bool async;
|
|
|
|
/*
|
|
* Don't expose private memslots to L2.
|
|
*/
|
|
if (is_guest_mode(vcpu) && !kvm_is_visible_gfn(vcpu->kvm, gfn)) {
|
|
*pfn = KVM_PFN_NOSLOT;
|
|
return false;
|
|
}
|
|
|
|
slot = kvm_vcpu_gfn_to_memslot(vcpu, gfn);
|
|
async = false;
|
|
*pfn = __gfn_to_pfn_memslot(slot, gfn, false, &async, write, writable);
|
|
if (!async)
|
|
return false; /* *pfn has correct page already */
|
|
|
|
if (!prefault && kvm_can_do_async_pf(vcpu)) {
|
|
trace_kvm_try_async_get_page(cr2_or_gpa, gfn);
|
|
if (kvm_find_async_pf_gfn(vcpu, gfn)) {
|
|
trace_kvm_async_pf_doublefault(cr2_or_gpa, gfn);
|
|
kvm_make_request(KVM_REQ_APF_HALT, vcpu);
|
|
return true;
|
|
} else if (kvm_arch_setup_async_pf(vcpu, cr2_or_gpa, gfn))
|
|
return true;
|
|
}
|
|
|
|
*pfn = __gfn_to_pfn_memslot(slot, gfn, false, NULL, write, writable);
|
|
return false;
|
|
}
|
|
|
|
int kvm_handle_page_fault(struct kvm_vcpu *vcpu, u64 error_code,
|
|
u64 fault_address, char *insn, int insn_len)
|
|
{
|
|
int r = 1;
|
|
|
|
#ifndef CONFIG_X86_64
|
|
/* A 64-bit CR2 should be impossible on 32-bit KVM. */
|
|
if (WARN_ON_ONCE(fault_address >> 32))
|
|
return -EFAULT;
|
|
#endif
|
|
|
|
vcpu->arch.l1tf_flush_l1d = true;
|
|
switch (vcpu->arch.apf.host_apf_reason) {
|
|
default:
|
|
trace_kvm_page_fault(fault_address, error_code);
|
|
|
|
if (kvm_event_needs_reinjection(vcpu))
|
|
kvm_mmu_unprotect_page_virt(vcpu, fault_address);
|
|
r = kvm_mmu_page_fault(vcpu, fault_address, error_code, insn,
|
|
insn_len);
|
|
break;
|
|
case KVM_PV_REASON_PAGE_NOT_PRESENT:
|
|
vcpu->arch.apf.host_apf_reason = 0;
|
|
local_irq_disable();
|
|
kvm_async_pf_task_wait(fault_address, 0);
|
|
local_irq_enable();
|
|
break;
|
|
case KVM_PV_REASON_PAGE_READY:
|
|
vcpu->arch.apf.host_apf_reason = 0;
|
|
local_irq_disable();
|
|
kvm_async_pf_task_wake(fault_address);
|
|
local_irq_enable();
|
|
break;
|
|
}
|
|
return r;
|
|
}
|
|
EXPORT_SYMBOL_GPL(kvm_handle_page_fault);
|
|
|
|
static bool
|
|
check_hugepage_cache_consistency(struct kvm_vcpu *vcpu, gfn_t gfn, int level)
|
|
{
|
|
int page_num = KVM_PAGES_PER_HPAGE(level);
|
|
|
|
gfn &= ~(page_num - 1);
|
|
|
|
return kvm_mtrr_check_gfn_range_consistency(vcpu, gfn, page_num);
|
|
}
|
|
|
|
static int tdp_page_fault(struct kvm_vcpu *vcpu, gpa_t gpa, u32 error_code,
|
|
bool prefault)
|
|
{
|
|
kvm_pfn_t pfn;
|
|
int r;
|
|
int level;
|
|
bool force_pt_level;
|
|
gfn_t gfn = gpa >> PAGE_SHIFT;
|
|
unsigned long mmu_seq;
|
|
int write = error_code & PFERR_WRITE_MASK;
|
|
bool map_writable;
|
|
bool lpage_disallowed = (error_code & PFERR_FETCH_MASK) &&
|
|
is_nx_huge_page_enabled();
|
|
|
|
MMU_WARN_ON(!VALID_PAGE(vcpu->arch.mmu.root_hpa));
|
|
|
|
if (page_fault_handle_page_track(vcpu, error_code, gfn))
|
|
return RET_PF_EMULATE;
|
|
|
|
r = mmu_topup_memory_caches(vcpu);
|
|
if (r)
|
|
return r;
|
|
|
|
force_pt_level =
|
|
lpage_disallowed ||
|
|
!check_hugepage_cache_consistency(vcpu, gfn, PT_DIRECTORY_LEVEL);
|
|
level = mapping_level(vcpu, gfn, &force_pt_level);
|
|
if (likely(!force_pt_level)) {
|
|
if (level > PT_DIRECTORY_LEVEL &&
|
|
!check_hugepage_cache_consistency(vcpu, gfn, level))
|
|
level = PT_DIRECTORY_LEVEL;
|
|
gfn &= ~(KVM_PAGES_PER_HPAGE(level) - 1);
|
|
}
|
|
|
|
if (fast_page_fault(vcpu, gpa, level, error_code))
|
|
return RET_PF_RETRY;
|
|
|
|
mmu_seq = vcpu->kvm->mmu_notifier_seq;
|
|
smp_rmb();
|
|
|
|
if (try_async_pf(vcpu, prefault, gfn, gpa, &pfn, write, &map_writable))
|
|
return RET_PF_RETRY;
|
|
|
|
if (handle_abnormal_pfn(vcpu, 0, gfn, pfn, ACC_ALL, &r))
|
|
return r;
|
|
|
|
r = RET_PF_RETRY;
|
|
spin_lock(&vcpu->kvm->mmu_lock);
|
|
if (mmu_notifier_retry(vcpu->kvm, mmu_seq))
|
|
goto out_unlock;
|
|
if (make_mmu_pages_available(vcpu) < 0)
|
|
goto out_unlock;
|
|
if (likely(!force_pt_level))
|
|
transparent_hugepage_adjust(vcpu, gfn, &pfn, &level);
|
|
r = __direct_map(vcpu, gpa, write, map_writable, level, pfn,
|
|
prefault, lpage_disallowed);
|
|
out_unlock:
|
|
spin_unlock(&vcpu->kvm->mmu_lock);
|
|
kvm_release_pfn_clean(pfn);
|
|
return r;
|
|
}
|
|
|
|
static void nonpaging_init_context(struct kvm_vcpu *vcpu,
|
|
struct kvm_mmu *context)
|
|
{
|
|
context->page_fault = nonpaging_page_fault;
|
|
context->gva_to_gpa = nonpaging_gva_to_gpa;
|
|
context->sync_page = nonpaging_sync_page;
|
|
context->invlpg = nonpaging_invlpg;
|
|
context->update_pte = nonpaging_update_pte;
|
|
context->root_level = 0;
|
|
context->shadow_root_level = PT32E_ROOT_LEVEL;
|
|
context->direct_map = true;
|
|
context->nx = false;
|
|
}
|
|
|
|
/*
|
|
* Find out if a previously cached root matching the new CR3/role is available.
|
|
* The current root is also inserted into the cache.
|
|
* If a matching root was found, it is assigned to kvm_mmu->root_hpa and true is
|
|
* returned.
|
|
* Otherwise, the LRU root from the cache is assigned to kvm_mmu->root_hpa and
|
|
* false is returned. This root should now be freed by the caller.
|
|
*/
|
|
static bool cached_root_available(struct kvm_vcpu *vcpu, gpa_t new_cr3,
|
|
union kvm_mmu_page_role new_role)
|
|
{
|
|
uint i;
|
|
struct kvm_mmu_root_info root;
|
|
struct kvm_mmu *mmu = &vcpu->arch.mmu;
|
|
|
|
root.cr3 = mmu->get_cr3(vcpu);
|
|
root.hpa = mmu->root_hpa;
|
|
|
|
for (i = 0; i < KVM_MMU_NUM_PREV_ROOTS; i++) {
|
|
swap(root, mmu->prev_roots[i]);
|
|
|
|
if (new_cr3 == root.cr3 && VALID_PAGE(root.hpa) &&
|
|
page_header(root.hpa) != NULL &&
|
|
new_role.word == page_header(root.hpa)->role.word)
|
|
break;
|
|
}
|
|
|
|
mmu->root_hpa = root.hpa;
|
|
|
|
return i < KVM_MMU_NUM_PREV_ROOTS;
|
|
}
|
|
|
|
static bool fast_cr3_switch(struct kvm_vcpu *vcpu, gpa_t new_cr3,
|
|
union kvm_mmu_page_role new_role,
|
|
bool skip_tlb_flush)
|
|
{
|
|
struct kvm_mmu *mmu = &vcpu->arch.mmu;
|
|
|
|
/*
|
|
* For now, limit the fast switch to 64-bit hosts+VMs in order to avoid
|
|
* having to deal with PDPTEs. We may add support for 32-bit hosts/VMs
|
|
* later if necessary.
|
|
*/
|
|
if (mmu->shadow_root_level >= PT64_ROOT_4LEVEL &&
|
|
mmu->root_level >= PT64_ROOT_4LEVEL) {
|
|
if (mmu_check_root(vcpu, new_cr3 >> PAGE_SHIFT))
|
|
return false;
|
|
|
|
if (cached_root_available(vcpu, new_cr3, new_role)) {
|
|
/*
|
|
* It is possible that the cached previous root page is
|
|
* obsolete because of a change in the MMU
|
|
* generation number. However, that is accompanied by
|
|
* KVM_REQ_MMU_RELOAD, which will free the root that we
|
|
* have set here and allocate a new one.
|
|
*/
|
|
|
|
kvm_make_request(KVM_REQ_LOAD_CR3, vcpu);
|
|
if (!skip_tlb_flush) {
|
|
kvm_make_request(KVM_REQ_MMU_SYNC, vcpu);
|
|
kvm_x86_ops->tlb_flush(vcpu, true);
|
|
}
|
|
|
|
/*
|
|
* The last MMIO access's GVA and GPA are cached in the
|
|
* VCPU. When switching to a new CR3, that GVA->GPA
|
|
* mapping may no longer be valid. So clear any cached
|
|
* MMIO info even when we don't need to sync the shadow
|
|
* page tables.
|
|
*/
|
|
vcpu_clear_mmio_info(vcpu, MMIO_GVA_ANY);
|
|
|
|
__clear_sp_write_flooding_count(
|
|
page_header(mmu->root_hpa));
|
|
|
|
return true;
|
|
}
|
|
}
|
|
|
|
return false;
|
|
}
|
|
|
|
static void __kvm_mmu_new_cr3(struct kvm_vcpu *vcpu, gpa_t new_cr3,
|
|
union kvm_mmu_page_role new_role,
|
|
bool skip_tlb_flush)
|
|
{
|
|
if (!fast_cr3_switch(vcpu, new_cr3, new_role, skip_tlb_flush))
|
|
kvm_mmu_free_roots(vcpu, KVM_MMU_ROOT_CURRENT);
|
|
}
|
|
|
|
void kvm_mmu_new_cr3(struct kvm_vcpu *vcpu, gpa_t new_cr3, bool skip_tlb_flush)
|
|
{
|
|
__kvm_mmu_new_cr3(vcpu, new_cr3, kvm_mmu_calc_root_page_role(vcpu),
|
|
skip_tlb_flush);
|
|
}
|
|
EXPORT_SYMBOL_GPL(kvm_mmu_new_cr3);
|
|
|
|
static unsigned long get_cr3(struct kvm_vcpu *vcpu)
|
|
{
|
|
return kvm_read_cr3(vcpu);
|
|
}
|
|
|
|
static void inject_page_fault(struct kvm_vcpu *vcpu,
|
|
struct x86_exception *fault)
|
|
{
|
|
vcpu->arch.mmu.inject_page_fault(vcpu, fault);
|
|
}
|
|
|
|
static bool sync_mmio_spte(struct kvm_vcpu *vcpu, u64 *sptep, gfn_t gfn,
|
|
unsigned access, int *nr_present)
|
|
{
|
|
if (unlikely(is_mmio_spte(*sptep))) {
|
|
if (gfn != get_mmio_spte_gfn(*sptep)) {
|
|
mmu_spte_clear_no_track(sptep);
|
|
return true;
|
|
}
|
|
|
|
(*nr_present)++;
|
|
mark_mmio_spte(vcpu, sptep, gfn, access);
|
|
return true;
|
|
}
|
|
|
|
return false;
|
|
}
|
|
|
|
static inline bool is_last_gpte(struct kvm_mmu *mmu,
|
|
unsigned level, unsigned gpte)
|
|
{
|
|
/*
|
|
* The RHS has bit 7 set iff level < mmu->last_nonleaf_level.
|
|
* If it is clear, there are no large pages at this level, so clear
|
|
* PT_PAGE_SIZE_MASK in gpte if that is the case.
|
|
*/
|
|
gpte &= level - mmu->last_nonleaf_level;
|
|
|
|
/*
|
|
* PT_PAGE_TABLE_LEVEL always terminates. The RHS has bit 7 set
|
|
* iff level <= PT_PAGE_TABLE_LEVEL, which for our purpose means
|
|
* level == PT_PAGE_TABLE_LEVEL; set PT_PAGE_SIZE_MASK in gpte then.
|
|
*/
|
|
gpte |= level - PT_PAGE_TABLE_LEVEL - 1;
|
|
|
|
return gpte & PT_PAGE_SIZE_MASK;
|
|
}
|
|
|
|
#define PTTYPE_EPT 18 /* arbitrary */
|
|
#define PTTYPE PTTYPE_EPT
|
|
#include "paging_tmpl.h"
|
|
#undef PTTYPE
|
|
|
|
#define PTTYPE 64
|
|
#include "paging_tmpl.h"
|
|
#undef PTTYPE
|
|
|
|
#define PTTYPE 32
|
|
#include "paging_tmpl.h"
|
|
#undef PTTYPE
|
|
|
|
static void
|
|
__reset_rsvds_bits_mask(struct kvm_vcpu *vcpu,
|
|
struct rsvd_bits_validate *rsvd_check,
|
|
int maxphyaddr, int level, bool nx, bool gbpages,
|
|
bool pse, bool amd)
|
|
{
|
|
u64 exb_bit_rsvd = 0;
|
|
u64 gbpages_bit_rsvd = 0;
|
|
u64 nonleaf_bit8_rsvd = 0;
|
|
|
|
rsvd_check->bad_mt_xwr = 0;
|
|
|
|
if (!nx)
|
|
exb_bit_rsvd = rsvd_bits(63, 63);
|
|
if (!gbpages)
|
|
gbpages_bit_rsvd = rsvd_bits(7, 7);
|
|
|
|
/*
|
|
* Non-leaf PML4Es and PDPEs reserve bit 8 (which would be the G bit for
|
|
* leaf entries) on AMD CPUs only.
|
|
*/
|
|
if (amd)
|
|
nonleaf_bit8_rsvd = rsvd_bits(8, 8);
|
|
|
|
switch (level) {
|
|
case PT32_ROOT_LEVEL:
|
|
/* no rsvd bits for 2 level 4K page table entries */
|
|
rsvd_check->rsvd_bits_mask[0][1] = 0;
|
|
rsvd_check->rsvd_bits_mask[0][0] = 0;
|
|
rsvd_check->rsvd_bits_mask[1][0] =
|
|
rsvd_check->rsvd_bits_mask[0][0];
|
|
|
|
if (!pse) {
|
|
rsvd_check->rsvd_bits_mask[1][1] = 0;
|
|
break;
|
|
}
|
|
|
|
if (is_cpuid_PSE36())
|
|
/* 36bits PSE 4MB page */
|
|
rsvd_check->rsvd_bits_mask[1][1] = rsvd_bits(17, 21);
|
|
else
|
|
/* 32 bits PSE 4MB page */
|
|
rsvd_check->rsvd_bits_mask[1][1] = rsvd_bits(13, 21);
|
|
break;
|
|
case PT32E_ROOT_LEVEL:
|
|
rsvd_check->rsvd_bits_mask[0][2] =
|
|
rsvd_bits(maxphyaddr, 63) |
|
|
rsvd_bits(5, 8) | rsvd_bits(1, 2); /* PDPTE */
|
|
rsvd_check->rsvd_bits_mask[0][1] = exb_bit_rsvd |
|
|
rsvd_bits(maxphyaddr, 62); /* PDE */
|
|
rsvd_check->rsvd_bits_mask[0][0] = exb_bit_rsvd |
|
|
rsvd_bits(maxphyaddr, 62); /* PTE */
|
|
rsvd_check->rsvd_bits_mask[1][1] = exb_bit_rsvd |
|
|
rsvd_bits(maxphyaddr, 62) |
|
|
rsvd_bits(13, 20); /* large page */
|
|
rsvd_check->rsvd_bits_mask[1][0] =
|
|
rsvd_check->rsvd_bits_mask[0][0];
|
|
break;
|
|
case PT64_ROOT_5LEVEL:
|
|
rsvd_check->rsvd_bits_mask[0][4] = exb_bit_rsvd |
|
|
nonleaf_bit8_rsvd | rsvd_bits(7, 7) |
|
|
rsvd_bits(maxphyaddr, 51);
|
|
rsvd_check->rsvd_bits_mask[1][4] =
|
|
rsvd_check->rsvd_bits_mask[0][4];
|
|
case PT64_ROOT_4LEVEL:
|
|
rsvd_check->rsvd_bits_mask[0][3] = exb_bit_rsvd |
|
|
nonleaf_bit8_rsvd | rsvd_bits(7, 7) |
|
|
rsvd_bits(maxphyaddr, 51);
|
|
rsvd_check->rsvd_bits_mask[0][2] = exb_bit_rsvd |
|
|
gbpages_bit_rsvd |
|
|
rsvd_bits(maxphyaddr, 51);
|
|
rsvd_check->rsvd_bits_mask[0][1] = exb_bit_rsvd |
|
|
rsvd_bits(maxphyaddr, 51);
|
|
rsvd_check->rsvd_bits_mask[0][0] = exb_bit_rsvd |
|
|
rsvd_bits(maxphyaddr, 51);
|
|
rsvd_check->rsvd_bits_mask[1][3] =
|
|
rsvd_check->rsvd_bits_mask[0][3];
|
|
rsvd_check->rsvd_bits_mask[1][2] = exb_bit_rsvd |
|
|
gbpages_bit_rsvd | rsvd_bits(maxphyaddr, 51) |
|
|
rsvd_bits(13, 29);
|
|
rsvd_check->rsvd_bits_mask[1][1] = exb_bit_rsvd |
|
|
rsvd_bits(maxphyaddr, 51) |
|
|
rsvd_bits(13, 20); /* large page */
|
|
rsvd_check->rsvd_bits_mask[1][0] =
|
|
rsvd_check->rsvd_bits_mask[0][0];
|
|
break;
|
|
}
|
|
}
|
|
|
|
static void reset_rsvds_bits_mask(struct kvm_vcpu *vcpu,
|
|
struct kvm_mmu *context)
|
|
{
|
|
__reset_rsvds_bits_mask(vcpu, &context->guest_rsvd_check,
|
|
cpuid_maxphyaddr(vcpu), context->root_level,
|
|
context->nx,
|
|
guest_cpuid_has(vcpu, X86_FEATURE_GBPAGES),
|
|
is_pse(vcpu), guest_cpuid_is_amd(vcpu));
|
|
}
|
|
|
|
static void
|
|
__reset_rsvds_bits_mask_ept(struct rsvd_bits_validate *rsvd_check,
|
|
int maxphyaddr, bool execonly)
|
|
{
|
|
u64 bad_mt_xwr;
|
|
|
|
rsvd_check->rsvd_bits_mask[0][4] =
|
|
rsvd_bits(maxphyaddr, 51) | rsvd_bits(3, 7);
|
|
rsvd_check->rsvd_bits_mask[0][3] =
|
|
rsvd_bits(maxphyaddr, 51) | rsvd_bits(3, 7);
|
|
rsvd_check->rsvd_bits_mask[0][2] =
|
|
rsvd_bits(maxphyaddr, 51) | rsvd_bits(3, 6);
|
|
rsvd_check->rsvd_bits_mask[0][1] =
|
|
rsvd_bits(maxphyaddr, 51) | rsvd_bits(3, 6);
|
|
rsvd_check->rsvd_bits_mask[0][0] = rsvd_bits(maxphyaddr, 51);
|
|
|
|
/* large page */
|
|
rsvd_check->rsvd_bits_mask[1][4] = rsvd_check->rsvd_bits_mask[0][4];
|
|
rsvd_check->rsvd_bits_mask[1][3] = rsvd_check->rsvd_bits_mask[0][3];
|
|
rsvd_check->rsvd_bits_mask[1][2] =
|
|
rsvd_bits(maxphyaddr, 51) | rsvd_bits(12, 29);
|
|
rsvd_check->rsvd_bits_mask[1][1] =
|
|
rsvd_bits(maxphyaddr, 51) | rsvd_bits(12, 20);
|
|
rsvd_check->rsvd_bits_mask[1][0] = rsvd_check->rsvd_bits_mask[0][0];
|
|
|
|
bad_mt_xwr = 0xFFull << (2 * 8); /* bits 3..5 must not be 2 */
|
|
bad_mt_xwr |= 0xFFull << (3 * 8); /* bits 3..5 must not be 3 */
|
|
bad_mt_xwr |= 0xFFull << (7 * 8); /* bits 3..5 must not be 7 */
|
|
bad_mt_xwr |= REPEAT_BYTE(1ull << 2); /* bits 0..2 must not be 010 */
|
|
bad_mt_xwr |= REPEAT_BYTE(1ull << 6); /* bits 0..2 must not be 110 */
|
|
if (!execonly) {
|
|
/* bits 0..2 must not be 100 unless VMX capabilities allow it */
|
|
bad_mt_xwr |= REPEAT_BYTE(1ull << 4);
|
|
}
|
|
rsvd_check->bad_mt_xwr = bad_mt_xwr;
|
|
}
|
|
|
|
static void reset_rsvds_bits_mask_ept(struct kvm_vcpu *vcpu,
|
|
struct kvm_mmu *context, bool execonly)
|
|
{
|
|
__reset_rsvds_bits_mask_ept(&context->guest_rsvd_check,
|
|
cpuid_maxphyaddr(vcpu), execonly);
|
|
}
|
|
|
|
/*
|
|
* the page table on host is the shadow page table for the page
|
|
* table in guest or amd nested guest, its mmu features completely
|
|
* follow the features in guest.
|
|
*/
|
|
void
|
|
reset_shadow_zero_bits_mask(struct kvm_vcpu *vcpu, struct kvm_mmu *context)
|
|
{
|
|
bool uses_nx = context->nx || context->base_role.smep_andnot_wp;
|
|
struct rsvd_bits_validate *shadow_zero_check;
|
|
int i;
|
|
|
|
/*
|
|
* Passing "true" to the last argument is okay; it adds a check
|
|
* on bit 8 of the SPTEs which KVM doesn't use anyway.
|
|
*/
|
|
shadow_zero_check = &context->shadow_zero_check;
|
|
__reset_rsvds_bits_mask(vcpu, shadow_zero_check,
|
|
shadow_phys_bits,
|
|
context->shadow_root_level, uses_nx,
|
|
guest_cpuid_has(vcpu, X86_FEATURE_GBPAGES),
|
|
is_pse(vcpu), true);
|
|
|
|
if (!shadow_me_mask)
|
|
return;
|
|
|
|
for (i = context->shadow_root_level; --i >= 0;) {
|
|
shadow_zero_check->rsvd_bits_mask[0][i] &= ~shadow_me_mask;
|
|
shadow_zero_check->rsvd_bits_mask[1][i] &= ~shadow_me_mask;
|
|
}
|
|
|
|
}
|
|
EXPORT_SYMBOL_GPL(reset_shadow_zero_bits_mask);
|
|
|
|
static inline bool boot_cpu_is_amd(void)
|
|
{
|
|
WARN_ON_ONCE(!tdp_enabled);
|
|
return shadow_x_mask == 0;
|
|
}
|
|
|
|
/*
|
|
* the direct page table on host, use as much mmu features as
|
|
* possible, however, kvm currently does not do execution-protection.
|
|
*/
|
|
static void
|
|
reset_tdp_shadow_zero_bits_mask(struct kvm_vcpu *vcpu,
|
|
struct kvm_mmu *context)
|
|
{
|
|
struct rsvd_bits_validate *shadow_zero_check;
|
|
int i;
|
|
|
|
shadow_zero_check = &context->shadow_zero_check;
|
|
|
|
if (boot_cpu_is_amd())
|
|
__reset_rsvds_bits_mask(vcpu, shadow_zero_check,
|
|
shadow_phys_bits,
|
|
context->shadow_root_level, false,
|
|
boot_cpu_has(X86_FEATURE_GBPAGES),
|
|
true, true);
|
|
else
|
|
__reset_rsvds_bits_mask_ept(shadow_zero_check,
|
|
shadow_phys_bits,
|
|
false);
|
|
|
|
if (!shadow_me_mask)
|
|
return;
|
|
|
|
for (i = context->shadow_root_level; --i >= 0;) {
|
|
shadow_zero_check->rsvd_bits_mask[0][i] &= ~shadow_me_mask;
|
|
shadow_zero_check->rsvd_bits_mask[1][i] &= ~shadow_me_mask;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* as the comments in reset_shadow_zero_bits_mask() except it
|
|
* is the shadow page table for intel nested guest.
|
|
*/
|
|
static void
|
|
reset_ept_shadow_zero_bits_mask(struct kvm_vcpu *vcpu,
|
|
struct kvm_mmu *context, bool execonly)
|
|
{
|
|
__reset_rsvds_bits_mask_ept(&context->shadow_zero_check,
|
|
shadow_phys_bits, execonly);
|
|
}
|
|
|
|
#define BYTE_MASK(access) \
|
|
((1 & (access) ? 2 : 0) | \
|
|
(2 & (access) ? 4 : 0) | \
|
|
(3 & (access) ? 8 : 0) | \
|
|
(4 & (access) ? 16 : 0) | \
|
|
(5 & (access) ? 32 : 0) | \
|
|
(6 & (access) ? 64 : 0) | \
|
|
(7 & (access) ? 128 : 0))
|
|
|
|
|
|
static void update_permission_bitmask(struct kvm_vcpu *vcpu,
|
|
struct kvm_mmu *mmu, bool ept)
|
|
{
|
|
unsigned byte;
|
|
|
|
const u8 x = BYTE_MASK(ACC_EXEC_MASK);
|
|
const u8 w = BYTE_MASK(ACC_WRITE_MASK);
|
|
const u8 u = BYTE_MASK(ACC_USER_MASK);
|
|
|
|
bool cr4_smep = kvm_read_cr4_bits(vcpu, X86_CR4_SMEP) != 0;
|
|
bool cr4_smap = kvm_read_cr4_bits(vcpu, X86_CR4_SMAP) != 0;
|
|
bool cr0_wp = is_write_protection(vcpu);
|
|
|
|
for (byte = 0; byte < ARRAY_SIZE(mmu->permissions); ++byte) {
|
|
unsigned pfec = byte << 1;
|
|
|
|
/*
|
|
* Each "*f" variable has a 1 bit for each UWX value
|
|
* that causes a fault with the given PFEC.
|
|
*/
|
|
|
|
/* Faults from writes to non-writable pages */
|
|
u8 wf = (pfec & PFERR_WRITE_MASK) ? (u8)~w : 0;
|
|
/* Faults from user mode accesses to supervisor pages */
|
|
u8 uf = (pfec & PFERR_USER_MASK) ? (u8)~u : 0;
|
|
/* Faults from fetches of non-executable pages*/
|
|
u8 ff = (pfec & PFERR_FETCH_MASK) ? (u8)~x : 0;
|
|
/* Faults from kernel mode fetches of user pages */
|
|
u8 smepf = 0;
|
|
/* Faults from kernel mode accesses of user pages */
|
|
u8 smapf = 0;
|
|
|
|
if (!ept) {
|
|
/* Faults from kernel mode accesses to user pages */
|
|
u8 kf = (pfec & PFERR_USER_MASK) ? 0 : u;
|
|
|
|
/* Not really needed: !nx will cause pte.nx to fault */
|
|
if (!mmu->nx)
|
|
ff = 0;
|
|
|
|
/* Allow supervisor writes if !cr0.wp */
|
|
if (!cr0_wp)
|
|
wf = (pfec & PFERR_USER_MASK) ? wf : 0;
|
|
|
|
/* Disallow supervisor fetches of user code if cr4.smep */
|
|
if (cr4_smep)
|
|
smepf = (pfec & PFERR_FETCH_MASK) ? kf : 0;
|
|
|
|
/*
|
|
* SMAP:kernel-mode data accesses from user-mode
|
|
* mappings should fault. A fault is considered
|
|
* as a SMAP violation if all of the following
|
|
* conditions are ture:
|
|
* - X86_CR4_SMAP is set in CR4
|
|
* - A user page is accessed
|
|
* - The access is not a fetch
|
|
* - Page fault in kernel mode
|
|
* - if CPL = 3 or X86_EFLAGS_AC is clear
|
|
*
|
|
* Here, we cover the first three conditions.
|
|
* The fourth is computed dynamically in permission_fault();
|
|
* PFERR_RSVD_MASK bit will be set in PFEC if the access is
|
|
* *not* subject to SMAP restrictions.
|
|
*/
|
|
if (cr4_smap)
|
|
smapf = (pfec & (PFERR_RSVD_MASK|PFERR_FETCH_MASK)) ? 0 : kf;
|
|
}
|
|
|
|
mmu->permissions[byte] = ff | uf | wf | smepf | smapf;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* PKU is an additional mechanism by which the paging controls access to
|
|
* user-mode addresses based on the value in the PKRU register. Protection
|
|
* key violations are reported through a bit in the page fault error code.
|
|
* Unlike other bits of the error code, the PK bit is not known at the
|
|
* call site of e.g. gva_to_gpa; it must be computed directly in
|
|
* permission_fault based on two bits of PKRU, on some machine state (CR4,
|
|
* CR0, EFER, CPL), and on other bits of the error code and the page tables.
|
|
*
|
|
* In particular the following conditions come from the error code, the
|
|
* page tables and the machine state:
|
|
* - PK is always zero unless CR4.PKE=1 and EFER.LMA=1
|
|
* - PK is always zero if RSVD=1 (reserved bit set) or F=1 (instruction fetch)
|
|
* - PK is always zero if U=0 in the page tables
|
|
* - PKRU.WD is ignored if CR0.WP=0 and the access is a supervisor access.
|
|
*
|
|
* The PKRU bitmask caches the result of these four conditions. The error
|
|
* code (minus the P bit) and the page table's U bit form an index into the
|
|
* PKRU bitmask. Two bits of the PKRU bitmask are then extracted and ANDed
|
|
* with the two bits of the PKRU register corresponding to the protection key.
|
|
* For the first three conditions above the bits will be 00, thus masking
|
|
* away both AD and WD. For all reads or if the last condition holds, WD
|
|
* only will be masked away.
|
|
*/
|
|
static void update_pkru_bitmask(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu,
|
|
bool ept)
|
|
{
|
|
unsigned bit;
|
|
bool wp;
|
|
|
|
if (ept) {
|
|
mmu->pkru_mask = 0;
|
|
return;
|
|
}
|
|
|
|
/* PKEY is enabled only if CR4.PKE and EFER.LMA are both set. */
|
|
if (!kvm_read_cr4_bits(vcpu, X86_CR4_PKE) || !is_long_mode(vcpu)) {
|
|
mmu->pkru_mask = 0;
|
|
return;
|
|
}
|
|
|
|
wp = is_write_protection(vcpu);
|
|
|
|
for (bit = 0; bit < ARRAY_SIZE(mmu->permissions); ++bit) {
|
|
unsigned pfec, pkey_bits;
|
|
bool check_pkey, check_write, ff, uf, wf, pte_user;
|
|
|
|
pfec = bit << 1;
|
|
ff = pfec & PFERR_FETCH_MASK;
|
|
uf = pfec & PFERR_USER_MASK;
|
|
wf = pfec & PFERR_WRITE_MASK;
|
|
|
|
/* PFEC.RSVD is replaced by ACC_USER_MASK. */
|
|
pte_user = pfec & PFERR_RSVD_MASK;
|
|
|
|
/*
|
|
* Only need to check the access which is not an
|
|
* instruction fetch and is to a user page.
|
|
*/
|
|
check_pkey = (!ff && pte_user);
|
|
/*
|
|
* write access is controlled by PKRU if it is a
|
|
* user access or CR0.WP = 1.
|
|
*/
|
|
check_write = check_pkey && wf && (uf || wp);
|
|
|
|
/* PKRU.AD stops both read and write access. */
|
|
pkey_bits = !!check_pkey;
|
|
/* PKRU.WD stops write access. */
|
|
pkey_bits |= (!!check_write) << 1;
|
|
|
|
mmu->pkru_mask |= (pkey_bits & 3) << pfec;
|
|
}
|
|
}
|
|
|
|
static void update_last_nonleaf_level(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu)
|
|
{
|
|
unsigned root_level = mmu->root_level;
|
|
|
|
mmu->last_nonleaf_level = root_level;
|
|
if (root_level == PT32_ROOT_LEVEL && is_pse(vcpu))
|
|
mmu->last_nonleaf_level++;
|
|
}
|
|
|
|
static void paging64_init_context_common(struct kvm_vcpu *vcpu,
|
|
struct kvm_mmu *context,
|
|
int level)
|
|
{
|
|
context->nx = is_nx(vcpu);
|
|
context->root_level = level;
|
|
|
|
reset_rsvds_bits_mask(vcpu, context);
|
|
update_permission_bitmask(vcpu, context, false);
|
|
update_pkru_bitmask(vcpu, context, false);
|
|
update_last_nonleaf_level(vcpu, context);
|
|
|
|
MMU_WARN_ON(!is_pae(vcpu));
|
|
context->page_fault = paging64_page_fault;
|
|
context->gva_to_gpa = paging64_gva_to_gpa;
|
|
context->sync_page = paging64_sync_page;
|
|
context->invlpg = paging64_invlpg;
|
|
context->update_pte = paging64_update_pte;
|
|
context->shadow_root_level = level;
|
|
context->direct_map = false;
|
|
}
|
|
|
|
static void paging64_init_context(struct kvm_vcpu *vcpu,
|
|
struct kvm_mmu *context)
|
|
{
|
|
int root_level = is_la57_mode(vcpu) ?
|
|
PT64_ROOT_5LEVEL : PT64_ROOT_4LEVEL;
|
|
|
|
paging64_init_context_common(vcpu, context, root_level);
|
|
}
|
|
|
|
static void paging32_init_context(struct kvm_vcpu *vcpu,
|
|
struct kvm_mmu *context)
|
|
{
|
|
context->nx = false;
|
|
context->root_level = PT32_ROOT_LEVEL;
|
|
|
|
reset_rsvds_bits_mask(vcpu, context);
|
|
update_permission_bitmask(vcpu, context, false);
|
|
update_pkru_bitmask(vcpu, context, false);
|
|
update_last_nonleaf_level(vcpu, context);
|
|
|
|
context->page_fault = paging32_page_fault;
|
|
context->gva_to_gpa = paging32_gva_to_gpa;
|
|
context->sync_page = paging32_sync_page;
|
|
context->invlpg = paging32_invlpg;
|
|
context->update_pte = paging32_update_pte;
|
|
context->shadow_root_level = PT32E_ROOT_LEVEL;
|
|
context->direct_map = false;
|
|
}
|
|
|
|
static void paging32E_init_context(struct kvm_vcpu *vcpu,
|
|
struct kvm_mmu *context)
|
|
{
|
|
paging64_init_context_common(vcpu, context, PT32E_ROOT_LEVEL);
|
|
}
|
|
|
|
static union kvm_mmu_page_role
|
|
kvm_calc_tdp_mmu_root_page_role(struct kvm_vcpu *vcpu)
|
|
{
|
|
union kvm_mmu_page_role role = {0};
|
|
|
|
role.guest_mode = is_guest_mode(vcpu);
|
|
role.smm = is_smm(vcpu);
|
|
role.ad_disabled = (shadow_accessed_mask == 0);
|
|
role.level = kvm_x86_ops->get_tdp_level(vcpu);
|
|
role.direct = true;
|
|
role.access = ACC_ALL;
|
|
|
|
return role;
|
|
}
|
|
|
|
static void init_kvm_tdp_mmu(struct kvm_vcpu *vcpu)
|
|
{
|
|
struct kvm_mmu *context = &vcpu->arch.mmu;
|
|
|
|
context->base_role.word = mmu_base_role_mask.word &
|
|
kvm_calc_tdp_mmu_root_page_role(vcpu).word;
|
|
context->page_fault = tdp_page_fault;
|
|
context->sync_page = nonpaging_sync_page;
|
|
context->invlpg = nonpaging_invlpg;
|
|
context->update_pte = nonpaging_update_pte;
|
|
context->shadow_root_level = kvm_x86_ops->get_tdp_level(vcpu);
|
|
context->direct_map = true;
|
|
context->set_cr3 = kvm_x86_ops->set_tdp_cr3;
|
|
context->get_cr3 = get_cr3;
|
|
context->get_pdptr = kvm_pdptr_read;
|
|
context->inject_page_fault = kvm_inject_page_fault;
|
|
|
|
if (!is_paging(vcpu)) {
|
|
context->nx = false;
|
|
context->gva_to_gpa = nonpaging_gva_to_gpa;
|
|
context->root_level = 0;
|
|
} else if (is_long_mode(vcpu)) {
|
|
context->nx = is_nx(vcpu);
|
|
context->root_level = is_la57_mode(vcpu) ?
|
|
PT64_ROOT_5LEVEL : PT64_ROOT_4LEVEL;
|
|
reset_rsvds_bits_mask(vcpu, context);
|
|
context->gva_to_gpa = paging64_gva_to_gpa;
|
|
} else if (is_pae(vcpu)) {
|
|
context->nx = is_nx(vcpu);
|
|
context->root_level = PT32E_ROOT_LEVEL;
|
|
reset_rsvds_bits_mask(vcpu, context);
|
|
context->gva_to_gpa = paging64_gva_to_gpa;
|
|
} else {
|
|
context->nx = false;
|
|
context->root_level = PT32_ROOT_LEVEL;
|
|
reset_rsvds_bits_mask(vcpu, context);
|
|
context->gva_to_gpa = paging32_gva_to_gpa;
|
|
}
|
|
|
|
update_permission_bitmask(vcpu, context, false);
|
|
update_pkru_bitmask(vcpu, context, false);
|
|
update_last_nonleaf_level(vcpu, context);
|
|
reset_tdp_shadow_zero_bits_mask(vcpu, context);
|
|
}
|
|
|
|
static union kvm_mmu_page_role
|
|
kvm_calc_shadow_mmu_root_page_role(struct kvm_vcpu *vcpu)
|
|
{
|
|
union kvm_mmu_page_role role = {0};
|
|
bool smep = kvm_read_cr4_bits(vcpu, X86_CR4_SMEP);
|
|
bool smap = kvm_read_cr4_bits(vcpu, X86_CR4_SMAP);
|
|
|
|
role.nxe = is_nx(vcpu);
|
|
role.cr4_pae = !!is_pae(vcpu);
|
|
role.cr0_wp = is_write_protection(vcpu);
|
|
role.smep_andnot_wp = smep && !is_write_protection(vcpu);
|
|
role.smap_andnot_wp = smap && !is_write_protection(vcpu);
|
|
role.guest_mode = is_guest_mode(vcpu);
|
|
role.smm = is_smm(vcpu);
|
|
role.direct = !is_paging(vcpu);
|
|
role.access = ACC_ALL;
|
|
|
|
if (!is_long_mode(vcpu))
|
|
role.level = PT32E_ROOT_LEVEL;
|
|
else if (is_la57_mode(vcpu))
|
|
role.level = PT64_ROOT_5LEVEL;
|
|
else
|
|
role.level = PT64_ROOT_4LEVEL;
|
|
|
|
return role;
|
|
}
|
|
|
|
void kvm_init_shadow_mmu(struct kvm_vcpu *vcpu)
|
|
{
|
|
struct kvm_mmu *context = &vcpu->arch.mmu;
|
|
|
|
if (!is_paging(vcpu))
|
|
nonpaging_init_context(vcpu, context);
|
|
else if (is_long_mode(vcpu))
|
|
paging64_init_context(vcpu, context);
|
|
else if (is_pae(vcpu))
|
|
paging32E_init_context(vcpu, context);
|
|
else
|
|
paging32_init_context(vcpu, context);
|
|
|
|
context->base_role.word = mmu_base_role_mask.word &
|
|
kvm_calc_shadow_mmu_root_page_role(vcpu).word;
|
|
reset_shadow_zero_bits_mask(vcpu, context);
|
|
}
|
|
EXPORT_SYMBOL_GPL(kvm_init_shadow_mmu);
|
|
|
|
static union kvm_mmu_page_role
|
|
kvm_calc_shadow_ept_root_page_role(struct kvm_vcpu *vcpu, bool accessed_dirty)
|
|
{
|
|
union kvm_mmu_page_role role = vcpu->arch.mmu.base_role;
|
|
|
|
role.level = PT64_ROOT_4LEVEL;
|
|
role.direct = false;
|
|
role.ad_disabled = !accessed_dirty;
|
|
role.guest_mode = true;
|
|
role.access = ACC_ALL;
|
|
|
|
return role;
|
|
}
|
|
|
|
void kvm_init_shadow_ept_mmu(struct kvm_vcpu *vcpu, bool execonly,
|
|
bool accessed_dirty, gpa_t new_eptp)
|
|
{
|
|
struct kvm_mmu *context = &vcpu->arch.mmu;
|
|
union kvm_mmu_page_role root_page_role =
|
|
kvm_calc_shadow_ept_root_page_role(vcpu, accessed_dirty);
|
|
|
|
__kvm_mmu_new_cr3(vcpu, new_eptp, root_page_role, false);
|
|
context->shadow_root_level = PT64_ROOT_4LEVEL;
|
|
|
|
context->nx = true;
|
|
context->ept_ad = accessed_dirty;
|
|
context->page_fault = ept_page_fault;
|
|
context->gva_to_gpa = ept_gva_to_gpa;
|
|
context->sync_page = ept_sync_page;
|
|
context->invlpg = ept_invlpg;
|
|
context->update_pte = ept_update_pte;
|
|
context->root_level = PT64_ROOT_4LEVEL;
|
|
context->direct_map = false;
|
|
context->base_role.word = root_page_role.word & mmu_base_role_mask.word;
|
|
update_permission_bitmask(vcpu, context, true);
|
|
update_pkru_bitmask(vcpu, context, true);
|
|
update_last_nonleaf_level(vcpu, context);
|
|
reset_rsvds_bits_mask_ept(vcpu, context, execonly);
|
|
reset_ept_shadow_zero_bits_mask(vcpu, context, execonly);
|
|
}
|
|
EXPORT_SYMBOL_GPL(kvm_init_shadow_ept_mmu);
|
|
|
|
static void init_kvm_softmmu(struct kvm_vcpu *vcpu)
|
|
{
|
|
struct kvm_mmu *context = &vcpu->arch.mmu;
|
|
|
|
kvm_init_shadow_mmu(vcpu);
|
|
context->set_cr3 = kvm_x86_ops->set_cr3;
|
|
context->get_cr3 = get_cr3;
|
|
context->get_pdptr = kvm_pdptr_read;
|
|
context->inject_page_fault = kvm_inject_page_fault;
|
|
}
|
|
|
|
static void init_kvm_nested_mmu(struct kvm_vcpu *vcpu)
|
|
{
|
|
struct kvm_mmu *g_context = &vcpu->arch.nested_mmu;
|
|
|
|
g_context->get_cr3 = get_cr3;
|
|
g_context->get_pdptr = kvm_pdptr_read;
|
|
g_context->inject_page_fault = kvm_inject_page_fault;
|
|
|
|
/*
|
|
* Note that arch.mmu.gva_to_gpa translates l2_gpa to l1_gpa using
|
|
* L1's nested page tables (e.g. EPT12). The nested translation
|
|
* of l2_gva to l1_gpa is done by arch.nested_mmu.gva_to_gpa using
|
|
* L2's page tables as the first level of translation and L1's
|
|
* nested page tables as the second level of translation. Basically
|
|
* the gva_to_gpa functions between mmu and nested_mmu are swapped.
|
|
*/
|
|
if (!is_paging(vcpu)) {
|
|
g_context->nx = false;
|
|
g_context->root_level = 0;
|
|
g_context->gva_to_gpa = nonpaging_gva_to_gpa_nested;
|
|
} else if (is_long_mode(vcpu)) {
|
|
g_context->nx = is_nx(vcpu);
|
|
g_context->root_level = is_la57_mode(vcpu) ?
|
|
PT64_ROOT_5LEVEL : PT64_ROOT_4LEVEL;
|
|
reset_rsvds_bits_mask(vcpu, g_context);
|
|
g_context->gva_to_gpa = paging64_gva_to_gpa_nested;
|
|
} else if (is_pae(vcpu)) {
|
|
g_context->nx = is_nx(vcpu);
|
|
g_context->root_level = PT32E_ROOT_LEVEL;
|
|
reset_rsvds_bits_mask(vcpu, g_context);
|
|
g_context->gva_to_gpa = paging64_gva_to_gpa_nested;
|
|
} else {
|
|
g_context->nx = false;
|
|
g_context->root_level = PT32_ROOT_LEVEL;
|
|
reset_rsvds_bits_mask(vcpu, g_context);
|
|
g_context->gva_to_gpa = paging32_gva_to_gpa_nested;
|
|
}
|
|
|
|
update_permission_bitmask(vcpu, g_context, false);
|
|
update_pkru_bitmask(vcpu, g_context, false);
|
|
update_last_nonleaf_level(vcpu, g_context);
|
|
}
|
|
|
|
void kvm_init_mmu(struct kvm_vcpu *vcpu, bool reset_roots)
|
|
{
|
|
if (reset_roots) {
|
|
uint i;
|
|
|
|
vcpu->arch.mmu.root_hpa = INVALID_PAGE;
|
|
|
|
for (i = 0; i < KVM_MMU_NUM_PREV_ROOTS; i++)
|
|
vcpu->arch.mmu.prev_roots[i] = KVM_MMU_ROOT_INFO_INVALID;
|
|
}
|
|
|
|
if (mmu_is_nested(vcpu))
|
|
init_kvm_nested_mmu(vcpu);
|
|
else if (tdp_enabled)
|
|
init_kvm_tdp_mmu(vcpu);
|
|
else
|
|
init_kvm_softmmu(vcpu);
|
|
}
|
|
EXPORT_SYMBOL_GPL(kvm_init_mmu);
|
|
|
|
static union kvm_mmu_page_role
|
|
kvm_mmu_calc_root_page_role(struct kvm_vcpu *vcpu)
|
|
{
|
|
if (tdp_enabled)
|
|
return kvm_calc_tdp_mmu_root_page_role(vcpu);
|
|
else
|
|
return kvm_calc_shadow_mmu_root_page_role(vcpu);
|
|
}
|
|
|
|
void kvm_mmu_reset_context(struct kvm_vcpu *vcpu)
|
|
{
|
|
kvm_mmu_unload(vcpu);
|
|
kvm_init_mmu(vcpu, true);
|
|
}
|
|
EXPORT_SYMBOL_GPL(kvm_mmu_reset_context);
|
|
|
|
int kvm_mmu_load(struct kvm_vcpu *vcpu)
|
|
{
|
|
int r;
|
|
|
|
r = mmu_topup_memory_caches(vcpu);
|
|
if (r)
|
|
goto out;
|
|
r = mmu_alloc_roots(vcpu);
|
|
kvm_mmu_sync_roots(vcpu);
|
|
if (r)
|
|
goto out;
|
|
kvm_mmu_load_cr3(vcpu);
|
|
kvm_x86_ops->tlb_flush(vcpu, true);
|
|
out:
|
|
return r;
|
|
}
|
|
EXPORT_SYMBOL_GPL(kvm_mmu_load);
|
|
|
|
void kvm_mmu_unload(struct kvm_vcpu *vcpu)
|
|
{
|
|
kvm_mmu_free_roots(vcpu, KVM_MMU_ROOTS_ALL);
|
|
WARN_ON(VALID_PAGE(vcpu->arch.mmu.root_hpa));
|
|
}
|
|
EXPORT_SYMBOL_GPL(kvm_mmu_unload);
|
|
|
|
static void mmu_pte_write_new_pte(struct kvm_vcpu *vcpu,
|
|
struct kvm_mmu_page *sp, u64 *spte,
|
|
const void *new)
|
|
{
|
|
if (sp->role.level != PT_PAGE_TABLE_LEVEL) {
|
|
++vcpu->kvm->stat.mmu_pde_zapped;
|
|
return;
|
|
}
|
|
|
|
++vcpu->kvm->stat.mmu_pte_updated;
|
|
vcpu->arch.mmu.update_pte(vcpu, sp, spte, new);
|
|
}
|
|
|
|
static bool need_remote_flush(u64 old, u64 new)
|
|
{
|
|
if (!is_shadow_present_pte(old))
|
|
return false;
|
|
if (!is_shadow_present_pte(new))
|
|
return true;
|
|
if ((old ^ new) & PT64_BASE_ADDR_MASK)
|
|
return true;
|
|
old ^= shadow_nx_mask;
|
|
new ^= shadow_nx_mask;
|
|
return (old & ~new & PT64_PERM_MASK) != 0;
|
|
}
|
|
|
|
static u64 mmu_pte_write_fetch_gpte(struct kvm_vcpu *vcpu, gpa_t *gpa,
|
|
int *bytes)
|
|
{
|
|
u64 gentry = 0;
|
|
int r;
|
|
|
|
/*
|
|
* Assume that the pte write on a page table of the same type
|
|
* as the current vcpu paging mode since we update the sptes only
|
|
* when they have the same mode.
|
|
*/
|
|
if (is_pae(vcpu) && *bytes == 4) {
|
|
/* Handle a 32-bit guest writing two halves of a 64-bit gpte */
|
|
*gpa &= ~(gpa_t)7;
|
|
*bytes = 8;
|
|
}
|
|
|
|
if (*bytes == 4 || *bytes == 8) {
|
|
r = kvm_vcpu_read_guest_atomic(vcpu, *gpa, &gentry, *bytes);
|
|
if (r)
|
|
gentry = 0;
|
|
}
|
|
|
|
return gentry;
|
|
}
|
|
|
|
/*
|
|
* If we're seeing too many writes to a page, it may no longer be a page table,
|
|
* or we may be forking, in which case it is better to unmap the page.
|
|
*/
|
|
static bool detect_write_flooding(struct kvm_mmu_page *sp)
|
|
{
|
|
/*
|
|
* Skip write-flooding detected for the sp whose level is 1, because
|
|
* it can become unsync, then the guest page is not write-protected.
|
|
*/
|
|
if (sp->role.level == PT_PAGE_TABLE_LEVEL)
|
|
return false;
|
|
|
|
atomic_inc(&sp->write_flooding_count);
|
|
return atomic_read(&sp->write_flooding_count) >= 3;
|
|
}
|
|
|
|
/*
|
|
* Misaligned accesses are too much trouble to fix up; also, they usually
|
|
* indicate a page is not used as a page table.
|
|
*/
|
|
static bool detect_write_misaligned(struct kvm_mmu_page *sp, gpa_t gpa,
|
|
int bytes)
|
|
{
|
|
unsigned offset, pte_size, misaligned;
|
|
|
|
pgprintk("misaligned: gpa %llx bytes %d role %x\n",
|
|
gpa, bytes, sp->role.word);
|
|
|
|
offset = offset_in_page(gpa);
|
|
pte_size = sp->role.cr4_pae ? 8 : 4;
|
|
|
|
/*
|
|
* Sometimes, the OS only writes the last one bytes to update status
|
|
* bits, for example, in linux, andb instruction is used in clear_bit().
|
|
*/
|
|
if (!(offset & (pte_size - 1)) && bytes == 1)
|
|
return false;
|
|
|
|
misaligned = (offset ^ (offset + bytes - 1)) & ~(pte_size - 1);
|
|
misaligned |= bytes < 4;
|
|
|
|
return misaligned;
|
|
}
|
|
|
|
static u64 *get_written_sptes(struct kvm_mmu_page *sp, gpa_t gpa, int *nspte)
|
|
{
|
|
unsigned page_offset, quadrant;
|
|
u64 *spte;
|
|
int level;
|
|
|
|
page_offset = offset_in_page(gpa);
|
|
level = sp->role.level;
|
|
*nspte = 1;
|
|
if (!sp->role.cr4_pae) {
|
|
page_offset <<= 1; /* 32->64 */
|
|
/*
|
|
* A 32-bit pde maps 4MB while the shadow pdes map
|
|
* only 2MB. So we need to double the offset again
|
|
* and zap two pdes instead of one.
|
|
*/
|
|
if (level == PT32_ROOT_LEVEL) {
|
|
page_offset &= ~7; /* kill rounding error */
|
|
page_offset <<= 1;
|
|
*nspte = 2;
|
|
}
|
|
quadrant = page_offset >> PAGE_SHIFT;
|
|
page_offset &= ~PAGE_MASK;
|
|
if (quadrant != sp->role.quadrant)
|
|
return NULL;
|
|
}
|
|
|
|
spte = &sp->spt[page_offset / sizeof(*spte)];
|
|
return spte;
|
|
}
|
|
|
|
static void kvm_mmu_pte_write(struct kvm_vcpu *vcpu, gpa_t gpa,
|
|
const u8 *new, int bytes,
|
|
struct kvm_page_track_notifier_node *node)
|
|
{
|
|
gfn_t gfn = gpa >> PAGE_SHIFT;
|
|
struct kvm_mmu_page *sp;
|
|
LIST_HEAD(invalid_list);
|
|
u64 entry, gentry, *spte;
|
|
int npte;
|
|
bool remote_flush, local_flush;
|
|
|
|
/*
|
|
* If we don't have indirect shadow pages, it means no page is
|
|
* write-protected, so we can exit simply.
|
|
*/
|
|
if (!READ_ONCE(vcpu->kvm->arch.indirect_shadow_pages))
|
|
return;
|
|
|
|
remote_flush = local_flush = false;
|
|
|
|
pgprintk("%s: gpa %llx bytes %d\n", __func__, gpa, bytes);
|
|
|
|
/*
|
|
* No need to care whether allocation memory is successful
|
|
* or not since pte prefetch is skiped if it does not have
|
|
* enough objects in the cache.
|
|
*/
|
|
mmu_topup_memory_caches(vcpu);
|
|
|
|
spin_lock(&vcpu->kvm->mmu_lock);
|
|
|
|
gentry = mmu_pte_write_fetch_gpte(vcpu, &gpa, &bytes);
|
|
|
|
++vcpu->kvm->stat.mmu_pte_write;
|
|
kvm_mmu_audit(vcpu, AUDIT_PRE_PTE_WRITE);
|
|
|
|
for_each_gfn_indirect_valid_sp(vcpu->kvm, sp, gfn) {
|
|
if (detect_write_misaligned(sp, gpa, bytes) ||
|
|
detect_write_flooding(sp)) {
|
|
kvm_mmu_prepare_zap_page(vcpu->kvm, sp, &invalid_list);
|
|
++vcpu->kvm->stat.mmu_flooded;
|
|
continue;
|
|
}
|
|
|
|
spte = get_written_sptes(sp, gpa, &npte);
|
|
if (!spte)
|
|
continue;
|
|
|
|
local_flush = true;
|
|
while (npte--) {
|
|
entry = *spte;
|
|
mmu_page_zap_pte(vcpu->kvm, sp, spte);
|
|
if (gentry &&
|
|
!((sp->role.word ^ vcpu->arch.mmu.base_role.word)
|
|
& mmu_base_role_mask.word) && rmap_can_add(vcpu))
|
|
mmu_pte_write_new_pte(vcpu, sp, spte, &gentry);
|
|
if (need_remote_flush(entry, *spte))
|
|
remote_flush = true;
|
|
++spte;
|
|
}
|
|
}
|
|
kvm_mmu_flush_or_zap(vcpu, &invalid_list, remote_flush, local_flush);
|
|
kvm_mmu_audit(vcpu, AUDIT_POST_PTE_WRITE);
|
|
spin_unlock(&vcpu->kvm->mmu_lock);
|
|
}
|
|
|
|
int kvm_mmu_unprotect_page_virt(struct kvm_vcpu *vcpu, gva_t gva)
|
|
{
|
|
gpa_t gpa;
|
|
int r;
|
|
|
|
if (vcpu->arch.mmu.direct_map)
|
|
return 0;
|
|
|
|
gpa = kvm_mmu_gva_to_gpa_read(vcpu, gva, NULL);
|
|
|
|
r = kvm_mmu_unprotect_page(vcpu->kvm, gpa >> PAGE_SHIFT);
|
|
|
|
return r;
|
|
}
|
|
EXPORT_SYMBOL_GPL(kvm_mmu_unprotect_page_virt);
|
|
|
|
static int make_mmu_pages_available(struct kvm_vcpu *vcpu)
|
|
{
|
|
LIST_HEAD(invalid_list);
|
|
|
|
if (likely(kvm_mmu_available_pages(vcpu->kvm) >= KVM_MIN_FREE_MMU_PAGES))
|
|
return 0;
|
|
|
|
while (kvm_mmu_available_pages(vcpu->kvm) < KVM_REFILL_PAGES) {
|
|
if (!prepare_zap_oldest_mmu_page(vcpu->kvm, &invalid_list))
|
|
break;
|
|
|
|
++vcpu->kvm->stat.mmu_recycled;
|
|
}
|
|
kvm_mmu_commit_zap_page(vcpu->kvm, &invalid_list);
|
|
|
|
if (!kvm_mmu_available_pages(vcpu->kvm))
|
|
return -ENOSPC;
|
|
return 0;
|
|
}
|
|
|
|
int kvm_mmu_page_fault(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa, u64 error_code,
|
|
void *insn, int insn_len)
|
|
{
|
|
int r, emulation_type = 0;
|
|
enum emulation_result er;
|
|
bool direct = vcpu->arch.mmu.direct_map;
|
|
|
|
/* With shadow page tables, fault_address contains a GVA or nGPA. */
|
|
if (vcpu->arch.mmu.direct_map) {
|
|
vcpu->arch.gpa_available = true;
|
|
vcpu->arch.gpa_val = cr2_or_gpa;
|
|
}
|
|
|
|
r = RET_PF_INVALID;
|
|
if (unlikely(error_code & PFERR_RSVD_MASK)) {
|
|
r = handle_mmio_page_fault(vcpu, cr2_or_gpa, direct);
|
|
if (r == RET_PF_EMULATE)
|
|
goto emulate;
|
|
}
|
|
|
|
if (r == RET_PF_INVALID) {
|
|
r = vcpu->arch.mmu.page_fault(vcpu, cr2_or_gpa,
|
|
lower_32_bits(error_code),
|
|
false);
|
|
WARN_ON(r == RET_PF_INVALID);
|
|
}
|
|
|
|
if (r == RET_PF_RETRY)
|
|
return 1;
|
|
if (r < 0)
|
|
return r;
|
|
|
|
/*
|
|
* Before emulating the instruction, check if the error code
|
|
* was due to a RO violation while translating the guest page.
|
|
* This can occur when using nested virtualization with nested
|
|
* paging in both guests. If true, we simply unprotect the page
|
|
* and resume the guest.
|
|
*/
|
|
if (vcpu->arch.mmu.direct_map &&
|
|
(error_code & PFERR_NESTED_GUEST_PAGE) == PFERR_NESTED_GUEST_PAGE) {
|
|
kvm_mmu_unprotect_page(vcpu->kvm, gpa_to_gfn(cr2_or_gpa));
|
|
return 1;
|
|
}
|
|
|
|
/*
|
|
* vcpu->arch.mmu.page_fault returned RET_PF_EMULATE, but we can still
|
|
* optimistically try to just unprotect the page and let the processor
|
|
* re-execute the instruction that caused the page fault. Do not allow
|
|
* retrying MMIO emulation, as it's not only pointless but could also
|
|
* cause us to enter an infinite loop because the processor will keep
|
|
* faulting on the non-existent MMIO address. Retrying an instruction
|
|
* from a nested guest is also pointless and dangerous as we are only
|
|
* explicitly shadowing L1's page tables, i.e. unprotecting something
|
|
* for L1 isn't going to magically fix whatever issue cause L2 to fail.
|
|
*/
|
|
if (!mmio_info_in_cache(vcpu, cr2_or_gpa, direct) && !is_guest_mode(vcpu))
|
|
emulation_type = EMULTYPE_ALLOW_RETRY;
|
|
emulate:
|
|
/*
|
|
* On AMD platforms, under certain conditions insn_len may be zero on #NPF.
|
|
* This can happen if a guest gets a page-fault on data access but the HW
|
|
* table walker is not able to read the instruction page (e.g instruction
|
|
* page is not present in memory). In those cases we simply restart the
|
|
* guest.
|
|
*/
|
|
if (unlikely(insn && !insn_len))
|
|
return 1;
|
|
|
|
er = x86_emulate_instruction(vcpu, cr2_or_gpa, emulation_type, insn, insn_len);
|
|
|
|
switch (er) {
|
|
case EMULATE_DONE:
|
|
return 1;
|
|
case EMULATE_USER_EXIT:
|
|
++vcpu->stat.mmio_exits;
|
|
/* fall through */
|
|
case EMULATE_FAIL:
|
|
return 0;
|
|
default:
|
|
BUG();
|
|
}
|
|
}
|
|
EXPORT_SYMBOL_GPL(kvm_mmu_page_fault);
|
|
|
|
void kvm_mmu_invlpg(struct kvm_vcpu *vcpu, gva_t gva)
|
|
{
|
|
struct kvm_mmu *mmu = &vcpu->arch.mmu;
|
|
int i;
|
|
|
|
/* INVLPG on a * non-canonical address is a NOP according to the SDM. */
|
|
if (is_noncanonical_address(gva, vcpu))
|
|
return;
|
|
|
|
mmu->invlpg(vcpu, gva, mmu->root_hpa);
|
|
|
|
/*
|
|
* INVLPG is required to invalidate any global mappings for the VA,
|
|
* irrespective of PCID. Since it would take us roughly similar amount
|
|
* of work to determine whether any of the prev_root mappings of the VA
|
|
* is marked global, or to just sync it blindly, so we might as well
|
|
* just always sync it.
|
|
*
|
|
* Mappings not reachable via the current cr3 or the prev_roots will be
|
|
* synced when switching to that cr3, so nothing needs to be done here
|
|
* for them.
|
|
*/
|
|
for (i = 0; i < KVM_MMU_NUM_PREV_ROOTS; i++)
|
|
if (VALID_PAGE(mmu->prev_roots[i].hpa))
|
|
mmu->invlpg(vcpu, gva, mmu->prev_roots[i].hpa);
|
|
|
|
kvm_x86_ops->tlb_flush_gva(vcpu, gva);
|
|
++vcpu->stat.invlpg;
|
|
}
|
|
EXPORT_SYMBOL_GPL(kvm_mmu_invlpg);
|
|
|
|
void kvm_mmu_invpcid_gva(struct kvm_vcpu *vcpu, gva_t gva, unsigned long pcid)
|
|
{
|
|
struct kvm_mmu *mmu = &vcpu->arch.mmu;
|
|
bool tlb_flush = false;
|
|
uint i;
|
|
|
|
if (pcid == kvm_get_active_pcid(vcpu)) {
|
|
mmu->invlpg(vcpu, gva, mmu->root_hpa);
|
|
tlb_flush = true;
|
|
}
|
|
|
|
for (i = 0; i < KVM_MMU_NUM_PREV_ROOTS; i++) {
|
|
if (VALID_PAGE(mmu->prev_roots[i].hpa) &&
|
|
pcid == kvm_get_pcid(vcpu, mmu->prev_roots[i].cr3)) {
|
|
mmu->invlpg(vcpu, gva, mmu->prev_roots[i].hpa);
|
|
tlb_flush = true;
|
|
}
|
|
}
|
|
|
|
if (tlb_flush)
|
|
kvm_x86_ops->tlb_flush_gva(vcpu, gva);
|
|
|
|
++vcpu->stat.invlpg;
|
|
|
|
/*
|
|
* Mappings not reachable via the current cr3 or the prev_roots will be
|
|
* synced when switching to that cr3, so nothing needs to be done here
|
|
* for them.
|
|
*/
|
|
}
|
|
EXPORT_SYMBOL_GPL(kvm_mmu_invpcid_gva);
|
|
|
|
void kvm_enable_tdp(void)
|
|
{
|
|
tdp_enabled = true;
|
|
}
|
|
EXPORT_SYMBOL_GPL(kvm_enable_tdp);
|
|
|
|
void kvm_disable_tdp(void)
|
|
{
|
|
tdp_enabled = false;
|
|
}
|
|
EXPORT_SYMBOL_GPL(kvm_disable_tdp);
|
|
|
|
static void free_mmu_pages(struct kvm_vcpu *vcpu)
|
|
{
|
|
free_page((unsigned long)vcpu->arch.mmu.pae_root);
|
|
free_page((unsigned long)vcpu->arch.mmu.lm_root);
|
|
}
|
|
|
|
static int alloc_mmu_pages(struct kvm_vcpu *vcpu)
|
|
{
|
|
struct page *page;
|
|
int i;
|
|
|
|
/*
|
|
* When using PAE paging, the four PDPTEs are treated as 'root' pages,
|
|
* while the PDP table is a per-vCPU construct that's allocated at MMU
|
|
* creation. When emulating 32-bit mode, cr3 is only 32 bits even on
|
|
* x86_64. Therefore we need to allocate the PDP table in the first
|
|
* 4GB of memory, which happens to fit the DMA32 zone. Except for
|
|
* SVM's 32-bit NPT support, TDP paging doesn't use PAE paging and can
|
|
* skip allocating the PDP table.
|
|
*/
|
|
if (tdp_enabled && kvm_x86_ops->get_tdp_level(vcpu) > PT32E_ROOT_LEVEL)
|
|
return 0;
|
|
|
|
/*
|
|
* When emulating 32-bit mode, cr3 is only 32 bits even on x86_64.
|
|
* Therefore we need to allocate shadow page tables in the first
|
|
* 4GB of memory, which happens to fit the DMA32 zone.
|
|
*/
|
|
page = alloc_page(GFP_KERNEL | __GFP_DMA32);
|
|
if (!page)
|
|
return -ENOMEM;
|
|
|
|
vcpu->arch.mmu.pae_root = page_address(page);
|
|
for (i = 0; i < 4; ++i)
|
|
vcpu->arch.mmu.pae_root[i] = INVALID_PAGE;
|
|
|
|
return 0;
|
|
}
|
|
|
|
int kvm_mmu_create(struct kvm_vcpu *vcpu)
|
|
{
|
|
uint i;
|
|
|
|
vcpu->arch.walk_mmu = &vcpu->arch.mmu;
|
|
vcpu->arch.mmu.root_hpa = INVALID_PAGE;
|
|
vcpu->arch.mmu.translate_gpa = translate_gpa;
|
|
vcpu->arch.nested_mmu.translate_gpa = translate_nested_gpa;
|
|
|
|
for (i = 0; i < KVM_MMU_NUM_PREV_ROOTS; i++)
|
|
vcpu->arch.mmu.prev_roots[i] = KVM_MMU_ROOT_INFO_INVALID;
|
|
|
|
return alloc_mmu_pages(vcpu);
|
|
}
|
|
|
|
void kvm_mmu_setup(struct kvm_vcpu *vcpu)
|
|
{
|
|
MMU_WARN_ON(VALID_PAGE(vcpu->arch.mmu.root_hpa));
|
|
|
|
/*
|
|
* kvm_mmu_setup() is called only on vCPU initialization.
|
|
* Therefore, no need to reset mmu roots as they are not yet
|
|
* initialized.
|
|
*/
|
|
kvm_init_mmu(vcpu, false);
|
|
}
|
|
|
|
static void kvm_mmu_invalidate_zap_pages_in_memslot(struct kvm *kvm,
|
|
struct kvm_memory_slot *slot,
|
|
struct kvm_page_track_notifier_node *node)
|
|
{
|
|
kvm_mmu_invalidate_zap_all_pages(kvm);
|
|
}
|
|
|
|
void kvm_mmu_init_vm(struct kvm *kvm)
|
|
{
|
|
struct kvm_page_track_notifier_node *node = &kvm->arch.mmu_sp_tracker;
|
|
|
|
node->track_write = kvm_mmu_pte_write;
|
|
node->track_flush_slot = kvm_mmu_invalidate_zap_pages_in_memslot;
|
|
kvm_page_track_register_notifier(kvm, node);
|
|
}
|
|
|
|
void kvm_mmu_uninit_vm(struct kvm *kvm)
|
|
{
|
|
struct kvm_page_track_notifier_node *node = &kvm->arch.mmu_sp_tracker;
|
|
|
|
kvm_page_track_unregister_notifier(kvm, node);
|
|
}
|
|
|
|
/* The return value indicates if tlb flush on all vcpus is needed. */
|
|
typedef bool (*slot_level_handler) (struct kvm *kvm, struct kvm_rmap_head *rmap_head);
|
|
|
|
/* The caller should hold mmu-lock before calling this function. */
|
|
static __always_inline bool
|
|
slot_handle_level_range(struct kvm *kvm, struct kvm_memory_slot *memslot,
|
|
slot_level_handler fn, int start_level, int end_level,
|
|
gfn_t start_gfn, gfn_t end_gfn, bool lock_flush_tlb)
|
|
{
|
|
struct slot_rmap_walk_iterator iterator;
|
|
bool flush = false;
|
|
|
|
for_each_slot_rmap_range(memslot, start_level, end_level, start_gfn,
|
|
end_gfn, &iterator) {
|
|
if (iterator.rmap)
|
|
flush |= fn(kvm, iterator.rmap);
|
|
|
|
if (need_resched() || spin_needbreak(&kvm->mmu_lock)) {
|
|
if (flush && lock_flush_tlb) {
|
|
kvm_flush_remote_tlbs(kvm);
|
|
flush = false;
|
|
}
|
|
cond_resched_lock(&kvm->mmu_lock);
|
|
}
|
|
}
|
|
|
|
if (flush && lock_flush_tlb) {
|
|
kvm_flush_remote_tlbs(kvm);
|
|
flush = false;
|
|
}
|
|
|
|
return flush;
|
|
}
|
|
|
|
static __always_inline bool
|
|
slot_handle_level(struct kvm *kvm, struct kvm_memory_slot *memslot,
|
|
slot_level_handler fn, int start_level, int end_level,
|
|
bool lock_flush_tlb)
|
|
{
|
|
return slot_handle_level_range(kvm, memslot, fn, start_level,
|
|
end_level, memslot->base_gfn,
|
|
memslot->base_gfn + memslot->npages - 1,
|
|
lock_flush_tlb);
|
|
}
|
|
|
|
static __always_inline bool
|
|
slot_handle_all_level(struct kvm *kvm, struct kvm_memory_slot *memslot,
|
|
slot_level_handler fn, bool lock_flush_tlb)
|
|
{
|
|
return slot_handle_level(kvm, memslot, fn, PT_PAGE_TABLE_LEVEL,
|
|
PT_MAX_HUGEPAGE_LEVEL, lock_flush_tlb);
|
|
}
|
|
|
|
static __always_inline bool
|
|
slot_handle_large_level(struct kvm *kvm, struct kvm_memory_slot *memslot,
|
|
slot_level_handler fn, bool lock_flush_tlb)
|
|
{
|
|
return slot_handle_level(kvm, memslot, fn, PT_PAGE_TABLE_LEVEL + 1,
|
|
PT_MAX_HUGEPAGE_LEVEL, lock_flush_tlb);
|
|
}
|
|
|
|
static __always_inline bool
|
|
slot_handle_leaf(struct kvm *kvm, struct kvm_memory_slot *memslot,
|
|
slot_level_handler fn, bool lock_flush_tlb)
|
|
{
|
|
return slot_handle_level(kvm, memslot, fn, PT_PAGE_TABLE_LEVEL,
|
|
PT_PAGE_TABLE_LEVEL, lock_flush_tlb);
|
|
}
|
|
|
|
void kvm_zap_gfn_range(struct kvm *kvm, gfn_t gfn_start, gfn_t gfn_end)
|
|
{
|
|
struct kvm_memslots *slots;
|
|
struct kvm_memory_slot *memslot;
|
|
int i;
|
|
|
|
spin_lock(&kvm->mmu_lock);
|
|
for (i = 0; i < KVM_ADDRESS_SPACE_NUM; i++) {
|
|
slots = __kvm_memslots(kvm, i);
|
|
kvm_for_each_memslot(memslot, slots) {
|
|
gfn_t start, end;
|
|
|
|
start = max(gfn_start, memslot->base_gfn);
|
|
end = min(gfn_end, memslot->base_gfn + memslot->npages);
|
|
if (start >= end)
|
|
continue;
|
|
|
|
slot_handle_level_range(kvm, memslot, kvm_zap_rmapp,
|
|
PT_PAGE_TABLE_LEVEL, PT_MAX_HUGEPAGE_LEVEL,
|
|
start, end - 1, true);
|
|
}
|
|
}
|
|
|
|
spin_unlock(&kvm->mmu_lock);
|
|
}
|
|
|
|
static bool slot_rmap_write_protect(struct kvm *kvm,
|
|
struct kvm_rmap_head *rmap_head)
|
|
{
|
|
return __rmap_write_protect(kvm, rmap_head, false);
|
|
}
|
|
|
|
void kvm_mmu_slot_remove_write_access(struct kvm *kvm,
|
|
struct kvm_memory_slot *memslot)
|
|
{
|
|
bool flush;
|
|
|
|
spin_lock(&kvm->mmu_lock);
|
|
flush = slot_handle_all_level(kvm, memslot, slot_rmap_write_protect,
|
|
false);
|
|
spin_unlock(&kvm->mmu_lock);
|
|
|
|
/*
|
|
* kvm_mmu_slot_remove_write_access() and kvm_vm_ioctl_get_dirty_log()
|
|
* which do tlb flush out of mmu-lock should be serialized by
|
|
* kvm->slots_lock otherwise tlb flush would be missed.
|
|
*/
|
|
lockdep_assert_held(&kvm->slots_lock);
|
|
|
|
/*
|
|
* We can flush all the TLBs out of the mmu lock without TLB
|
|
* corruption since we just change the spte from writable to
|
|
* readonly so that we only need to care the case of changing
|
|
* spte from present to present (changing the spte from present
|
|
* to nonpresent will flush all the TLBs immediately), in other
|
|
* words, the only case we care is mmu_spte_update() where we
|
|
* haved checked SPTE_HOST_WRITEABLE | SPTE_MMU_WRITEABLE
|
|
* instead of PT_WRITABLE_MASK, that means it does not depend
|
|
* on PT_WRITABLE_MASK anymore.
|
|
*/
|
|
if (flush)
|
|
kvm_flush_remote_tlbs(kvm);
|
|
}
|
|
|
|
static bool kvm_mmu_zap_collapsible_spte(struct kvm *kvm,
|
|
struct kvm_rmap_head *rmap_head)
|
|
{
|
|
u64 *sptep;
|
|
struct rmap_iterator iter;
|
|
int need_tlb_flush = 0;
|
|
kvm_pfn_t pfn;
|
|
struct kvm_mmu_page *sp;
|
|
|
|
restart:
|
|
for_each_rmap_spte(rmap_head, &iter, sptep) {
|
|
sp = page_header(__pa(sptep));
|
|
pfn = spte_to_pfn(*sptep);
|
|
|
|
/*
|
|
* We cannot do huge page mapping for indirect shadow pages,
|
|
* which are found on the last rmap (level = 1) when not using
|
|
* tdp; such shadow pages are synced with the page table in
|
|
* the guest, and the guest page table is using 4K page size
|
|
* mapping if the indirect sp has level = 1.
|
|
*/
|
|
if (sp->role.direct && !kvm_is_reserved_pfn(pfn) &&
|
|
!kvm_is_zone_device_pfn(pfn) &&
|
|
PageTransCompoundMap(pfn_to_page(pfn))) {
|
|
drop_spte(kvm, sptep);
|
|
need_tlb_flush = 1;
|
|
goto restart;
|
|
}
|
|
}
|
|
|
|
return need_tlb_flush;
|
|
}
|
|
|
|
void kvm_mmu_zap_collapsible_sptes(struct kvm *kvm,
|
|
const struct kvm_memory_slot *memslot)
|
|
{
|
|
/* FIXME: const-ify all uses of struct kvm_memory_slot. */
|
|
spin_lock(&kvm->mmu_lock);
|
|
slot_handle_leaf(kvm, (struct kvm_memory_slot *)memslot,
|
|
kvm_mmu_zap_collapsible_spte, true);
|
|
spin_unlock(&kvm->mmu_lock);
|
|
}
|
|
|
|
void kvm_mmu_slot_leaf_clear_dirty(struct kvm *kvm,
|
|
struct kvm_memory_slot *memslot)
|
|
{
|
|
bool flush;
|
|
|
|
spin_lock(&kvm->mmu_lock);
|
|
flush = slot_handle_leaf(kvm, memslot, __rmap_clear_dirty, false);
|
|
spin_unlock(&kvm->mmu_lock);
|
|
|
|
lockdep_assert_held(&kvm->slots_lock);
|
|
|
|
/*
|
|
* It's also safe to flush TLBs out of mmu lock here as currently this
|
|
* function is only used for dirty logging, in which case flushing TLB
|
|
* out of mmu lock also guarantees no dirty pages will be lost in
|
|
* dirty_bitmap.
|
|
*/
|
|
if (flush)
|
|
kvm_flush_remote_tlbs(kvm);
|
|
}
|
|
EXPORT_SYMBOL_GPL(kvm_mmu_slot_leaf_clear_dirty);
|
|
|
|
void kvm_mmu_slot_largepage_remove_write_access(struct kvm *kvm,
|
|
struct kvm_memory_slot *memslot)
|
|
{
|
|
bool flush;
|
|
|
|
spin_lock(&kvm->mmu_lock);
|
|
flush = slot_handle_large_level(kvm, memslot, slot_rmap_write_protect,
|
|
false);
|
|
spin_unlock(&kvm->mmu_lock);
|
|
|
|
/* see kvm_mmu_slot_remove_write_access */
|
|
lockdep_assert_held(&kvm->slots_lock);
|
|
|
|
if (flush)
|
|
kvm_flush_remote_tlbs(kvm);
|
|
}
|
|
EXPORT_SYMBOL_GPL(kvm_mmu_slot_largepage_remove_write_access);
|
|
|
|
void kvm_mmu_slot_set_dirty(struct kvm *kvm,
|
|
struct kvm_memory_slot *memslot)
|
|
{
|
|
bool flush;
|
|
|
|
spin_lock(&kvm->mmu_lock);
|
|
flush = slot_handle_all_level(kvm, memslot, __rmap_set_dirty, false);
|
|
spin_unlock(&kvm->mmu_lock);
|
|
|
|
lockdep_assert_held(&kvm->slots_lock);
|
|
|
|
/* see kvm_mmu_slot_leaf_clear_dirty */
|
|
if (flush)
|
|
kvm_flush_remote_tlbs(kvm);
|
|
}
|
|
EXPORT_SYMBOL_GPL(kvm_mmu_slot_set_dirty);
|
|
|
|
#define BATCH_ZAP_PAGES 10
|
|
static void kvm_zap_obsolete_pages(struct kvm *kvm)
|
|
{
|
|
struct kvm_mmu_page *sp, *node;
|
|
int batch = 0;
|
|
|
|
restart:
|
|
list_for_each_entry_safe_reverse(sp, node,
|
|
&kvm->arch.active_mmu_pages, link) {
|
|
int ret;
|
|
|
|
/*
|
|
* No obsolete page exists before new created page since
|
|
* active_mmu_pages is the FIFO list.
|
|
*/
|
|
if (!is_obsolete_sp(kvm, sp))
|
|
break;
|
|
|
|
/*
|
|
* Since we are reversely walking the list and the invalid
|
|
* list will be moved to the head, skip the invalid page
|
|
* can help us to avoid the infinity list walking.
|
|
*/
|
|
if (sp->role.invalid)
|
|
continue;
|
|
|
|
/*
|
|
* Need not flush tlb since we only zap the sp with invalid
|
|
* generation number.
|
|
*/
|
|
if (batch >= BATCH_ZAP_PAGES &&
|
|
cond_resched_lock(&kvm->mmu_lock)) {
|
|
batch = 0;
|
|
goto restart;
|
|
}
|
|
|
|
ret = kvm_mmu_prepare_zap_page(kvm, sp,
|
|
&kvm->arch.zapped_obsolete_pages);
|
|
batch += ret;
|
|
|
|
if (ret)
|
|
goto restart;
|
|
}
|
|
|
|
/*
|
|
* Should flush tlb before free page tables since lockless-walking
|
|
* may use the pages.
|
|
*/
|
|
kvm_mmu_commit_zap_page(kvm, &kvm->arch.zapped_obsolete_pages);
|
|
}
|
|
|
|
/*
|
|
* Fast invalidate all shadow pages and use lock-break technique
|
|
* to zap obsolete pages.
|
|
*
|
|
* It's required when memslot is being deleted or VM is being
|
|
* destroyed, in these cases, we should ensure that KVM MMU does
|
|
* not use any resource of the being-deleted slot or all slots
|
|
* after calling the function.
|
|
*/
|
|
void kvm_mmu_invalidate_zap_all_pages(struct kvm *kvm)
|
|
{
|
|
spin_lock(&kvm->mmu_lock);
|
|
trace_kvm_mmu_invalidate_zap_all_pages(kvm);
|
|
kvm->arch.mmu_valid_gen++;
|
|
|
|
/*
|
|
* Notify all vcpus to reload its shadow page table
|
|
* and flush TLB. Then all vcpus will switch to new
|
|
* shadow page table with the new mmu_valid_gen.
|
|
*
|
|
* Note: we should do this under the protection of
|
|
* mmu-lock, otherwise, vcpu would purge shadow page
|
|
* but miss tlb flush.
|
|
*/
|
|
kvm_reload_remote_mmus(kvm);
|
|
|
|
kvm_zap_obsolete_pages(kvm);
|
|
spin_unlock(&kvm->mmu_lock);
|
|
}
|
|
|
|
static bool kvm_has_zapped_obsolete_pages(struct kvm *kvm)
|
|
{
|
|
return unlikely(!list_empty_careful(&kvm->arch.zapped_obsolete_pages));
|
|
}
|
|
|
|
void kvm_mmu_invalidate_mmio_sptes(struct kvm *kvm, u64 gen)
|
|
{
|
|
gen &= MMIO_GEN_MASK;
|
|
|
|
/*
|
|
* Shift to eliminate the "update in-progress" flag, which isn't
|
|
* included in the spte's generation number.
|
|
*/
|
|
gen >>= 1;
|
|
|
|
/*
|
|
* Generation numbers are incremented in multiples of the number of
|
|
* address spaces in order to provide unique generations across all
|
|
* address spaces. Strip what is effectively the address space
|
|
* modifier prior to checking for a wrap of the MMIO generation so
|
|
* that a wrap in any address space is detected.
|
|
*/
|
|
gen &= ~((u64)KVM_ADDRESS_SPACE_NUM - 1);
|
|
|
|
/*
|
|
* The very rare case: if the MMIO generation number has wrapped,
|
|
* zap all shadow pages.
|
|
*/
|
|
if (unlikely(gen == 0)) {
|
|
kvm_debug_ratelimited("kvm: zapping shadow pages for mmio generation wraparound\n");
|
|
kvm_mmu_invalidate_zap_all_pages(kvm);
|
|
}
|
|
}
|
|
|
|
static unsigned long
|
|
mmu_shrink_scan(struct shrinker *shrink, struct shrink_control *sc)
|
|
{
|
|
struct kvm *kvm;
|
|
int nr_to_scan = sc->nr_to_scan;
|
|
unsigned long freed = 0;
|
|
|
|
mutex_lock(&kvm_lock);
|
|
|
|
list_for_each_entry(kvm, &vm_list, vm_list) {
|
|
int idx;
|
|
LIST_HEAD(invalid_list);
|
|
|
|
/*
|
|
* Never scan more than sc->nr_to_scan VM instances.
|
|
* Will not hit this condition practically since we do not try
|
|
* to shrink more than one VM and it is very unlikely to see
|
|
* !n_used_mmu_pages so many times.
|
|
*/
|
|
if (!nr_to_scan--)
|
|
break;
|
|
/*
|
|
* n_used_mmu_pages is accessed without holding kvm->mmu_lock
|
|
* here. We may skip a VM instance errorneosly, but we do not
|
|
* want to shrink a VM that only started to populate its MMU
|
|
* anyway.
|
|
*/
|
|
if (!kvm->arch.n_used_mmu_pages &&
|
|
!kvm_has_zapped_obsolete_pages(kvm))
|
|
continue;
|
|
|
|
idx = srcu_read_lock(&kvm->srcu);
|
|
spin_lock(&kvm->mmu_lock);
|
|
|
|
if (kvm_has_zapped_obsolete_pages(kvm)) {
|
|
kvm_mmu_commit_zap_page(kvm,
|
|
&kvm->arch.zapped_obsolete_pages);
|
|
goto unlock;
|
|
}
|
|
|
|
if (prepare_zap_oldest_mmu_page(kvm, &invalid_list))
|
|
freed++;
|
|
kvm_mmu_commit_zap_page(kvm, &invalid_list);
|
|
|
|
unlock:
|
|
spin_unlock(&kvm->mmu_lock);
|
|
srcu_read_unlock(&kvm->srcu, idx);
|
|
|
|
/*
|
|
* unfair on small ones
|
|
* per-vm shrinkers cry out
|
|
* sadness comes quickly
|
|
*/
|
|
list_move_tail(&kvm->vm_list, &vm_list);
|
|
break;
|
|
}
|
|
|
|
mutex_unlock(&kvm_lock);
|
|
return freed;
|
|
}
|
|
|
|
static unsigned long
|
|
mmu_shrink_count(struct shrinker *shrink, struct shrink_control *sc)
|
|
{
|
|
return percpu_counter_read_positive(&kvm_total_used_mmu_pages);
|
|
}
|
|
|
|
static struct shrinker mmu_shrinker = {
|
|
.count_objects = mmu_shrink_count,
|
|
.scan_objects = mmu_shrink_scan,
|
|
.seeks = DEFAULT_SEEKS * 10,
|
|
};
|
|
|
|
static void mmu_destroy_caches(void)
|
|
{
|
|
kmem_cache_destroy(pte_list_desc_cache);
|
|
kmem_cache_destroy(mmu_page_header_cache);
|
|
}
|
|
|
|
static bool get_nx_auto_mode(void)
|
|
{
|
|
/* Return true when CPU has the bug, and mitigations are ON */
|
|
return boot_cpu_has_bug(X86_BUG_ITLB_MULTIHIT) && !cpu_mitigations_off();
|
|
}
|
|
|
|
static void __set_nx_huge_pages(bool val)
|
|
{
|
|
nx_huge_pages = itlb_multihit_kvm_mitigation = val;
|
|
}
|
|
|
|
static int set_nx_huge_pages(const char *val, const struct kernel_param *kp)
|
|
{
|
|
bool old_val = nx_huge_pages;
|
|
bool new_val;
|
|
|
|
/* In "auto" mode deploy workaround only if CPU has the bug. */
|
|
if (sysfs_streq(val, "off"))
|
|
new_val = 0;
|
|
else if (sysfs_streq(val, "force"))
|
|
new_val = 1;
|
|
else if (sysfs_streq(val, "auto"))
|
|
new_val = get_nx_auto_mode();
|
|
else if (strtobool(val, &new_val) < 0)
|
|
return -EINVAL;
|
|
|
|
__set_nx_huge_pages(new_val);
|
|
|
|
if (new_val != old_val) {
|
|
struct kvm *kvm;
|
|
int idx;
|
|
|
|
mutex_lock(&kvm_lock);
|
|
|
|
list_for_each_entry(kvm, &vm_list, vm_list) {
|
|
idx = srcu_read_lock(&kvm->srcu);
|
|
kvm_mmu_invalidate_zap_all_pages(kvm);
|
|
srcu_read_unlock(&kvm->srcu, idx);
|
|
|
|
wake_up_process(kvm->arch.nx_lpage_recovery_thread);
|
|
}
|
|
mutex_unlock(&kvm_lock);
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
static void kvm_set_mmio_spte_mask(void)
|
|
{
|
|
u64 mask;
|
|
|
|
/*
|
|
* Set a reserved PA bit in MMIO SPTEs to generate page faults with
|
|
* PFEC.RSVD=1 on MMIO accesses. 64-bit PTEs (PAE, x86-64, and EPT
|
|
* paging) support a maximum of 52 bits of PA, i.e. if the CPU supports
|
|
* 52-bit physical addresses then there are no reserved PA bits in the
|
|
* PTEs and so the reserved PA approach must be disabled.
|
|
*/
|
|
if (shadow_phys_bits < 52)
|
|
mask = BIT_ULL(51) | PT_PRESENT_MASK;
|
|
else
|
|
mask = 0;
|
|
|
|
kvm_mmu_set_mmio_spte_mask(mask, mask);
|
|
}
|
|
|
|
int kvm_mmu_module_init(void)
|
|
{
|
|
int ret = -ENOMEM;
|
|
|
|
if (nx_huge_pages == -1)
|
|
__set_nx_huge_pages(get_nx_auto_mode());
|
|
|
|
kvm_mmu_reset_all_pte_masks();
|
|
|
|
kvm_set_mmio_spte_mask();
|
|
|
|
pte_list_desc_cache = kmem_cache_create("pte_list_desc",
|
|
sizeof(struct pte_list_desc),
|
|
0, SLAB_ACCOUNT, NULL);
|
|
if (!pte_list_desc_cache)
|
|
goto out;
|
|
|
|
mmu_page_header_cache = kmem_cache_create("kvm_mmu_page_header",
|
|
sizeof(struct kvm_mmu_page),
|
|
0, SLAB_ACCOUNT, NULL);
|
|
if (!mmu_page_header_cache)
|
|
goto out;
|
|
|
|
if (percpu_counter_init(&kvm_total_used_mmu_pages, 0, GFP_KERNEL))
|
|
goto out;
|
|
|
|
ret = register_shrinker(&mmu_shrinker);
|
|
if (ret)
|
|
goto out;
|
|
|
|
return 0;
|
|
|
|
out:
|
|
mmu_destroy_caches();
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* Caculate mmu pages needed for kvm.
|
|
*/
|
|
unsigned long kvm_mmu_calculate_mmu_pages(struct kvm *kvm)
|
|
{
|
|
unsigned long nr_mmu_pages;
|
|
unsigned long nr_pages = 0;
|
|
struct kvm_memslots *slots;
|
|
struct kvm_memory_slot *memslot;
|
|
int i;
|
|
|
|
for (i = 0; i < KVM_ADDRESS_SPACE_NUM; i++) {
|
|
slots = __kvm_memslots(kvm, i);
|
|
|
|
kvm_for_each_memslot(memslot, slots)
|
|
nr_pages += memslot->npages;
|
|
}
|
|
|
|
nr_mmu_pages = nr_pages * KVM_PERMILLE_MMU_PAGES / 1000;
|
|
nr_mmu_pages = max(nr_mmu_pages, KVM_MIN_ALLOC_MMU_PAGES);
|
|
|
|
return nr_mmu_pages;
|
|
}
|
|
|
|
void kvm_mmu_destroy(struct kvm_vcpu *vcpu)
|
|
{
|
|
kvm_mmu_unload(vcpu);
|
|
free_mmu_pages(vcpu);
|
|
mmu_free_memory_caches(vcpu);
|
|
}
|
|
|
|
void kvm_mmu_module_exit(void)
|
|
{
|
|
mmu_destroy_caches();
|
|
percpu_counter_destroy(&kvm_total_used_mmu_pages);
|
|
unregister_shrinker(&mmu_shrinker);
|
|
mmu_audit_disable();
|
|
}
|
|
|
|
static int set_nx_huge_pages_recovery_ratio(const char *val, const struct kernel_param *kp)
|
|
{
|
|
unsigned int old_val;
|
|
int err;
|
|
|
|
old_val = nx_huge_pages_recovery_ratio;
|
|
err = param_set_uint(val, kp);
|
|
if (err)
|
|
return err;
|
|
|
|
if (READ_ONCE(nx_huge_pages) &&
|
|
!old_val && nx_huge_pages_recovery_ratio) {
|
|
struct kvm *kvm;
|
|
|
|
mutex_lock(&kvm_lock);
|
|
|
|
list_for_each_entry(kvm, &vm_list, vm_list)
|
|
wake_up_process(kvm->arch.nx_lpage_recovery_thread);
|
|
|
|
mutex_unlock(&kvm_lock);
|
|
}
|
|
|
|
return err;
|
|
}
|
|
|
|
static void kvm_recover_nx_lpages(struct kvm *kvm)
|
|
{
|
|
int rcu_idx;
|
|
struct kvm_mmu_page *sp;
|
|
unsigned int ratio;
|
|
LIST_HEAD(invalid_list);
|
|
ulong to_zap;
|
|
|
|
rcu_idx = srcu_read_lock(&kvm->srcu);
|
|
spin_lock(&kvm->mmu_lock);
|
|
|
|
ratio = READ_ONCE(nx_huge_pages_recovery_ratio);
|
|
to_zap = ratio ? DIV_ROUND_UP(kvm->stat.nx_lpage_splits, ratio) : 0;
|
|
while (to_zap && !list_empty(&kvm->arch.lpage_disallowed_mmu_pages)) {
|
|
/*
|
|
* We use a separate list instead of just using active_mmu_pages
|
|
* because the number of lpage_disallowed pages is expected to
|
|
* be relatively small compared to the total.
|
|
*/
|
|
sp = list_first_entry(&kvm->arch.lpage_disallowed_mmu_pages,
|
|
struct kvm_mmu_page,
|
|
lpage_disallowed_link);
|
|
WARN_ON_ONCE(!sp->lpage_disallowed);
|
|
kvm_mmu_prepare_zap_page(kvm, sp, &invalid_list);
|
|
WARN_ON_ONCE(sp->lpage_disallowed);
|
|
|
|
if (!--to_zap || need_resched() || spin_needbreak(&kvm->mmu_lock)) {
|
|
kvm_mmu_commit_zap_page(kvm, &invalid_list);
|
|
if (to_zap)
|
|
cond_resched_lock(&kvm->mmu_lock);
|
|
}
|
|
}
|
|
kvm_mmu_commit_zap_page(kvm, &invalid_list);
|
|
|
|
spin_unlock(&kvm->mmu_lock);
|
|
srcu_read_unlock(&kvm->srcu, rcu_idx);
|
|
}
|
|
|
|
static long get_nx_lpage_recovery_timeout(u64 start_time)
|
|
{
|
|
return READ_ONCE(nx_huge_pages) && READ_ONCE(nx_huge_pages_recovery_ratio)
|
|
? start_time + 60 * HZ - get_jiffies_64()
|
|
: MAX_SCHEDULE_TIMEOUT;
|
|
}
|
|
|
|
static int kvm_nx_lpage_recovery_worker(struct kvm *kvm, uintptr_t data)
|
|
{
|
|
u64 start_time;
|
|
long remaining_time;
|
|
|
|
while (true) {
|
|
start_time = get_jiffies_64();
|
|
remaining_time = get_nx_lpage_recovery_timeout(start_time);
|
|
|
|
set_current_state(TASK_INTERRUPTIBLE);
|
|
while (!kthread_should_stop() && remaining_time > 0) {
|
|
schedule_timeout(remaining_time);
|
|
remaining_time = get_nx_lpage_recovery_timeout(start_time);
|
|
set_current_state(TASK_INTERRUPTIBLE);
|
|
}
|
|
|
|
set_current_state(TASK_RUNNING);
|
|
|
|
if (kthread_should_stop())
|
|
return 0;
|
|
|
|
kvm_recover_nx_lpages(kvm);
|
|
}
|
|
}
|
|
|
|
int kvm_mmu_post_init_vm(struct kvm *kvm)
|
|
{
|
|
int err;
|
|
|
|
err = kvm_vm_create_worker_thread(kvm, kvm_nx_lpage_recovery_worker, 0,
|
|
"kvm-nx-lpage-recovery",
|
|
&kvm->arch.nx_lpage_recovery_thread);
|
|
if (!err)
|
|
kthread_unpark(kvm->arch.nx_lpage_recovery_thread);
|
|
|
|
return err;
|
|
}
|
|
|
|
void kvm_mmu_pre_destroy_vm(struct kvm *kvm)
|
|
{
|
|
if (kvm->arch.nx_lpage_recovery_thread)
|
|
kthread_stop(kvm->arch.nx_lpage_recovery_thread);
|
|
}
|