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coral / linux-mtk / 179f152db81e94a68ea807c5152cf34fa2b1cd45 / . / arch / x86 / kvm / mmu.c
blob: 62f1e4663bc3ca568e6ea66e250843d632b14916 [file] [log] [blame]
/*
* Kernel-based Virtual Machine driver for Linux
*
* This module enables machines with Intel VT-x extensions to run virtual
* machines without emulation or binary translation.
*
* MMU support
*
* Copyright (C) 2006 Qumranet, Inc.
* Copyright 2010 Red Hat, Inc. and/or its affiliates.
*
* Authors:
* Yaniv Kamay <yaniv@qumranet.com>
* Avi Kivity <avi@qumranet.com>
*
* This work is licensed under the terms of the GNU GPL, version 2. See
* the COPYING file in the top-level directory.
*
*/
#include "irq.h"
#include "mmu.h"
#include "x86.h"
#include "kvm_cache_regs.h"
#include "cpuid.h"
#include <linux/kvm_host.h>
#include <linux/types.h>
#include <linux/string.h>
#include <linux/mm.h>
#include <linux/highmem.h>
#include <linux/moduleparam.h>
#include <linux/export.h>
#include <linux/swap.h>
#include <linux/hugetlb.h>
#include <linux/compiler.h>
#include <linux/srcu.h>
#include <linux/slab.h>
#include <linux/sched/signal.h>
#include <linux/uaccess.h>
#include <linux/hash.h>
#include <linux/kern_levels.h>
#include <linux/kthread.h>
#include <asm/page.h>
#include <asm/pat.h>
#include <asm/cmpxchg.h>
#include <asm/io.h>
#include <asm/vmx.h>
#include <asm/kvm_page_track.h>
#include "trace.h"
extern bool itlb_multihit_kvm_mitigation;
static int __read_mostly nx_huge_pages = -1;
static uint __read_mostly nx_huge_pages_recovery_ratio = 60;
static int set_nx_huge_pages(const char *val, const struct kernel_param *kp);
static int set_nx_huge_pages_recovery_ratio(const char *val, const struct kernel_param *kp);
static struct kernel_param_ops nx_huge_pages_ops = {
.set = set_nx_huge_pages,
.get = param_get_bool,
};
static struct kernel_param_ops nx_huge_pages_recovery_ratio_ops = {
.set = set_nx_huge_pages_recovery_ratio,
.get = param_get_uint,
};
module_param_cb(nx_huge_pages, &nx_huge_pages_ops, &nx_huge_pages, 0644);
__MODULE_PARM_TYPE(nx_huge_pages, "bool");
module_param_cb(nx_huge_pages_recovery_ratio, &nx_huge_pages_recovery_ratio_ops,
&nx_huge_pages_recovery_ratio, 0644);
__MODULE_PARM_TYPE(nx_huge_pages_recovery_ratio, "uint");
/*
* When setting this variable to true it enables Two-Dimensional-Paging
* where the hardware walks 2 page tables:
* 1. the guest-virtual to guest-physical
* 2. while doing 1. it walks guest-physical to host-physical
* If the hardware supports that we don't need to do shadow paging.
*/
bool tdp_enabled = false;
enum {
AUDIT_PRE_PAGE_FAULT,
AUDIT_POST_PAGE_FAULT,
AUDIT_PRE_PTE_WRITE,
AUDIT_POST_PTE_WRITE,
AUDIT_PRE_SYNC,
AUDIT_POST_SYNC
};
#undef MMU_DEBUG
#ifdef MMU_DEBUG
static bool dbg = 0;
module_param(dbg, bool, 0644);
#define pgprintk(x...) do { if (dbg) printk(x); } while (0)
#define rmap_printk(x...) do { if (dbg) printk(x); } while (0)
#define MMU_WARN_ON(x) WARN_ON(x)
#else
#define pgprintk(x...) do { } while (0)
#define rmap_printk(x...) do { } while (0)
#define MMU_WARN_ON(x) do { } while (0)
#endif
#define PTE_PREFETCH_NUM 8
#define PT_FIRST_AVAIL_BITS_SHIFT 10
#define PT64_SECOND_AVAIL_BITS_SHIFT 52
#define PT64_LEVEL_BITS 9
#define PT64_LEVEL_SHIFT(level) \
(PAGE_SHIFT + (level - 1) * PT64_LEVEL_BITS)
#define PT64_INDEX(address, level)\
(((address) >> PT64_LEVEL_SHIFT(level)) & ((1 << PT64_LEVEL_BITS) - 1))
#define PT32_LEVEL_BITS 10
#define PT32_LEVEL_SHIFT(level) \
(PAGE_SHIFT + (level - 1) * PT32_LEVEL_BITS)
#define PT32_LVL_OFFSET_MASK(level) \
(PT32_BASE_ADDR_MASK & ((1ULL << (PAGE_SHIFT + (((level) - 1) \
* PT32_LEVEL_BITS))) - 1))
#define PT32_INDEX(address, level)\
(((address) >> PT32_LEVEL_SHIFT(level)) & ((1 << PT32_LEVEL_BITS) - 1))
#define PT64_BASE_ADDR_MASK __sme_clr((((1ULL << 52) - 1) & ~(u64)(PAGE_SIZE-1)))
#define PT64_DIR_BASE_ADDR_MASK \
(PT64_BASE_ADDR_MASK & ~((1ULL << (PAGE_SHIFT + PT64_LEVEL_BITS)) - 1))
#define PT64_LVL_ADDR_MASK(level) \
(PT64_BASE_ADDR_MASK & ~((1ULL << (PAGE_SHIFT + (((level) - 1) \
* PT64_LEVEL_BITS))) - 1))
#define PT64_LVL_OFFSET_MASK(level) \
(PT64_BASE_ADDR_MASK & ((1ULL << (PAGE_SHIFT + (((level) - 1) \
* PT64_LEVEL_BITS))) - 1))
#define PT32_BASE_ADDR_MASK PAGE_MASK
#define PT32_DIR_BASE_ADDR_MASK \
(PAGE_MASK & ~((1ULL << (PAGE_SHIFT + PT32_LEVEL_BITS)) - 1))
#define PT32_LVL_ADDR_MASK(level) \
(PAGE_MASK & ~((1ULL << (PAGE_SHIFT + (((level) - 1) \
* PT32_LEVEL_BITS))) - 1))
#define PT64_PERM_MASK (PT_PRESENT_MASK | PT_WRITABLE_MASK | shadow_user_mask \
| shadow_x_mask | shadow_nx_mask | shadow_me_mask)
#define ACC_EXEC_MASK 1
#define ACC_WRITE_MASK PT_WRITABLE_MASK
#define ACC_USER_MASK PT_USER_MASK
#define ACC_ALL (ACC_EXEC_MASK | ACC_WRITE_MASK | ACC_USER_MASK)
/* The mask for the R/X bits in EPT PTEs */
#define PT64_EPT_READABLE_MASK 0x1ull
#define PT64_EPT_EXECUTABLE_MASK 0x4ull
#include <trace/events/kvm.h>
#define SPTE_HOST_WRITEABLE (1ULL << PT_FIRST_AVAIL_BITS_SHIFT)
#define SPTE_MMU_WRITEABLE (1ULL << (PT_FIRST_AVAIL_BITS_SHIFT + 1))
#define SHADOW_PT_INDEX(addr, level) PT64_INDEX(addr, level)
/* make pte_list_desc fit well in cache line */
#define PTE_LIST_EXT 3
/*
* Return values of handle_mmio_page_fault and mmu.page_fault:
* RET_PF_RETRY: let CPU fault again on the address.
* RET_PF_EMULATE: mmio page fault, emulate the instruction directly.
*
* For handle_mmio_page_fault only:
* RET_PF_INVALID: the spte is invalid, let the real page fault path update it.
*/
enum {
RET_PF_RETRY = 0,
RET_PF_EMULATE = 1,
RET_PF_INVALID = 2,
};
struct pte_list_desc {
u64 *sptes[PTE_LIST_EXT];
struct pte_list_desc *more;
};
struct kvm_shadow_walk_iterator {
u64 addr;
hpa_t shadow_addr;
u64 *sptep;
int level;
unsigned index;
};
static const union kvm_mmu_page_role mmu_base_role_mask = {
.cr0_wp = 1,
.cr4_pae = 1,
.nxe = 1,
.smep_andnot_wp = 1,
.smap_andnot_wp = 1,
.smm = 1,
.guest_mode = 1,
.ad_disabled = 1,
};
#define for_each_shadow_entry_using_root(_vcpu, _root, _addr, _walker) \
for (shadow_walk_init_using_root(&(_walker), (_vcpu), \
(_root), (_addr)); \
shadow_walk_okay(&(_walker)); \
shadow_walk_next(&(_walker)))
#define for_each_shadow_entry(_vcpu, _addr, _walker) \
for (shadow_walk_init(&(_walker), _vcpu, _addr); \
shadow_walk_okay(&(_walker)); \
shadow_walk_next(&(_walker)))
#define for_each_shadow_entry_lockless(_vcpu, _addr, _walker, spte) \
for (shadow_walk_init(&(_walker), _vcpu, _addr); \
shadow_walk_okay(&(_walker)) && \
({ spte = mmu_spte_get_lockless(_walker.sptep); 1; }); \
__shadow_walk_next(&(_walker), spte))
static struct kmem_cache *pte_list_desc_cache;
static struct kmem_cache *mmu_page_header_cache;
static struct percpu_counter kvm_total_used_mmu_pages;
static u64 __read_mostly shadow_nx_mask;
static u64 __read_mostly shadow_x_mask; /* mutual exclusive with nx_mask */
static u64 __read_mostly shadow_user_mask;
static u64 __read_mostly shadow_accessed_mask;
static u64 __read_mostly shadow_dirty_mask;
static u64 __read_mostly shadow_mmio_mask;
static u64 __read_mostly shadow_mmio_value;
static u64 __read_mostly shadow_present_mask;
static u64 __read_mostly shadow_me_mask;
/*
* SPTEs used by MMUs without A/D bits are marked with shadow_acc_track_value.
* Non-present SPTEs with shadow_acc_track_value set are in place for access
* tracking.
*/
static u64 __read_mostly shadow_acc_track_mask;
static const u64 shadow_acc_track_value = SPTE_SPECIAL_MASK;
/*
* The mask/shift to use for saving the original R/X bits when marking the PTE
* as not-present for access tracking purposes. We do not save the W bit as the
* PTEs being access tracked also need to be dirty tracked, so the W bit will be
* restored only when a write is attempted to the page.
*/
static const u64 shadow_acc_track_saved_bits_mask = PT64_EPT_READABLE_MASK |
PT64_EPT_EXECUTABLE_MASK;
static const u64 shadow_acc_track_saved_bits_shift = PT64_SECOND_AVAIL_BITS_SHIFT;
/*
* This mask must be set on all non-zero Non-Present or Reserved SPTEs in order
* to guard against L1TF attacks.
*/
static u64 __read_mostly shadow_nonpresent_or_rsvd_mask;
/*
* The number of high-order 1 bits to use in the mask above.
*/
static const u64 shadow_nonpresent_or_rsvd_mask_len = 5;
/*
* In some cases, we need to preserve the GFN of a non-present or reserved
* SPTE when we usurp the upper five bits of the physical address space to
* defend against L1TF, e.g. for MMIO SPTEs. To preserve the GFN, we'll
* shift bits of the GFN that overlap with shadow_nonpresent_or_rsvd_mask
* left into the reserved bits, i.e. the GFN in the SPTE will be split into
* high and low parts. This mask covers the lower bits of the GFN.
*/
static u64 __read_mostly shadow_nonpresent_or_rsvd_lower_gfn_mask;
static void mmu_spte_set(u64 *sptep, u64 spte);
static bool is_executable_pte(u64 spte);
static union kvm_mmu_page_role
kvm_mmu_calc_root_page_role(struct kvm_vcpu *vcpu);
#define CREATE_TRACE_POINTS
#include "mmutrace.h"
void kvm_mmu_set_mmio_spte_mask(u64 mmio_mask, u64 mmio_value)
{
BUG_ON((mmio_mask & mmio_value) != mmio_value);
shadow_mmio_value = mmio_value | SPTE_SPECIAL_MASK;
shadow_mmio_mask = mmio_mask | SPTE_SPECIAL_MASK;
}
EXPORT_SYMBOL_GPL(kvm_mmu_set_mmio_spte_mask);
static inline bool sp_ad_disabled(struct kvm_mmu_page *sp)
{
return sp->role.ad_disabled;
}
static inline bool spte_ad_enabled(u64 spte)
{
MMU_WARN_ON((spte & shadow_mmio_mask) == shadow_mmio_value);
return !(spte & shadow_acc_track_value);
}
static bool is_nx_huge_page_enabled(void)
{
return READ_ONCE(nx_huge_pages);
}
static inline u64 spte_shadow_accessed_mask(u64 spte)
{
MMU_WARN_ON((spte & shadow_mmio_mask) == shadow_mmio_value);
return spte_ad_enabled(spte) ? shadow_accessed_mask : 0;
}
static inline u64 spte_shadow_dirty_mask(u64 spte)
{
MMU_WARN_ON((spte & shadow_mmio_mask) == shadow_mmio_value);
return spte_ad_enabled(spte) ? shadow_dirty_mask : 0;
}
static inline bool is_access_track_spte(u64 spte)
{
return !spte_ad_enabled(spte) && (spte & shadow_acc_track_mask) == 0;
}
/*
* the low bit of the generation number is always presumed to be zero.
* This disables mmio caching during memslot updates. The concept is
* similar to a seqcount but instead of retrying the access we just punt
* and ignore the cache.
*
* spte bits 3-11 are used as bits 1-9 of the generation number,
* the bits 52-61 are used as bits 10-19 of the generation number.
*/
#define MMIO_SPTE_GEN_LOW_SHIFT 2
#define MMIO_SPTE_GEN_HIGH_SHIFT 52
#define MMIO_GEN_SHIFT 20
#define MMIO_GEN_LOW_SHIFT 10
#define MMIO_GEN_LOW_MASK ((1 << MMIO_GEN_LOW_SHIFT) - 2)
#define MMIO_GEN_MASK ((1 << MMIO_GEN_SHIFT) - 1)
static u64 generation_mmio_spte_mask(unsigned int gen)
{
u64 mask;
WARN_ON(gen & ~MMIO_GEN_MASK);
mask = (gen & MMIO_GEN_LOW_MASK) << MMIO_SPTE_GEN_LOW_SHIFT;
mask |= ((u64)gen >> MMIO_GEN_LOW_SHIFT) << MMIO_SPTE_GEN_HIGH_SHIFT;
return mask;
}
static unsigned int get_mmio_spte_generation(u64 spte)
{
unsigned int gen;
spte &= ~shadow_mmio_mask;
gen = (spte >> MMIO_SPTE_GEN_LOW_SHIFT) & MMIO_GEN_LOW_MASK;
gen |= (spte >> MMIO_SPTE_GEN_HIGH_SHIFT) << MMIO_GEN_LOW_SHIFT;
return gen;
}
static unsigned int kvm_current_mmio_generation(struct kvm_vcpu *vcpu)
{
return kvm_vcpu_memslots(vcpu)->generation & MMIO_GEN_MASK;
}
static void mark_mmio_spte(struct kvm_vcpu *vcpu, u64 *sptep, u64 gfn,
unsigned access)
{
unsigned int gen = kvm_current_mmio_generation(vcpu);
u64 mask = generation_mmio_spte_mask(gen);
u64 gpa = gfn << PAGE_SHIFT;
access &= ACC_WRITE_MASK | ACC_USER_MASK;
mask |= shadow_mmio_value | access;
mask |= gpa | shadow_nonpresent_or_rsvd_mask;
mask |= (gpa & shadow_nonpresent_or_rsvd_mask)
<< shadow_nonpresent_or_rsvd_mask_len;
trace_mark_mmio_spte(sptep, gfn, access, gen);
mmu_spte_set(sptep, mask);
}
static bool is_mmio_spte(u64 spte)
{
return (spte & shadow_mmio_mask) == shadow_mmio_value;
}
static gfn_t get_mmio_spte_gfn(u64 spte)
{
u64 gpa = spte & shadow_nonpresent_or_rsvd_lower_gfn_mask;
gpa |= (spte >> shadow_nonpresent_or_rsvd_mask_len)
& shadow_nonpresent_or_rsvd_mask;
return gpa >> PAGE_SHIFT;
}
static unsigned get_mmio_spte_access(u64 spte)
{
u64 mask = generation_mmio_spte_mask(MMIO_GEN_MASK) | shadow_mmio_mask;
return (spte & ~mask) & ~PAGE_MASK;
}
static bool set_mmio_spte(struct kvm_vcpu *vcpu, u64 *sptep, gfn_t gfn,
kvm_pfn_t pfn, unsigned access)
{
if (unlikely(is_noslot_pfn(pfn))) {
mark_mmio_spte(vcpu, sptep, gfn, access);
return true;
}
return false;
}
static bool check_mmio_spte(struct kvm_vcpu *vcpu, u64 spte)
{
unsigned int kvm_gen, spte_gen;
kvm_gen = kvm_current_mmio_generation(vcpu);
spte_gen = get_mmio_spte_generation(spte);
trace_check_mmio_spte(spte, kvm_gen, spte_gen);
return likely(kvm_gen == spte_gen);
}
/*
* Sets the shadow PTE masks used by the MMU.
*
* Assumptions:
* - Setting either @accessed_mask or @dirty_mask requires setting both
* - At least one of @accessed_mask or @acc_track_mask must be set
*/
void kvm_mmu_set_mask_ptes(u64 user_mask, u64 accessed_mask,
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 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;
/*
* 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.
*/
low_phys_bits = boot_cpu_data.x86_phys_bits;
if (boot_cpu_data.x86_phys_bits <
52 - shadow_nonpresent_or_rsvd_mask_len) {
shadow_nonpresent_or_rsvd_mask =
rsvd_bits(boot_cpu_data.x86_phys_bits -
shadow_nonpresent_or_rsvd_mask_len,
boot_cpu_data.x86_phys_bits - 1);
low_phys_bits -= shadow_nonpresent_or_rsvd_mask_len;
}
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)
{
if (kvm_x86_ops->write_log_dirty)
return kvm_x86_ops->write_log_dirty(vcpu);
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)
{
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 |
nonleaf_bit8_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,
boot_cpu_data.x86_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,
boot_cpu_data.x86_phys_bits,
context->shadow_root_level, false,
boot_cpu_has(X86_FEATURE_GBPAGES),
true, true);
else
__reset_rsvds_bits_mask_ept(shadow_zero_check,
boot_cpu_data.x86_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,
boot_cpu_data.x86_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;
}
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();
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);
}
}
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);
}