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kvm: x86: MMU support for EPT accessed/dirty bits
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This prepares the MMU paging code for EPT accessed and dirty bits,
which can be enabled optionally at runtime.  Code that updates the
accessed and dirty bits will need a pointer to the struct kvm_mmu.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
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Paolo Bonzini authored and Radim Krčmář committed Apr 7, 2017
1 parent 0047723 commit 86407bc
Showing 1 changed file with 15 additions and 8 deletions.
23 changes: 15 additions & 8 deletions arch/x86/kvm/paging_tmpl.h
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Original file line number Diff line number Diff line change
Expand Up @@ -43,6 +43,7 @@ extern u64 __pure __using_nonexistent_pte_bit(void)
#define PT_GUEST_DIRTY_MASK PT_DIRTY_MASK
#define PT_GUEST_DIRTY_SHIFT PT_DIRTY_SHIFT
#define PT_GUEST_ACCESSED_SHIFT PT_ACCESSED_SHIFT
#define PT_HAVE_ACCESSED_DIRTY(mmu) true
#ifdef CONFIG_X86_64
#define PT_MAX_FULL_LEVELS 4
#define CMPXCHG cmpxchg
Expand All @@ -64,6 +65,7 @@ extern u64 __pure __using_nonexistent_pte_bit(void)
#define PT_GUEST_DIRTY_MASK PT_DIRTY_MASK
#define PT_GUEST_DIRTY_SHIFT PT_DIRTY_SHIFT
#define PT_GUEST_ACCESSED_SHIFT PT_ACCESSED_SHIFT
#define PT_HAVE_ACCESSED_DIRTY(mmu) true
#define CMPXCHG cmpxchg
#elif PTTYPE == PTTYPE_EPT
#define pt_element_t u64
Expand All @@ -78,6 +80,7 @@ extern u64 __pure __using_nonexistent_pte_bit(void)
#define PT_GUEST_DIRTY_MASK 0
#define PT_GUEST_DIRTY_SHIFT __using_nonexistent_pte_bit()
#define PT_GUEST_ACCESSED_SHIFT __using_nonexistent_pte_bit()
#define PT_HAVE_ACCESSED_DIRTY(mmu) false
#define CMPXCHG cmpxchg64
#define PT_MAX_FULL_LEVELS 4
#else
Expand Down Expand Up @@ -111,12 +114,13 @@ static gfn_t gpte_to_gfn_lvl(pt_element_t gpte, int lvl)
return (gpte & PT_LVL_ADDR_MASK(lvl)) >> PAGE_SHIFT;
}

static inline void FNAME(protect_clean_gpte)(unsigned *access, unsigned gpte)
static inline void FNAME(protect_clean_gpte)(struct kvm_mmu *mmu, unsigned *access,
unsigned gpte)
{
unsigned mask;

/* dirty bit is not supported, so no need to track it */
if (!PT_GUEST_DIRTY_MASK)
if (!PT_HAVE_ACCESSED_DIRTY(mmu))
return;

BUILD_BUG_ON(PT_WRITABLE_MASK != ACC_WRITE_MASK);
Expand Down Expand Up @@ -171,7 +175,7 @@ static bool FNAME(prefetch_invalid_gpte)(struct kvm_vcpu *vcpu,
goto no_present;

/* if accessed bit is not supported prefetch non accessed gpte */
if (PT_GUEST_ACCESSED_MASK && !(gpte & PT_GUEST_ACCESSED_MASK))
if (PT_HAVE_ACCESSED_DIRTY(&vcpu->arch.mmu) && !(gpte & PT_GUEST_ACCESSED_MASK))
goto no_present;

return false;
Expand Down Expand Up @@ -217,7 +221,7 @@ static int FNAME(update_accessed_dirty_bits)(struct kvm_vcpu *vcpu,
int ret;

/* dirty/accessed bits are not supported, so no need to update them */
if (!PT_GUEST_DIRTY_MASK)
if (!PT_HAVE_ACCESSED_DIRTY(mmu))
return 0;

for (level = walker->max_level; level >= walker->level; --level) {
Expand Down Expand Up @@ -287,6 +291,7 @@ static int FNAME(walk_addr_generic)(struct guest_walker *walker,
gfn_t table_gfn;
unsigned index, pt_access, pte_access, accessed_dirty, pte_pkey;
gpa_t pte_gpa;
bool have_ad;
int offset;
const int write_fault = access & PFERR_WRITE_MASK;
const int user_fault = access & PFERR_USER_MASK;
Expand All @@ -299,6 +304,7 @@ static int FNAME(walk_addr_generic)(struct guest_walker *walker,
retry_walk:
walker->level = mmu->root_level;
pte = mmu->get_cr3(vcpu);
have_ad = PT_HAVE_ACCESSED_DIRTY(mmu);

#if PTTYPE == 64
if (walker->level == PT32E_ROOT_LEVEL) {
Expand All @@ -312,7 +318,7 @@ static int FNAME(walk_addr_generic)(struct guest_walker *walker,
walker->max_level = walker->level;
ASSERT(!(is_long_mode(vcpu) && !is_pae(vcpu)));

accessed_dirty = PT_GUEST_ACCESSED_MASK;
accessed_dirty = have_ad ? PT_GUEST_ACCESSED_MASK : 0;
pt_access = pte_access = ACC_ALL;
++walker->level;

Expand Down Expand Up @@ -394,7 +400,7 @@ static int FNAME(walk_addr_generic)(struct guest_walker *walker,
walker->gfn = real_gpa >> PAGE_SHIFT;

if (!write_fault)
FNAME(protect_clean_gpte)(&pte_access, pte);
FNAME(protect_clean_gpte)(mmu, &pte_access, pte);
else
/*
* On a write fault, fold the dirty bit into accessed_dirty.
Expand Down Expand Up @@ -485,7 +491,7 @@ FNAME(prefetch_gpte)(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp,

gfn = gpte_to_gfn(gpte);
pte_access = sp->role.access & FNAME(gpte_access)(vcpu, gpte);
FNAME(protect_clean_gpte)(&pte_access, gpte);
FNAME(protect_clean_gpte)(&vcpu->arch.mmu, &pte_access, gpte);
pfn = pte_prefetch_gfn_to_pfn(vcpu, gfn,
no_dirty_log && (pte_access & ACC_WRITE_MASK));
if (is_error_pfn(pfn))
Expand Down Expand Up @@ -979,7 +985,7 @@ static int FNAME(sync_page)(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp)
gfn = gpte_to_gfn(gpte);
pte_access = sp->role.access;
pte_access &= FNAME(gpte_access)(vcpu, gpte);
FNAME(protect_clean_gpte)(&pte_access, gpte);
FNAME(protect_clean_gpte)(&vcpu->arch.mmu, &pte_access, gpte);

if (sync_mmio_spte(vcpu, &sp->spt[i], gfn, pte_access,
&nr_present))
Expand Down Expand Up @@ -1025,3 +1031,4 @@ static int FNAME(sync_page)(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp)
#undef PT_GUEST_DIRTY_MASK
#undef PT_GUEST_DIRTY_SHIFT
#undef PT_GUEST_ACCESSED_SHIFT
#undef PT_HAVE_ACCESSED_DIRTY

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