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KVM: MMU: Don't drop accessed bit while updating an spte 

__set_spte() will happily replace an spte with the accessed bit set with
one that has the accessed bit clear.  Add a helper update_spte() which checks
for this condition and updates the page flag if needed.

Signed-off-by: Avi Kivity <avi@redhat.com>
This commit is contained in:
Avi Kivity 2010-06-06 15:46:44 +03:00
parent a9221dd5ec
commit b79b93f92c
1 changed files with 21 additions and 4 deletions
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25
arch/x86/kvm/mmu.c
View File

@ -303,6 +303,19 @@ static u64 __xchg_spte(u64 *sptep, u64 new_spte)
#endif
}
static void update_spte(u64 *sptep, u64 new_spte)
{
u64 old_spte;
if (!shadow_accessed_mask || (new_spte & shadow_accessed_mask)) {
__set_spte(sptep, new_spte);
} else {
old_spte = __xchg_spte(sptep, new_spte);
if (old_spte & shadow_accessed_mask)
mark_page_accessed(pfn_to_page(spte_to_pfn(old_spte)));
}
}
static int mmu_topup_memory_cache(struct kvm_mmu_memory_cache *cache,
struct kmem_cache *base_cache, int min)
{
@ -721,7 +734,7 @@ static int rmap_write_protect(struct kvm *kvm, u64 gfn)
BUG_ON(!(*spte & PT_PRESENT_MASK));
rmap_printk("rmap_write_protect: spte %p %llx\n", spte, *spte);
if (is_writable_pte(*spte)) {
__set_spte(spte, *spte & ~PT_WRITABLE_MASK);
update_spte(spte, *spte & ~PT_WRITABLE_MASK);
write_protected = 1;
}
spte = rmap_next(kvm, rmapp, spte);
@ -777,7 +790,7 @@ static int kvm_set_pte_rmapp(struct kvm *kvm, unsigned long *rmapp,
unsigned long data)
{
int need_flush = 0;
u64 *spte, new_spte;
u64 *spte, new_spte, old_spte;
pte_t *ptep = (pte_t *)data;
pfn_t new_pfn;
@ -797,9 +810,13 @@ static int kvm_set_pte_rmapp(struct kvm *kvm, unsigned long *rmapp,
new_spte &= ~PT_WRITABLE_MASK;
new_spte &= ~SPTE_HOST_WRITEABLE;
new_spte &= ~shadow_accessed_mask;
if (is_writable_pte(*spte))
kvm_set_pfn_dirty(spte_to_pfn(*spte));
__set_spte(spte, new_spte);
old_spte = __xchg_spte(spte, new_spte);
if (is_shadow_present_pte(old_spte)
&& (old_spte & shadow_accessed_mask))
mark_page_accessed(pfn_to_page(spte_to_pfn(old_spte)));
spte = rmap_next(kvm, rmapp, spte);
}
}
@ -1922,7 +1939,7 @@ static int set_spte(struct kvm_vcpu *vcpu, u64 *sptep,
mark_page_dirty(vcpu->kvm, gfn);
set_pte:
__set_spte(sptep, spte);
update_spte(sptep, spte);
done:
return ret;
}