Commit b79b93f9 authored by Avi Kivity's avatar Avi Kivity
Browse files

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: default avatarAvi Kivity <avi@redhat.com>
parent a9221dd5

arch/x86/kvm/mmu.c

+21 −4
Original line number Diff line number Diff line
@@ -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;

}