From b79b93f92cb3b66b89d75525fdfd2454b1e1f446 Mon Sep 17 00:00:00 2001 From: Avi Kivity Date: Sun, 6 Jun 2010 15:46:44 +0300 Subject: [PATCH] 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 --- arch/x86/kvm/mmu.c | 25 +++++++++++++++++++++---- 1 file changed, 21 insertions(+), 4 deletions(-) diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c index ba2efcf2b86e..d8d48329cb82 100644 --- a/arch/x86/kvm/mmu.c +++ b/arch/x86/kvm/mmu.c @@ -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; }