From fb341f572d26e0786167cd96b90cc4febed830cf Mon Sep 17 00:00:00 2001 From: Marcelo Tosatti Date: Sat, 5 Dec 2009 12:34:11 -0200 Subject: [PATCH] KVM: MMU: remove prefault from invlpg handler The invlpg prefault optimization breaks Windows 2008 R2 occasionally. The visible effect is that the invlpg handler instantiates a pte which is, microseconds later, written with a different gfn by another vcpu. The OS could have other mechanisms to prevent a present translation from being used, which the hypervisor is unaware of. While the documentation states that the cpu is at liberty to prefetch tlb entries, it looks like this is not heeded, so remove tlb prefetch from invlpg. Cc: stable@kernel.org Signed-off-by: Marcelo Tosatti Signed-off-by: Avi Kivity --- arch/x86/kvm/paging_tmpl.h | 18 ------------------ 1 file changed, 18 deletions(-) diff --git a/arch/x86/kvm/paging_tmpl.h b/arch/x86/kvm/paging_tmpl.h index a6017132fba..58a0f1e8859 100644 --- a/arch/x86/kvm/paging_tmpl.h +++ b/arch/x86/kvm/paging_tmpl.h @@ -455,8 +455,6 @@ out_unlock: static void FNAME(invlpg)(struct kvm_vcpu *vcpu, gva_t gva) { struct kvm_shadow_walk_iterator iterator; - pt_element_t gpte; - gpa_t pte_gpa = -1; int level; u64 *sptep; int need_flush = 0; @@ -470,10 +468,6 @@ static void FNAME(invlpg)(struct kvm_vcpu *vcpu, gva_t gva) if (level == PT_PAGE_TABLE_LEVEL || ((level == PT_DIRECTORY_LEVEL && is_large_pte(*sptep))) || ((level == PT_PDPE_LEVEL && is_large_pte(*sptep)))) { - struct kvm_mmu_page *sp = page_header(__pa(sptep)); - - pte_gpa = (sp->gfn << PAGE_SHIFT); - pte_gpa += (sptep - sp->spt) * sizeof(pt_element_t); if (is_shadow_present_pte(*sptep)) { rmap_remove(vcpu->kvm, sptep); @@ -492,18 +486,6 @@ static void FNAME(invlpg)(struct kvm_vcpu *vcpu, gva_t gva) if (need_flush) kvm_flush_remote_tlbs(vcpu->kvm); spin_unlock(&vcpu->kvm->mmu_lock); - - if (pte_gpa == -1) - return; - if (kvm_read_guest_atomic(vcpu->kvm, pte_gpa, &gpte, - sizeof(pt_element_t))) - return; - if (is_present_gpte(gpte) && (gpte & PT_ACCESSED_MASK)) { - if (mmu_topup_memory_caches(vcpu)) - return; - kvm_mmu_pte_write(vcpu, pte_gpa, (const u8 *)&gpte, - sizeof(pt_element_t), 0); - } } static gpa_t FNAME(gva_to_gpa)(struct kvm_vcpu *vcpu, gva_t vaddr) -- 2.39.5