From 4539b35881ae9664b0e2953438dd83f5ee02c0b4 Mon Sep 17 00:00:00 2001 From: Andrea Arcangeli Date: Thu, 12 Mar 2009 18:18:43 +0100 Subject: [PATCH] KVM: Fix missing smp tlb flush in invlpg When kvm emulates an invlpg instruction, it can drop a shadow pte, but leaves the guest tlbs intact. This can cause memory corruption when swapping out. Without this the other cpu can still write to a freed host physical page. tlb smp flush must happen if rmap_remove is called always before mmu_lock is released because the VM will take the mmu_lock before it can finally add the page to the freelist after swapout. mmu notifier makes it safe to flush the tlb after freeing the page (otherwise it would never be safe) so we can do a single flush for multiple sptes invalidated. Cc: stable@kernel.org Signed-off-by: Andrea Arcangeli Acked-by: Marcelo Tosatti Signed-off-by: Avi Kivity --- arch/x86/kvm/paging_tmpl.h | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/arch/x86/kvm/paging_tmpl.h b/arch/x86/kvm/paging_tmpl.h index 0f11792fafa..6bd70206c56 100644 --- a/arch/x86/kvm/paging_tmpl.h +++ b/arch/x86/kvm/paging_tmpl.h @@ -446,6 +446,7 @@ static void FNAME(invlpg)(struct kvm_vcpu *vcpu, gva_t gva) gpa_t pte_gpa = -1; int level; u64 *sptep; + int need_flush = 0; spin_lock(&vcpu->kvm->mmu_lock); @@ -465,6 +466,7 @@ static void FNAME(invlpg)(struct kvm_vcpu *vcpu, gva_t gva) rmap_remove(vcpu->kvm, sptep); if (is_large_pte(*sptep)) --vcpu->kvm->stat.lpages; + need_flush = 1; } set_shadow_pte(sptep, shadow_trap_nonpresent_pte); break; @@ -474,6 +476,8 @@ static void FNAME(invlpg)(struct kvm_vcpu *vcpu, gva_t gva) break; } + if (need_flush) + kvm_flush_remote_tlbs(vcpu->kvm); spin_unlock(&vcpu->kvm->mmu_lock); if (pte_gpa == -1) -- 2.41.1