From: Joerg Roedel Date: Sat, 13 Sep 2008 05:38:41 +0000 (+0300) Subject: KVM: SVM: fix random segfaults with NPT enabled X-Git-Tag: v2.6.26.6~55 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=feec4f615504a766e1897412d5a9a28b1c4eec6c;p=thirdparty%2Fkernel%2Fstable.git KVM: SVM: fix random segfaults with NPT enabled (cherry picked from commit 44874f84918e37b64bec6df1587e5fe2fdf6ab62) This patch introduces a guest TLB flush on every NPF exit in KVM. This fixes random segfaults and #UD exceptions in the guest seen under some workloads (e.g. long running compile workloads or tbench). A kernbench run with and without that fix showed that it has a slowdown lower than 0.5% Signed-off-by: Joerg Roedel Signed-off-by: Alexander Graf Signed-off-by: Avi Kivity Signed-off-by: Greg Kroah-Hartman --- diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c index 7d6071d11eb89..fe88513a32960 100644 --- a/arch/x86/kvm/svm.c +++ b/arch/x86/kvm/svm.c @@ -60,6 +60,7 @@ static int npt = 1; module_param(npt, int, S_IRUGO); static void kvm_reput_irq(struct vcpu_svm *svm); +static void svm_flush_tlb(struct kvm_vcpu *vcpu); static inline struct vcpu_svm *to_svm(struct kvm_vcpu *vcpu) { @@ -1017,6 +1018,15 @@ static int pf_interception(struct vcpu_svm *svm, struct kvm_run *kvm_run) fault_address = svm->vmcb->control.exit_info_2; error_code = svm->vmcb->control.exit_info_1; + + /* + * FIXME: Tis shouldn't be necessary here, but there is a flush + * missing in the MMU code. Until we find this bug, flush the + * complete TLB here on an NPF + */ + if (npt_enabled) + svm_flush_tlb(&svm->vcpu); + if (event_injection) kvm_mmu_unprotect_page_virt(&svm->vcpu, fault_address); return kvm_mmu_page_fault(&svm->vcpu, fault_address, error_code);