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Commit 44874f84 authored by Joerg Roedel's avatar Joerg Roedel Committed by Avi Kivity
Browse files

KVM: SVM: fix random segfaults with NPT enabled 



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%

Cc: stable@kernel.org
Signed-off-by: default avatarJoerg Roedel <joerg.roedel@amd.com>
Signed-off-by: default avatarAlexander Graf <agraf@suse.de>
Signed-off-by: default avatarAvi Kivity <avi@qumranet.com>
parent adee14b2

arch/x86/kvm/svm.c

+8 −0
Original line number Original line Diff line number Diff line
@@ -62,6 +62,7 @@ static int npt = 1; 
module_param(npt, int, S_IRUGO);

module_param(npt, int, S_IRUGO);





static void kvm_reput_irq(struct vcpu_svm *svm);

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)

static inline struct vcpu_svm *to_svm(struct kvm_vcpu *vcpu)

{

{
@@ -1027,6 +1028,13 @@ static int pf_interception(struct vcpu_svm *svm, struct kvm_run *kvm_run) 
		KVMTRACE_3D(TDP_FAULT, &svm->vcpu, error_code,

		KVMTRACE_3D(TDP_FAULT, &svm->vcpu, error_code,

			    (u32)fault_address, (u32)(fault_address >> 32),

			    (u32)fault_address, (u32)(fault_address >> 32),

			    handler);

			    handler);

	/*

	 * 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)

	if (event_injection)

		kvm_mmu_unprotect_page_virt(&svm->vcpu, fault_address);

		kvm_mmu_unprotect_page_virt(&svm->vcpu, fault_address);