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KVM: SVM: fix random segfaults with NPT enabled

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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: Joerg Roedel <joerg.roedel@amd.com>
Signed-off-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Avi Kivity <avi@qumranet.com>
This commit is contained in:
Joerg Roedel 2008-08-27 14:18:43 +02:00 committed by Avi Kivity
parent adee14b2e1
commit 44874f8491
1 changed files with 8 additions and 0 deletions
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8
arch/x86/kvm/svm.c
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@ -62,6 +62,7 @@ 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)
{
@ -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,
(u32)fault_address, (u32)(fault_address >> 32),
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)
kvm_mmu_unprotect_page_virt(&svm->vcpu, fault_address);