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Subject[patch 17/71] KVM: SVM: fix random segfaults with NPT enabled

2.6.26-stable review patch. If anyone has any objections, please let us
know.

------------------
From: Joerg Roedel <joerg.roedel@amd.com>
(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 <joerg.roedel@amd.com>
Signed-off-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Avi Kivity <avi@qumranet.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
arch/x86/kvm/svm.c | 10 ++++++++++
1 file changed, 10 insertions(+)
--- 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_s

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);
--


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