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authorBandan Das <bsd@redhat.com>2015-06-11 02:05:33 -0400
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2015-07-03 19:48:09 -0700
commitea0d66be1c27f55825a80d01ad1ff72f6e005c29 (patch)
treea6b5f1a327416e24b63c4c3598a814acd3a1a741
parent4cae4bbc1a8f5258a986801d72678752f9075a64 (diff)
KVM: nSVM: Check for NRIPS support before updating control field
commit f104765b4f81fd74d69e0eb161e89096deade2db upstream. If hardware doesn't support DecodeAssist - a feature that provides more information about the intercept in the VMCB, KVM decodes the instruction and then updates the next_rip vmcb control field. However, NRIP support itself depends on cpuid Fn8000_000A_EDX[NRIPS]. Since skip_emulated_instruction() doesn't verify nrip support before accepting control.next_rip as valid, avoid writing this field if support isn't present. Signed-off-by: Bandan Das <bsd@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--arch/x86/kvm/svm.c8
1 files changed, 6 insertions, 2 deletions
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 8bf40a243d75..224d2ef754cc 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -495,8 +495,10 @@ static void skip_emulated_instruction(struct kvm_vcpu *vcpu)
{
struct vcpu_svm *svm = to_svm(vcpu);
- if (svm->vmcb->control.next_rip != 0)
+ if (svm->vmcb->control.next_rip != 0) {
+ WARN_ON(!static_cpu_has(X86_FEATURE_NRIPS));
svm->next_rip = svm->vmcb->control.next_rip;
+ }
if (!svm->next_rip) {
if (emulate_instruction(vcpu, EMULTYPE_SKIP) !=
@@ -4229,7 +4231,9 @@ static int svm_check_intercept(struct kvm_vcpu *vcpu,
break;
}
- vmcb->control.next_rip = info->next_rip;
+ /* TODO: Advertise NRIPS to guest hypervisor unconditionally */
+ if (static_cpu_has(X86_FEATURE_NRIPS))
+ vmcb->control.next_rip = info->next_rip;
vmcb->control.exit_code = icpt_info.exit_code;
vmexit = nested_svm_exit_handled(svm);