Messages in this thread Patch in this message | ![/](/images/icornerl.gif) | | From | Kamal Mostafa <> | Subject | [PATCH 3.19.y-ckt 023/155] KVM: nSVM: Check for NRIPS support before updating control field | Date | Thu, 12 Nov 2015 15:16:17 -0800 |
| |
3.19.8-ckt10 -stable review patch. If anyone has any objections, please let me know.
------------------
From: Bandan Das <bsd@redhat.com>
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: Kamal Mostafa <kamal@canonical.com> --- arch/x86/kvm/svm.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c index 67f8457..dd68f32 100644 --- a/arch/x86/kvm/svm.c +++ b/arch/x86/kvm/svm.c @@ -511,8 +511,10 @@ 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) != @@ -4315,7 +4317,9 @@ 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); -- 1.9.1
| ![\](/images/icornerr.gif) |