Commit 32935497 authored by Bandan Das's avatar Bandan Das Committed by Luis Henriques

KVM: nSVM: Check for NRIPS support before updating control field

commit f104765b 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: default avatarBandan Das <bsd@redhat.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: default avatarLuis Henriques <luis.henriques@canonical.com>
parent 1115b893
......@@ -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) !=
......@@ -4282,7 +4284,9 @@ 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);
......
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