Allow testing code for old processors that lack the next RIP save
feature, by disabling usage of the next_rip field.
Nested hypervisors however get the feature unconditionally.
Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
---
arch/x86/kvm/svm.c | 15 ++++++++++++---
1 file changed, 12 insertions(+), 3 deletions(-)
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 735b8c01895e..fe046c13f03b 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -367,6 +367,10 @@ struct amd_svm_iommu_ir {
module_param(avic, int, S_IRUGO);
#endif
+/* enable/disable Next RIP Save */
+static int nrips = true;
+module_param(nrips, int, 0444);
+
/* enable/disable Virtual VMLOAD VMSAVE */
static int vls = true;
module_param(vls, int, 0444);
@@ -773,7 +777,7 @@ static void skip_emulated_instruction(struct kvm_vcpu *vcpu)
{
struct vcpu_svm *svm = to_svm(vcpu);
- if (svm->vmcb->control.next_rip != 0) {
+ if (nrips && svm->vmcb->control.next_rip != 0) {
WARN_ON_ONCE(!static_cpu_has(X86_FEATURE_NRIPS));
svm->next_rip = svm->vmcb->control.next_rip;
}
@@ -810,7 +814,7 @@ static void svm_queue_exception(struct kvm_vcpu *vcpu)
kvm_deliver_exception_payload(&svm->vcpu);
- if (nr == BP_VECTOR && !static_cpu_has(X86_FEATURE_NRIPS)) {
+ if (nr == BP_VECTOR && !nrips) {
unsigned long rip, old_rip = kvm_rip_read(&svm->vcpu);
/*
@@ -1367,6 +1371,11 @@ static __init int svm_hardware_setup(void)
} else
kvm_disable_tdp();
+ if (nrips) {
+ if (!boot_cpu_has(X86_FEATURE_NRIPS))
+ nrips = false;
+ }
+
if (avic) {
if (!npt_enabled ||
!boot_cpu_has(X86_FEATURE_AVIC) ||
@@ -3938,7 +3947,7 @@ static int rdpmc_interception(struct vcpu_svm *svm)
{
int err;
- if (!static_cpu_has(X86_FEATURE_NRIPS))
+ if (!nrips)
return emulate_on_interception(svm);
err = kvm_rdpmc(&svm->vcpu);
--
1.8.3.1
