[PATCH v2 65/66] KVM: nSVM: Advertise and enable NRIPS for L1 iff nrips is enabled

Sean Christopherson
2020-03-02T23:59:16Z

Set NRIPS in KVM capabilities if and only if nrips=true, which naturally
incorporates the boot_cpu_has() check, and set nrips_enabled only if the
KVM capability is enabled.

Note, previously KVM would set nrips_enabled based purely on userspace
input, but at worst that would cause KVM to propagate garbage into L1,
i.e. userspace would simply be hosing its VM.

Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
---
arch/x86/kvm/svm.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 8e39dcd3160d..32d9c13ec6b9 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -1377,7 +1377,7 @@ static __init void svm_set_cpu_caps(void)
if (nested) {
kvm_cpu_cap_set(X86_FEATURE_SVM);

- if (boot_cpu_has(X86_FEATURE_NRIPS))
+ if (nrips)
kvm_cpu_cap_set(X86_FEATURE_NRIPS);

if (npt_enabled)
@@ -6031,7 +6031,8 @@ static void svm_cpuid_update(struct kvm_vcpu *vcpu)
boot_cpu_has(X86_FEATURE_XSAVES);

/* Update nrips enabled cache */
- svm->nrips_enabled = !!guest_cpuid_has(&svm->vcpu, X86_FEATURE_NRIPS);
+ svm->nrips_enabled = kvm_cpu_cap_has(X86_FEATURE_NRIPS) &&
+ guest_cpuid_has(&svm->vcpu, X86_FEATURE_NRIPS);

if (!kvm_vcpu_apicv_active(vcpu))
return;
--
2.24.1