[PATCH v3 14/15] KVM: nSVM: Use KVM-governed feature framework to track "vNMI enabled"

From: Sean Christopherson
Date: Tue Aug 15 2023 - 16:38:57 EST


Track "virtual NMI exposed to L1" via a governed feature flag instead of
using a dedicated bit/flag in vcpu_svm.

Note, checking KVM's capabilities instead of the "vnmi" param means that
the code isn't strictly equivalent, as vnmi_enabled could have been set
if nested=false where as that the governed feature cannot. But that's a
glorified nop as the feature/flag is consumed only by paths that are
gated by nSVM being enabled.

Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
---
arch/x86/kvm/governed_features.h | 1 +
arch/x86/kvm/svm/svm.c | 3 +--
arch/x86/kvm/svm/svm.h | 5 +----
3 files changed, 3 insertions(+), 6 deletions(-)

diff --git a/arch/x86/kvm/governed_features.h b/arch/x86/kvm/governed_features.h
index 368696c2e96b..423a73395c10 100644
--- a/arch/x86/kvm/governed_features.h
+++ b/arch/x86/kvm/governed_features.h
@@ -15,6 +15,7 @@ KVM_GOVERNED_X86_FEATURE(LBRV)
KVM_GOVERNED_X86_FEATURE(PAUSEFILTER)
KVM_GOVERNED_X86_FEATURE(PFTHRESHOLD)
KVM_GOVERNED_X86_FEATURE(VGIF)
+KVM_GOVERNED_X86_FEATURE(VNMI)

#undef KVM_GOVERNED_X86_FEATURE
#undef KVM_GOVERNED_FEATURE
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index 9eac0ad3403e..a139c626fa8b 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -4303,8 +4303,7 @@ static void svm_vcpu_after_set_cpuid(struct kvm_vcpu *vcpu)
kvm_governed_feature_check_and_set(vcpu, X86_FEATURE_PAUSEFILTER);
kvm_governed_feature_check_and_set(vcpu, X86_FEATURE_PFTHRESHOLD);
kvm_governed_feature_check_and_set(vcpu, X86_FEATURE_VGIF);
-
- svm->vnmi_enabled = vnmi && guest_cpuid_has(vcpu, X86_FEATURE_VNMI);
+ kvm_governed_feature_check_and_set(vcpu, X86_FEATURE_VNMI);

svm_recalc_instruction_intercepts(vcpu, svm);

diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h
index eaddaac6bf18..2237230aad98 100644
--- a/arch/x86/kvm/svm/svm.h
+++ b/arch/x86/kvm/svm/svm.h
@@ -259,9 +259,6 @@ struct vcpu_svm {
unsigned long soft_int_next_rip;
bool soft_int_injected;

- /* optional nested SVM features that are enabled for this guest */
- bool vnmi_enabled : 1;
-
u32 ldr_reg;
u32 dfr_reg;
struct page *avic_backing_page;
@@ -495,7 +492,7 @@ static inline bool nested_npt_enabled(struct vcpu_svm *svm)

static inline bool nested_vnmi_enabled(struct vcpu_svm *svm)
{
- return svm->vnmi_enabled &&
+ return guest_can_use(&svm->vcpu, X86_FEATURE_VNMI) &&
(svm->nested.ctl.int_ctl & V_NMI_ENABLE_MASK);
}

--
2.41.0.694.ge786442a9b-goog