KVM: nSVM: Use KVM-governed feature framework to track "vNMI enabled"

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.

Link: https://lore.kernel.org/r/20230815203653.519297-15-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>

diff --git a/arch/x86/kvm/governed_features.h b/arch/x86/kvm/governed_features.h
index 368696c2e96b9eb5a10ee652ccc9f54e71e61499..423a73395c102ca908453016e416dbdfb7fc2b5b 100644 (file)
--- 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 d8b7e0c71313f750e841f21fcec6e16c12cbf233..226b3a780d0fcb20120040da0fb4e1c494c01e95 100644 (file)
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -4274,8 +4274,7 @@ 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 6eb5877cc6c399caebebca907a31d53b2564e1b2..06400cfe2244b01a6736c28030f777387859d116 100644 (file)
--- 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;
@@ -537,7 +534,7 @@ 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);
 }