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

Track "virtual GIF 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 "vgif" param means that
the code isn't strictly equivalent, as vgif_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

Link: https://lore.kernel.org/r/20230815203653.519297-14-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 9afd34f..368696c 100644 (file)
--- a/arch/x86/kvm/governed_features.h
+++ b/arch/x86/kvm/governed_features.h
@@ -14,6 +14,7 @@ KVM_GOVERNED_X86_FEATURE(V_VMSAVE_VMLOAD)
 KVM_GOVERNED_X86_FEATURE(LBRV)
 KVM_GOVERNED_X86_FEATURE(PAUSEFILTER)
 KVM_GOVERNED_X86_FEATURE(PFTHRESHOLD)
+KVM_GOVERNED_X86_FEATURE(VGIF)
 
 #undef KVM_GOVERNED_X86_FEATURE
 #undef KVM_GOVERNED_FEATURE

diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c
index ac03b2b..dd496c9 100644 (file)
--- a/arch/x86/kvm/svm/nested.c
+++ b/arch/x86/kvm/svm/nested.c
@@ -660,7 +660,8 @@ static void nested_vmcb02_prepare_control(struct vcpu_svm *svm,
         * exit_int_info, exit_int_info_err, next_rip, insn_len, insn_bytes.
         */
 
-       if (svm->vgif_enabled && (svm->nested.ctl.int_ctl & V_GIF_ENABLE_MASK))
+       if (guest_can_use(vcpu, X86_FEATURE_VGIF) &&
+           (svm->nested.ctl.int_ctl & V_GIF_ENABLE_MASK))
                int_ctl_vmcb12_bits |= (V_GIF_MASK | V_GIF_ENABLE_MASK);
        else
                int_ctl_vmcb01_bits |= (V_GIF_MASK | V_GIF_ENABLE_MASK);

diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index 0dc70ad..d8b7e0c 100644 (file)
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -4273,8 +4273,7 @@ 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);
-
-       svm->vgif_enabled = vgif && guest_cpuid_has(vcpu, X86_FEATURE_VGIF);
+       kvm_governed_feature_check_and_set(vcpu, X86_FEATURE_VGIF);
 
        svm->vnmi_enabled = vnmi && guest_cpuid_has(vcpu, X86_FEATURE_VNMI);
 

diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h
index fb43843..6eb5877 100644 (file)
--- a/arch/x86/kvm/svm/svm.h
+++ b/arch/x86/kvm/svm/svm.h
@@ -22,6 +22,7 @@
 #include <asm/svm.h>
 #include <asm/sev-common.h>
 
+#include "cpuid.h"
 #include "kvm_cache_regs.h"
 
 #define __sme_page_pa(x) __sme_set(page_to_pfn(x) << PAGE_SHIFT)
@@ -259,7 +260,6 @@ struct vcpu_svm {
        bool soft_int_injected;
 
        /* optional nested SVM features that are enabled for this guest  */
-       bool vgif_enabled                 : 1;
        bool vnmi_enabled                 : 1;
 
        u32 ldr_reg;
@@ -485,7 +485,8 @@ static inline bool svm_is_intercept(struct vcpu_svm *svm, int bit)
 
 static inline bool nested_vgif_enabled(struct vcpu_svm *svm)
 {
-       return svm->vgif_enabled && (svm->nested.ctl.int_ctl & V_GIF_ENABLE_MASK);
+       return guest_can_use(&svm->vcpu, X86_FEATURE_VGIF) &&
+              (svm->nested.ctl.int_ctl & V_GIF_ENABLE_MASK);
 }
 
 static inline struct vmcb *get_vgif_vmcb(struct vcpu_svm *svm)