linux-kernel - [PATCH 07/12] KVM: nSVM: Use KVM-governed feature framework to track "TSC scaling enabled"

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Date:   Fri, 17 Feb 2023 15:10:17 -0800
From:   Sean Christopherson <seanjc@...gle.com>
To:     Sean Christopherson <seanjc@...gle.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>
Cc:     kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH 07/12] KVM: nSVM: Use KVM-governed feature framework to track
 "TSC scaling enabled"

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

No functional change intended.

Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 arch/x86/kvm/governed_features.h |  1 +
 arch/x86/kvm/svm/nested.c        |  4 ++--
 arch/x86/kvm/svm/svm.c           | 12 ++++++++----
 arch/x86/kvm/svm/svm.h           |  1 -
 4 files changed, 11 insertions(+), 7 deletions(-)

diff --git a/arch/x86/kvm/governed_features.h b/arch/x86/kvm/governed_features.h
index 359914112615..0335576a80a8 100644
--- a/arch/x86/kvm/governed_features.h
+++ b/arch/x86/kvm/governed_features.h
@@ -8,6 +8,7 @@ BUILD_BUG()
 KVM_GOVERNED_X86_FEATURE(GBPAGES)
 KVM_GOVERNED_X86_FEATURE(XSAVES)
 KVM_GOVERNED_X86_FEATURE(NRIPS)
+KVM_GOVERNED_X86_FEATURE(TSCRATEMSR)
 
 #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 0641cb943450..30e00c4e07c7 100644
--- a/arch/x86/kvm/svm/nested.c
+++ b/arch/x86/kvm/svm/nested.c
@@ -673,7 +673,7 @@ static void nested_vmcb02_prepare_control(struct vcpu_svm *svm,
 	vmcb02->control.tsc_offset = vcpu->arch.tsc_offset;
 
 	if (svm->tsc_ratio_msr != kvm_caps.default_tsc_scaling_ratio) {
-		WARN_ON(!svm->tsc_scaling_enabled);
+		WARN_ON(!guest_can_use(vcpu, X86_FEATURE_TSCRATEMSR));
 		nested_svm_update_tsc_ratio_msr(vcpu);
 	}
 
@@ -1043,7 +1043,7 @@ int nested_svm_vmexit(struct vcpu_svm *svm)
 	}
 
 	if (svm->tsc_ratio_msr != kvm_caps.default_tsc_scaling_ratio) {
-		WARN_ON(!svm->tsc_scaling_enabled);
+		WARN_ON(!guest_can_use(vcpu, X86_FEATURE_TSCRATEMSR));
 		vcpu->arch.tsc_scaling_ratio = vcpu->arch.l1_tsc_scaling_ratio;
 		__svm_write_tsc_multiplier(vcpu->arch.tsc_scaling_ratio);
 	}
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index cdffc6db8bc5..dd4aead5462c 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -2737,7 +2737,8 @@ static int svm_get_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
 
 	switch (msr_info->index) {
 	case MSR_AMD64_TSC_RATIO:
-		if (!msr_info->host_initiated && !svm->tsc_scaling_enabled)
+		if (!msr_info->host_initiated &&
+		    !guest_can_use(vcpu, X86_FEATURE_TSCRATEMSR))
 			return 1;
 		msr_info->data = svm->tsc_ratio_msr;
 		break;
@@ -2879,7 +2880,7 @@ static int svm_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr)
 	switch (ecx) {
 	case MSR_AMD64_TSC_RATIO:
 
-		if (!svm->tsc_scaling_enabled) {
+		if (!guest_can_use(vcpu, X86_FEATURE_TSCRATEMSR)) {
 
 			if (!msr->host_initiated)
 				return 1;
@@ -2901,7 +2902,8 @@ static int svm_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr)
 
 		svm->tsc_ratio_msr = data;
 
-		if (svm->tsc_scaling_enabled && is_guest_mode(vcpu))
+		if (guest_can_use(vcpu, X86_FEATURE_TSCRATEMSR) &&
+		    is_guest_mode(vcpu))
 			nested_svm_update_tsc_ratio_msr(vcpu);
 
 		break;
@@ -4146,7 +4148,9 @@ static void svm_vcpu_after_set_cpuid(struct kvm_vcpu *vcpu)
 	if (kvm_cpu_cap_has(X86_FEATURE_NRIPS))
 		kvm_governed_feature_check_and_set(vcpu, X86_FEATURE_NRIPS);
 
-	svm->tsc_scaling_enabled = tsc_scaling && guest_cpuid_has(vcpu, X86_FEATURE_TSCRATEMSR);
+	if (tsc_scaling)
+		kvm_governed_feature_check_and_set(vcpu, X86_FEATURE_TSCRATEMSR);
+
 	svm->lbrv_enabled = lbrv && guest_cpuid_has(vcpu, X86_FEATURE_LBRV);
 
 	svm->v_vmload_vmsave_enabled = vls && guest_cpuid_has(vcpu, X86_FEATURE_V_VMSAVE_VMLOAD);
diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h
index bd6ee6945bdd..a523cfcdd12e 100644
--- a/arch/x86/kvm/svm/svm.h
+++ b/arch/x86/kvm/svm/svm.h
@@ -258,7 +258,6 @@ struct vcpu_svm {
 	bool soft_int_injected;
 
 	/* optional nested SVM features that are enabled for this guest  */
-	bool tsc_scaling_enabled          : 1;
 	bool v_vmload_vmsave_enabled      : 1;
 	bool lbrv_enabled                 : 1;
 	bool pause_filter_enabled         : 1;
-- 
2.39.2.637.g21b0678d19-goog