1 files changed, 35 insertions, 8 deletions

diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index f283eb47f6ac..9507df93f410 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -683,6 +683,21 @@ static int svm_hardware_enable(void)
 
 	amd_pmu_enable_virt();
 
+	/*
+	 * If TSC_AUX virtualization is supported, TSC_AUX becomes a swap type
+	 * "B" field (see sev_es_prepare_switch_to_guest()) for SEV-ES guests.
+	 * Since Linux does not change the value of TSC_AUX once set, prime the
+	 * TSC_AUX field now to avoid a RDMSR on every vCPU run.
+	 */
+	if (boot_cpu_has(X86_FEATURE_V_TSC_AUX)) {
+		struct sev_es_save_area *hostsa;
+		u32 msr_hi;
+
+		hostsa = (struct sev_es_save_area *)(page_address(sd->save_area) + 0x400);
+
+		rdmsr(MSR_TSC_AUX, hostsa->tsc_aux, msr_hi);
+	}
+
 	return 0;
 }
 
@@ -1532,7 +1547,14 @@ static void svm_prepare_switch_to_guest(struct kvm_vcpu *vcpu)
 	if (tsc_scaling)
 		__svm_write_tsc_multiplier(vcpu->arch.tsc_scaling_ratio);
 
-	if (likely(tsc_aux_uret_slot >= 0))
+	/*
+	 * TSC_AUX is always virtualized for SEV-ES guests when the feature is
+	 * available. The user return MSR support is not required in this case
+	 * because TSC_AUX is restored on #VMEXIT from the host save area
+	 * (which has been initialized in svm_hardware_enable()).
+	 */
+	if (likely(tsc_aux_uret_slot >= 0) &&
+	    (!boot_cpu_has(X86_FEATURE_V_TSC_AUX) || !sev_es_guest(vcpu->kvm)))
 		kvm_set_user_return_msr(tsc_aux_uret_slot, svm->tsc_aux, -1ull);
 
 	svm->guest_state_loaded = true;
@@ -3087,6 +3109,16 @@ static int svm_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr)
 		break;
 	case MSR_TSC_AUX:
 		/*
+		 * TSC_AUX is always virtualized for SEV-ES guests when the
+		 * feature is available. The user return MSR support is not
+		 * required in this case because TSC_AUX is restored on #VMEXIT
+		 * from the host save area (which has been initialized in
+		 * svm_hardware_enable()).
+		 */
+		if (boot_cpu_has(X86_FEATURE_V_TSC_AUX) && sev_es_guest(vcpu->kvm))
+			break;
+
+		/*
 		 * TSC_AUX is usually changed only during boot and never read
 		 * directly.  Intercept TSC_AUX instead of exposing it to the
 		 * guest via direct_access_msrs, and switch it via user return.
@@ -4284,7 +4316,6 @@ static bool svm_has_emulated_msr(struct kvm *kvm, u32 index)
 static void svm_vcpu_after_set_cpuid(struct kvm_vcpu *vcpu)
 {
 	struct vcpu_svm *svm = to_svm(vcpu);
-	struct kvm_cpuid_entry2 *best;
 
 	/*
 	 * SVM doesn't provide a way to disable just XSAVES in the guest, KVM
@@ -4328,12 +4359,8 @@ static void svm_vcpu_after_set_cpuid(struct kvm_vcpu *vcpu)
 		set_msr_interception(vcpu, svm->msrpm, MSR_IA32_FLUSH_CMD, 0,
 				     !!guest_cpuid_has(vcpu, X86_FEATURE_FLUSH_L1D));
 
-	/* For sev guests, the memory encryption bit is not reserved in CR3.  */
-	if (sev_guest(vcpu->kvm)) {
-		best = kvm_find_cpuid_entry(vcpu, 0x8000001F);
-		if (best)
-			vcpu->arch.reserved_gpa_bits &= ~(1UL << (best->ebx & 0x3f));
-	}
+	if (sev_guest(vcpu->kvm))
+		sev_vcpu_after_set_cpuid(svm);
 
 	init_vmcb_after_set_cpuid(vcpu);
 }