KVM: selftests: Test Hyper-V invariant TSC control

Add a test for the newly introduced Hyper-V invariant TSC control feature:
- HV_X64_MSR_TSC_INVARIANT_CONTROL is not available without
 HV_ACCESS_TSC_INVARIANT CPUID bit set and available with it.
- BIT(0) of HV_X64_MSR_TSC_INVARIANT_CONTROL controls the filtering of
architectural invariant TSC (CPUID.80000007H:EDX[8]) bit.
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Reviewed-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20221013095849.705943-8-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

tools/testing/selftests/kvm/include/x86_64/hyperv.h

@@ -335,4 +335,7 @@ struct hyperv_test_pages {
 struct hyperv_test_pages *vcpu_alloc_hyperv_test_pages(struct kvm_vm *vm,
 						       vm_vaddr_t *p_hv_pages_gva);
 
+/* HV_X64_MSR_TSC_INVARIANT_CONTROL bits */
+#define HV_INVARIANT_TSC_EXPOSED               BIT_ULL(0)
+
 #endif /* !SELFTEST_KVM_HYPERV_H */

tools/testing/selftests/kvm/include/x86_64/processor.h

@@ -137,6 +137,7 @@ struct kvm_x86_cpu_feature {
 #define	X86_FEATURE_GBPAGES		KVM_X86_CPU_FEATURE(0x80000001, 0, EDX, 26)
 #define	X86_FEATURE_RDTSCP		KVM_X86_CPU_FEATURE(0x80000001, 0, EDX, 27)
 #define	X86_FEATURE_LM			KVM_X86_CPU_FEATURE(0x80000001, 0, EDX, 29)
+#define	X86_FEATURE_INVTSC		KVM_X86_CPU_FEATURE(0x80000007, 0, EDX, 8)
 #define	X86_FEATURE_RDPRU		KVM_X86_CPU_FEATURE(0x80000008, 0, EBX, 4)
 #define	X86_FEATURE_AMD_IBPB		KVM_X86_CPU_FEATURE(0x80000008, 0, EBX, 12)
 #define	X86_FEATURE_NPT			KVM_X86_CPU_FEATURE(0x8000000A, 0, EDX, 0)

tools/testing/selftests/kvm/x86_64/hyperv_features.c

@@ -63,6 +63,16 @@ static void guest_msr(struct msr_data *msr)
 	if (msr->write)
 		GUEST_ASSERT_3(msr_val == msr->write_val, msr->idx,
 			       msr_val, msr->write_val);
+
+	/* Invariant TSC bit appears when TSC invariant control MSR is written to */
+	if (msr->idx == HV_X64_MSR_TSC_INVARIANT_CONTROL) {
+		if (!this_cpu_has(HV_ACCESS_TSC_INVARIANT))
+			GUEST_ASSERT(this_cpu_has(X86_FEATURE_INVTSC));
+		else
+			GUEST_ASSERT(this_cpu_has(X86_FEATURE_INVTSC) ==
+				     !!(msr_val & HV_INVARIANT_TSC_EXPOSED));
+	}
+
 done:
 	GUEST_DONE();
 }
@@ -118,6 +128,7 @@ static void guest_test_msrs_access(void)
 	int stage = 0;
 	vm_vaddr_t msr_gva;
 	struct msr_data *msr;
+	bool has_invtsc = kvm_cpu_has(X86_FEATURE_INVTSC);
 
 	while (true) {
 		vm = vm_create_with_one_vcpu(&vcpu, guest_msr);
@@ -435,6 +446,42 @@ static void guest_test_msrs_access(void)
 			break;
 
 		case 44:
+			/* MSR is not available when CPUID feature bit is unset */
+			if (!has_invtsc)
+				continue;
+			msr->idx = HV_X64_MSR_TSC_INVARIANT_CONTROL;
+			msr->write = false;
+			msr->fault_expected = true;
+			break;
+		case 45:
+			/* MSR is vailable when CPUID feature bit is set */
+			if (!has_invtsc)
+				continue;
+			vcpu_set_cpuid_feature(vcpu, HV_ACCESS_TSC_INVARIANT);
+			msr->idx = HV_X64_MSR_TSC_INVARIANT_CONTROL;
+			msr->write = false;
+			msr->fault_expected = false;
+			break;
+		case 46:
+			/* Writing bits other than 0 is forbidden */
+			if (!has_invtsc)
+				continue;
+			msr->idx = HV_X64_MSR_TSC_INVARIANT_CONTROL;
+			msr->write = true;
+			msr->write_val = 0xdeadbeef;
+			msr->fault_expected = true;
+			break;
+		case 47:
+			/* Setting bit 0 enables the feature */
+			if (!has_invtsc)
+				continue;
+			msr->idx = HV_X64_MSR_TSC_INVARIANT_CONTROL;
+			msr->write = true;
+			msr->write_val = 1;
+			msr->fault_expected = false;
+			break;
+
+		default:
 			kvm_vm_free(vm);
 			return;
 		}