[PATCH v2 5/6] KVM: selftests: Update nSVM EFER test to expect #GP when clearing SVME in L2

[Sean Christopherson]

Adjust the nSVM EFER test to expect a #GP on WRMSR if L2 attempts to clear
EFER.SVME to match KVM's new behavior (synthesizing #GP is safer for KVM as
it doesn't require yanking the vCPU out of L2, and is fully synchronous).

Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
---
 .../selftests/kvm/x86/svm_nested_efer_test.c  | 75 ++++++++++++-------
 1 file changed, 46 insertions(+), 29 deletions(-)

diff --git a/tools/testing/selftests/kvm/x86/svm_nested_efer_test.c b/tools/testing/selftests/kvm/x86/svm_nested_efer_test.c
index fa0d76a9c390..fa9cfe8b1242 100644
--- a/tools/testing/selftests/kvm/x86/svm_nested_efer_test.c
+++ b/tools/testing/selftests/kvm/x86/svm_nested_efer_test.c
@@ -15,22 +15,34 @@ static bool l2_ran;
 static void l2_clear_efer_svme(void)
 {
 	u64 efer = rdmsr(MSR_EFER);
+	u8 vector;
 
 	/* generic_svm_setup() initializes EFER_SVME set for L2 */
 	GUEST_ASSERT(efer & EFER_SVME);
-	wrmsr(MSR_EFER, efer & ~EFER_SVME);
 
-	/* Unreachable, L1 should be shutdown */
-	GUEST_ASSERT(0);
+	vector = wrmsr_safe(MSR_EFER, efer & ~EFER_SVME);
+	__GUEST_ASSERT(vector == GP_VECTOR,
+		       "Expected #GP when clearing EFER.SVME in L2, got %s",
+		       ex_str(vector));
+
+	efer = rdmsr(MSR_EFER);
+	GUEST_ASSERT(efer & EFER_SVME);
+
+	l2_ran = true;
+	vmmcall();
 }
 
 static void l1_clear_efer_svme(struct svm_test_data *svm)
 {
+	struct vmcb *vmcb = svm->vmcb;
+
 	generic_svm_setup(svm, l2_clear_efer_svme);
-	run_guest(svm->vmcb, svm->vmcb_gpa);
+	run_guest(vmcb, svm->vmcb_gpa);
 
-	/* Unreachable, L1 should be shutdown */
-	GUEST_ASSERT(0);
+	GUEST_ASSERT_EQ(vmcb->control.exit_code, SVM_EXIT_VMMCALL);
+	GUEST_ASSERT(l2_ran);
+	GUEST_ASSERT(vmcb->save.efer & EFER_SVME);
+	GUEST_DONE();
 }
 
 static void l2_lmsle(void)
@@ -130,31 +142,10 @@ static void test_enumeration(void)
 	ksft_test_result_pass("KVM enumerates EFER_LMSLE_MBZ=%d\n", lmsle_mbz);
 }
 
-static void test_clear_efer_svme(void)
+static void test_efer_in_guest(struct kvm_vcpu *vcpu)
 {
-	struct kvm_vcpu *vcpu;
-	struct kvm_vm *vm;
-
-	vcpu = create_l1_vcpu(&vm, l1_clear_efer_svme);
-
-	vcpu_run(vcpu);
-	TEST_ASSERT_KVM_EXIT_REASON(vcpu, KVM_EXIT_SHUTDOWN);
-
-	kvm_vm_free(vm);
-	ksft_test_result_pass("L2 clearing EFER.SVME shuts down L1\n");
-}
-
-static void test_lmsle(bool lmsle_mbz)
-{
-	struct kvm_vcpu *vcpu;
-	struct kvm_vm *vm;
 	struct ucall uc;
 
-	vcpu = create_l1_vcpu(&vm, l1_lmsle);
-
-	vcpu_set_or_clear_cpuid_feature(vcpu, X86_FEATURE_EFER_LMSLE_MBZ,
-					lmsle_mbz);
-
 	vcpu_run(vcpu);
 	TEST_ASSERT_KVM_EXIT_REASON(vcpu, KVM_EXIT_IO);
 
@@ -166,6 +157,32 @@ static void test_lmsle(bool lmsle_mbz)
 	default:
 		TEST_FAIL("Unexpected ucall: %lu", uc.cmd);
 	}
+}
+
+static void test_clear_efer_svme(void)
+{
+	struct kvm_vcpu *vcpu;
+	struct kvm_vm *vm;
+
+	vcpu = create_l1_vcpu(&vm, l1_clear_efer_svme);
+
+	test_efer_in_guest(vcpu);
+
+	kvm_vm_free(vm);
+	ksft_test_result_pass("L2 clearing EFER.SVME gets #GP\n");
+}
+
+static void test_lmsle(bool lmsle_mbz)
+{
+	struct kvm_vcpu *vcpu;
+	struct kvm_vm *vm;
+
+	vcpu = create_l1_vcpu(&vm, l1_lmsle);
+
+	vcpu_set_or_clear_cpuid_feature(vcpu, X86_FEATURE_EFER_LMSLE_MBZ,
+					lmsle_mbz);
+
+	test_efer_in_guest(vcpu);
 
 	kvm_vm_free(vm);
 	ksft_test_result_pass("Guest EFER_LMSLE_MBZ=%d\n", lmsle_mbz);
@@ -248,7 +265,7 @@ int main(int argc, char *argv[])
 		test_clear_efer_svme();
 		test_lmsle(true);
 	} else {
-		ksft_test_result_skip("L2 clearing EFER.SVME shuts down L1\n");
+		ksft_test_result_skip("L2 clearing EFER.SVME gets #GP\n");
 		ksft_test_result_skip("Guest EFER_LMSLE_MBZ=1\n");
 	}
 
-- 
2.56.0.307.g5fe7bd680c-goog