Commit e4d86fb9 authored by Sean Christopherson's avatar Sean Christopherson
Browse files

KVM: selftests: Split PMU caps sub-tests to avoid writing MSR after KVM_RUN 

Split the PERF_CAPABILITIES subtests into two parts so that the LBR format
testcases don't execute after KVM_RUN.  Similar to the guest CPUID model,
KVM will soon disallow changing PERF_CAPABILITIES after KVM_RUN, at which
point attempting to set the MSR after KVM_RUN will yield false positives
and/or false negatives depending on what the test is trying to do.

Land the LBR format test in a more generic "immutable features" test in
anticipation of expanding its scope to other immutable features.

Link: https://lore.kernel.org/r/20230311004618.920745-6-seanjc@google.com


Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
parent 9eb6ba31

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

+31 −20
Original line number Diff line number Diff line
@@ -41,24 +41,10 @@ static void guest_code(void) 
	wrmsr(MSR_IA32_PERF_CAPABILITIES, PMU_CAP_LBR_FMT);

}



int main(int argc, char *argv[])

static void test_fungible_perf_capabilities(union perf_capabilities host_cap)

{

	struct kvm_vm *vm;

	struct kvm_vcpu *vcpu;

	int ret;

	union perf_capabilities host_cap;

	uint64_t val;



	host_cap.capabilities = kvm_get_feature_msr(MSR_IA32_PERF_CAPABILITIES);

	host_cap.capabilities &= (PMU_CAP_FW_WRITES | PMU_CAP_LBR_FMT);



	/* Create VM */

	vm = vm_create_with_one_vcpu(&vcpu, guest_code);



	TEST_REQUIRE(kvm_cpu_has(X86_FEATURE_PDCM));



	TEST_REQUIRE(kvm_cpu_has_p(X86_PROPERTY_PMU_VERSION));

	TEST_REQUIRE(kvm_cpu_property(X86_PROPERTY_PMU_VERSION) > 0);

	struct kvm_vm *vm = vm_create_with_one_vcpu(&vcpu, guest_code);



	/* testcase 1, set capabilities when we have PDCM bit */

	vcpu_set_msr(vcpu, MSR_IA32_PERF_CAPABILITIES, PMU_CAP_FW_WRITES);
@@ -70,7 +56,16 @@ int main(int argc, char *argv[]) 
	vcpu_run(vcpu);

	ASSERT_EQ(vcpu_get_msr(vcpu, MSR_IA32_PERF_CAPABILITIES), PMU_CAP_FW_WRITES);



	/* testcase 2, check valid LBR formats are accepted */

	kvm_vm_free(vm);

}



static void test_immutable_perf_capabilities(union perf_capabilities host_cap)

{

	struct kvm_vcpu *vcpu;

	struct kvm_vm *vm = vm_create_with_one_vcpu(&vcpu, NULL);

	uint64_t val;

	int ret;



	vcpu_set_msr(vcpu, MSR_IA32_PERF_CAPABILITIES, 0);

	ASSERT_EQ(vcpu_get_msr(vcpu, MSR_IA32_PERF_CAPABILITIES), 0);
@@ -78,8 +73,8 @@ int main(int argc, char *argv[]) 
	ASSERT_EQ(vcpu_get_msr(vcpu, MSR_IA32_PERF_CAPABILITIES), (u64)host_cap.lbr_format);



	/*

	 * Testcase 3, check that an "invalid" LBR format is rejected.  Only an

	 * exact match of the host's format (and 0/disabled) is allowed.

	 * KVM only supports the host's native LBR format, as well as '0' (to

	 * disable LBR support).  Verify KVM rejects all other LBR formats.

	 */

	for (val = 1; val <= PMU_CAP_LBR_FMT; val++) {

		if (val == (host_cap.capabilities & PMU_CAP_LBR_FMT))
@@ -88,7 +83,23 @@ int main(int argc, char *argv[]) 
		ret = _vcpu_set_msr(vcpu, MSR_IA32_PERF_CAPABILITIES, val);

		TEST_ASSERT(!ret, "Bad LBR FMT = 0x%lx didn't fail", val);

	}

	kvm_vm_free(vm);

}



int main(int argc, char *argv[])

{

	union perf_capabilities host_cap;



	TEST_REQUIRE(kvm_cpu_has(X86_FEATURE_PDCM));



	TEST_REQUIRE(kvm_cpu_has_p(X86_PROPERTY_PMU_VERSION));

	TEST_REQUIRE(kvm_cpu_property(X86_PROPERTY_PMU_VERSION) > 0);



	host_cap.capabilities = kvm_get_feature_msr(MSR_IA32_PERF_CAPABILITIES);

	host_cap.capabilities &= (PMU_CAP_FW_WRITES | PMU_CAP_LBR_FMT);



	test_fungible_perf_capabilities(host_cap);

	test_immutable_perf_capabilities(host_cap);



	printf("Completed perf capability tests.\n");

	kvm_vm_free(vm);

}