Commit baa36dac authored by Sean Christopherson's avatar Sean Christopherson
Browse files

KVM: selftests: Expand negative testing of guest writes to PERF_CAPABILITIES 

Test that the guest can't write 0 to PERF_CAPABILITIES, can't write the
current value, and can't toggle _any_ bits.  There is no reason to special
case the LBR format.

Link: https://lore.kernel.org/r/20230311004618.920745-17-seanjc@google.com


Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
parent a2a34d14

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

+54 −7
Original line number Diff line number Diff line
@@ -54,9 +54,59 @@ static const union perf_capabilities format_caps = { 
	.pebs_format = -1,

};



static void guest_code(void)

static void guest_code(uint64_t current_val)

{

	wrmsr(MSR_IA32_PERF_CAPABILITIES, PMU_CAP_LBR_FMT);

	uint8_t vector;

	int i;



	vector = wrmsr_safe(MSR_IA32_PERF_CAPABILITIES, current_val);

	GUEST_ASSERT_2(vector == GP_VECTOR, current_val, vector);



	vector = wrmsr_safe(MSR_IA32_PERF_CAPABILITIES, 0);

	GUEST_ASSERT_2(vector == GP_VECTOR, 0, vector);



	for (i = 0; i < 64; i++) {

		vector = wrmsr_safe(MSR_IA32_PERF_CAPABILITIES,

				    current_val ^ BIT_ULL(i));

		GUEST_ASSERT_2(vector == GP_VECTOR,

			       current_val ^ BIT_ULL(i), vector);

	}



	GUEST_DONE();

}



/*

 * Verify that guest WRMSRs to PERF_CAPABILITIES #GP regardless of the value

 * written, that the guest always sees the userspace controlled value, and that

 * PERF_CAPABILITIES is immutable after KVM_RUN.

 */

static void test_guest_wrmsr_perf_capabilities(union perf_capabilities host_cap)

{

	struct kvm_vcpu *vcpu;

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

	struct ucall uc;



	vm_init_descriptor_tables(vm);

	vcpu_init_descriptor_tables(vcpu);



	vcpu_set_msr(vcpu, MSR_IA32_PERF_CAPABILITIES, host_cap.capabilities);



	vcpu_args_set(vcpu, 1, host_cap.capabilities);

	vcpu_run(vcpu);



	switch (get_ucall(vcpu, &uc)) {

	case UCALL_ABORT:

		REPORT_GUEST_ASSERT_2(uc, "val = 0x%lx, vector = %lu");

		break;

	case UCALL_DONE:

		break;

	default:

		TEST_FAIL("Unexpected ucall: %lu", uc.cmd);

	}



	ASSERT_EQ(vcpu_get_msr(vcpu, MSR_IA32_PERF_CAPABILITIES), host_cap.capabilities);



	kvm_vm_free(vm);

}



/*
@@ -79,7 +129,7 @@ static void test_fungible_perf_capabilities(union perf_capabilities host_cap) 
	const uint64_t fungible_caps = host_cap.capabilities & ~immutable_caps.capabilities;



	struct kvm_vcpu *vcpu;

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

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

	int bit;



	for_each_set_bit(bit, &fungible_caps, 64) {
@@ -89,10 +139,6 @@ static void test_fungible_perf_capabilities(union perf_capabilities host_cap) 
	}

	vcpu_set_msr(vcpu, MSR_IA32_PERF_CAPABILITIES, host_cap.capabilities);



	/* check whatever we write with KVM_SET_MSR is _not_ modified */

	vcpu_run(vcpu);

	ASSERT_EQ(vcpu_get_msr(vcpu, MSR_IA32_PERF_CAPABILITIES), host_cap.capabilities);



	kvm_vm_free(vm);

}
@@ -153,6 +199,7 @@ int main(int argc, char *argv[]) 
	test_basic_perf_capabilities(host_cap);

	test_fungible_perf_capabilities(host_cap);

	test_immutable_perf_capabilities(host_cap);

	test_guest_wrmsr_perf_capabilities(host_cap);



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

}