Re: [PATCH 9/9] KVM: selftests: Add fixed counters enumeration test case

["Mi, Dapeng" <dapeng1.mi@linux.intel.com>]

On 9/1/2023 3:28 PM, Xiong Zhang wrote:
> vPMU v5 adds fixed counter enumeration, which allows user space to
> specify which fixed counters are supported through emulated
> CPUID.0Ah.ECX.
>
> This commit adds a test case which specify the max fixed counter
> supported only, so guest can access the max fixed counter only, #GP
> exception will be happen once guest access other fixed counters.
>
> Signed-off-by: Xiong Zhang <xiong.y.zhang@intel.com>
> ---
>   .../selftests/kvm/x86_64/vmx_pmu_caps_test.c  | 84 +++++++++++++++++++
>   1 file changed, 84 insertions(+)
>
> diff --git a/tools/testing/selftests/kvm/x86_64/vmx_pmu_caps_test.c b/tools/testing/selftests/kvm/x86_64/vmx_pmu_caps_test.c
> index ebbcb0a3f743..e37dc39164fe 100644
> --- a/tools/testing/selftests/kvm/x86_64/vmx_pmu_caps_test.c
> +++ b/tools/testing/selftests/kvm/x86_64/vmx_pmu_caps_test.c


since we added new test cases  in this file, this file is not just test 
'perf_capablities' anymore, we may change the file name 
vmx_pmu_caps_test.c to a more generic name like "vmx_pmu_test.c" or 
something else.

> @@ -18,6 +18,8 @@
>   #include "kvm_util.h"
>   #include "vmx.h"
>   
> +uint8_t fixed_counter_num;
> +
>   union perf_capabilities {
>   	struct {
>   		u64	lbr_format:6;
> @@ -233,6 +235,86 @@ static void test_lbr_perf_capabilities(union perf_capabilities host_cap)
>   	kvm_vm_free(vm);
>   }
>   
> +static void guest_v5_code(void)
> +{
> +	uint8_t  vector, i;
> +	uint64_t val;
> +
> +	for (i = 0; i < fixed_counter_num; i++) {
> +		vector = rdmsr_safe(MSR_CORE_PERF_FIXED_CTR0 + i, &val);
> +
> +		/*
> +		 * Only the max fixed counter is supported, #GP will be generated
> +		 * when guest access other fixed counters.
> +		 */
> +		if (i == fixed_counter_num - 1)
> +			__GUEST_ASSERT(vector != GP_VECTOR,
> +				       "Max Fixed counter is accessible, but get #GP");
> +		else
> +			__GUEST_ASSERT(vector == GP_VECTOR,
> +				       "Fixed counter isn't accessible, but access is ok");
> +	}
> +
> +	GUEST_DONE();
> +}
> +
> +#define PMU_NR_FIXED_COUNTERS_MASK  0x1f
> +
> +static void test_fixed_counter_enumeration(void)
> +{
> +	struct kvm_vcpu *vcpu;
> +	struct kvm_vm *vm;
> +	int r;
> +	struct kvm_cpuid_entry2 *ent;
> +	struct ucall uc;
> +	uint32_t fixed_counter_bit_mask;
> +
> +	if (kvm_cpu_property(X86_PROPERTY_PMU_VERSION) != 5)
> +		return;


We'd better check if the version is less than 5 here, since we might 
have higher version than 5 in the future.


> +
> +	vm = vm_create_with_one_vcpu(&vcpu, guest_v5_code);
> +	vm_init_descriptor_tables(vm);
> +	vcpu_init_descriptor_tables(vcpu);
> +
> +	ent = vcpu_get_cpuid_entry(vcpu, 0xa);
> +	fixed_counter_num = ent->edx & PMU_NR_FIXED_COUNTERS_MASK;
> +	TEST_ASSERT(fixed_counter_num > 0, "fixed counter isn't supported");
> +	fixed_counter_bit_mask = (1ul << fixed_counter_num) - 1;
> +	TEST_ASSERT(ent->ecx == fixed_counter_bit_mask,
> +		    "cpuid.0xa.ecx != %x", fixed_counter_bit_mask);
> +
> +	/* Fixed counter 0 isn't in ecx, but in edx, set_cpuid should be error. */
> +	ent->ecx &= ~0x1;
> +	r = __vcpu_set_cpuid(vcpu);
> +	TEST_ASSERT(r, "Setting in-consistency cpuid.0xa.ecx and edx success");
> +
> +	if (fixed_counter_num == 1) {
> +		kvm_vm_free(vm);
> +		return;
> +	}
> +
> +	/* Support the max Fixed Counter only */
> +	ent->ecx = 1UL << (fixed_counter_num - 1);
> +	ent->edx &= ~(u32)PMU_NR_FIXED_COUNTERS_MASK;
> +
> +	r = __vcpu_set_cpuid(vcpu);
> +	TEST_ASSERT(!r, "Setting modified cpuid.0xa.ecx and edx failed");
> +
> +	vcpu_run(vcpu);
> +
> +	switch (get_ucall(vcpu, &uc)) {
> +	case UCALL_ABORT:
> +		REPORT_GUEST_ASSERT(uc);
> +		break;
> +	case UCALL_DONE:
> +		break;
> +	default:
> +		TEST_FAIL("Unexpected ucall: %lu", uc.cmd);
> +	}
> +
> +	kvm_vm_free(vm);
> +}
> +
>   int main(int argc, char *argv[])
>   {
>   	union perf_capabilities host_cap;
> @@ -253,4 +335,6 @@ int main(int argc, char *argv[])
>   	test_immutable_perf_capabilities(host_cap);
>   	test_guest_wrmsr_perf_capabilities(host_cap);
>   	test_lbr_perf_capabilities(host_cap);
> +
> +	test_fixed_counter_enumeration();
>   }