Re: [PATCH v7 12/19] KVM: selftests: Test consistency of CPUID with num of fixed counters

Mi, Dapeng
2023-11-09T07:34:54Z

On 11/8/2023 8:31 AM, Sean Christopherson wrote:
> From: Jinrong Liang <cloudliang@tencent.com>
>
> Extend the PMU counters test to verify KVM emulation of fixed counters in
> addition to general purpose counters. Fixed counters add an extra wrinkle
> in the form of an extra supported bitmask. Thus quoth the SDM:
>
> fixed-function performance counter 'i' is supported if ECX[i] || (EDX[4:0] > i)
>
> Test that KVM handles a counter being available through either method.
>
> Co-developed-by: Like Xu <likexu@tencent.com>
> Signed-off-by: Like Xu <likexu@tencent.com>
> Signed-off-by: Jinrong Liang <cloudliang@tencent.com>
> Co-developed-by: Sean Christopherson <seanjc@google.com>
> Signed-off-by: Sean Christopherson <seanjc@google.com>
> ---
> .../selftests/kvm/x86_64/pmu_counters_test.c | 60 ++++++++++++++++++-
> 1 file changed, 57 insertions(+), 3 deletions(-)
>
> diff --git a/tools/testing/selftests/kvm/x86_64/pmu_counters_test.c b/tools/testing/selftests/kvm/x86_64/pmu_counters_test.c
> index 6f2d3a64a118..8c934e261f2d 100644
> --- a/tools/testing/selftests/kvm/x86_64/pmu_counters_test.c
> +++ b/tools/testing/selftests/kvm/x86_64/pmu_counters_test.c
> @@ -285,13 +285,19 @@ __GUEST_ASSERT(expect_gp ? vector == GP_VECTOR : !vector, \
> expect_gp ? "#GP" : "no fault", msr, vector) \
>
> static void guest_rd_wr_counters(uint32_t base_msr, uint8_t nr_possible_counters,
> - uint8_t nr_counters)
> + uint8_t nr_counters, uint32_t or_mask)

'or_mask' doesn't show a clear meaning, "counters_bitmap" may be a
better name.

Reviewed-by: Dapeng Mi <dapeng1.mi@linux.intel.com>

> {
> uint8_t i;
>
> for (i = 0; i < nr_possible_counters; i++) {
> const uint32_t msr = base_msr + i;
> - const bool expect_success = i < nr_counters;
> +
> + /*
> + * Fixed counters are supported if the counter is less than the
> + * number of enumerated contiguous counters *or* the counter is
> + * explicitly enumerated in the supported counters mask.
> + */
> + const bool expect_success = i < nr_counters || (or_mask & BIT(i));
>
> /*
> * KVM drops writes to MSR_P6_PERFCTR[0|1] if the counters are
> @@ -335,7 +341,7 @@ static void guest_test_gp_counters(void)
> else
> base_msr = MSR_IA32_PERFCTR0;
>
> - guest_rd_wr_counters(base_msr, MAX_NR_GP_COUNTERS, nr_gp_counters);
> + guest_rd_wr_counters(base_msr, MAX_NR_GP_COUNTERS, nr_gp_counters, 0);
> }
>
> static void test_gp_counters(uint8_t pmu_version, uint64_t perf_capabilities,
> @@ -355,9 +361,50 @@ static void test_gp_counters(uint8_t pmu_version, uint64_t perf_capabilities,
> kvm_vm_free(vm);
> }
>
> +static void guest_test_fixed_counters(void)
> +{
> + uint64_t supported_bitmask = 0;
> + uint8_t nr_fixed_counters = 0;
> +
> + /* Fixed counters require Architectural vPMU Version 2+. */
> + if (guest_get_pmu_version() >= 2)
> + nr_fixed_counters = this_cpu_property(X86_PROPERTY_PMU_NR_FIXED_COUNTERS);
> +
> + /*
> + * The supported bitmask for fixed counters was introduced in PMU
> + * version 5.
> + */
> + if (guest_get_pmu_version() >= 5)
> + supported_bitmask = this_cpu_property(X86_PROPERTY_PMU_FIXED_COUNTERS_BITMASK);
> +
> + guest_rd_wr_counters(MSR_CORE_PERF_FIXED_CTR0, MAX_NR_FIXED_COUNTERS,
> + nr_fixed_counters, supported_bitmask);
> +}
> +
> +static void test_fixed_counters(uint8_t pmu_version, uint64_t perf_capabilities,
> + uint8_t nr_fixed_counters,
> + uint32_t supported_bitmask)
> +{
> + struct kvm_vcpu *vcpu;
> + struct kvm_vm *vm;
> +
> + vm = pmu_vm_create_with_one_vcpu(&vcpu, guest_test_fixed_counters,
> + pmu_version, perf_capabilities);
> +
> + vcpu_set_cpuid_property(vcpu, X86_PROPERTY_PMU_FIXED_COUNTERS_BITMASK,
> + supported_bitmask);
> + vcpu_set_cpuid_property(vcpu, X86_PROPERTY_PMU_NR_FIXED_COUNTERS,
> + nr_fixed_counters);
> +
> + run_vcpu(vcpu);
> +
> + kvm_vm_free(vm);
> +}
> +
> static void test_intel_counters(void)
> {
> uint8_t nr_arch_events = kvm_cpu_property(X86_PROPERTY_PMU_EBX_BIT_VECTOR_LENGTH);
> + uint8_t nr_fixed_counters = kvm_cpu_property(X86_PROPERTY_PMU_NR_FIXED_COUNTERS);
> uint8_t nr_gp_counters = kvm_cpu_property(X86_PROPERTY_PMU_NR_GP_COUNTERS);
> uint8_t pmu_version = kvm_cpu_property(X86_PROPERTY_PMU_VERSION);
> unsigned int i;
> @@ -427,6 +474,13 @@ static void test_intel_counters(void)
> v, perf_caps[i]);
> for (j = 0; j <= nr_gp_counters; j++)
> test_gp_counters(v, perf_caps[i], j);
> +
> + pr_info("Testing fixed counters, PMU version %u, perf_caps = %lx\n",
> + v, perf_caps[i]);
> + for (j = 0; j <= nr_fixed_counters; j++) {
> + for (k = 0; k <= (BIT(nr_fixed_counters) - 1); k++)
> + test_fixed_counters(v, perf_caps[i], j, k);
> + }
> }
> }
> }