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

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Message-ID: <fa25f3eb-eb9a-4d83-8fdf-f133c60484da@linux.intel.com>
Date:   Thu, 9 Nov 2023 15:34:48 +0800
From:   "Mi, Dapeng" <dapeng1.mi@...ux.intel.com>
To:     Sean Christopherson <seanjc@...gle.com>,
        Paolo Bonzini <pbonzini@...hat.com>
Cc:     kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
        Kan Liang <kan.liang@...ux.intel.com>,
        Jim Mattson <jmattson@...gle.com>,
        Jinrong Liang <cloudliang@...cent.com>,
        Aaron Lewis <aaronlewis@...gle.com>,
        Like Xu <likexu@...cent.com>
Subject: Re: [PATCH v7 12/19] KVM: selftests: Test consistency of CPUID with
 num of fixed counters


On 11/8/2023 8:31 AM, Sean Christopherson wrote:
> From: Jinrong Liang <cloudliang@...cent.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@...cent.com>
> Signed-off-by: Like Xu <likexu@...cent.com>
> Signed-off-by: Jinrong Liang <cloudliang@...cent.com>
> Co-developed-by: Sean Christopherson <seanjc@...gle.com>
> Signed-off-by: Sean Christopherson <seanjc@...gle.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@...ux.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);
> +			}
>   		}
>   	}
>   }