linux-kernel - Re: [PATCH v7 13/19] KVM: selftests: Add functional test for Intel's fixed PMU counters

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Message-ID: <b62e34cc-2756-4d69-b75a-26919a3e0ef7@linux.intel.com>
Date:   Thu, 9 Nov 2023 15:39:05 +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 13/19] KVM: selftests: Add functional test for Intel's
 fixed PMU counters


On 11/8/2023 8:31 AM, Sean Christopherson wrote:
> From: Jinrong Liang <cloudliang@...cent.com>
>
> Extend the fixed counters test to verify that supported counters can
> actually be enabled in the control MSRs, that unsupported counters cannot,
> and that enabled counters actually count.
>
> Co-developed-by: Like Xu <likexu@...cent.com>
> Signed-off-by: Like Xu <likexu@...cent.com>
> Signed-off-by: Jinrong Liang <cloudliang@...cent.com>
> [sean: fold into the rd/wr access test, massage changelog]
> Signed-off-by: Sean Christopherson <seanjc@...gle.com>
> ---
>   .../selftests/kvm/x86_64/pmu_counters_test.c  | 31 ++++++++++++++++++-
>   1 file changed, 30 insertions(+), 1 deletion(-)
>
> 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 8c934e261f2d..b9c073d3ade9 100644
> --- a/tools/testing/selftests/kvm/x86_64/pmu_counters_test.c
> +++ b/tools/testing/selftests/kvm/x86_64/pmu_counters_test.c
> @@ -324,7 +324,6 @@ static void guest_rd_wr_counters(uint32_t base_msr, uint8_t nr_possible_counters
>   		vector = wrmsr_safe(msr, 0);
>   		GUEST_ASSERT_PMC_MSR_ACCESS(WRMSR, msr, expect_gp, vector);
>   	}
> -	GUEST_DONE();
>   }
>   
>   static void guest_test_gp_counters(void)
> @@ -342,6 +341,7 @@ static void guest_test_gp_counters(void)
>   		base_msr = MSR_IA32_PERFCTR0;
>   
>   	guest_rd_wr_counters(base_msr, MAX_NR_GP_COUNTERS, nr_gp_counters, 0);
> +	GUEST_DONE();
>   }
>   
>   static void test_gp_counters(uint8_t pmu_version, uint64_t perf_capabilities,
> @@ -365,6 +365,7 @@ static void guest_test_fixed_counters(void)
>   {
>   	uint64_t supported_bitmask = 0;
>   	uint8_t nr_fixed_counters = 0;
> +	uint8_t i;
>   
>   	/* Fixed counters require Architectural vPMU Version 2+. */
>   	if (guest_get_pmu_version() >= 2)
> @@ -379,6 +380,34 @@ static void guest_test_fixed_counters(void)
>   
>   	guest_rd_wr_counters(MSR_CORE_PERF_FIXED_CTR0, MAX_NR_FIXED_COUNTERS,
>   			     nr_fixed_counters, supported_bitmask);
> +
> +	for (i = 0; i < MAX_NR_FIXED_COUNTERS; i++) {
> +		uint8_t vector;
> +		uint64_t val;
> +
> +		if (i >= nr_fixed_counters && !(supported_bitmask & BIT_ULL(i))) {
> +			vector = wrmsr_safe(MSR_CORE_PERF_FIXED_CTR_CTRL,
> +					    FIXED_PMC_CTRL(i, FIXED_PMC_KERNEL));
> +			__GUEST_ASSERT(vector == GP_VECTOR,
> +				       "Expected #GP for counter %u in FIXED_CTR_CTRL", i);
> +
> +			vector = wrmsr_safe(MSR_CORE_PERF_GLOBAL_CTRL,
> +					    FIXED_PMC_GLOBAL_CTRL_ENABLE(i));
> +			__GUEST_ASSERT(vector == GP_VECTOR,
> +				       "Expected #GP for counter %u in PERF_GLOBAL_CTRL", i);
> +			continue;
> +		}
> +
> +		wrmsr(MSR_CORE_PERF_FIXED_CTR0 + i, 0);
> +		wrmsr(MSR_CORE_PERF_FIXED_CTR_CTRL, FIXED_PMC_CTRL(i, FIXED_PMC_KERNEL));
> +		wrmsr(MSR_CORE_PERF_GLOBAL_CTRL, FIXED_PMC_GLOBAL_CTRL_ENABLE(i));
> +		__asm__ __volatile__("loop ." : "+c"((int){NUM_BRANCHES}));

This assembly code seems to be called many times, we may wrap it into a 
macro or function.

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


> +		wrmsr(MSR_CORE_PERF_GLOBAL_CTRL, 0);
> +		val = rdmsr(MSR_CORE_PERF_FIXED_CTR0 + i);
> +
> +		GUEST_ASSERT_NE(val, 0);
> +	}
> +	GUEST_DONE();
>   }
>   
>   static void test_fixed_counters(uint8_t pmu_version, uint64_t perf_capabilities,