Re: [PATCH v6 5/6] KVM: selftests: Test if event filter meets expectations on fixed counters

[Isaku Yamahata]

On Thu, Aug 10, 2023 at 05:09:44PM +0800,
Jinrong Liang <ljr.kernel@xxxxxxxxx> wrote:

> From: Jinrong Liang <cloudliang@xxxxxxxxxxx>
> 
> Add tests to cover that pmu event_filter works as expected when it's
> applied to fixed performance counters, even if there is none fixed
> counter exists (e.g. Intel guest pmu version=1 or AMD guest).
> 
> Signed-off-by: Jinrong Liang <cloudliang@xxxxxxxxxxx>
> ---
>  .../kvm/x86_64/pmu_event_filter_test.c        | 80 +++++++++++++++++++
>  1 file changed, 80 insertions(+)
> 
> diff --git a/tools/testing/selftests/kvm/x86_64/pmu_event_filter_test.c b/tools/testing/selftests/kvm/x86_64/pmu_event_filter_test.c
> index 8b8bfee11016..732c76c41bb0 100644
> --- a/tools/testing/selftests/kvm/x86_64/pmu_event_filter_test.c
> +++ b/tools/testing/selftests/kvm/x86_64/pmu_event_filter_test.c
> @@ -27,6 +27,7 @@
>  #define ARCH_PERFMON_BRANCHES_RETIRED		5
>  
>  #define NUM_BRANCHES 42
> +#define INTEL_PMC_IDX_FIXED		32
>  
>  /* Matches KVM_PMU_EVENT_FILTER_MAX_EVENTS in pmu.c */
>  #define MAX_FILTER_EVENTS		300
> @@ -808,6 +809,84 @@ static void test_filter_ioctl(struct kvm_vcpu *vcpu)
>  	TEST_ASSERT(!r, "Masking non-existent fixed counters should be allowed");
>  }
>  
> +static void intel_run_fixed_counter_guest_code(uint8_t fixed_ctr_idx)
> +{
> +	for (;;) {
> +		wrmsr(MSR_CORE_PERF_GLOBAL_CTRL, 0);
> +		wrmsr(MSR_CORE_PERF_FIXED_CTR0 + fixed_ctr_idx, 0);
> +
> +		/* Only OS_EN bit is enabled for fixed counter[idx]. */
> +		wrmsr(MSR_CORE_PERF_FIXED_CTR_CTRL, BIT_ULL(4 * fixed_ctr_idx));
> +		wrmsr(MSR_CORE_PERF_GLOBAL_CTRL,
> +		      BIT_ULL(INTEL_PMC_IDX_FIXED + fixed_ctr_idx));
> +		__asm__ __volatile__("loop ." : "+c"((int){NUM_BRANCHES}));
> +		wrmsr(MSR_CORE_PERF_GLOBAL_CTRL, 0);
> +
> +		GUEST_SYNC(rdmsr(MSR_CORE_PERF_FIXED_CTR0 + fixed_ctr_idx));
> +	}
> +}
> +
> +static uint64_t test_with_fixed_counter_filter(struct kvm_vcpu *vcpu,
> +					       uint32_t action, uint32_t bitmap)
> +{
> +	struct __kvm_pmu_event_filter f = {
> +		.action = action,
> +		.fixed_counter_bitmap = bitmap,
> +	};
> +	do_vcpu_set_pmu_event_filter(vcpu, &f);
> +
> +	return run_vcpu_to_sync(vcpu);
> +}
> +
> +static void __test_fixed_counter_bitmap(struct kvm_vcpu *vcpu, uint8_t idx,
> +					uint8_t nr_fixed_counters)
> +{
> +	unsigned int i;
> +	uint32_t bitmap;
> +	uint64_t count;
> +
> +	TEST_ASSERT(nr_fixed_counters < sizeof(bitmap) * 8,
> +		    "Invalid nr_fixed_counters");
> +
> +	/*
> +	 * Check the fixed performance counter can count normally when KVM
> +	 * userspace doesn't set any pmu filter.
> +	 */
> +	count = run_vcpu_to_sync(vcpu);
> +	TEST_ASSERT(count, "Unexpected count value: %ld\n", count);
> +
> +	for (i = 0; i < BIT(nr_fixed_counters); i++) {
> +		bitmap = BIT(i);
> +		count = test_with_fixed_counter_filter(vcpu, KVM_PMU_EVENT_ALLOW,
> +						       bitmap);
> +		TEST_ASSERT_EQ(!!count, !!(bitmap & BIT(idx)));
> +
> +		count = test_with_fixed_counter_filter(vcpu, KVM_PMU_EVENT_DENY,
> +						       bitmap);
> +		TEST_ASSERT_EQ(!!count, !(bitmap & BIT(idx)));
> +	}
> +}
> +
> +static void test_fixed_counter_bitmap(void)
> +{
> +	uint8_t nr_fixed_counters = kvm_cpu_property(X86_PROPERTY_PMU_NR_FIXED_COUNTERS);
> +	struct kvm_vm *vm;
> +	struct kvm_vcpu *vcpu;
> +	uint8_t idx;
> +
> +	/*
> +	 * Check that pmu_event_filter works as expected when it's applied to
> +	 * fixed performance counters.
> +	 */
> +	for (idx = 0; idx < nr_fixed_counters; idx++) {
> +		vm = vm_create_with_one_vcpu(&vcpu,
> +					     intel_run_fixed_counter_guest_code);
> +		vcpu_args_set(vcpu, 1, idx);
> +		__test_fixed_counter_bitmap(vcpu, idx, nr_fixed_counters);
> +		kvm_vm_free(vm);
> +	}
> +}
> +
>  int main(int argc, char *argv[])
>  {
>  	void (*guest_code)(void);
> @@ -851,6 +930,7 @@ int main(int argc, char *argv[])
>  	kvm_vm_free(vm);
>  
>  	test_pmu_config_disable(guest_code);
> +	test_fixed_counter_bitmap();
>  
>  	return 0;
>  }
> -- 
> 2.39.3
> 

Reviewed-by: Isaku Yamahata <isaku.yamahata@xxxxxxxxx>

-- 
Isaku Yamahata <isaku.yamahata@xxxxxxxxx>