linux-kernel - Re: [kvm-unit-tests PATCH] x86/pmu: Verify all available GP counters in check_counters

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Message-ID: <d00a02f8-2ebe-4952-8dc8-abf722f2af65@amd.com>
Date: Thu, 12 Jun 2025 13:05:30 +0530
From: Sandipan Das <sandipan.das@....com>
To: Dapeng Mi <dapeng1.mi@...ux.intel.com>,
 Sean Christopherson <seanjc@...gle.com>, Paolo Bonzini <pbonzini@...hat.com>
Cc: kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
 Jim Mattson <jmattson@...gle.com>, Mingwei Zhang <mizhang@...gle.com>,
 Zide Chen <zide.chen@...el.com>, Shukla Manali <Manali.Shukla@....com>,
 Dapeng Mi <dapeng1.mi@...el.com>
Subject: Re: [kvm-unit-tests PATCH] x86/pmu: Verify all available GP counters
 in check_counters_many()

On 6/11/2025 1:28 PM, Dapeng Mi wrote:
> The intent of check_counters_many() is to verify all available counters
> can count correctly at the same time. So an alternative event should be
> picked to verify the avaialbe GP counter instead of skiping the counter
> if the initial event is not available.
> 
> Signed-off-by: Dapeng Mi <dapeng1.mi@...ux.intel.com>
> ---
> Please notice this patch is based on Sean's "x86: Add CPUID properties,
>  clean up related code" v2 patchset (https://lore.kernel.org/all/20250610195415.115404-1-seanjc@google.com/).
> 
>  x86/pmu.c | 22 +++++++++++++++++++---
>  1 file changed, 19 insertions(+), 3 deletions(-)
> 

For AMD processors
Tested-by: Sandipan Das <sandipan.das@....com>

> diff --git a/x86/pmu.c b/x86/pmu.c
> index 3987311c..a6b0cfcc 100644
> --- a/x86/pmu.c
> +++ b/x86/pmu.c
> @@ -457,18 +457,34 @@ static void check_fixed_counters(void)
>  	}
>  }
>  
> +static struct pmu_event *get_one_event(int idx)
> +{
> +	int i;
> +
> +	if (pmu_arch_event_is_available(idx))
> +		return &gp_events[idx % gp_events_size];
> +
> +	for (i = 0; i < gp_events_size; i++) {
> +		if (pmu_arch_event_is_available(i))
> +			return &gp_events[i];
> +	}
> +
> +	return NULL;
> +}
> +
>  static void check_counters_many(void)
>  {
> +	struct pmu_event *evt;
>  	pmu_counter_t cnt[48];
>  	int i, n;
>  
>  	for (i = 0, n = 0; n < pmu.nr_gp_counters; i++) {
> -		if (!pmu_arch_event_is_available(i))
> +		evt = get_one_event(i);
> +		if (!evt)
>  			continue;
>  
>  		cnt[n].ctr = MSR_GP_COUNTERx(n);
> -		cnt[n].config = EVNTSEL_OS | EVNTSEL_USR |
> -			gp_events[i % gp_events_size].unit_sel;
> +		cnt[n].config = EVNTSEL_OS | EVNTSEL_USR | evt->unit_sel;
>  		n++;
>  	}
>  	for (i = 0; i < fixed_counters_num; i++) {