Re: [kvm-unit-tests PATCH 08/16] x86/pmu: Rename gp_counter_mask_length to arch_event_mask_length

["Mi, Dapeng" <dapeng1.mi@linux.intel.com>]

On 5/30/2025 6:19 AM, Sean Christopherson wrote:
> Rename gp_counter_mask_length to arch_event_mask_length to reflect what
> the field actually tracks.  The availablity of architectural events has
> nothing to do with the GP counters themselves.
>
> No functional change intended.
>
> Signed-off-by: Sean Christopherson <seanjc@google.com>
> ---
>  lib/x86/pmu.c | 4 ++--
>  lib/x86/pmu.h | 2 +-
>  x86/pmu.c     | 2 +-
>  3 files changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/lib/x86/pmu.c b/lib/x86/pmu.c
> index 599168ac..b97e2c4a 100644
> --- a/lib/x86/pmu.c
> +++ b/lib/x86/pmu.c
> @@ -18,7 +18,7 @@ void pmu_init(void)
>  
>  		pmu.nr_gp_counters = (cpuid_10.a >> 8) & 0xff;
>  		pmu.gp_counter_width = (cpuid_10.a >> 16) & 0xff;
> -		pmu.gp_counter_mask_length = (cpuid_10.a >> 24) & 0xff;
> +		pmu.arch_event_mask_length = (cpuid_10.a >> 24) & 0xff;
>  
>  		/* CPUID.0xA.EBX bit is '1' if a counter is NOT available. */
>  		pmu.arch_event_available = ~cpuid_10.b;

Better to change to "pmu.arch_event_available = ~cpuid_10.b &
(BIT(pmu.arch_event_mask_length) - 1)" to follow SDM. Some newly introduced
architectural events like topdown metrics events doesn't exist on older
platforms.


> @@ -50,7 +50,7 @@ void pmu_init(void)
>  			pmu.msr_gp_event_select_base = MSR_K7_EVNTSEL0;
>  		}
>  		pmu.gp_counter_width = PMC_DEFAULT_WIDTH;
> -		pmu.gp_counter_mask_length = pmu.nr_gp_counters;
> +		pmu.arch_event_mask_length = pmu.nr_gp_counters;
>  		pmu.arch_event_available = (1u << pmu.nr_gp_counters) - 1;
>  
>  		if (this_cpu_has_perf_global_status()) {
> diff --git a/lib/x86/pmu.h b/lib/x86/pmu.h
> index d0ad280a..c7dc68c1 100644
> --- a/lib/x86/pmu.h
> +++ b/lib/x86/pmu.h
> @@ -63,7 +63,7 @@ struct pmu_caps {
>  	u8 fixed_counter_width;
>  	u8 nr_gp_counters;
>  	u8 gp_counter_width;
> -	u8 gp_counter_mask_length;
> +	u8 arch_event_mask_length;
>  	u32 arch_event_available;
>  	u32 msr_gp_counter_base;
>  	u32 msr_gp_event_select_base;
> diff --git a/x86/pmu.c b/x86/pmu.c
> index 0ce34433..63eae3db 100644
> --- a/x86/pmu.c
> +++ b/x86/pmu.c
> @@ -992,7 +992,7 @@ int main(int ac, char **av)
>  	printf("PMU version:         %d\n", pmu.version);
>  	printf("GP counters:         %d\n", pmu.nr_gp_counters);
>  	printf("GP counter width:    %d\n", pmu.gp_counter_width);
> -	printf("Mask length:         %d\n", pmu.gp_counter_mask_length);
> +	printf("Event Mask length:   %d\n", pmu.arch_event_mask_length);
>  	printf("Fixed counters:      %d\n", pmu.nr_fixed_counters);
>  	printf("Fixed counter width: %d\n", pmu.fixed_counter_width);
>  

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