Re: [kvm-unit-tests PATCH v2 06/14] x86/pmu: Mark all arch events as available on AMD, and rename fields

[Liam Merwick <liam.merwick@oracle.com>]

On 10/06/2025 20:54, Sean Christopherson wrote:
> Mark all arch events as available on AMD, as AMD PMUs don't provide the
> "not available" CPUID field, and the number of GP counters has nothing to
> do with which architectural events are available/supported.
> 
> Rename gp_counter_mask_length to arch_event_mask_length, and
> pmu_gp_counter_is_available() to pmu_arch_event_is_available(), to
> reflect what the field and helper actually track.
> 
> Cc: Dapeng Mi <dapeng1.mi@linux.intel.com>
> Fixes: b883751a ("x86/pmu: Update testcases to cover AMD PMU")
> Signed-off-by: Sean Christopherson <seanjc@google.com>

Reviewed-by: Liam Merwick <liam.merwick@oracle.com>

> ---
>   lib/x86/pmu.c | 10 +++++-----
>   lib/x86/pmu.h |  8 ++++----
>   x86/pmu.c     |  8 ++++----
>   3 files changed, 13 insertions(+), 13 deletions(-)
> 
> diff --git a/lib/x86/pmu.c b/lib/x86/pmu.c
> index d06e9455..d37c874c 100644
> --- a/lib/x86/pmu.c
> +++ b/lib/x86/pmu.c
> @@ -18,10 +18,10 @@ 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.gp_counter_available = ~cpuid_10.b;
> +		/* CPUID.0xA.EBX bit is '1' if an arch event is NOT available. */
> +		pmu.arch_event_available = ~cpuid_10.b;
>   
>   		if (this_cpu_has(X86_FEATURE_PDCM))
>   			pmu.perf_cap = rdmsr(MSR_IA32_PERF_CAPABILITIES);
> @@ -50,8 +50,8 @@ 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.gp_counter_available = (1u << pmu.nr_gp_counters) - 1;
> +		pmu.arch_event_mask_length = 32;
> +		pmu.arch_event_available = -1u;
>   
>   		if (this_cpu_has_perf_global_status()) {
>   			pmu.msr_global_status = MSR_AMD64_PERF_CNTR_GLOBAL_STATUS;
> diff --git a/lib/x86/pmu.h b/lib/x86/pmu.h
> index f07fbd93..c7dc68c1 100644
> --- a/lib/x86/pmu.h
> +++ b/lib/x86/pmu.h
> @@ -63,8 +63,8 @@ struct pmu_caps {
>   	u8 fixed_counter_width;
>   	u8 nr_gp_counters;
>   	u8 gp_counter_width;
> -	u8 gp_counter_mask_length;
> -	u32 gp_counter_available;
> +	u8 arch_event_mask_length;
> +	u32 arch_event_available;
>   	u32 msr_gp_counter_base;
>   	u32 msr_gp_event_select_base;
>   
> @@ -110,9 +110,9 @@ static inline bool this_cpu_has_perf_global_status(void)
>   	return pmu.version > 1;
>   }
>   
> -static inline bool pmu_gp_counter_is_available(int i)
> +static inline bool pmu_arch_event_is_available(int i)
>   {
> -	return pmu.gp_counter_available & BIT(i);
> +	return pmu.arch_event_available & BIT(i);
>   }
>   
>   static inline u64 pmu_lbr_version(void)
> diff --git a/x86/pmu.c b/x86/pmu.c
> index 45c6db3c..e79122ed 100644
> --- a/x86/pmu.c
> +++ b/x86/pmu.c
> @@ -436,7 +436,7 @@ static void check_gp_counters(void)
>   	int i;
>   
>   	for (i = 0; i < gp_events_size; i++)
> -		if (pmu_gp_counter_is_available(i))
> +		if (pmu_arch_event_is_available(i))
>   			check_gp_counter(&gp_events[i]);
>   		else
>   			printf("GP event '%s' is disabled\n",
> @@ -463,7 +463,7 @@ static void check_counters_many(void)
>   	int i, n;
>   
>   	for (i = 0, n = 0; n < pmu.nr_gp_counters; i++) {
> -		if (!pmu_gp_counter_is_available(i))
> +		if (!pmu_arch_event_is_available(i))
>   			continue;
>   
>   		cnt[n].ctr = MSR_GP_COUNTERx(n);
> @@ -902,7 +902,7 @@ static void set_ref_cycle_expectations(void)
>   	uint64_t t0, t1, t2, t3;
>   
>   	/* Bit 2 enumerates the availability of reference cycles events. */
> -	if (!pmu.nr_gp_counters || !pmu_gp_counter_is_available(2))
> +	if (!pmu.nr_gp_counters || !pmu_arch_event_is_available(2))
>   		return;
>   
>   	t0 = fenced_rdtsc();
> @@ -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);
>