Re: [PATCH 02/12] drivers/perf: arm_spe: Expose events capability

[James Clark <james.clark@linaro.org>]

On 13/06/2025 4:53 pm, Leo Yan wrote:
> Expose an events entry in the caps folder to inform user space which
> events are valid.
> 
> Signed-off-by: Leo Yan <leo.yan@arm.com>
> ---
>   drivers/perf/arm_spe_pmu.c | 8 ++++++--
>   1 file changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/perf/arm_spe_pmu.c b/drivers/perf/arm_spe_pmu.c
> index be2ed326bb794d7e5dd1d6cfa89330753ced3ca5..b59c394b715bc49af0ae30c521f97813a046755d 100644
> --- a/drivers/perf/arm_spe_pmu.c
> +++ b/drivers/perf/arm_spe_pmu.c
> @@ -116,6 +116,7 @@ enum arm_spe_pmu_capabilities {
>   	SPE_PMU_CAP_FEAT_MAX,
>   	SPE_PMU_CAP_CNT_SZ = SPE_PMU_CAP_FEAT_MAX,
>   	SPE_PMU_CAP_MIN_IVAL,
> +	SPE_PMU_CAP_EVENTS,
>   };
>   
>   static int arm_spe_pmu_feat_caps[SPE_PMU_CAP_FEAT_MAX] = {
> @@ -123,7 +124,7 @@ static int arm_spe_pmu_feat_caps[SPE_PMU_CAP_FEAT_MAX] = {
>   	[SPE_PMU_CAP_ERND]	= SPE_PMU_FEAT_ERND,
>   };
>   
> -static u32 arm_spe_pmu_cap_get(struct arm_spe_pmu *spe_pmu, int cap)
> +static u64 arm_spe_pmu_cap_get(struct arm_spe_pmu *spe_pmu, int cap)
>   {
>   	if (cap < SPE_PMU_CAP_FEAT_MAX)
>   		return !!(spe_pmu->features & arm_spe_pmu_feat_caps[cap]);
> @@ -133,6 +134,8 @@ static u32 arm_spe_pmu_cap_get(struct arm_spe_pmu *spe_pmu, int cap)
>   		return spe_pmu->counter_sz;
>   	case SPE_PMU_CAP_MIN_IVAL:
>   		return spe_pmu->min_period;
> +	case SPE_PMU_CAP_EVENTS:
> +		return ~spe_pmu->pmsevfr_res0;
>   	default:
>   		WARN(1, "unknown cap %d\n", cap);
>   	}
> @@ -149,7 +152,7 @@ static ssize_t arm_spe_pmu_cap_show(struct device *dev,
>   		container_of(attr, struct dev_ext_attribute, attr);
>   	int cap = (long)ea->var;
>   
> -	return sysfs_emit(buf, "%u\n", arm_spe_pmu_cap_get(spe_pmu, cap));
> +	return sysfs_emit(buf, "%llu\n", arm_spe_pmu_cap_get(spe_pmu, cap));
>   }
>   
>   #define SPE_EXT_ATTR_ENTRY(_name, _func, _var)				\
> @@ -165,6 +168,7 @@ static struct attribute *arm_spe_pmu_cap_attr[] = {
>   	SPE_CAP_EXT_ATTR_ENTRY(ernd, SPE_PMU_CAP_ERND),
>   	SPE_CAP_EXT_ATTR_ENTRY(count_size, SPE_PMU_CAP_CNT_SZ),
>   	SPE_CAP_EXT_ATTR_ENTRY(min_interval, SPE_PMU_CAP_MIN_IVAL),
> +	SPE_CAP_EXT_ATTR_ENTRY(events, SPE_PMU_CAP_EVENTS),

Would "event_filters" be a better name? Technically an SPE version can 
support a filter but the event itself might not be implemented.

>   	NULL,
>   };
>   
>