Re: [PATCH v2 1/9] perf/cxl: Program the requested event group on configurable counters

On Wed, 29 Jul 2026 07:55:47 -0700
Dave Jiang <[email protected]> wrote:

> cxl_pmu_get_event_idx() sets *counter_idx for a configurable counter but
> never sets *event_idx, so hwc->event_base stays 0 and cxl_pmu_event_start()
> programs event group 0 regardless of the group the user requested.
> 
> Return the matched capability's event_idx.
> 
> Fixes: 5d7107c72796 ("perf: CXL Performance Monitoring Unit driver")
> Reported-by: [email protected]
> Closes: https://sashiko.dev/#/patchset/[email protected]?part=1
> Assisted-by: Claude:claude-opus-4-8
> Signed-off-by: Dave Jiang <[email protected]>

One minor thing.  Otherwise LGTM
Reviewed-by: Jonathan Cameron <[email protected]>

> ---

>  drivers/perf/cxl_pmu.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/perf/cxl_pmu.c b/drivers/perf/cxl_pmu.c
> index 68a54d97d2a8..e77c0650a7eb 100644
> --- a/drivers/perf/cxl_pmu.c
> +++ b/drivers/perf/cxl_pmu.c
> @@ -552,6 +552,8 @@ static int cxl_pmu_get_event_idx(struct perf_event *event, int *counter_idx,
>  			return -EINVAL;
>  
>  		*counter_idx = i;
> +		if (event_idx)
Hmm. We never want to get counter_idx and not event_idx.  Perhaps
add this check to the one for counter_idx at the top of this scope.

> +			*event_idx = pmu_ev->event_idx;
>  		return 0;
>  	}
>