Re: [PATCH v2 4/5] perf/arm-cmn: Plumb in new filter types

[Ilkka Koskinen <ilkka@os.amperecomputing.com>]

On Tue, 28 Jul 2026, Robin Murphy wrote:

> Add the logic to handle events with the upcoming new filter controls.
> Since for now we will have the sole invariant of all EVICT_STATE_SEL
> events having HBT_LBT_SEL as a secondary filter, for the sake of
> simplicity we can just special-case that, and save the complication
> of a full multi-filter abstraction until unavoidably necessary.
>
> Reviewed-by: Leo Yan <leo.yan@arm.com>
> Signed-off-by: Robin Murphy <robin.murphy@arm.com>

LGTM:

Reviewed-by: Ilkka Koskinen <ilkka@os.amperecomputing.com>

Cheers, Ilkka

> ---
>
> v2: Tweak commit message
>
> drivers/perf/arm-cmn.c | 19 +++++++++++++++++++
> 1 file changed, 19 insertions(+)
>
> diff --git a/drivers/perf/arm-cmn.c b/drivers/perf/arm-cmn.c
> index 74bc2aae4a06..e25f46c38c23 100644
> --- a/drivers/perf/arm-cmn.c
> +++ b/drivers/perf/arm-cmn.c
> @@ -166,12 +166,14 @@
> #define CMN_CONFIG_FILTER		GENMASK_ULL(30, 27)
> #define CMN_CONFIG_BYNODEID		BIT_ULL(31)
> #define CMN_CONFIG_NODEID		GENMASK_ULL(47, 32)
> +#define CMN_CONFIG_FILTER2		GENMASK_ULL(51, 48)
>
> #define CMN_EVENT_TYPE(event)		FIELD_GET(CMN_CONFIG_TYPE, (event)->attr.config)
> #define CMN_EVENT_EVENTID(event)	FIELD_GET(CMN_CONFIG_EVENTID, (event)->attr.config)
> #define CMN_EVENT_FILTER(event)		FIELD_GET(CMN_CONFIG_FILTER, (event)->attr.config)
> #define CMN_EVENT_BYNODEID(event)	FIELD_GET(CMN_CONFIG_BYNODEID, (event)->attr.config)
> #define CMN_EVENT_NODEID(event)		FIELD_GET(CMN_CONFIG_NODEID, (event)->attr.config)
> +#define CMN_EVENT_FILTER2(event)	FIELD_GET(CMN_CONFIG_FILTER2, (event)->attr.config)
>
> #define CMN_CONFIG_WP_COMBINE		GENMASK_ULL(30, 27)
> #define CMN_CONFIG_WP_DEV_SEL		GENMASK_ULL(50, 48)
> @@ -284,6 +286,9 @@ enum cmn_filter_select {
> 	SEL_CBUSY_SNTHROTTLE_SEL,
> 	SEL_HBT_LBT_SEL,
> 	SEL_SN_HOME_SEL,
> +	SEL_SNP_VC_SEL,
> +	SEL_ENHANCED_HBT_LBT_SEL,
> +	SEL_EVICT_STATE_SEL,
> 	SEL_MAX
> };
>
> @@ -1377,6 +1382,7 @@ static struct attribute *arm_cmn_format_attrs[] = {
> 	CMN_FORMAT_ATTR(filter, CMN_CONFIG_FILTER),
> 	CMN_FORMAT_ATTR(bynodeid, CMN_CONFIG_BYNODEID),
> 	CMN_FORMAT_ATTR(nodeid, CMN_CONFIG_NODEID),
> +	CMN_FORMAT_ATTR(filter2, CMN_CONFIG_FILTER2),
>
> 	CMN_FORMAT_ATTR(wp_dev_sel, CMN_CONFIG_WP_DEV_SEL),
> 	CMN_FORMAT_ATTR(wp_chn_sel, CMN_CONFIG_WP_CHN_SEL),
> @@ -1745,6 +1751,8 @@ static void arm_cmn_val_add_event(struct arm_cmn *cmn, struct arm_cmn_val *val,
>
> 		if (sel)
> 			val->filter[dtm][sel] = CMN_EVENT_FILTER(event) + 1;
> +		if (sel == SEL_EVICT_STATE_SEL)
> +			val->filter[dtm][SEL_HBT_LBT_SEL] = CMN_EVENT_FILTER2(event) + 1;
>
> 		if (type != CMN_TYPE_WP)
> 			continue;
> @@ -1799,6 +1807,10 @@ static int arm_cmn_validate_group(struct arm_cmn *cmn, struct perf_event *event)
> 		    val->filter[dtm][sel] != CMN_EVENT_FILTER(event) + 1)
> 			goto done;
>
> +		if (sel == SEL_EVICT_STATE_SEL && val->filter[dtm][SEL_HBT_LBT_SEL] &&
> +		    val->filter[dtm][SEL_HBT_LBT_SEL] != CMN_EVENT_FILTER2(event) + 1)
> +			goto done;
> +
> 		if (type != CMN_TYPE_WP)
> 			continue;
>
> @@ -1943,6 +1955,8 @@ static void arm_cmn_event_clear(struct arm_cmn *cmn, struct perf_event *event,
>
> 		if (hw->filter_sel)
> 			hw->dn[i].filter[hw->filter_sel].count--;
> +		if (hw->filter_sel == SEL_EVICT_STATE_SEL)
> +			hw->dn[i].filter[SEL_HBT_LBT_SEL].count--;
>
> 		dtm->pmu_config_low &= ~CMN__PMEVCNT_PAIRED(dtm_idx);
> 		writel_relaxed(dtm->pmu_config_low, dtm->base + CMN_DTM_PMU_CONFIG);
> @@ -1961,6 +1975,11 @@ static int arm_cmn_set_event_filter(struct arm_cmn_node *dn, struct perf_event *
> 	if (fsel)
> 		ret = arm_cmn_set_event_sel_hi(dn, fsel, CMN_EVENT_FILTER(event));
>
> +	if (fsel == SEL_EVICT_STATE_SEL && !ret) {
> +		ret = arm_cmn_set_event_sel_hi(dn, SEL_HBT_LBT_SEL, CMN_EVENT_FILTER2(event));
> +		if (ret)
> +			dn->filter[fsel].count--;
> +	}
> 	return ret;
> }
>
> -- 
> 2.54.0.dirty
>
>