[PATCH] perf/arm-cmn: Fix multi-filter encoding

[Ilkka Koskinen]

On Mon, 14 Sep 2026, Robin Murphy wrote:
> The current special-case for EVICT_STATE_SEL filtering effectively
> assigns the "filter" and "filter2" controls in the opposite order from
> how the CMN S3 r2 TRM states "Filtering is programmed in pmu_hbt_lbt_sel
> and pmu_evict_state_sel". On reflection, not only does this seem
> unnecessarily non-obvious to users, but it's also likely to be a problem
> for scaling to a full multi-filter abstraction in future. There is a
> logical order to filters based on their bitfield positions in the
> pmu_event_sel register, which the TRM descriptions allude to, and the
> cmn_filter_select enum already (almost) follows, so let's fix the UABI
> to follow suit while it's still unreleased.
>
> Fixes: 09178f536bb9 ("perf/arm-cmn: Plumb in new filter types")
> Signed-off-by: Robin Murphy <robin.murphy at arm.com>

Looks reasonable,

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

> ---
> drivers/perf/arm-cmn.c | 54 ++++++++++++++++++++++++------------------
> 1 file changed, 31 insertions(+), 23 deletions(-)
>
> diff --git a/drivers/perf/arm-cmn.c b/drivers/perf/arm-cmn.c
> index b162de3d9d16..6464b815bd3b 100644
> --- a/drivers/perf/arm-cmn.c
> +++ b/drivers/perf/arm-cmn.c
> @@ -305,9 +305,9 @@ enum cmn_filter_select {
> 	SEL_NONE,
> 	SEL_OCCUP1_ID,
> 	SEL_CLASS_OCCUP_ID,
> -	SEL_CBUSY_SNTHROTTLE_SEL,
> 	SEL_HBT_LBT_SEL,
> 	SEL_SN_HOME_SEL,
> +	SEL_CBUSY_SNTHROTTLE_SEL,
> 	SEL_SNP_VC_SEL,
> 	SEL_ENHANCED_HBT_LBT_SEL,
> 	SEL_EVICT_STATE_SEL,
> @@ -978,10 +978,14 @@ static umode_t arm_cmn_event_attr_is_visible(struct kobject *kobj,
> 	_CMN_EVENT_HNS(_model, _name##_all, _event, _sel, 0),		\
> 	_CMN_EVENT_HNS(_model, _name##_hbt, _event, _sel, 1),		\
> 	_CMN_EVENT_HNS(_model, _name##_lbt, _event, _sel, 2)
> -#define _CMN_EVENT_HNS_HBT2(_model, _name, _event, _fsel1, f1)		\
> -	_CMN_EVENT_HNS(_model, _name##_all, _event, _fsel1, f1, SEL_HBT_LBT_SEL, 0), \
> -	_CMN_EVENT_HNS(_model, _name##_hbt, _event, _fsel1, f1, SEL_HBT_LBT_SEL, 1), \
> -	_CMN_EVENT_HNS(_model, _name##_lbt, _event, _fsel1, f1, SEL_HBT_LBT_SEL, 2)
> +#define _CMN_EVENT_HNS_EVICT(_model, _name, _event, _fsel1, f1)			\
> +	_CMN_EVENT_HNS(_model, _name##_all, _event, _fsel1, f1, SEL_EVICT_STATE_SEL, 0), \
> +	_CMN_EVENT_HNS(_model, _name##_eu, _event, _fsel1, f1, SEL_EVICT_STATE_SEL, 1), \
> +	_CMN_EVENT_HNS(_model, _name##_en, _event, _fsel1, f1, SEL_EVICT_STATE_SEL, 2), \
> +	_CMN_EVENT_HNS(_model, _name##_su, _event, _fsel1, f1, SEL_EVICT_STATE_SEL, 3), \
> +	_CMN_EVENT_HNS(_model, _name##_sn, _event, _fsel1, f1, SEL_EVICT_STATE_SEL, 4), \
> +	_CMN_EVENT_HNS(_model, _name##_mu, _event, _fsel1, f1, SEL_EVICT_STATE_SEL, 5), \
> +	_CMN_EVENT_HNS(_model, _name##_mn, _event, _fsel1, f1, SEL_EVICT_STATE_SEL, 6)
>
> #define CMN_EVENT_HNS_OCC(_model, _name, _event)			\
> 	CMN_EVENT_HN_OCC(_model, hns_##_name, CMN_TYPE_HNS, _event),	\
> @@ -1014,13 +1018,9 @@ static umode_t arm_cmn_event_attr_is_visible(struct kobject *kobj,
> 	_CMN_EVENT_HNS(CMNS3R2, _name##_ccglcn, _event, SEL_ENHANCED_HBT_LBT_SEL, 5), \
> 	_CMN_EVENT_HNS(CMNS3R2, _name##_ccgrn, _event, SEL_ENHANCED_HBT_LBT_SEL, 6)
> #define CMN_EVENT_HNS_EVICT(_model, _name, _event)			\
> -	_CMN_EVENT_HNS_HBT2(_model, _name##_all, _event, SEL_EVICT_STATE_SEL, 0), \
> -	_CMN_EVENT_HNS_HBT2(_model, _name##_eu, _event, SEL_EVICT_STATE_SEL, 1), \
> -	_CMN_EVENT_HNS_HBT2(_model, _name##_en, _event, SEL_EVICT_STATE_SEL, 2), \
> -	_CMN_EVENT_HNS_HBT2(_model, _name##_su, _event, SEL_EVICT_STATE_SEL, 3), \
> -	_CMN_EVENT_HNS_HBT2(_model, _name##_sn, _event, SEL_EVICT_STATE_SEL, 4), \
> -	_CMN_EVENT_HNS_HBT2(_model, _name##_mu, _event, SEL_EVICT_STATE_SEL, 5), \
> -	_CMN_EVENT_HNS_HBT2(_model, _name##_mn, _event, SEL_EVICT_STATE_SEL, 6)
> +	_CMN_EVENT_HNS_EVICT(_model, _name##_all, _event, SEL_HBT_LBT_SEL, 0), \
> +	_CMN_EVENT_HNS_EVICT(_model, _name##_hbt, _event, SEL_HBT_LBT_SEL, 1), \
> +	_CMN_EVENT_HNS_EVICT(_model, _name##_lbt, _event, SEL_HBT_LBT_SEL, 2)
>
> #define CMN_EVENT_HNSR0_HBT(_name, _event)				\
> 	_CMN_EVENT_HNS_HBT(CMN700 | CMNS3R01, _name, _event, SEL_HBT_LBT_SEL)
> @@ -1856,10 +1856,12 @@ static void arm_cmn_val_add_event(struct arm_cmn *cmn, struct arm_cmn_val *val,
>
> 		val->dtm_count[dtm]++;
>
> +		if (sel == SEL_EVICT_STATE_SEL) {
> +			val->filter[dtm][sel] = CMN_EVENT_FILTER2(event) + 1;
> +			sel = SEL_HBT_LBT_SEL;
> +		}
> 		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;
> @@ -1910,14 +1912,17 @@ static int arm_cmn_validate_group(struct arm_cmn *cmn, struct perf_event *event)
> 		if (val->dtm_count[dtm] == CMN_DTM_NUM_COUNTERS)
> 			goto done;
>
> +		if (sel == SEL_EVICT_STATE_SEL) {
> +			if (val->filter[dtm][sel] &&
> +			    val->filter[dtm][sel] != CMN_EVENT_FILTER2(event) + 1)
> +				goto done;
> +			sel = SEL_HBT_LBT_SEL;
> +		}
> +
> 		if (sel && val->filter[dtm][sel] &&
> 		    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;
>
> @@ -2077,16 +2082,19 @@ static void arm_cmn_event_clear(struct arm_cmn *cmn, struct perf_event *event,
> static int arm_cmn_set_event_filter(struct arm_cmn_node *dn, struct perf_event *event)
> {
> 	enum cmn_filter_select fsel = to_cmn_hw(event)->filter_sel;
> +	bool evict_state = fsel == SEL_EVICT_STATE_SEL;
> 	int ret = 0;
>
> +	if (evict_state) {
> +		ret = arm_cmn_set_event_sel_hi(dn, fsel, CMN_EVENT_FILTER2(event));
> +		fsel = SEL_HBT_LBT_SEL;
> +	}
> 	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--;
> -	}
> +	if (ret && evict_state)
> +		dn->filter[SEL_EVICT_STATE_SEL].count--;
> +
> 	return ret;
> }
>
> -- 
> 2.54.0.dirty
>
>