[PATCH] arm_mpam: Set feature bits on default partition config

[Fenghua Yu]

Currently we only set the default values (cpbm, mbw_pbm, mbw_max)
and do not set the corresponding feature bits. As a result,
the MBW_MIN/MBW_MAX and CPBM/MBW_PBM blocks in
mpam_reprogram_ris_partid() does not apply the default config
because they require both rprops and cfg to have the feature.
The missing feature bits may cause other issues in the future.

When initializing default per-partition config in
mpam_reset_component_cfg(), set the feature bits on cfg for
each resource we program (cpor_part, mbw_part, mbw_max)
so that "configured" matches the default values.

Set mpam_feat_cpor_part on cfg whenever we set default cpbm
(cpbm_wd implies cpor_part).

Set mpam_feat_mbw_part and mpam_feat_mbw_max on cfg only when the
class has the feature (mbw_pbm_bits/bwa_wd can be set without
HAS_PBM/HAS_MAX).

Fixes: 09b89d2a72f3 ("arm_mpam: Allow configuration to be applied and restored during cpu online")
Signed-off-by: Fenghua Yu <fenghuay@xxxxxxxxxx>
---
Without the fix, mpam_wa_t241_calc_min_from_max() in the patch:
https://lore.kernel.org/lkml/20260224175720.2663924-39-ben.horgan@xxxxxxx/
sees mpam_has_feature(mpam_feat_mbw_max, cfg) as false and always returned 0
on hardware that supports mbw_max. This causes performance degration
because of too small mbw_min on T241 platform.

 drivers/resctrl/mpam_devices.c | 14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/drivers/resctrl/mpam_devices.c b/drivers/resctrl/mpam_devices.c
index 9182c8fcf003..be4b554104e3 100644
--- a/drivers/resctrl/mpam_devices.c
+++ b/drivers/resctrl/mpam_devices.c
@@ -2618,12 +2618,20 @@ static void mpam_reset_component_cfg(struct mpam_component *comp)
 
 	for (i = 0; i <= mpam_partid_max; i++) {
 		comp->cfg[i] = (struct mpam_config) {};
-		if (cprops->cpbm_wd)
+		if (cprops->cpbm_wd) {
 			comp->cfg[i].cpbm = GENMASK(cprops->cpbm_wd - 1, 0);
-		if (cprops->mbw_pbm_bits)
+			mpam_set_feature(mpam_feat_cpor_part, &comp->cfg[i]);
+		}
+		if (cprops->mbw_pbm_bits) {
 			comp->cfg[i].mbw_pbm = GENMASK(cprops->mbw_pbm_bits - 1, 0);
-		if (cprops->bwa_wd)
+			if (mpam_has_feature(mpam_feat_mbw_part, cprops))
+				mpam_set_feature(mpam_feat_mbw_part, &comp->cfg[i]);
+		}
+		if (cprops->bwa_wd) {
 			comp->cfg[i].mbw_max = GENMASK(15, 16 - cprops->bwa_wd);
+			if (mpam_has_feature(mpam_feat_mbw_max, cprops))
+				mpam_set_feature(mpam_feat_mbw_max, &comp->cfg[i]);
+		}
 	}
 }
 
-- 
2.43.0