[RFC PATCH v2 18/19] arm_mpam: resctrl: Expose the L2 monitor events

[Jinjie Ruan]

Allow an L2 cache class to supply the CSU counters for l2c_occupancy and
the MBWU counters for mbm_core_bytes.

The L2 bandwidth event is a normal MBM event, so resctrl gives it a
counter for the life of the monitoring group. MBWU needs that: rewriting
the PARTID/PMG filter restarts the byte count, so the filter must stay
in place while traffic is counted. CSU occupancy is only a snapshot and
can still borrow a monitor for each read.

Signed-off-by: Jinjie Ruan <ruanjinjie@xxxxxxxxxx>
---
 drivers/resctrl/mpam_resctrl.c | 20 ++++++++++++++++----
 1 file changed, 16 insertions(+), 4 deletions(-)

diff --git a/drivers/resctrl/mpam_resctrl.c b/drivers/resctrl/mpam_resctrl.c
index b9487f3c648d..62214557b673 100644
--- a/drivers/resctrl/mpam_resctrl.c
+++ b/drivers/resctrl/mpam_resctrl.c
@@ -1123,9 +1123,10 @@ static void mpam_resctrl_pick_counters(void)
 	guard(srcu)(&mpam_srcu);
 	list_for_each_entry_srcu(class, &mpam_classes, classes_list,
 				 srcu_read_lock_held(&mpam_srcu)) {
-		/* The name of the resource is L3... */
-		if (class->type == MPAM_CLASS_CACHE && class->level != 3) {
-			pr_debug("class %u is a cache but not the L3", class->level);
+		if (class->type == MPAM_CLASS_CACHE && class->level != 2 &&
+		    class->level != 3) {
+			pr_debug("class %u is a cache but not L2 or L3",
+				 class->level);
 			continue;
 		}
 
@@ -1145,7 +1146,10 @@ static void mpam_resctrl_pick_counters(void)
 				if (update_rmid_limits(class))
 					break;
 
-				counter_update_class(RDT_RESOURCE_L3, QOS_OCCUP_EVENT_ID, class);
+				counter_update_class(class->level == 2 ?
+						     RDT_RESOURCE_L2 :
+						     RDT_RESOURCE_L3,
+						     QOS_OCCUP_EVENT_ID, class);
 				break;
 			default:
 				break;
@@ -1169,6 +1173,14 @@ static void mpam_resctrl_pick_counters(void)
 			 */
 			counter_update_class(RDT_RESOURCE_L3, QOS_MBM_TOTAL_EVENT_ID, class);
 		}
+
+		if (class->type == MPAM_CLASS_CACHE && class->level == 2 &&
+		    class_has_usable_mbwu(class)) {
+			pr_debug("class %u has usable MBWU for the L2 resource\n",
+				 class->level);
+			counter_update_class(RDT_RESOURCE_L2,
+					     QOS_MBM_TOTAL_EVENT_ID, class);
+		}
 	}
 }
 
-- 
2.34.1