diff --git a/arch/x86/kernel/cpu/resctrl/monitor.c b/arch/x86/kernel/cpu/resctrl/monitor.c
index a98519a3a2e6..3075624723b2 100644
--- a/arch/x86/kernel/cpu/resctrl/monitor.c
+++ b/arch/x86/kernel/cpu/resctrl/monitor.c
@@ -222,15 +222,14 @@ static u64 mbm_overflow_count(u64 prev_msr, u64 cur_msr, unsigned int width)
 	return chunks >>= shift;
 }
 
-static int __mon_event_count(u32 rmid, struct rmid_read *rr)
+static u64 __mon_event_count(u32 rmid, struct rmid_read *rr)
 {
 	struct mbm_state *m;
 	u64 chunks, tval;
 
 	tval = __rmid_read(rmid, rr->evtid);
 	if (tval & (RMID_VAL_ERROR | RMID_VAL_UNAVAIL)) {
-		rr->val = tval;
-		return -EINVAL;
+		return tval;
 	}
 	switch (rr->evtid) {
 	case QOS_L3_OCCUP_EVENT_ID:
@@ -242,12 +241,6 @@ static int __mon_event_count(u32 rmid, struct rmid_read *rr)
 	case QOS_L3_MBM_LOCAL_EVENT_ID:
 		m = &rr->d->mbm_local[rmid];
 		break;
-	default:
-		/*
-		 * Code would never reach here because
-		 * an invalid event id would fail the __rmid_read.
-		 */
-		return -EINVAL;
 	}
 
 	if (rr->first) {
@@ -297,23 +290,29 @@ void mon_event_count(void *info)
 	struct rdtgroup *rdtgrp, *entry;
 	struct rmid_read *rr = info;
 	struct list_head *head;
+	u64 ret_val;
 
 	rdtgrp = rr->rgrp;
 
-	if (__mon_event_count(rdtgrp->mon.rmid, rr))
-		return;
+	ret_val = __mon_event_count(rdtgrp->mon.rmid, rr);
 
 	/*
-	 * For Ctrl groups read data from child monitor groups.
+	 * For Ctrl groups read data from child monitor groups and
+	 * add them together. Count events which are read successfully.
+	 * Discard the rmid_read's reporting errors.
 	 */
 	head = &rdtgrp->mon.crdtgrp_list;
 
 	if (rdtgrp->type == RDTCTRL_GROUP) {
 		list_for_each_entry(entry, head, mon.crdtgrp_list) {
-			if (__mon_event_count(entry->mon.rmid, rr))
-				return;
+			if (__mon_event_count(entry->mon.rmid, rr) == 0)
+				ret_val = 0;
 		}
 	}
+
+	/* Report error if none of rmid_reads are successful */
+	if (ret_val)
+		rr->val = ret_val;
 }
 
 /*