bus: arm-ccn: Do not group CCN events with other PMUs

Groups must not mix events from different PMUs (software events are
allowed). Unfortunately the core does not ensures that, so it is
necessary to validate the group at the PMU driver level.
Signed-off-by: Pawel Moll <pawel.moll@arm.com>

drivers/bus/arm-ccn.c

@@ -660,6 +660,7 @@ static int arm_ccn_pmu_event_init(struct perf_event *event)
 	int valid, bit;
 	struct arm_ccn_component *source;
 	int i;
+	struct perf_event *sibling;
 
 	if (event->attr.type != event->pmu->type)
 		return -ENOENT;
@@ -762,6 +763,21 @@ static int arm_ccn_pmu_event_init(struct perf_event *event)
 				node_xp, type, port);
 	}
 
+	/*
+	 * We must NOT create groups containing mixed PMUs, although software
+	 * events are acceptable (for example to create a CCN group
+	 * periodically read when a hrtimer aka cpu-clock leader triggers).
+	 */
+	if (event->group_leader->pmu != event->pmu &&
+			!is_software_event(event->group_leader))
+		return -EINVAL;
+
+	list_for_each_entry(sibling, &event->group_leader->sibling_list,
+			group_entry)
+		if (sibling->pmu != event->pmu &&
+				!is_software_event(sibling))
+			return -EINVAL;
+
 	/* Allocate the cycle counter */
 	if (type == CCN_TYPE_CYCLES) {
 		if (test_and_set_bit(CCN_IDX_PMU_CYCLE_COUNTER,