perf/arm-cmn: Move IRQs when migrating context

[ Upstream commit 1c8147e ]

If we migrate the PMU context to another CPU, we need to remember to
retarget the IRQs as well.

Fixes: 0ba6477 ("perf: Add Arm CMN-600 PMU driver")
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Link: https://lore.kernel.org/r/e080640aea4ed8dfa870b8549dfb31221803eb6b.1611839564.git.robin.murphy@arm.com
Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

Author: rmurphy-arm

drivers/perf/arm-cmn.c

@@ -1150,7 +1150,7 @@ static int arm_cmn_commit_txn(struct pmu *pmu)
 static int arm_cmn_pmu_offline_cpu(unsigned int cpu, struct hlist_node *node)
 {
 	struct arm_cmn *cmn;
-	unsigned int target;
+	unsigned int i, target;
 
 	cmn = hlist_entry_safe(node, struct arm_cmn, cpuhp_node);
 	if (cpu != cmn->cpu)
@@ -1161,6 +1161,8 @@ static int arm_cmn_pmu_offline_cpu(unsigned int cpu, struct hlist_node *node)
 		return 0;
 
 	perf_pmu_migrate_context(&cmn->pmu, cpu, target);
+	for (i = 0; i < cmn->num_dtcs; i++)
+		irq_set_affinity_hint(cmn->dtc[i].irq, cpumask_of(target));
 	cmn->cpu = target;
 	return 0;
 }