BACKPORT: perf/arm-cmn: Move IRQs when migrating context

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

This patch is needed to fix issue when mitigrate context to another CPU.

This patch is backported from:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/drivers/perf/arm-cmn.c?id=1c8147ea89c883d1f4e20f1b1d9c879291430102

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

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;
 }