3 files changed, 16 insertions, 1 deletions

diff --git a/drivers/perf/arm_pmu.c b/drivers/perf/arm_pmu.c
index f70090897fdf..f2d01d4d9364 100644
--- a/drivers/perf/arm_pmu.c
+++ b/drivers/perf/arm_pmu.c
@@ -847,6 +847,14 @@ static int cpu_pmu_init(struct arm_pmu *cpu_pmu)
         if (!platform_get_irq(cpu_pmu->plat_device, 0))
                 cpu_pmu->pmu.capabilities |= PERF_PMU_CAP_NO_INTERRUPT;
 
+        /*
+         * This is a CPU PMU potentially in a heterogeneous configuration (e.g.
+         * big.LITTLE). This is not an uncore PMU, and we have taken ctx
+         * sharing into account (e.g. with our pmu::filter_match callback and
+         * pmu::event_init group validation).
+         */
+        cpu_pmu->pmu.capabilities |= PERF_PMU_CAP_HETEROGENEOUS_CPUS;
+
         return 0;
 
 out_unregister:
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index c77e4a159fa2..9e1c3ada91c4 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -225,6 +225,7 @@ struct perf_event;
 #define PERF_PMU_CAP_AUX_SW_DOUBLEBUF           0x08
 #define PERF_PMU_CAP_EXCLUSIVE                  0x10
 #define PERF_PMU_CAP_ITRACE                     0x20
+#define PERF_PMU_CAP_HETEROGENEOUS_CPUS         0x40
 
 /**
  * struct pmu - generic performance monitoring unit
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 63be65437e9e..fc0290f25482 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -8443,7 +8443,13 @@ skip_type:
         if (pmu->task_ctx_nr == perf_hw_context) {
                 static int hw_context_taken = 0;
 
-                if (WARN_ON_ONCE(hw_context_taken))
+                /*
+                 * Other than systems with heterogeneous CPUs, it never makes
+                 * sense for two PMUs to share perf_hw_context. PMUs which are
+                 * uncore must use perf_invalid_context.
+                 */
+                if (WARN_ON_ONCE(hw_context_taken &&
+                    !(pmu->capabilities & PERF_PMU_CAP_HETEROGENEOUS_CPUS)))
                         pmu->task_ctx_nr = perf_invalid_context;
 
                 hw_context_taken = 1;