perf/core: Add PERF_PMU_CAP_NO_EXCLUDE for exclusion incapable PMUs

Many PMU drivers do not have the capability to exclude counting events
that occur in specific contexts such as idle, kernel, guest, etc. These
drivers indicate this by returning an error in their event_init upon
testing the events attribute flags. This approach is error prone and
often inconsistent.

Let's instead allow PMU drivers to advertise their inability to exclude
based on context via a new capability: PERF_PMU_CAP_NO_EXCLUDE. This
allows the perf core to reject requests for exclusion events where
there is no support in the PMU.

Signed-off-by: Andrew Murray <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Cc: Arnaldo Carvalho de Melo <[email protected]>
Cc: Benjamin Herrenschmidt <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Ivan Kokshaysky <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Mark Rutland <[email protected]>
Cc: Matt Turner <[email protected]>
Cc: Michael Ellerman <[email protected]>
Cc: Paul Mackerras <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Richard Henderson <[email protected]>
Cc: Russell King <[email protected]>
Cc: Sascha Hauer <[email protected]>
Cc: Shawn Guo <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Will Deacon <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>

include/linux/perf_event.h

@@ -244,6 +244,7 @@ struct perf_event;
 #define PERF_PMU_CAP_EXCLUSIVE			0x10
 #define PERF_PMU_CAP_ITRACE			0x20
 #define PERF_PMU_CAP_HETEROGENEOUS_CPUS		0x40
+#define PERF_PMU_CAP_NO_EXCLUDE			0x80
 
 /**
  * struct pmu - generic performance monitoring unit

kernel/events/core.c

@@ -9772,6 +9772,15 @@ static int perf_try_init_event(struct pmu *pmu, struct perf_event *event)
 	if (ctx)
 		perf_event_ctx_unlock(event->group_leader, ctx);
 
+	if (!ret) {
+		if (pmu->capabilities & PERF_PMU_CAP_NO_EXCLUDE &&
+				event_has_any_exclude_flag(event)) {
+			if (event->destroy)
+				event->destroy(event);
+			ret = -EINVAL;
+		}
+	}
+
 	if (ret)
 		module_put(pmu->module);