perf: Extend PERF_TYPE_HARDWARE and PERF_TYPE_HW_CACHE

Current Hardware events and Hardware cache events have special perf
types, PERF_TYPE_HARDWARE and PERF_TYPE_HW_CACHE. The two types don't
pass the PMU type in the user interface. For a hybrid system, the perf
subsystem doesn't know which PMU the events belong to. The first capable
PMU will always be assigned to the events. The events never get a chance
to run on the other capable PMUs.

Extend the two types to become PMU aware types. The PMU type ID is
stored at attr.config[63:32].

Add a new PMU capability, PERF_PMU_CAP_EXTENDED_HW_TYPE, to indicate a
PMU which supports the extended PERF_TYPE_HARDWARE and
PERF_TYPE_HW_CACHE.

The PMU type is only required when searching a specific PMU. The PMU
specific codes will only be interested in the 'real' config value, which
is stored in the low 32 bit of the event->attr.config. Update the
event->attr.config in the generic code, so the PMU specific codes don't
need to calculate it separately.

If a user specifies a PMU type, but the PMU doesn't support the extended
type, error out.

If an event cannot be initialized in a PMU specified by a user, error
out immediately. Perf should not try to open it on other PMUs.

The new PMU capability is only set for the X86 hybrid PMUs for now.
Other architectures, e.g., ARM, may need it as well. The support on ARM
may be implemented later separately.

Suggested-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/1618237865-33448-22-git-send-email-kan.liang@linux.intel.com

1 files changed, 16 insertions, 3 deletions

diff --git a/kernel/events/core.c b/kernel/events/core.c
index 6f0723c711a9..928b166d888e 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -11220,6 +11220,7 @@ static int perf_try_init_event(struct pmu *pmu, struct perf_event *event)
 
 static struct pmu *perf_init_event(struct perf_event *event)
 {
+	bool extended_type = false;
 	int idx, type, ret;
 	struct pmu *pmu;
 
@@ -11238,16 +11239,27 @@ static struct pmu *perf_init_event(struct perf_event *event)
 	 * are often aliases for PERF_TYPE_RAW.
 	 */
 	type = event->attr.type;
-	if (type == PERF_TYPE_HARDWARE || type == PERF_TYPE_HW_CACHE)
-		type = PERF_TYPE_RAW;
+	if (type == PERF_TYPE_HARDWARE || type == PERF_TYPE_HW_CACHE) {
+		type = event->attr.config >> PERF_PMU_TYPE_SHIFT;
+		if (!type) {
+			type = PERF_TYPE_RAW;
+		} else {
+			extended_type = true;
+			event->attr.config &= PERF_HW_EVENT_MASK;
+		}
+	}
 
 again:
 	rcu_read_lock();
 	pmu = idr_find(&pmu_idr, type);
 	rcu_read_unlock();
 	if (pmu) {
+		if (event->attr.type != type && type != PERF_TYPE_RAW &&
+		    !(pmu->capabilities & PERF_PMU_CAP_EXTENDED_HW_TYPE))
+			goto fail;
+
 		ret = perf_try_init_event(pmu, event);
-		if (ret == -ENOENT && event->attr.type != type) {
+		if (ret == -ENOENT && event->attr.type != type && !extended_type) {
 			type = event->attr.type;
 			goto again;
 		}
@@ -11268,6 +11280,7 @@ again:
 			goto unlock;
 		}
 	}
+fail:
 	pmu = ERR_PTR(-ENOENT);
 unlock:
 	srcu_read_unlock(&pmus_srcu, idx);