[PATCH v9 5/5] drm/xe/xe_pmu: Acquire forcewake on event init for engine events

[Riana Tauro]

When the engine events are created, acquire GT forcewake to read gpm
timestamp required for the events and release on event destroy. This
cannot be done during read due to the raw spinlock held my pmu.

v2: remove forcewake counting (Umesh)
v3: remove extra space (Umesh)
v4: use event pmu private data (Lucas)
    free local copy (Umesh)

Signed-off-by: Riana Tauro <riana.tauro at intel.com>
Reviewed-by: Umesh Nerlige Ramappa <umesh.nerlige.ramappa at intel.com>
Reviewed-by: Himal Prasad Ghimiray <himal.prasad.ghimiray at intel.com>
---
 drivers/gpu/drm/xe/xe_pmu.c | 50 +++++++++++++++++++++++++++++++++++++
 1 file changed, 50 insertions(+)

diff --git a/drivers/gpu/drm/xe/xe_pmu.c b/drivers/gpu/drm/xe/xe_pmu.c
index d2c035c1924e..4f62a6e515d6 100644
--- a/drivers/gpu/drm/xe/xe_pmu.c
+++ b/drivers/gpu/drm/xe/xe_pmu.c
@@ -7,6 +7,7 @@
 #include <linux/device.h>
 
 #include "xe_device.h"
+#include "xe_force_wake.h"
 #include "xe_gt_idle.h"
 #include "xe_guc_engine_activity.h"
 #include "xe_hw_engine.h"
@@ -102,6 +103,41 @@ static struct xe_hw_engine *event_to_hwe(struct perf_event *event)
 	return hwe;
 }
 
+static bool is_engine_event(u64 config)
+{
+	unsigned int event_id = config_to_event_id(config);
+
+	return (event_id == XE_PMU_EVENT_ENGINE_TOTAL_TICKS ||
+		event_id == XE_PMU_EVENT_ENGINE_ACTIVE_TICKS);
+}
+
+static bool event_gt_forcewake(struct perf_event *event)
+{
+	struct xe_device *xe = container_of(event->pmu, typeof(*xe), pmu.base);
+	u64 config = event->attr.config;
+	struct xe_gt *gt;
+	unsigned int *fw_ref;
+
+	if (!is_engine_event(config))
+		return true;
+
+	gt = xe_device_get_gt(xe, config_to_gt_id(config));
+
+	fw_ref = kzalloc(sizeof(*fw_ref), GFP_KERNEL);
+	if (!fw_ref)
+		return false;
+
+	*fw_ref = xe_force_wake_get(gt_to_fw(gt), XE_FW_GT);
+	if (!*fw_ref) {
+		kfree(fw_ref);
+		return false;
+	}
+
+	event->pmu_private = fw_ref;
+
+	return true;
+}
+
 static bool event_supported(struct xe_pmu *pmu, unsigned int gt,
 			    unsigned int id)
 {
@@ -144,6 +180,15 @@ static bool event_param_valid(struct perf_event *event)
 static void xe_pmu_event_destroy(struct perf_event *event)
 {
 	struct xe_device *xe = container_of(event->pmu, typeof(*xe), pmu.base);
+	struct xe_gt *gt;
+	unsigned int *fw_ref = event->pmu_private;
+
+	if (fw_ref) {
+		gt = xe_device_get_gt(xe, config_to_gt_id(event->attr.config));
+		xe_force_wake_put(gt_to_fw(gt), *fw_ref);
+		kfree(fw_ref);
+		event->pmu_private = NULL;
+	}
 
 	drm_WARN_ON(&xe->drm, event->parent);
 	xe_pm_runtime_put(xe);
@@ -183,6 +228,11 @@ static int xe_pmu_event_init(struct perf_event *event)
 	if (!event->parent) {
 		drm_dev_get(&xe->drm);
 		xe_pm_runtime_get(xe);
+		if (!event_gt_forcewake(event)) {
+			xe_pm_runtime_put(xe);
+			drm_dev_put(&xe->drm);
+			return -EINVAL;
+		}
 		event->destroy = xe_pmu_event_destroy;
 	}
 
-- 
2.47.1