[PATCH v6 5/8] 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)

Cc: Rodrigo Vivi <rodrigo.vivi at intel.com>
Cc: Himal Prasad Ghimiray <himal.prasad.ghimiray at intel.com>
Signed-off-by: Riana Tauro <riana.tauro at intel.com>
---
 drivers/gpu/drm/xe/xe_pmu.c       | 52 +++++++++++++++++++++++++++++--
 drivers/gpu/drm/xe/xe_pmu_types.h |  4 +++
 2 files changed, 54 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/xe/xe_pmu.c b/drivers/gpu/drm/xe/xe_pmu.c
index dc89fa6d0ec5..0539dd61ddc3 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 +103,37 @@ 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_pmu *pmu = &xe->pmu;
+	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 = xe_force_wake_get(gt_to_fw(gt), XE_FW_GT);
+	if (!fw_ref)
+		return false;
+
+	if (!pmu->fw_ref)
+		pmu->fw_ref = fw_ref;
+
+	return true;
+}
+
 static bool event_supported(struct xe_pmu *pmu, unsigned int gt,
 			    unsigned int id)
 {
@@ -144,6 +176,13 @@ 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_pmu *pmu = &xe->pmu;
+	struct xe_gt *gt;
+
+	if (pmu->fw_ref) {
+		gt = xe_device_get_gt(xe, config_to_gt_id(event->attr.config));
+		xe_force_wake_put(gt_to_fw(gt), pmu->fw_ref);
+	}
 
 	drm_WARN_ON(&xe->drm, event->parent);
 	xe_pm_runtime_put(xe);
@@ -183,18 +222,27 @@ 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;
 	}
 
 	return 0;
 }
 
-static u64 read_engine_events(struct xe_gt *gt, struct perf_event *event)
+static u64 read_engine_events(struct xe_gt *gt, struct perf_event *event,  u64 prev)
 {
 	struct xe_device *xe = gt_to_xe(gt);
+	struct xe_pmu *pmu = &xe->pmu;
 	struct xe_hw_engine *hwe;
 	u64 val = 0;
 
+	if (!pmu->fw_ref)
+		return prev;
+
 	hwe = event_to_hwe(event);
 	if (!hwe)
 		drm_warn(&xe->drm, "unknown engine\n");
@@ -218,7 +266,7 @@ static u64 __xe_pmu_event_read(struct perf_event *event, u64 prev)
 		return xe_gt_idle_residency_msec(&gt->gtidle);
 	case XE_PMU_EVENT_ENGINE_ACTIVE_TICKS:
 	case XE_PMU_EVENT_ENGINE_TOTAL_TICKS:
-		return read_engine_events(gt, event);
+		return read_engine_events(gt, event, prev);
 	}
 
 	return 0;
diff --git a/drivers/gpu/drm/xe/xe_pmu_types.h b/drivers/gpu/drm/xe/xe_pmu_types.h
index f5ba4d56622c..07c4e592106e 100644
--- a/drivers/gpu/drm/xe/xe_pmu_types.h
+++ b/drivers/gpu/drm/xe/xe_pmu_types.h
@@ -30,6 +30,10 @@ struct xe_pmu {
 	 * @name: Name as registered with perf core.
 	 */
 	const char *name;
+	/**
+	 * @fw_ref: force_wake ref
+	 */
+	unsigned int fw_ref;
 	/**
 	 * @supported_events: Bitmap of supported events, indexed by event id
 	 */
-- 
2.47.1