[PATCH v5 1/4] drm/xe/forcewake: synchronize engine-cycle access with unplug

Prepare engine-cycle queries for delayed forcewake release by
protecting their forcewake and MMIO section with drm_dev_enter(). This
lets unplug wait for admitted queries before flushing delayed-release
timers.

Use drm_dev_unplug() on post-registration probe failure to provide the
same synchronization before teardown.

Assisted-by: GitHub-Copilot:gpt-5.6-sol
Signed-off-by: Zongyao Bai <[email protected]>
---
 drivers/gpu/drm/xe/xe_device.c |  2 +-
 drivers/gpu/drm/xe/xe_query.c  | 34 ++++++++++++++++++++++++++--------
 2 files changed, 27 insertions(+), 9 deletions(-)

diff --git a/drivers/gpu/drm/xe/xe_device.c b/drivers/gpu/drm/xe/xe_device.c
index 71111ad32465..81b31325e581 100644
--- a/drivers/gpu/drm/xe/xe_device.c
+++ b/drivers/gpu/drm/xe/xe_device.c
@@ -1166,7 +1166,7 @@ int xe_device_probe(struct xe_device *xe)
 
 err_unregister_display:
 	xe_display_unregister(xe);
-	drm_dev_unregister(&xe->drm);
+	drm_dev_unplug(&xe->drm);
 
 	return err;
 }
diff --git a/drivers/gpu/drm/xe/xe_query.c b/drivers/gpu/drm/xe/xe_query.c
index dc975f595368..3c356bc48e2a 100644
--- a/drivers/gpu/drm/xe/xe_query.c
+++ b/drivers/gpu/drm/xe/xe_query.c
@@ -8,6 +8,7 @@
 #include <linux/nospec.h>
 #include <linux/sched/clock.h>
 
+#include <drm/drm_drv.h>
 #include <drm/ttm/ttm_placement.h>
 #include <generated/xe_wa_oob.h>
 #include <uapi/drm/xe_drm.h>
@@ -123,6 +124,7 @@ query_engine_cycles(struct xe_device *xe,
 	__ktime_func_t cpu_clock;
 	struct xe_hw_engine *hwe;
 	struct xe_gt *gt;
+	int dev_idx, err = 0;
 
 	if (IS_SRIOV_VF(xe))
 		return -EOPNOTSUPP;
@@ -143,28 +145,44 @@ query_engine_cycles(struct xe_device *xe,
 		return -EINVAL;
 
 	eci = &resp.eci;
+	if (!drm_dev_enter(&xe->drm, &dev_idx))
+		return -ENODEV;
+
 	gt = xe_device_get_gt(xe, eci->gt_id);
-	if (!gt)
-		return -EINVAL;
+	if (!gt) {
+		err = -EINVAL;
+		goto out;
+	}
 
-	if (eci->engine_class >= ARRAY_SIZE(user_to_xe_engine_class))
-		return -EINVAL;
+	if (eci->engine_class >= ARRAY_SIZE(user_to_xe_engine_class)) {
+		err = -EINVAL;
+		goto out;
+	}
 
 	hwe = xe_gt_hw_engine(gt, user_to_xe_engine_class[eci->engine_class],
 			      eci->engine_instance, true);
-	if (!hwe)
-		return -EINVAL;
+	if (!hwe) {
+		err = -EINVAL;
+		goto out;
+	}
 
 	fw_domain = xe_hw_engine_to_fw_domain(hwe);
 
 	xe_with_force_wake(fw_ref, gt_to_fw(gt), fw_domain) {
-		if (!xe_force_wake_ref_has_domain(fw_ref.domains, fw_domain))
-			return -EIO;
+		if (!xe_force_wake_ref_has_domain(fw_ref.domains, fw_domain)) {
+			err = -EIO;
+			goto out;
+		}
 
 		hwe_read_timestamp(hwe, &resp.engine_cycles, &resp.cpu_timestamp,
 				   &resp.cpu_delta, cpu_clock);
 	}
 
+out:
+	drm_dev_exit(dev_idx);
+	if (err)
+		return err;
+
 	if (GRAPHICS_VER(xe) >= 20)
 		resp.width = 64;
 	else
-- 
2.43.0