[PATCH v5 4/4] drm/amdgpu: Signal GPU_RESET EVENTFD notifications

Signal GPU_RESET EVENTFD subscriptions after successful GPU reset
completion.

GPU reset notifications allow userspace to observe that GPU recovery has
completed and the device is operational again.

GPU_RESET is a device-scoped event, so no queue object is used. All
processes that subscribed to GPU_RESET on the device are notified.

EVENTFD remains notification-only.

v2:
- Move GPU_RESET EVENTFD signaling to the path that confirms a real
  GPU hardware reset occurred.
- Notify only after successful hardware reset completion.
- Do not signal reset-skip or recovery-only paths.

Cc: Alex Deucher <[email protected]>
Cc: Christian König <[email protected]>
Signed-off-by: Srinivasan Shanmugam <[email protected]>
Reviewed-by: Alex Deucher <[email protected]>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_device.c | 51 +++++++++++++++++++++-
 1 file changed, 49 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
index c924a55fd16f..15aaceae13d1 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
@@ -5390,15 +5390,43 @@ static void amdgpu_device_halt_activities(struct amdgpu_device *adev,
 	}
 }
 
+/*
+ * Signal GPU_RESET EVENTFD subscriptions for all open DRM files.
+ *
+ * GPU reset is a device-wide event rather than being associated with a
+ * specific user queue. Notify every process that subscribed to the
+ * GPU_RESET event on this device.
+ */
+static void amdgpu_device_eventfd_signal_gpu_reset(struct amdgpu_device *adev)
+{
+	struct drm_device *ddev = adev_to_drm(adev);
+	struct drm_file *file;
+
+	mutex_lock(&ddev->filelist_mutex);
+
+	list_for_each_entry(file, &ddev->filelist, lhead) {
+		struct amdgpu_fpriv *fpriv = file->driver_priv;
+
+		if (fpriv)
+			amdgpu_eventfd_signal(&fpriv->eventfd_mgr,
+					      DRM_AMDGPU_EVENT_TYPE_GPU_RESET,
+					      NULL);
+	}
+
+	mutex_unlock(&ddev->filelist_mutex);
+}
+
 static int amdgpu_device_asic_reset(struct amdgpu_device *adev,
 			      struct list_head *device_list,
 			      struct amdgpu_reset_context *reset_context)
 {
 	struct amdgpu_device *tmp_adev = NULL;
+	bool need_full_reset, skip_hw_reset;
 	int retry_limit = AMDGPU_MAX_RETRY_LIMIT;
 	int r = 0;
 
-retry:	/* Rest of adevs pre asic reset from XGMI hive. */
+retry:
+	/* Rest of adevs pre asic reset from XGMI hive. */
 	list_for_each_entry(tmp_adev, device_list, reset_list) {
 		r = amdgpu_device_pre_asic_reset(tmp_adev, reset_context);
 		/*TODO Should we stop ?*/
@@ -5430,10 +5458,30 @@ static int amdgpu_device_asic_reset(struct amdgpu_device *adev,
 		}
 		if (r)
 			adev->asic_reset_res = r;
+		else
+			amdgpu_device_eventfd_signal_gpu_reset(adev);
 	} else {
+		/*
+		 * Save the reset decision before amdgpu_do_asic_reset(),
+		 * which may clear AMDGPU_NEED_FULL_RESET before returning.
+		 */
+		need_full_reset =
+			test_bit(AMDGPU_NEED_FULL_RESET, &reset_context->flags);
+		skip_hw_reset =
+			test_bit(AMDGPU_SKIP_HW_RESET, &reset_context->flags);
+
 		r = amdgpu_do_asic_reset(device_list, reset_context);
 		if (r && r == -EAGAIN)
 			goto retry;
+
+		/*
+		 * Notify only after a real hardware reset completed.
+		 * Do not notify recovery-only or reset-skip paths.
+		 */
+		if (!r && need_full_reset && !skip_hw_reset) {
+			list_for_each_entry(tmp_adev, device_list, reset_list)
+				amdgpu_device_eventfd_signal_gpu_reset(tmp_adev);
+		}
 	}
 
 	list_for_each_entry(tmp_adev, device_list, reset_list) {
@@ -5530,7 +5578,6 @@ static void amdgpu_device_gpu_resume(struct amdgpu_device *adev,
 	}
 }
 
-
 /**
  * amdgpu_device_gpu_recover - reset the asic and recover scheduler
  *
-- 
2.34.1