drm/xe: Fix missing workqueue destroy in xe_gt_pagefault

On driver reload we never free up the memory for the pagefault and
access counter workqueues. Add those destroy calls here.

Fixes: dd08ebf6 ("drm/xe: Introduce a new DRM driver for Intel GPUs")
Signed-off-by: Stuart Summers <stuart.summers@intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/c9a951505271dc3a7aee76de7656679f69c11518.1723862633.git.stuart.summers@intel.com

drivers/gpu/drm/xe/xe_gt_pagefault.c

@@ -382,6 +382,18 @@ static void pf_queue_work_func(struct work_struct *w)
 
 static void acc_queue_work_func(struct work_struct *w);
 
+static void pagefault_fini(void *arg)
+{
+	struct xe_gt *gt = arg;
+	struct xe_device *xe = gt_to_xe(gt);
+
+	if (!xe->info.has_usm)
+		return;
+
+	destroy_workqueue(gt->usm.acc_wq);
+	destroy_workqueue(gt->usm.pf_wq);
+}
+
 int xe_gt_pagefault_init(struct xe_gt *gt)
 {
 	struct xe_device *xe = gt_to_xe(gt);
@@ -409,10 +421,12 @@ int xe_gt_pagefault_init(struct xe_gt *gt)
 	gt->usm.acc_wq = alloc_workqueue("xe_gt_access_counter_work_queue",
 					 WQ_UNBOUND | WQ_HIGHPRI,
 					 NUM_ACC_QUEUE);
-	if (!gt->usm.acc_wq)
+	if (!gt->usm.acc_wq) {
+		destroy_workqueue(gt->usm.pf_wq);
 		return -ENOMEM;
+	}
 
-	return 0;
+	return devm_add_action_or_reset(xe->drm.dev, pagefault_fini, gt);
 }
 
 void xe_gt_pagefault_reset(struct xe_gt *gt)