drm/xe: Allocate dedicated workqueue for SR-IOV workers

We plan to use several workers where we might be running long
operations. Allocate dedicated workqueue to avoid undesired
interaction with non-virtualized workers.

Reviewed-by: Piotr Piórkowski <piotr.piorkowski@intel.com>
Link: https://lore.kernel.org/r/20240104222031.277-2-michal.wajdeczko@intel.com
Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>

drivers/gpu/drm/xe/xe_device.c

@@ -438,6 +438,10 @@ int xe_device_probe(struct xe_device *xe)
 
 	xe_pat_init_early(xe);
 
+	err = xe_sriov_init(xe);
+	if (err)
+		return err;
+
 	xe->info.mem_region_mask = 1;
 	err = xe_display_init_nommio(xe);
 	if (err)

drivers/gpu/drm/xe/xe_device_types.h

@@ -321,6 +321,8 @@ struct xe_device {
 	struct {
 		/** @sriov.__mode: SR-IOV mode (Don't access directly!) */
 		enum xe_sriov_mode __mode;
+		/** @sriov.wq: workqueue used by the virtualization workers */
+		struct workqueue_struct *wq;
 	} sriov;
 
 	/** @clients: drm clients info */

drivers/gpu/drm/xe/xe_sriov.c

@@ -3,6 +3,8 @@
  * Copyright © 2023 Intel Corporation
  */
 
+#include <drm/drm_managed.h>
+
 #include "xe_assert.h"
 #include "xe_sriov.h"
 
@@ -53,3 +55,33 @@ void xe_sriov_probe_early(struct xe_device *xe, bool has_sriov)
 		drm_info(&xe->drm, "Running in %s mode\n",
 			 xe_sriov_mode_to_string(xe_device_sriov_mode(xe)));
 }
+
+static void fini_sriov(struct drm_device *drm, void *arg)
+{
+	struct xe_device *xe = arg;
+
+	destroy_workqueue(xe->sriov.wq);
+	xe->sriov.wq = NULL;
+}
+
+/**
+ * xe_sriov_init - Initialize SR-IOV specific data.
+ * @xe: the &xe_device to initialize
+ *
+ * In this function we create dedicated workqueue that will be used
+ * by the SR-IOV specific workers.
+ *
+ * Return: 0 on success or a negative error code on failure.
+ */
+int xe_sriov_init(struct xe_device *xe)
+{
+	if (!IS_SRIOV(xe))
+		return 0;
+
+	xe_assert(xe, !xe->sriov.wq);
+	xe->sriov.wq = alloc_workqueue("xe-sriov-wq", 0, 0);
+	if (!xe->sriov.wq)
+		return -ENOMEM;
+
+	return drmm_add_action_or_reset(&xe->drm, fini_sriov, xe);
+}

drivers/gpu/drm/xe/xe_sriov.h

@@ -13,6 +13,7 @@
 const char *xe_sriov_mode_to_string(enum xe_sriov_mode mode);
 
 void xe_sriov_probe_early(struct xe_device *xe, bool has_sriov);
+int xe_sriov_init(struct xe_device *xe);
 
 static inline enum xe_sriov_mode xe_device_sriov_mode(struct xe_device *xe)
 {