drm/i915/guc: Move GuC guc_id allocation under submission state sub-struct

Move guc_id allocation under submission state sub-struct as a future
patch will reuse the spin lock as a global submission state lock. Moving
this into sub-struct makes ownership of fields / lock clear.

v2:
 (Docs)
  - Add comment for submission_state sub-structure
v3:
 (John Harrison)
  - Fixup a few comments
v4:
 (John Harrison)
  - Fix typo
Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Reviewed-by: John Harrison <John.C.Harrison@Intel.com>
Signed-off-by: John Harrison <John.C.Harrison@Intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20211014172005.27155-2-matthew.brost@intel.com

drivers/gpu/drm/i915/gt/intel_context_types.h

@@ -197,18 +197,18 @@ struct intel_context {
 	struct {
 		/**
 		 * @id: handle which is used to uniquely identify this context
-		 * with the GuC, protected by guc->contexts_lock
+		 * with the GuC, protected by guc->submission_state.lock
 		 */
 		u16 id;
 		/**
 		 * @ref: the number of references to the guc_id, when
 		 * transitioning in and out of zero protected by
-		 * guc->contexts_lock
+		 * guc->submission_state.lock
 		 */
 		atomic_t ref;
 		/**
 		 * @link: in guc->guc_id_list when the guc_id has no refs but is
-		 * still valid, protected by guc->contexts_lock
+		 * still valid, protected by guc->submission_state.lock
 		 */
 		struct list_head link;
 	} guc_id;

drivers/gpu/drm/i915/gt/uc/intel_guc.h

@@ -71,16 +71,26 @@ struct intel_guc {
 	} interrupts;
 
 	/**
-	 * @contexts_lock: protects guc_ids, guc_id_list, ce->guc_id.id, and
-	 * ce->guc_id.ref when transitioning in and out of zero
+	 * @submission_state: sub-structure for submission state protected by
+	 * single lock
+	 */
+	struct {
+		/**
+		 * @lock: protects everything in submission_state,
+		 * ce->guc_id.id, and ce->guc_id.ref when transitioning in and
+		 * out of zero
+		 */
+		spinlock_t lock;
+		/**
+		 * @guc_ids: used to allocate new guc_ids
 		 */
-	spinlock_t contexts_lock;
-	/** @guc_ids: used to allocate unique ce->guc_id.id values */
 		struct ida guc_ids;
 		/**
-	 * @guc_id_list: list of intel_context with valid guc_ids but no refs
+		 * @guc_id_list: list of intel_context with valid guc_ids but no
+		 * refs
 		 */
 		struct list_head guc_id_list;
+	} submission_state;
 
 	/**
 	 * @submission_supported: tracks whether we support GuC submission on

drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c

@@ -68,7 +68,7 @@
  * fence is used to stall all requests associated with this guc_id until the
  * corresponding G2H returns indicating the guc_id has been deregistered.
  *
- * guc_ids:
+ * submission_state.guc_ids:
  * Unique number associated with private GuC context data passed in during
  * context registration / submission / deregistration. 64k available. Simple ida
  * is used for allocation.
@@ -89,7 +89,7 @@
  * sched_engine can be submitting at a time. Currently only one sched_engine is
  * used for all of GuC submission but that could change in the future.
  *
- * guc->contexts_lock
+ * guc->submission_state.lock
  * Protects guc_id allocation for the given GuC, i.e. only one context can be
  * doing guc_id allocation operations at a time for each GuC in the system.
  *
@@ -103,7 +103,7 @@
  *
  * Lock ordering rules:
  * sched_engine->lock -> ce->guc_state.lock
- * guc->contexts_lock -> ce->guc_state.lock
+ * guc->submission_state.lock -> ce->guc_state.lock
  *
  * Reset races:
  * When a full GT reset is triggered it is assumed that some G2H responses to
@@ -1148,9 +1148,9 @@ int intel_guc_submission_init(struct intel_guc *guc)
 
 	xa_init_flags(&guc->context_lookup, XA_FLAGS_LOCK_IRQ);
 
-	spin_lock_init(&guc->contexts_lock);
-	INIT_LIST_HEAD(&guc->guc_id_list);
-	ida_init(&guc->guc_ids);
+	spin_lock_init(&guc->submission_state.lock);
+	INIT_LIST_HEAD(&guc->submission_state.guc_id_list);
+	ida_init(&guc->submission_state.guc_ids);
 
 	return 0;
 }
@@ -1215,7 +1215,7 @@ static void guc_submit_request(struct i915_request *rq)
 
 static int new_guc_id(struct intel_guc *guc)
 {
-	return ida_simple_get(&guc->guc_ids, 0,
+	return ida_simple_get(&guc->submission_state.guc_ids, 0,
 			      GUC_MAX_LRC_DESCRIPTORS, GFP_KERNEL |
 			      __GFP_RETRY_MAYFAIL | __GFP_NOWARN);
 }
@@ -1223,7 +1223,8 @@ static int new_guc_id(struct intel_guc *guc)
 static void __release_guc_id(struct intel_guc *guc, struct intel_context *ce)
 {
 	if (!context_guc_id_invalid(ce)) {
-		ida_simple_remove(&guc->guc_ids, ce->guc_id.id);
+		ida_simple_remove(&guc->submission_state.guc_ids,
+				  ce->guc_id.id);
 		reset_lrc_desc(guc, ce->guc_id.id);
 		set_context_guc_id_invalid(ce);
 	}
@@ -1235,9 +1236,9 @@ static void release_guc_id(struct intel_guc *guc, struct intel_context *ce)
 {
 	unsigned long flags;
 
-	spin_lock_irqsave(&guc->contexts_lock, flags);
+	spin_lock_irqsave(&guc->submission_state.lock, flags);
 	__release_guc_id(guc, ce);
-	spin_unlock_irqrestore(&guc->contexts_lock, flags);
+	spin_unlock_irqrestore(&guc->submission_state.lock, flags);
 }
 
 static int steal_guc_id(struct intel_guc *guc)
@@ -1245,10 +1246,10 @@ static int steal_guc_id(struct intel_guc *guc)
 	struct intel_context *ce;
 	int guc_id;
 
-	lockdep_assert_held(&guc->contexts_lock);
+	lockdep_assert_held(&guc->submission_state.lock);
 
-	if (!list_empty(&guc->guc_id_list)) {
-		ce = list_first_entry(&guc->guc_id_list,
+	if (!list_empty(&guc->submission_state.guc_id_list)) {
+		ce = list_first_entry(&guc->submission_state.guc_id_list,
 				      struct intel_context,
 				      guc_id.link);
 
@@ -1273,7 +1274,7 @@ static int assign_guc_id(struct intel_guc *guc, u16 *out)
 {
 	int ret;
 
-	lockdep_assert_held(&guc->contexts_lock);
+	lockdep_assert_held(&guc->submission_state.lock);
 
 	ret = new_guc_id(guc);
 	if (unlikely(ret < 0)) {
@@ -1295,7 +1296,7 @@ static int pin_guc_id(struct intel_guc *guc, struct intel_context *ce)
 	GEM_BUG_ON(atomic_read(&ce->guc_id.ref));
 
 try_again:
-	spin_lock_irqsave(&guc->contexts_lock, flags);
+	spin_lock_irqsave(&guc->submission_state.lock, flags);
 
 	might_lock(&ce->guc_state.lock);
 
@@ -1310,7 +1311,7 @@ static int pin_guc_id(struct intel_guc *guc, struct intel_context *ce)
 	atomic_inc(&ce->guc_id.ref);
 
 out_unlock:
-	spin_unlock_irqrestore(&guc->contexts_lock, flags);
+	spin_unlock_irqrestore(&guc->submission_state.lock, flags);
 
 	/*
 	 * -EAGAIN indicates no guc_id are available, let's retire any
@@ -1346,11 +1347,12 @@ static void unpin_guc_id(struct intel_guc *guc, struct intel_context *ce)
 	if (unlikely(context_guc_id_invalid(ce)))
 		return;
 
-	spin_lock_irqsave(&guc->contexts_lock, flags);
+	spin_lock_irqsave(&guc->submission_state.lock, flags);
 	if (!context_guc_id_invalid(ce) && list_empty(&ce->guc_id.link) &&
 	    !atomic_read(&ce->guc_id.ref))
-		list_add_tail(&ce->guc_id.link, &guc->guc_id_list);
-	spin_unlock_irqrestore(&guc->contexts_lock, flags);
+		list_add_tail(&ce->guc_id.link,
+			      &guc->submission_state.guc_id_list);
+	spin_unlock_irqrestore(&guc->submission_state.lock, flags);
 }
 
 static int __guc_action_register_context(struct intel_guc *guc,
@@ -1921,16 +1923,16 @@ static void guc_context_destroy(struct kref *kref)
 	 * returns indicating this context has been deregistered the guc_id is
 	 * returned to the pool of available guc_id.
 	 */
-	spin_lock_irqsave(&guc->contexts_lock, flags);
+	spin_lock_irqsave(&guc->submission_state.lock, flags);
 	if (context_guc_id_invalid(ce)) {
-		spin_unlock_irqrestore(&guc->contexts_lock, flags);
+		spin_unlock_irqrestore(&guc->submission_state.lock, flags);
 		__guc_context_destroy(ce);
 		return;
 	}
 
 	if (!list_empty(&ce->guc_id.link))
 		list_del_init(&ce->guc_id.link);
-	spin_unlock_irqrestore(&guc->contexts_lock, flags);
+	spin_unlock_irqrestore(&guc->submission_state.lock, flags);
 
 	/* Seal race with Reset */
 	spin_lock_irqsave(&ce->guc_state.lock, flags);