drm/i915: Switch back to an array of logical per-engine HW contexts

We switched to a tree of per-engine HW context to accommodate the
introduction of virtual engines. However, we plan to also support
multiple instances of the same engine within the GEM context, defeating
our use of the engine as a key to looking up the HW context. Just
allocate a logical per-engine instance and always use an index into the
ctx->engines[]. Later on, this ctx->engines[] may be replaced by a user
specified map.

v2: Add for_each_gem_engine() helper to iterator within the engines lock
v3: intel_context_create_request() helper
v4: s/unsigned long/unsigned int/ 4 billion engines is quite enough.
v5: Push iterator locking to caller
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190426163336.15906-7-chris@chris-wilson.co.uk

drivers/gpu/drm/i915/gt/intel_context.c

@@ -17,7 +17,7 @@ static struct i915_global_context {
 	struct kmem_cache *slab_ce;
 } global;
 
-struct intel_context *intel_context_alloc(void)
+static struct intel_context *intel_context_alloc(void)
 {
 	return kmem_cache_zalloc(global.slab_ce, GFP_KERNEL);
 }
@@ -28,104 +28,17 @@ void intel_context_free(struct intel_context *ce)
 }
 
 struct intel_context *
-intel_context_lookup(struct i915_gem_context *ctx,
+intel_context_create(struct i915_gem_context *ctx,
 		     struct intel_engine_cs *engine)
 {
-	struct intel_context *ce = NULL;
-	struct rb_node *p;
-
-	spin_lock(&ctx->hw_contexts_lock);
-	p = ctx->hw_contexts.rb_node;
-	while (p) {
-		struct intel_context *this =
-			rb_entry(p, struct intel_context, node);
-
-		if (this->engine == engine) {
-			GEM_BUG_ON(this->gem_context != ctx);
-			ce = this;
-			break;
-		}
-
-		if (this->engine < engine)
-			p = p->rb_right;
-		else
-			p = p->rb_left;
-	}
-	spin_unlock(&ctx->hw_contexts_lock);
-
-	return ce;
-}
-
-struct intel_context *
-__intel_context_insert(struct i915_gem_context *ctx,
-		       struct intel_engine_cs *engine,
-		       struct intel_context *ce)
-{
-	struct rb_node **p, *parent;
-	int err = 0;
-
-	spin_lock(&ctx->hw_contexts_lock);
-
-	parent = NULL;
-	p = &ctx->hw_contexts.rb_node;
-	while (*p) {
-		struct intel_context *this;
-
-		parent = *p;
-		this = rb_entry(parent, struct intel_context, node);
-
-		if (this->engine == engine) {
-			err = -EEXIST;
-			ce = this;
-			break;
-		}
-
-		if (this->engine < engine)
-			p = &parent->rb_right;
-		else
-			p = &parent->rb_left;
-	}
-	if (!err) {
-		rb_link_node(&ce->node, parent, p);
-		rb_insert_color(&ce->node, &ctx->hw_contexts);
-	}
-
-	spin_unlock(&ctx->hw_contexts_lock);
-
-	return ce;
-}
-
-void __intel_context_remove(struct intel_context *ce)
-{
-	struct i915_gem_context *ctx = ce->gem_context;
-
-	spin_lock(&ctx->hw_contexts_lock);
-	rb_erase(&ce->node, &ctx->hw_contexts);
-	spin_unlock(&ctx->hw_contexts_lock);
-}
-
-struct intel_context *
-intel_context_instance(struct i915_gem_context *ctx,
-		       struct intel_engine_cs *engine)
-{
-	struct intel_context *ce, *pos;
-
-	ce = intel_context_lookup(ctx, engine);
-	if (likely(ce))
-		return intel_context_get(ce);
+	struct intel_context *ce;
 
 	ce = intel_context_alloc();
 	if (!ce)
 		return ERR_PTR(-ENOMEM);
 
 	intel_context_init(ce, ctx, engine);
-
-	pos = __intel_context_insert(ctx, engine, ce);
-	if (unlikely(pos != ce)) /* Beaten! Use their HW context instead */
-		intel_context_free(ce);
-
-	GEM_BUG_ON(intel_context_lookup(ctx, engine) != pos);
-	return intel_context_get(pos);
+	return ce;
 }
 
 int __intel_context_do_pin(struct intel_context *ce)
@@ -204,6 +117,8 @@ intel_context_init(struct intel_context *ce,
 		   struct i915_gem_context *ctx,
 		   struct intel_engine_cs *engine)
 {
+	GEM_BUG_ON(!engine->cops);
+
 	kref_init(&ce->ref);
 
 	ce->gem_context = ctx;
@@ -254,3 +169,18 @@ void intel_context_exit_engine(struct intel_context *ce)
 {
 	intel_engine_pm_put(ce->engine);
 }
+
+struct i915_request *intel_context_create_request(struct intel_context *ce)
+{
+	struct i915_request *rq;
+	int err;
+
+	err = intel_context_pin(ce);
+	if (unlikely(err))
+		return ERR_PTR(err);
+
+	rq = i915_request_create(ce);
+	intel_context_unpin(ce);
+
+	return rq;
+}

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

@@ -12,24 +12,16 @@
 #include "intel_context_types.h"
 #include "intel_engine_types.h"
 
-struct intel_context *intel_context_alloc(void);
-void intel_context_free(struct intel_context *ce);
-
 void intel_context_init(struct intel_context *ce,
 			struct i915_gem_context *ctx,
 			struct intel_engine_cs *engine);
 
-/**
- * intel_context_lookup - Find the matching HW context for this (ctx, engine)
- * @ctx - the parent GEM context
- * @engine - the target HW engine
- *
- * May return NULL if the HW context hasn't been instantiated (i.e. unused).
- */
 struct intel_context *
-intel_context_lookup(struct i915_gem_context *ctx,
+intel_context_create(struct i915_gem_context *ctx,
 		     struct intel_engine_cs *engine);
 
+void intel_context_free(struct intel_context *ce);
+
 /**
  * intel_context_lock_pinned - Stablises the 'pinned' status of the HW context
  * @ce - the context
@@ -71,17 +63,6 @@ static inline void intel_context_unlock_pinned(struct intel_context *ce)
 	mutex_unlock(&ce->pin_mutex);
 }
 
-struct intel_context *
-__intel_context_insert(struct i915_gem_context *ctx,
-		       struct intel_engine_cs *engine,
-		       struct intel_context *ce);
-void
-__intel_context_remove(struct intel_context *ce);
-
-struct intel_context *
-intel_context_instance(struct i915_gem_context *ctx,
-		       struct intel_engine_cs *engine);
-
 int __intel_context_do_pin(struct intel_context *ce);
 
 static inline int intel_context_pin(struct intel_context *ce)
@@ -144,4 +125,6 @@ static inline void intel_context_timeline_unlock(struct intel_context *ce)
 	mutex_unlock(&ce->ring->timeline->mutex);
 }
 
+struct i915_request *intel_context_create_request(struct intel_context *ce);
+
 #endif /* __INTEL_CONTEXT_H__ */

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

@@ -10,7 +10,6 @@
 #include <linux/kref.h>
 #include <linux/list.h>
 #include <linux/mutex.h>
-#include <linux/rbtree.h>
 #include <linux/types.h>
 
 #include "i915_active_types.h"
@@ -61,7 +60,6 @@ struct intel_context {
 	struct i915_active_request active_tracker;
 
 	const struct intel_context_ops *ops;
-	struct rb_node node;
 
 	/** sseu: Control eu/slice partitioning */
 	struct intel_sseu sseu;

drivers/gpu/drm/i915/gt/intel_engine_cs.c

@@ -732,7 +732,7 @@ static int pin_context(struct i915_gem_context *ctx,
 	struct intel_context *ce;
 	int err;
 
-	ce = intel_context_instance(ctx, engine);
+	ce = i915_gem_context_get_engine(ctx, engine->id);
 	if (IS_ERR(ce))
 		return PTR_ERR(ce);
 

drivers/gpu/drm/i915/gt/mock_engine.c

@@ -23,6 +23,7 @@
  */
 
 #include "i915_drv.h"
+#include "i915_gem_context.h"
 #include "intel_context.h"
 #include "intel_engine_pm.h"
 
@@ -286,7 +287,7 @@ int mock_engine_init(struct intel_engine_cs *engine)
 	i915_timeline_set_subclass(&engine->timeline, TIMELINE_ENGINE);
 
 	engine->kernel_context =
-		intel_context_instance(i915->kernel_context, engine);
+		i915_gem_context_get_engine(i915->kernel_context, engine->id);
 	if (IS_ERR(engine->kernel_context))
 		goto err_timeline;
 

drivers/gpu/drm/i915/gvt/scheduler.c

@@ -1183,7 +1183,7 @@ int intel_vgpu_setup_submission(struct intel_vgpu *vgpu)
 		INIT_LIST_HEAD(&s->workload_q_head[i]);
 		s->shadow[i] = ERR_PTR(-EINVAL);
 
-		ce = intel_context_instance(ctx, engine);
+		ce = i915_gem_context_get_engine(ctx, i);
 		if (IS_ERR(ce)) {
 			ret = PTR_ERR(ce);
 			goto out_shadow_ctx;

drivers/gpu/drm/i915/i915_gem.c

@@ -4289,8 +4289,9 @@ int i915_gem_init_hw(struct drm_i915_private *dev_priv)
 
 static int __intel_engines_record_defaults(struct drm_i915_private *i915)
 {
-	struct i915_gem_context *ctx;
 	struct intel_engine_cs *engine;
+	struct i915_gem_context *ctx;
+	struct i915_gem_engines *e;
 	enum intel_engine_id id;
 	int err = 0;
 
@@ -4307,18 +4308,21 @@ static int __intel_engines_record_defaults(struct drm_i915_private *i915)
 	if (IS_ERR(ctx))
 		return PTR_ERR(ctx);
 
+	e = i915_gem_context_lock_engines(ctx);
+
 	for_each_engine(engine, i915, id) {
+		struct intel_context *ce = e->engines[id];
 		struct i915_request *rq;
 
-		rq = i915_request_alloc(engine, ctx);
+		rq = intel_context_create_request(ce);
 		if (IS_ERR(rq)) {
 			err = PTR_ERR(rq);
-			goto out_ctx;
+			goto err_active;
 		}
 
 		err = 0;
-		if (engine->init_context)
-			err = engine->init_context(rq);
+		if (rq->engine->init_context)
+			err = rq->engine->init_context(rq);
 
 		i915_request_add(rq);
 		if (err)
@@ -4332,15 +4336,10 @@ static int __intel_engines_record_defaults(struct drm_i915_private *i915)
 	}
 
 	for_each_engine(engine, i915, id) {
-		struct intel_context *ce;
-		struct i915_vma *state;
+		struct intel_context *ce = e->engines[id];
+		struct i915_vma *state = ce->state;
 		void *vaddr;
 
-		ce = intel_context_lookup(ctx, engine);
-		if (!ce)
-			continue;
-
-		state = ce->state;
 		if (!state)
 			continue;
 
@@ -4396,6 +4395,7 @@ static int __intel_engines_record_defaults(struct drm_i915_private *i915)
 	}
 
 out_ctx:
+	i915_gem_context_unlock_engines(ctx);
 	i915_gem_context_set_closed(ctx);
 	i915_gem_context_put(ctx);
 	return err;

drivers/gpu/drm/i915/i915_gem_context.c

@@ -150,7 +150,7 @@ lookup_user_engine(struct i915_gem_context *ctx, u16 class, u16 instance)
 	if (!engine)
 		return ERR_PTR(-EINVAL);
 
-	return intel_context_instance(ctx, engine);
+	return i915_gem_context_get_engine(ctx, engine->id);
 }
 
 static inline int new_hw_id(struct drm_i915_private *i915, gfp_t gfp)
@@ -242,10 +242,51 @@ static void release_hw_id(struct i915_gem_context *ctx)
 	mutex_unlock(&i915->contexts.mutex);
 }
 
-static void i915_gem_context_free(struct i915_gem_context *ctx)
+static void __free_engines(struct i915_gem_engines *e, unsigned int count)
 {
-	struct intel_context *it, *n;
+	while (count--) {
+		if (!e->engines[count])
+			continue;
+
+		intel_context_put(e->engines[count]);
+	}
+	kfree(e);
+}
+
+static void free_engines(struct i915_gem_engines *e)
+{
+	__free_engines(e, e->num_engines);
+}
+
+static struct i915_gem_engines *default_engines(struct i915_gem_context *ctx)
+{
+	struct intel_engine_cs *engine;
+	struct i915_gem_engines *e;
+	enum intel_engine_id id;
+
+	e = kzalloc(struct_size(e, engines, I915_NUM_ENGINES), GFP_KERNEL);
+	if (!e)
+		return ERR_PTR(-ENOMEM);
+
+	e->i915 = ctx->i915;
+	for_each_engine(engine, ctx->i915, id) {
+		struct intel_context *ce;
+
+		ce = intel_context_create(ctx, engine);
+		if (IS_ERR(ce)) {
+			__free_engines(e, id);
+			return ERR_CAST(ce);
+		}
 
+		e->engines[id] = ce;
+	}
+	e->num_engines = id;
+
+	return e;
+}
+
+static void i915_gem_context_free(struct i915_gem_context *ctx)
+{
 	lockdep_assert_held(&ctx->i915->drm.struct_mutex);
 	GEM_BUG_ON(!i915_gem_context_is_closed(ctx));
 	GEM_BUG_ON(!list_empty(&ctx->active_engines));
@@ -253,8 +294,8 @@ static void i915_gem_context_free(struct i915_gem_context *ctx)
 	release_hw_id(ctx);
 	i915_ppgtt_put(ctx->ppgtt);
 
-	rbtree_postorder_for_each_entry_safe(it, n, &ctx->hw_contexts, node)
-		intel_context_put(it);
+	free_engines(rcu_access_pointer(ctx->engines));
+	mutex_destroy(&ctx->engines_mutex);
 
 	if (ctx->timeline)
 		i915_timeline_put(ctx->timeline);
@@ -363,6 +404,8 @@ static struct i915_gem_context *
 __create_context(struct drm_i915_private *dev_priv)
 {
 	struct i915_gem_context *ctx;
+	struct i915_gem_engines *e;
+	int err;
 	int i;
 
 	ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
@@ -376,8 +419,13 @@ __create_context(struct drm_i915_private *dev_priv)
 	INIT_LIST_HEAD(&ctx->active_engines);
 	mutex_init(&ctx->mutex);
 
-	ctx->hw_contexts = RB_ROOT;
-	spin_lock_init(&ctx->hw_contexts_lock);
+	mutex_init(&ctx->engines_mutex);
+	e = default_engines(ctx);
+	if (IS_ERR(e)) {
+		err = PTR_ERR(e);
+		goto err_free;
+	}
+	RCU_INIT_POINTER(ctx->engines, e);
 
 	INIT_RADIX_TREE(&ctx->handles_vma, GFP_KERNEL);
 	INIT_LIST_HEAD(&ctx->handles_list);
@@ -399,6 +447,10 @@ __create_context(struct drm_i915_private *dev_priv)
 		ctx->hang_timestamp[i] = jiffies - CONTEXT_FAST_HANG_JIFFIES;
 
 	return ctx;
+
+err_free:
+	kfree(ctx);
+	return ERR_PTR(err);
 }
 
 static struct i915_hw_ppgtt *
@@ -857,7 +909,8 @@ static int context_barrier_task(struct i915_gem_context *ctx,
 {
 	struct drm_i915_private *i915 = ctx->i915;
 	struct context_barrier_task *cb;
-	struct intel_context *ce, *next;
+	struct i915_gem_engines_iter it;
+	struct intel_context *ce;
 	int err = 0;
 
 	lockdep_assert_held(&i915->drm.struct_mutex);
@@ -870,20 +923,19 @@ static int context_barrier_task(struct i915_gem_context *ctx,
 	i915_active_init(i915, &cb->base, cb_retire);
 	i915_active_acquire(&cb->base);
 
-	rbtree_postorder_for_each_entry_safe(ce, next, &ctx->hw_contexts, node) {
-		struct intel_engine_cs *engine = ce->engine;
+	for_each_gem_engine(ce, i915_gem_context_lock_engines(ctx), it) {
 		struct i915_request *rq;
 
-		if (!(engine->mask & engines))
+		if (!(ce->engine->mask & engines))
 			continue;
 
 		if (I915_SELFTEST_ONLY(context_barrier_inject_fault &
-				       engine->mask)) {
+				       ce->engine->mask)) {
 			err = -ENXIO;
 			break;
 		}
 
-		rq = i915_request_alloc(engine, ctx);
+		rq = intel_context_create_request(ce);
 		if (IS_ERR(rq)) {
 			err = PTR_ERR(rq);
 			break;
@@ -899,6 +951,7 @@ static int context_barrier_task(struct i915_gem_context *ctx,
 		if (err)
 			break;
 	}
+	i915_gem_context_unlock_engines(ctx);
 
 	cb->task = err ? NULL : task; /* caller needs to unwind instead */
 	cb->data = data;
@@ -1729,6 +1782,23 @@ int __i915_gem_context_pin_hw_id(struct i915_gem_context *ctx)
 	return err;
 }
 
+/* GEM context-engines iterator: for_each_gem_engine() */
+struct intel_context *
+i915_gem_engines_iter_next(struct i915_gem_engines_iter *it)
+{
+	const struct i915_gem_engines *e = it->engines;
+	struct intel_context *ctx;
+
+	do {
+		if (it->idx >= e->num_engines)
+			return NULL;
+
+		ctx = e->engines[it->idx++];
+	} while (!ctx);
+
+	return ctx;
+}
+
 #if IS_ENABLED(CONFIG_DRM_I915_SELFTEST)
 #include "selftests/mock_context.c"
 #include "selftests/i915_gem_context.c"

drivers/gpu/drm/i915/i915_gem_context.h

@@ -176,6 +176,64 @@ static inline void i915_gem_context_put(struct i915_gem_context *ctx)
 	kref_put(&ctx->ref, i915_gem_context_release);
 }
 
+static inline struct i915_gem_engines *
+i915_gem_context_engines(struct i915_gem_context *ctx)
+{
+	return rcu_dereference_protected(ctx->engines,
+					 lockdep_is_held(&ctx->engines_mutex));
+}
+
+static inline struct i915_gem_engines *
+i915_gem_context_lock_engines(struct i915_gem_context *ctx)
+	__acquires(&ctx->engines_mutex)
+{
+	mutex_lock(&ctx->engines_mutex);
+	return i915_gem_context_engines(ctx);
+}
+
+static inline void
+i915_gem_context_unlock_engines(struct i915_gem_context *ctx)
+	__releases(&ctx->engines_mutex)
+{
+	mutex_unlock(&ctx->engines_mutex);
+}
+
+static inline struct intel_context *
+i915_gem_context_lookup_engine(struct i915_gem_context *ctx, unsigned int idx)
+{
+	return i915_gem_context_engines(ctx)->engines[idx];
+}
+
+static inline struct intel_context *
+i915_gem_context_get_engine(struct i915_gem_context *ctx, unsigned int idx)
+{
+	struct intel_context *ce = ERR_PTR(-EINVAL);
+
+	rcu_read_lock(); {
+		struct i915_gem_engines *e = rcu_dereference(ctx->engines);
+		if (likely(idx < e->num_engines && e->engines[idx]))
+			ce = intel_context_get(e->engines[idx]);
+	} rcu_read_unlock();
+
+	return ce;
+}
+
+static inline void
+i915_gem_engines_iter_init(struct i915_gem_engines_iter *it,
+			   struct i915_gem_engines *engines)
+{
+	GEM_BUG_ON(!engines);
+	it->engines = engines;
+	it->idx = 0;
+}
+
+struct intel_context *
+i915_gem_engines_iter_next(struct i915_gem_engines_iter *it);
+
+#define for_each_gem_engine(ce, engines, it) \
+	for (i915_gem_engines_iter_init(&(it), (engines)); \
+	     ((ce) = i915_gem_engines_iter_next(&(it)));)
+
 struct i915_lut_handle *i915_lut_handle_alloc(void);
 void i915_lut_handle_free(struct i915_lut_handle *lut);
 

drivers/gpu/drm/i915/i915_gem_context_types.h

@@ -29,6 +29,18 @@ struct i915_hw_ppgtt;
 struct i915_timeline;
 struct intel_ring;
 
+struct i915_gem_engines {
+	struct rcu_work rcu;
+	struct drm_i915_private *i915;
+	unsigned int num_engines;
+	struct intel_context *engines[];
+};
+
+struct i915_gem_engines_iter {
+	unsigned int idx;
+	const struct i915_gem_engines *engines;
+};
+
 /**
  * struct i915_gem_context - client state
  *
@@ -42,6 +54,30 @@ struct i915_gem_context {
 	/** file_priv: owning file descriptor */
 	struct drm_i915_file_private *file_priv;
 
+	/**
+	 * @engines: User defined engines for this context
+	 *
+	 * Various uAPI offer the ability to lookup up an
+	 * index from this array to select an engine operate on.
+	 *
+	 * Multiple logically distinct instances of the same engine
+	 * may be defined in the array, as well as composite virtual
+	 * engines.
+	 *
+	 * Execbuf uses the I915_EXEC_RING_MASK as an index into this
+	 * array to select which HW context + engine to execute on. For
+	 * the default array, the user_ring_map[] is used to translate
+	 * the legacy uABI onto the approprate index (e.g. both
+	 * I915_EXEC_DEFAULT and I915_EXEC_RENDER select the same
+	 * context, and I915_EXEC_BSD is weird). For a use defined
+	 * array, execbuf uses I915_EXEC_RING_MASK as a plain index.
+	 *
+	 * User defined by I915_CONTEXT_PARAM_ENGINE (when the
+	 * CONTEXT_USER_ENGINES flag is set).
+	 */
+	struct i915_gem_engines __rcu *engines;
+	struct mutex engines_mutex; /* guards writes to engines */
+
 	struct i915_timeline *timeline;
 
 	/**
@@ -134,10 +170,6 @@ struct i915_gem_context {
 
 	struct i915_sched_attr sched;
 
-	/** hw_contexts: per-engine logical HW state */
-	struct rb_root hw_contexts;
-	spinlock_t hw_contexts_lock;
-
 	/** ring_size: size for allocating the per-engine ring buffer */
 	u32 ring_size;
 	/** desc_template: invariant fields for the HW context descriptor */

drivers/gpu/drm/i915/i915_gem_execbuffer.c

@@ -2076,9 +2076,7 @@ gen8_dispatch_bsd_engine(struct drm_i915_private *dev_priv,
 	return file_priv->bsd_engine;
 }
 
-#define I915_USER_RINGS (4)
-
-static const enum intel_engine_id user_ring_map[I915_USER_RINGS + 1] = {
+static const enum intel_engine_id user_ring_map[] = {
 	[I915_EXEC_DEFAULT]	= RCS0,
 	[I915_EXEC_RENDER]	= RCS0,
 	[I915_EXEC_BLT]		= BCS0,
@@ -2086,10 +2084,8 @@ static const enum intel_engine_id user_ring_map[I915_USER_RINGS + 1] = {
 	[I915_EXEC_VEBOX]	= VECS0
 };
 
-static int eb_pin_context(struct i915_execbuffer *eb,
-			  struct intel_engine_cs *engine)
+static int eb_pin_context(struct i915_execbuffer *eb, struct intel_context *ce)
 {
-	struct intel_context *ce;
 	int err;
 
 	/*
@@ -2100,21 +2096,16 @@ static int eb_pin_context(struct i915_execbuffer *eb,
 	if (err)
 		return err;
 
-	ce = intel_context_instance(eb->gem_context, engine);
-	if (IS_ERR(ce))
-		return PTR_ERR(ce);
-
 	/*
 	 * Pinning the contexts may generate requests in order to acquire
 	 * GGTT space, so do this first before we reserve a seqno for
 	 * ourselves.
 	 */
 	err = intel_context_pin(ce);
-	intel_context_put(ce);
 	if (err)
 		return err;
 
-	eb->engine = engine;
+	eb->engine = ce->engine;
 	eb->context = ce;
 	return 0;
 }
@@ -2124,25 +2115,19 @@ static void eb_unpin_context(struct i915_execbuffer *eb)
 	intel_context_unpin(eb->context);
 }
 
-static int
-eb_select_engine(struct i915_execbuffer *eb,
-		 struct drm_file *file,
-		 struct drm_i915_gem_execbuffer2 *args)
+static unsigned int
+eb_select_legacy_ring(struct i915_execbuffer *eb,
+		      struct drm_file *file,
+		      struct drm_i915_gem_execbuffer2 *args)
 {
 	struct drm_i915_private *i915 = eb->i915;
 	unsigned int user_ring_id = args->flags & I915_EXEC_RING_MASK;
-	struct intel_engine_cs *engine;
-
-	if (user_ring_id > I915_USER_RINGS) {
-		DRM_DEBUG("execbuf with unknown ring: %u\n", user_ring_id);
-		return -EINVAL;
-	}
 
-	if ((user_ring_id != I915_EXEC_BSD) &&
-	    ((args->flags & I915_EXEC_BSD_MASK) != 0)) {
+	if (user_ring_id != I915_EXEC_BSD &&
+	    (args->flags & I915_EXEC_BSD_MASK)) {
 		DRM_DEBUG("execbuf with non bsd ring but with invalid "
 			  "bsd dispatch flags: %d\n", (int)(args->flags));
-		return -EINVAL;
+		return -1;
 	}
 
 	if (user_ring_id == I915_EXEC_BSD && HAS_ENGINE(i915, VCS1)) {
@@ -2157,20 +2142,39 @@ eb_select_engine(struct i915_execbuffer *eb,
 		} else {
 			DRM_DEBUG("execbuf with unknown bsd ring: %u\n",
 				  bsd_idx);
-			return -EINVAL;
+			return -1;
 		}
 
-		engine = i915->engine[_VCS(bsd_idx)];
-	} else {
-		engine = i915->engine[user_ring_map[user_ring_id]];
+		return _VCS(bsd_idx);
 	}
 
-	if (!engine) {
-		DRM_DEBUG("execbuf with invalid ring: %u\n", user_ring_id);
-		return -EINVAL;
+	if (user_ring_id >= ARRAY_SIZE(user_ring_map)) {
+		DRM_DEBUG("execbuf with unknown ring: %u\n", user_ring_id);
+		return -1;
 	}
 
-	return eb_pin_context(eb, engine);
+	return user_ring_map[user_ring_id];
+}
+
+static int
+eb_select_engine(struct i915_execbuffer *eb,
+		 struct drm_file *file,
+		 struct drm_i915_gem_execbuffer2 *args)
+{
+	struct intel_context *ce;
+	unsigned int idx;
+	int err;
+
+	idx = eb_select_legacy_ring(eb, file, args);
+
+	ce = i915_gem_context_get_engine(eb->gem_context, idx);
+	if (IS_ERR(ce))
+		return PTR_ERR(ce);
+
+	err = eb_pin_context(eb, ce);
+	intel_context_put(ce);
+
+	return err;
 }
 
 static void

drivers/gpu/drm/i915/i915_perf.c

@@ -1203,35 +1203,35 @@ static int i915_oa_read(struct i915_perf_stream *stream,
 static struct intel_context *oa_pin_context(struct drm_i915_private *i915,
 					    struct i915_gem_context *ctx)
 {
-	struct intel_engine_cs *engine = i915->engine[RCS0];
+	struct i915_gem_engines_iter it;
 	struct intel_context *ce;
 	int err;
 
-	ce = intel_context_instance(ctx, engine);
-	if (IS_ERR(ce))
-		return ce;
-
 	err = i915_mutex_lock_interruptible(&i915->drm);
-	if (err) {
-		intel_context_put(ce);
+	if (err)
 		return ERR_PTR(err);
+
+	for_each_gem_engine(ce, i915_gem_context_lock_engines(ctx), it) {
+		if (ce->engine->class != RENDER_CLASS)
+			continue;
+
+		/*
+		 * As the ID is the gtt offset of the context's vma we
+		 * pin the vma to ensure the ID remains fixed.
+		 */
+		err = intel_context_pin(ce);
+		if (err == 0) {
+			i915->perf.oa.pinned_ctx = ce;
+			break;
+		}
 	}
+	i915_gem_context_unlock_engines(ctx);
 
-	/*
-	 * As the ID is the gtt offset of the context's vma we
-	 * pin the vma to ensure the ID remains fixed.
-	 *
-	 * NB: implied RCS engine...
-	 */
-	err = intel_context_pin(ce);
 	mutex_unlock(&i915->drm.struct_mutex);
-	intel_context_put(ce);
 	if (err)
 		return ERR_PTR(err);
 
-	i915->perf.oa.pinned_ctx = ce;
-
-	return ce;
+	return i915->perf.oa.pinned_ctx;
 }
 
 /**
@@ -1717,7 +1717,6 @@ gen8_update_reg_state_unlocked(struct intel_context *ce,
 static int gen8_configure_all_contexts(struct drm_i915_private *dev_priv,
 				       const struct i915_oa_config *oa_config)
 {
-	struct intel_engine_cs *engine = dev_priv->engine[RCS0];
 	unsigned int map_type = i915_coherent_map_type(dev_priv);
 	struct i915_gem_context *ctx;
 	struct i915_request *rq;
@@ -1746,30 +1745,43 @@ static int gen8_configure_all_contexts(struct drm_i915_private *dev_priv,
 
 	/* Update all contexts now that we've stalled the submission. */
 	list_for_each_entry(ctx, &dev_priv->contexts.list, link) {
-		struct intel_context *ce = intel_context_lookup(ctx, engine);
-		u32 *regs;
-
-		/* OA settings will be set upon first use */
-		if (!ce || !ce->state)
-			continue;
-
-		regs = i915_gem_object_pin_map(ce->state->obj, map_type);
-		if (IS_ERR(regs))
-			return PTR_ERR(regs);
+		struct i915_gem_engines_iter it;
+		struct intel_context *ce;
+
+		for_each_gem_engine(ce,
+				    i915_gem_context_lock_engines(ctx),
+				    it) {
+			u32 *regs;
+
+			if (ce->engine->class != RENDER_CLASS)
+				continue;
+
+			/* OA settings will be set upon first use */
+			if (!ce->state)
+				continue;
+
+			regs = i915_gem_object_pin_map(ce->state->obj,
+						       map_type);
+			if (IS_ERR(regs)) {
+				i915_gem_context_unlock_engines(ctx);
+				return PTR_ERR(regs);
+			}
 
-		ce->state->obj->mm.dirty = true;
-		regs += LRC_STATE_PN * PAGE_SIZE / sizeof(*regs);
+			ce->state->obj->mm.dirty = true;
+			regs += LRC_STATE_PN * PAGE_SIZE / sizeof(*regs);
 
-		gen8_update_reg_state_unlocked(ce, regs, oa_config);
+			gen8_update_reg_state_unlocked(ce, regs, oa_config);
 
-		i915_gem_object_unpin_map(ce->state->obj);
+			i915_gem_object_unpin_map(ce->state->obj);
+		}
+		i915_gem_context_unlock_engines(ctx);
 	}
 
 	/*
 	 * Apply the configuration by doing one context restore of the edited
 	 * context image.
 	 */
-	rq = i915_request_create(engine->kernel_context);
+	rq = i915_request_create(dev_priv->engine[RCS0]->kernel_context);
 	if (IS_ERR(rq))
 		return PTR_ERR(rq);
 

drivers/gpu/drm/i915/i915_request.c

@@ -785,7 +785,6 @@ i915_request_alloc(struct intel_engine_cs *engine, struct i915_gem_context *ctx)
 	struct drm_i915_private *i915 = engine->i915;
 	struct intel_context *ce;
 	struct i915_request *rq;
-	int err;
 
 	/*
 	 * Preempt contexts are reserved for exclusive use to inject a
@@ -799,21 +798,13 @@ i915_request_alloc(struct intel_engine_cs *engine, struct i915_gem_context *ctx)
 	 * GGTT space, so do this first before we reserve a seqno for
 	 * ourselves.
 	 */
-	ce = intel_context_instance(ctx, engine);
+	ce = i915_gem_context_get_engine(ctx, engine->id);
 	if (IS_ERR(ce))
 		return ERR_CAST(ce);
 
-	err = intel_context_pin(ce);
-	if (err) {
-		rq = ERR_PTR(err);
-		goto err_put;
-	}
-
-	rq = i915_request_create(ce);
-	intel_context_unpin(ce);
-
-err_put:
+	rq = intel_context_create_request(ce);
 	intel_context_put(ce);
+
 	return rq;
 }
 

drivers/gpu/drm/i915/intel_guc_submission.c

@@ -364,11 +364,10 @@ static void guc_stage_desc_pool_destroy(struct intel_guc *guc)
 static void guc_stage_desc_init(struct intel_guc_client *client)
 {
 	struct intel_guc *guc = client->guc;
-	struct drm_i915_private *dev_priv = guc_to_i915(guc);
-	struct intel_engine_cs *engine;
 	struct i915_gem_context *ctx = client->owner;
+	struct i915_gem_engines_iter it;
 	struct guc_stage_desc *desc;
-	unsigned int tmp;
+	struct intel_context *ce;
 	u32 gfx_addr;
 
 	desc = __get_stage_desc(client);
@@ -382,10 +381,11 @@ static void guc_stage_desc_init(struct intel_guc_client *client)
 	desc->priority = client->priority;
 	desc->db_id = client->doorbell_id;
 
-	for_each_engine_masked(engine, dev_priv, client->engines, tmp) {
-		struct intel_context *ce = intel_context_lookup(ctx, engine);
-		u32 guc_engine_id = engine->guc_id;
-		struct guc_execlist_context *lrc = &desc->lrc[guc_engine_id];
+	for_each_gem_engine(ce, i915_gem_context_lock_engines(ctx), it) {
+		struct guc_execlist_context *lrc;
+
+		if (!(ce->engine->mask & client->engines))
+			continue;
 
 		/* TODO: We have a design issue to be solved here. Only when we
 		 * receive the first batch, we know which engine is used by the
@@ -394,7 +394,7 @@ static void guc_stage_desc_init(struct intel_guc_client *client)
 		 * for now who owns a GuC client. But for future owner of GuC
 		 * client, need to make sure lrc is pinned prior to enter here.
 		 */
-		if (!ce || !ce->state)
+		if (!ce->state)
 			break;	/* XXX: continue? */
 
 		/*
@@ -404,6 +404,7 @@ static void guc_stage_desc_init(struct intel_guc_client *client)
 		 * Instead, the GuC uses the LRCA of the user mode context (see
 		 * guc_add_request below).
 		 */
+		lrc = &desc->lrc[ce->engine->guc_id];
 		lrc->context_desc = lower_32_bits(ce->lrc_desc);
 
 		/* The state page is after PPHWSP */
@@ -414,15 +415,16 @@ static void guc_stage_desc_init(struct intel_guc_client *client)
 		 * here. In proxy submission, it wants the stage id
 		 */
 		lrc->context_id = (client->stage_id << GUC_ELC_CTXID_OFFSET) |
-				(guc_engine_id << GUC_ELC_ENGINE_OFFSET);
+				(ce->engine->guc_id << GUC_ELC_ENGINE_OFFSET);
 
 		lrc->ring_begin = intel_guc_ggtt_offset(guc, ce->ring->vma);
 		lrc->ring_end = lrc->ring_begin + ce->ring->size - 1;
 		lrc->ring_next_free_location = lrc->ring_begin;
 		lrc->ring_current_tail_pointer_value = 0;
 
-		desc->engines_used |= (1 << guc_engine_id);
+		desc->engines_used |= BIT(ce->engine->guc_id);
 	}
+	i915_gem_context_unlock_engines(ctx);
 
 	DRM_DEBUG_DRIVER("Host engines 0x%x => GuC engines used 0x%x\n",
 			 client->engines, desc->engines_used);

drivers/gpu/drm/i915/selftests/i915_gem_context.c

@@ -1094,7 +1094,7 @@ __igt_ctx_sseu(struct drm_i915_private *i915,
 
 	wakeref = intel_runtime_pm_get(i915);
 
-	ce = intel_context_instance(ctx, i915->engine[RCS0]);
+	ce = i915_gem_context_get_engine(ctx, RCS0);
 	if (IS_ERR(ce)) {
 		ret = PTR_ERR(ce);
 		goto out_rpm;

drivers/gpu/drm/i915/selftests/mock_context.c

@@ -30,6 +30,7 @@ mock_context(struct drm_i915_private *i915,
 	     const char *name)
 {
 	struct i915_gem_context *ctx;
+	struct i915_gem_engines *e;
 	int ret;
 
 	ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
@@ -40,8 +41,11 @@ mock_context(struct drm_i915_private *i915,
 	INIT_LIST_HEAD(&ctx->link);
 	ctx->i915 = i915;
 
-	ctx->hw_contexts = RB_ROOT;
-	spin_lock_init(&ctx->hw_contexts_lock);
+	mutex_init(&ctx->engines_mutex);
+	e = default_engines(ctx);
+	if (IS_ERR(e))
+		goto err_free;
+	RCU_INIT_POINTER(ctx->engines, e);
 
 	INIT_RADIX_TREE(&ctx->handles_vma, GFP_KERNEL);
 	INIT_LIST_HEAD(&ctx->handles_list);
@@ -51,7 +55,7 @@ mock_context(struct drm_i915_private *i915,
 
 	ret = i915_gem_context_pin_hw_id(ctx);
 	if (ret < 0)
-		goto err_handles;
+		goto err_engines;
 
 	if (name) {
 		struct i915_hw_ppgtt *ppgtt;
@@ -69,7 +73,9 @@ mock_context(struct drm_i915_private *i915,
 
 	return ctx;
 
-err_handles:
+err_engines:
+	free_engines(rcu_access_pointer(ctx->engines));
+err_free:
 	kfree(ctx);
 	return NULL;