drm/i915: Track active engines within a context

For use in the next patch, if we track which engines have been used by
the HW, we can reduce the work required to flush our state off the HW to
those engines.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190308132522.21573-1-chris@chris-wilson.co.uk

drivers/gpu/drm/i915/i915_debugfs.c

@@ -388,12 +388,9 @@ static void print_context_stats(struct seq_file *m,
 	struct i915_gem_context *ctx;
 
 	list_for_each_entry(ctx, &i915->contexts.list, link) {
-		struct intel_engine_cs *engine;
-		enum intel_engine_id id;
-
-		for_each_engine(engine, i915, id) {
-			struct intel_context *ce = to_intel_context(ctx, engine);
+		struct intel_context *ce;
 
+		list_for_each_entry(ce, &ctx->active_engines, active_link) {
 			if (ce->state)
 				per_file_stats(0, ce->state->obj, &kstats);
 			if (ce->ring)
@@ -1880,9 +1877,7 @@ static int i915_context_status(struct seq_file *m, void *unused)
 {
 	struct drm_i915_private *dev_priv = node_to_i915(m->private);
 	struct drm_device *dev = &dev_priv->drm;
-	struct intel_engine_cs *engine;
 	struct i915_gem_context *ctx;
-	enum intel_engine_id id;
 	int ret;
 
 	ret = mutex_lock_interruptible(&dev->struct_mutex);
@@ -1890,6 +1885,8 @@ static int i915_context_status(struct seq_file *m, void *unused)
 		return ret;
 
 	list_for_each_entry(ctx, &dev_priv->contexts.list, link) {
+		struct intel_context *ce;
+
 		seq_puts(m, "HW context ");
 		if (!list_empty(&ctx->hw_id_link))
 			seq_printf(m, "%x [pin %u]", ctx->hw_id,
@@ -1912,11 +1909,8 @@ static int i915_context_status(struct seq_file *m, void *unused)
 		seq_putc(m, ctx->remap_slice ? 'R' : 'r');
 		seq_putc(m, '\n');
 
-		for_each_engine(engine, dev_priv, id) {
-			struct intel_context *ce =
-				to_intel_context(ctx, engine);
-
-			seq_printf(m, "%s: ", engine->name);
+		list_for_each_entry(ce, &ctx->active_engines, active_link) {
+			seq_printf(m, "%s: ", ce->engine->name);
 			if (ce->state)
 				describe_obj(m, ce->state->obj);
 			if (ce->ring)

drivers/gpu/drm/i915/i915_gem_context.c

@@ -226,6 +226,7 @@ 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));
 
 	release_hw_id(ctx);
 	i915_ppgtt_put(ctx->ppgtt);
@@ -241,6 +242,7 @@ static void i915_gem_context_free(struct i915_gem_context *ctx)
 	put_pid(ctx->pid);
 
 	list_del(&ctx->link);
+	mutex_destroy(&ctx->mutex);
 
 	kfree_rcu(ctx, rcu);
 }
@@ -353,6 +355,7 @@ intel_context_init(struct intel_context *ce,
 		   struct intel_engine_cs *engine)
 {
 	ce->gem_context = ctx;
+	ce->engine = engine;
 
 	INIT_LIST_HEAD(&ce->signal_link);
 	INIT_LIST_HEAD(&ce->signals);
@@ -381,6 +384,8 @@ __create_hw_context(struct drm_i915_private *dev_priv,
 	list_add_tail(&ctx->link, &dev_priv->contexts.list);
 	ctx->i915 = dev_priv;
 	ctx->sched.priority = I915_USER_PRIORITY(I915_PRIORITY_NORMAL);
+	INIT_LIST_HEAD(&ctx->active_engines);
+	mutex_init(&ctx->mutex);
 
 	for (n = 0; n < ARRAY_SIZE(ctx->__engine); n++)
 		intel_context_init(&ctx->__engine[n], ctx, dev_priv->engine[n]);

drivers/gpu/drm/i915/i915_gem_context.h

@@ -163,6 +163,9 @@ struct i915_gem_context {
 	atomic_t hw_id_pin_count;
 	struct list_head hw_id_link;
 
+	struct list_head active_engines;
+	struct mutex mutex;
+
 	/**
 	 * @user_handle: userspace identifier
 	 *
@@ -176,7 +179,9 @@ struct i915_gem_context {
 	/** engine: per-engine logical HW state */
 	struct intel_context {
 		struct i915_gem_context *gem_context;
+		struct intel_engine_cs *engine;
 		struct intel_engine_cs *active;
+		struct list_head active_link;
 		struct list_head signal_link;
 		struct list_head signals;
 		struct i915_vma *state;

drivers/gpu/drm/i915/intel_lrc.c

@@ -1282,6 +1282,7 @@ static void execlists_context_unpin(struct intel_context *ce)
 	i915_gem_object_unpin_map(ce->state->obj);
 	i915_vma_unpin(ce->state);
 
+	list_del(&ce->active_link);
 	i915_gem_context_put(ce->gem_context);
 }
 
@@ -1366,6 +1367,11 @@ __execlists_context_pin(struct intel_engine_cs *engine,
 	__execlists_update_reg_state(engine, ce);
 
 	ce->state->obj->pin_global++;
+
+	mutex_lock(&ctx->mutex);
+	list_add(&ce->active_link, &ctx->active_engines);
+	mutex_unlock(&ctx->mutex);
+
 	i915_gem_context_get(ctx);
 	return ce;
 
@@ -2887,9 +2893,8 @@ static int execlists_context_deferred_alloc(struct i915_gem_context *ctx,
 
 void intel_lr_context_resume(struct drm_i915_private *i915)
 {
-	struct intel_engine_cs *engine;
 	struct i915_gem_context *ctx;
-	enum intel_engine_id id;
+	struct intel_context *ce;
 
 	/*
 	 * Because we emit WA_TAIL_DWORDS there may be a disparity
@@ -2903,17 +2908,10 @@ void intel_lr_context_resume(struct drm_i915_private *i915)
 	 * simplicity, we just zero everything out.
 	 */
 	list_for_each_entry(ctx, &i915->contexts.list, link) {
-		for_each_engine(engine, i915, id) {
-			struct intel_context *ce =
-				to_intel_context(ctx, engine);
-
-			if (!ce->state)
-				continue;
-
+		list_for_each_entry(ce, &ctx->active_engines, active_link) {
+			GEM_BUG_ON(!ce->ring);
 			intel_ring_reset(ce->ring, 0);
-
-			if (ce->pin_count) /* otherwise done in context_pin */
-				__execlists_update_reg_state(engine, ce);
+			__execlists_update_reg_state(ce->engine, ce);
 		}
 	}
 }

drivers/gpu/drm/i915/intel_ringbuffer.c

@@ -1431,6 +1431,7 @@ static void intel_ring_context_unpin(struct intel_context *ce)
 	__context_unpin_ppgtt(ce->gem_context);
 	__context_unpin(ce);
 
+	list_del(&ce->active_link);
 	i915_gem_context_put(ce->gem_context);
 }
 
@@ -1510,6 +1511,10 @@ __ring_context_pin(struct intel_engine_cs *engine,
 {
 	int err;
 
+	/* One ringbuffer to rule them all */
+	GEM_BUG_ON(!engine->buffer);
+	ce->ring = engine->buffer;
+
 	if (!ce->state && engine->context_size) {
 		struct i915_vma *vma;
 
@@ -1530,12 +1535,11 @@ __ring_context_pin(struct intel_engine_cs *engine,
 	if (err)
 		goto err_unpin;
 
-	i915_gem_context_get(ctx);
-
-	/* One ringbuffer to rule them all */
-	GEM_BUG_ON(!engine->buffer);
-	ce->ring = engine->buffer;
+	mutex_lock(&ctx->mutex);
+	list_add(&ce->active_link, &ctx->active_engines);
+	mutex_unlock(&ctx->mutex);
 
+	i915_gem_context_get(ctx);
 	return ce;
 
 err_unpin:

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

@@ -44,6 +44,8 @@ mock_context(struct drm_i915_private *i915,
 	INIT_RADIX_TREE(&ctx->handles_vma, GFP_KERNEL);
 	INIT_LIST_HEAD(&ctx->handles_list);
 	INIT_LIST_HEAD(&ctx->hw_id_link);
+	INIT_LIST_HEAD(&ctx->active_engines);
+	mutex_init(&ctx->mutex);
 
 	for (n = 0; n < ARRAY_SIZE(ctx->__engine); n++)
 		intel_context_init(&ctx->__engine[n], ctx, i915->engine[n]);

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

@@ -125,6 +125,7 @@ static void hw_delay_complete(struct timer_list *t)
 static void mock_context_unpin(struct intel_context *ce)
 {
 	mock_timeline_unpin(ce->ring->timeline);
+	list_del(&ce->active_link);
 	i915_gem_context_put(ce->gem_context);
 }
 
@@ -160,6 +161,11 @@ mock_context_pin(struct intel_engine_cs *engine,
 	mock_timeline_pin(ce->ring->timeline);
 
 	ce->ops = &mock_context_ops;
+
+	mutex_lock(&ctx->mutex);
+	list_add(&ce->active_link, &ctx->active_engines);
+	mutex_unlock(&ctx->mutex);
+
 	i915_gem_context_get(ctx);
 	return ce;