[PATCH v4 18/25] drm/i915: Refactor execlists default context pinning

[Chris Wilson <chris@chris-wilson.co.uk>]

Refactor pinning and unpinning of contexts, such that the default
context for an engine is pinned during initialisation and unpinned
during teardown (pinning of the context handles the reference counting).
Thus we can eliminate the special case handling of the default context
that was required to mask that it was not being pinned normally.

v2: Rebalance context_queue after rebasing.
v3: Rebase to -nightly (not 40 patches in)

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
Reviewed-by: Mika Kuoppala <mika.kuoppala@intel.com>
---
 drivers/gpu/drm/i915/i915_debugfs.c |   5 +-
 drivers/gpu/drm/i915/i915_gem.c     |   2 +-
 drivers/gpu/drm/i915/intel_lrc.c    | 107 ++++++++++++++----------------------
 3 files changed, 43 insertions(+), 71 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
index be2a4a0fae13..5bc9789e1f1e 100644
--- a/drivers/gpu/drm/i915/i915_debugfs.c
+++ b/drivers/gpu/drm/i915/i915_debugfs.c
@@ -2095,9 +2095,8 @@ static int i915_dump_lrc(struct seq_file *m, void *unused)
 		return ret;
 
 	list_for_each_entry(ctx, &dev_priv->context_list, link)
-		if (ctx != dev_priv->kernel_context)
-			for_each_engine(engine, dev_priv)
-				i915_dump_lrc_obj(m, ctx, engine);
+		for_each_engine(engine, dev_priv)
+			i915_dump_lrc_obj(m, ctx, engine);
 
 	mutex_unlock(&dev->struct_mutex);
 
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index d7ff5e79182f..df9d43397492 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -2719,7 +2719,7 @@ void i915_gem_request_free(struct kref *req_ref)
 		i915_gem_request_remove_from_client(req);
 
 	if (ctx) {
-		if (i915.enable_execlists && ctx != req->i915->kernel_context)
+		if (i915.enable_execlists)
 			intel_lr_context_unpin(ctx, req->engine);
 
 		i915_gem_context_unreference(ctx);
diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
index b621b1addd42..93b2d1317433 100644
--- a/drivers/gpu/drm/i915/intel_lrc.c
+++ b/drivers/gpu/drm/i915/intel_lrc.c
@@ -588,9 +588,7 @@ static void execlists_context_queue(struct drm_i915_gem_request *request)
 	struct drm_i915_gem_request *cursor;
 	int num_elements = 0;
 
-	if (request->ctx != request->i915->kernel_context)
-		intel_lr_context_pin(request->ctx, engine);
-
+	intel_lr_context_pin(request->ctx, request->engine);
 	i915_gem_request_reference(request);
 
 	spin_lock_bh(&engine->execlist_lock);
@@ -699,10 +697,7 @@ int intel_logical_ring_alloc_request_extras(struct drm_i915_gem_request *request
 			return ret;
 	}
 
-	if (request->ctx != request->i915->kernel_context)
-		ret = intel_lr_context_pin(request->ctx, request->engine);
-
-	return ret;
+	return intel_lr_context_pin(request->ctx, request->engine);
 }
 
 /*
@@ -740,12 +735,8 @@ intel_logical_ring_advance_and_submit(struct drm_i915_gem_request *request)
 	if (engine->last_context != request->ctx) {
 		if (engine->last_context)
 			intel_lr_context_unpin(engine->last_context, engine);
-		if (request->ctx != request->i915->kernel_context) {
-			intel_lr_context_pin(request->ctx, engine);
-			engine->last_context = request->ctx;
-		} else {
-			engine->last_context = NULL;
-		}
+		intel_lr_context_pin(request->ctx, engine);
+		engine->last_context = request->ctx;
 	}
 
 	if (dev_priv->guc.execbuf_client)
@@ -865,12 +856,7 @@ void intel_execlists_retire_requests(struct intel_engine_cs *engine)
 	spin_unlock_bh(&engine->execlist_lock);
 
 	list_for_each_entry_safe(req, tmp, &retired_list, execlist_link) {
-		struct intel_context *ctx = req->ctx;
-		struct drm_i915_gem_object *ctx_obj =
-				ctx->engine[engine->id].state;
-
-		if (ctx_obj && (ctx != req->i915->kernel_context))
-			intel_lr_context_unpin(ctx, engine);
+		intel_lr_context_unpin(req->ctx, engine);
 
 		list_del(&req->execlist_link);
 		i915_gem_request_unreference(req);
@@ -915,23 +901,26 @@ int logical_ring_flush_all_caches(struct drm_i915_gem_request *req)
 	return 0;
 }
 
-static int intel_lr_context_do_pin(struct intel_context *ctx,
-				   struct intel_engine_cs *engine)
+static int intel_lr_context_pin(struct intel_context *ctx,
+				struct intel_engine_cs *engine)
 {
-	struct drm_device *dev = engine->dev;
-	struct drm_i915_private *dev_priv = dev->dev_private;
-	struct drm_i915_gem_object *ctx_obj = ctx->engine[engine->id].state;
-	struct intel_ringbuffer *ringbuf = ctx->engine[engine->id].ringbuf;
+	struct drm_i915_private *dev_priv = ctx->i915;
+	struct drm_i915_gem_object *ctx_obj;
+	struct intel_ringbuffer *ringbuf;
 	void *vaddr;
 	u32 *lrc_reg_state;
 	int ret;
 
-	WARN_ON(!mutex_is_locked(&engine->dev->struct_mutex));
+	lockdep_assert_held(&ctx->i915->dev->struct_mutex);
 
+	if (ctx->engine[engine->id].pin_count++)
+		return 0;
+
+	ctx_obj = ctx->engine[engine->id].state;
 	ret = i915_gem_obj_ggtt_pin(ctx_obj, GEN8_LR_CONTEXT_ALIGN,
 			PIN_OFFSET_BIAS | GUC_WOPCM_TOP);
 	if (ret)
-		return ret;
+		goto err;
 
 	vaddr = i915_gem_object_pin_map(ctx_obj);
 	if (IS_ERR(vaddr)) {
@@ -941,10 +930,12 @@ static int intel_lr_context_do_pin(struct intel_context *ctx,
 
 	lrc_reg_state = vaddr + LRC_STATE_PN * PAGE_SIZE;
 
+	ringbuf = ctx->engine[engine->id].ringbuf;
 	ret = intel_pin_and_map_ringbuffer_obj(engine->dev, ringbuf);
 	if (ret)
 		goto unpin_map;
 
+	i915_gem_context_reference(ctx);
 	ctx->engine[engine->id].lrc_vma = i915_gem_obj_to_ggtt(ctx_obj);
 	intel_lr_context_descriptor_update(ctx, engine);
 	lrc_reg_state[CTX_RING_BUFFER_START+1] = ringbuf->vma->node.start;
@@ -955,51 +946,39 @@ static int intel_lr_context_do_pin(struct intel_context *ctx,
 	if (i915.enable_guc_submission)
 		I915_WRITE(GEN8_GTCR, GEN8_GTCR_INVALIDATE);
 
-	return ret;
+	return 0;
 
 unpin_map:
 	i915_gem_object_unpin_map(ctx_obj);
 unpin_ctx_obj:
 	i915_gem_object_ggtt_unpin(ctx_obj);
-
+err:
+	ctx->engine[engine->id].pin_count = 0;
 	return ret;
 }
 
-static int intel_lr_context_pin(struct intel_context *ctx,
-				struct intel_engine_cs *engine)
+void intel_lr_context_unpin(struct intel_context *ctx,
+			    struct intel_engine_cs *engine)
 {
-	int ret = 0;
+	struct drm_i915_gem_object *ctx_obj;
 
-	if (ctx->engine[engine->id].pin_count++ == 0) {
-		ret = intel_lr_context_do_pin(ctx, engine);
-		if (ret)
-			goto reset_pin_count;
+	lockdep_assert_held(&ctx->i915->dev->struct_mutex);
+	GEM_BUG_ON(ctx->engine[engine->id].pin_count == 0);
 
-		i915_gem_context_reference(ctx);
-	}
-	return ret;
+	if (--ctx->engine[engine->id].pin_count)
+		return;
 
-reset_pin_count:
-	ctx->engine[engine->id].pin_count = 0;
-	return ret;
-}
+	intel_unpin_ringbuffer_obj(ctx->engine[engine->id].ringbuf);
 
-void intel_lr_context_unpin(struct intel_context *ctx,
-			    struct intel_engine_cs *engine)
-{
-	struct drm_i915_gem_object *ctx_obj = ctx->engine[engine->id].state;
+	ctx_obj = ctx->engine[engine->id].state;
+	i915_gem_object_unpin_map(ctx_obj);
+	i915_gem_object_ggtt_unpin(ctx_obj);
 
-	WARN_ON(!mutex_is_locked(&ctx->i915->dev->struct_mutex));
-	if (--ctx->engine[engine->id].pin_count == 0) {
-		i915_gem_object_unpin_map(ctx_obj);
-		intel_unpin_ringbuffer_obj(ctx->engine[engine->id].ringbuf);
-		i915_gem_object_ggtt_unpin(ctx_obj);
-		ctx->engine[engine->id].lrc_vma = NULL;
-		ctx->engine[engine->id].lrc_desc = 0;
-		ctx->engine[engine->id].lrc_reg_state = NULL;
+	ctx->engine[engine->id].lrc_vma = NULL;
+	ctx->engine[engine->id].lrc_desc = 0;
+	ctx->engine[engine->id].lrc_reg_state = NULL;
 
-		i915_gem_context_unreference(ctx);
-	}
+	i915_gem_context_unreference(ctx);
 }
 
 static int intel_logical_ring_workarounds_emit(struct drm_i915_gem_request *req)
@@ -1897,6 +1876,7 @@ void intel_logical_ring_cleanup(struct intel_engine_cs *engine)
 		i915_gem_object_unpin_map(engine->status_page.obj);
 		engine->status_page.obj = NULL;
 	}
+	intel_lr_context_unpin(dev_priv->kernel_context, engine);
 
 	engine->idle_lite_restore_wa = 0;
 	engine->disable_lite_restore_wa = false;
@@ -2000,11 +1980,10 @@ logical_ring_init(struct drm_device *dev, struct intel_engine_cs *engine)
 		goto error;
 
 	/* As this is the default context, always pin it */
-	ret = intel_lr_context_do_pin(dctx, engine);
+	ret = intel_lr_context_pin(dctx, engine);
 	if (ret) {
-		DRM_ERROR(
-			"Failed to pin and map ringbuffer %s: %d\n",
-			engine->name, ret);
+		DRM_ERROR("Failed to pin context for %s: %d\n",
+			  engine->name, ret);
 		goto error;
 	}
 
@@ -2425,12 +2404,6 @@ void intel_lr_context_free(struct intel_context *ctx)
 		if (!ctx_obj)
 			continue;
 
-		if (ctx == ctx->i915->kernel_context) {
-			intel_unpin_ringbuffer_obj(ringbuf);
-			i915_gem_object_ggtt_unpin(ctx_obj);
-			i915_gem_object_unpin_map(ctx_obj);
-		}
-
 		WARN_ON(ctx->engine[i].pin_count);
 		intel_ringbuffer_free(ringbuf);
 		drm_gem_object_unreference(&ctx_obj->base);
-- 
2.8.1

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