[PATCH 05/13] drm/i915: Cache LRCA in the context

[Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>]

From: Tvrtko Ursulin <tvrtko.ursulin@intel.com>

We are not allowed to call i915_gem_obj_ggtt_offset from irq
context without the big kernel lock held.

LRCA lifetime is well defined so cache it so it can be looked up
cheaply from the interrupt context and at command submission
time.

v2: Added irq context reasoning to the commit message. (Daniel Vetter)

Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
---
 drivers/gpu/drm/i915/i915_debugfs.c | 15 ++++++--------
 drivers/gpu/drm/i915/i915_drv.h     |  1 +
 drivers/gpu/drm/i915/intel_lrc.c    | 40 ++++++++++++++++---------------------
 drivers/gpu/drm/i915/intel_lrc.h    |  3 ++-
 4 files changed, 26 insertions(+), 33 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
index 3b05bd189eab..714a45cf8a51 100644
--- a/drivers/gpu/drm/i915/i915_debugfs.c
+++ b/drivers/gpu/drm/i915/i915_debugfs.c
@@ -1976,12 +1976,13 @@ static int i915_context_status(struct seq_file *m, void *unused)
 }
 
 static void i915_dump_lrc_obj(struct seq_file *m,
-			      struct intel_engine_cs *ring,
-			      struct drm_i915_gem_object *ctx_obj)
+			      struct intel_context *ctx,
+			      struct intel_engine_cs *ring)
 {
 	struct page *page;
 	uint32_t *reg_state;
 	int j;
+	struct drm_i915_gem_object *ctx_obj = ctx->engine[ring->id].state;
 	unsigned long ggtt_offset = 0;
 
 	if (ctx_obj == NULL) {
@@ -1991,7 +1992,7 @@ static void i915_dump_lrc_obj(struct seq_file *m,
 	}
 
 	seq_printf(m, "CONTEXT: %s %u\n", ring->name,
-		   intel_execlists_ctx_id(ctx_obj));
+		   intel_execlists_ctx_id(ctx, ring));
 
 	if (!i915_gem_obj_ggtt_bound(ctx_obj))
 		seq_puts(m, "\tNot bound in GGTT\n");
@@ -2040,8 +2041,7 @@ static int i915_dump_lrc(struct seq_file *m, void *unused)
 	list_for_each_entry(ctx, &dev_priv->context_list, link) {
 		for_each_ring(ring, dev_priv, i) {
 			if (ring->default_context != ctx)
-				i915_dump_lrc_obj(m, ring,
-						  ctx->engine[i].state);
+				i915_dump_lrc_obj(m, ctx, ring);
 		}
 	}
 
@@ -2115,11 +2115,8 @@ static int i915_execlists(struct seq_file *m, void *data)
 
 		seq_printf(m, "\t%d requests in queue\n", count);
 		if (head_req) {
-			struct drm_i915_gem_object *ctx_obj;
-
-			ctx_obj = head_req->ctx->engine[ring_id].state;
 			seq_printf(m, "\tHead request id: %u\n",
-				   intel_execlists_ctx_id(ctx_obj));
+				   intel_execlists_ctx_id(head_req->ctx, ring));
 			seq_printf(m, "\tHead request tail: %u\n",
 				   head_req->tail);
 		}
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 8cf655c6fc03..b77a5d84eac2 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -881,6 +881,7 @@ struct intel_context {
 		struct drm_i915_gem_object *state;
 		struct intel_ringbuffer *ringbuf;
 		int pin_count;
+		u32 lrca;
 	} engine[I915_NUM_RINGS];
 
 	struct list_head link;
diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
index ff146a15d395..ffe004de22b0 100644
--- a/drivers/gpu/drm/i915/intel_lrc.c
+++ b/drivers/gpu/drm/i915/intel_lrc.c
@@ -265,7 +265,8 @@ int intel_sanitize_enable_execlists(struct drm_device *dev, int enable_execlists
 
 /**
  * intel_execlists_ctx_id() - get the Execlists Context ID
- * @ctx_obj: Logical Ring Context backing object.
+ * @ctx: Context to get the ID for
+ * @ring: Engine to get the ID for
  *
  * Do not confuse with ctx->id! Unfortunately we have a name overload
  * here: the old context ID we pass to userspace as a handler so that
@@ -275,14 +276,12 @@ int intel_sanitize_enable_execlists(struct drm_device *dev, int enable_execlists
  *
  * Return: 20-bits globally unique context ID.
  */
-u32 intel_execlists_ctx_id(struct drm_i915_gem_object *ctx_obj)
+u32 intel_execlists_ctx_id(struct intel_context *ctx,
+			   struct intel_engine_cs *ring)
 {
-	u32 lrca = i915_gem_obj_ggtt_offset(ctx_obj) +
-			LRC_PPHWSP_PN * PAGE_SIZE;
-
 	/* LRCA is required to be 4K aligned so the more significant 20 bits
 	 * are globally unique */
-	return lrca >> 12;
+	return ctx->engine[ring->id].lrca >> 12;
 }
 
 static bool disable_lite_restore_wa(struct intel_engine_cs *ring)
@@ -297,13 +296,11 @@ static bool disable_lite_restore_wa(struct intel_engine_cs *ring)
 uint64_t intel_lr_context_descriptor(struct intel_context *ctx,
 				     struct intel_engine_cs *ring)
 {
-	struct drm_i915_gem_object *ctx_obj = ctx->engine[ring->id].state;
+	uint64_t lrca = ctx->engine[ring->id].lrca;
 	uint64_t desc = ring->ctx_desc_template;
-	uint64_t lrca = i915_gem_obj_ggtt_offset(ctx_obj) +
-			LRC_PPHWSP_PN * PAGE_SIZE;
 
 	desc |= lrca;
-	desc |= (u64)intel_execlists_ctx_id(ctx_obj) << GEN8_CTX_ID_SHIFT;
+	desc |= (u64)intel_execlists_ctx_id(ctx, ring) << GEN8_CTX_ID_SHIFT;
 
 	return desc;
 }
@@ -461,9 +458,7 @@ static bool execlists_check_remove_request(struct intel_engine_cs *ring,
 					    execlist_link);
 
 	if (head_req != NULL) {
-		struct drm_i915_gem_object *ctx_obj =
-				head_req->ctx->engine[ring->id].state;
-		if (intel_execlists_ctx_id(ctx_obj) == request_id) {
+		if (intel_execlists_ctx_id(head_req->ctx, ring) == request_id) {
 			WARN(head_req->elsp_submitted == 0,
 			     "Never submitted head request\n");
 
@@ -1023,15 +1018,17 @@ int logical_ring_flush_all_caches(struct drm_i915_gem_request *req)
 }
 
 static int intel_lr_context_do_pin(struct intel_engine_cs *ring,
-		struct drm_i915_gem_object *ctx_obj,
-		struct intel_ringbuffer *ringbuf)
+				   struct intel_context *ctx)
 {
 	struct drm_device *dev = ring->dev;
 	struct drm_i915_private *dev_priv = dev->dev_private;
+	struct drm_i915_gem_object *ctx_obj = ctx->engine[ring->id].state;
+	struct intel_ringbuffer *ringbuf = ctx->engine[ring->id].ringbuf;
 	u64 lrca;
-	int ret = 0;
+	int ret;
 
 	WARN_ON(!mutex_is_locked(&ring->dev->struct_mutex));
+
 	ret = i915_gem_obj_ggtt_pin(ctx_obj, GEN8_LR_CONTEXT_ALIGN,
 			PIN_OFFSET_BIAS | GUC_WOPCM_TOP);
 	if (ret)
@@ -1047,6 +1044,7 @@ static int intel_lr_context_do_pin(struct intel_engine_cs *ring,
 	if (ret)
 		goto unpin_ctx_obj;
 
+	ctx->engine[ring->id].lrca = lrca;
 	ctx_obj->dirty = true;
 
 	/* Invalidate GuC TLB. */
@@ -1065,11 +1063,9 @@ static int intel_lr_context_pin(struct drm_i915_gem_request *rq)
 {
 	int ret = 0;
 	struct intel_engine_cs *ring = rq->ring;
-	struct drm_i915_gem_object *ctx_obj = rq->ctx->engine[ring->id].state;
-	struct intel_ringbuffer *ringbuf = rq->ringbuf;
 
 	if (rq->ctx->engine[ring->id].pin_count++ == 0) {
-		ret = intel_lr_context_do_pin(ring, ctx_obj, ringbuf);
+		ret = intel_lr_context_do_pin(ring, rq->ctx);
 		if (ret)
 			goto reset_pin_count;
 	}
@@ -1091,6 +1087,7 @@ void intel_lr_context_unpin(struct drm_i915_gem_request *rq)
 		if (--rq->ctx->engine[ring->id].pin_count == 0) {
 			intel_unpin_ringbuffer_obj(ringbuf);
 			i915_gem_object_ggtt_unpin(ctx_obj);
+			rq->ctx->engine[ring->id].lrca = 0;
 		}
 	}
 }
@@ -1960,10 +1957,7 @@ static int logical_ring_init(struct drm_device *dev, struct intel_engine_cs *rin
 		goto error;
 
 	/* As this is the default context, always pin it */
-	ret = intel_lr_context_do_pin(
-			ring,
-			ring->default_context->engine[ring->id].state,
-			ring->default_context->engine[ring->id].ringbuf);
+	ret = intel_lr_context_do_pin(ring, ring->default_context);
 	if (ret) {
 		DRM_ERROR(
 			"Failed to pin and map ringbuffer %s: %d\n",
diff --git a/drivers/gpu/drm/i915/intel_lrc.h b/drivers/gpu/drm/i915/intel_lrc.h
index de41ad6cd63d..f9db5f187d77 100644
--- a/drivers/gpu/drm/i915/intel_lrc.h
+++ b/drivers/gpu/drm/i915/intel_lrc.h
@@ -106,6 +106,8 @@ void intel_lr_context_reset(struct drm_device *dev,
 			struct intel_context *ctx);
 uint64_t intel_lr_context_descriptor(struct intel_context *ctx,
 				     struct intel_engine_cs *ring);
+u32 intel_execlists_ctx_id(struct intel_context *ctx,
+			   struct intel_engine_cs *ring);
 
 /* Execlists */
 int intel_sanitize_enable_execlists(struct drm_device *dev, int enable_execlists);
@@ -113,7 +115,6 @@ struct i915_execbuffer_params;
 int intel_execlists_submission(struct i915_execbuffer_params *params,
 			       struct drm_i915_gem_execbuffer2 *args,
 			       struct list_head *vmas);
-u32 intel_execlists_ctx_id(struct drm_i915_gem_object *ctx_obj);
 
 void intel_lrc_irq_handler(struct intel_engine_cs *ring);
 void intel_execlists_retire_requests(struct intel_engine_cs *ring);
-- 
1.9.1

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