[PATCH v6 18/25] drm/i915: Replace the pinned context address with its unique ID

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

Rather than reuse the current location of the context in the global GTT
for its hardware identifier, use the context's unique ID assigned to it
for its whole lifetime.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
---
 drivers/gpu/drm/i915/i915_debugfs.c | 12 +++++-------
 drivers/gpu/drm/i915/intel_lrc.c    | 39 +++++++++----------------------------
 drivers/gpu/drm/i915/intel_lrc.h    |  3 ---
 3 files changed, 14 insertions(+), 40 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
index 3bd2f89933ff..be2a4a0fae13 100644
--- a/drivers/gpu/drm/i915/i915_debugfs.c
+++ b/drivers/gpu/drm/i915/i915_debugfs.c
@@ -2043,15 +2043,13 @@ static void i915_dump_lrc_obj(struct seq_file *m,
 	struct drm_i915_gem_object *ctx_obj = ctx->engine[engine->id].state;
 	unsigned long ggtt_offset = 0;
 
+	seq_printf(m, "CONTEXT: %s %u\n", engine->name, ctx->hw_id);
+
 	if (ctx_obj == NULL) {
-		seq_printf(m, "Context on %s with no gem object\n",
-			   engine->name);
+		seq_puts(m, "\tNot allocated\n");
 		return;
 	}
 
-	seq_printf(m, "CONTEXT: %s %u\n", engine->name,
-		   intel_execlists_ctx_id(ctx, engine));
-
 	if (!i915_gem_obj_ggtt_bound(ctx_obj))
 		seq_puts(m, "\tNot bound in GGTT\n");
 	else
@@ -2170,8 +2168,8 @@ static int i915_execlists(struct seq_file *m, void *data)
 
 		seq_printf(m, "\t%d requests in queue\n", count);
 		if (head_req) {
-			seq_printf(m, "\tHead request id: %u\n",
-				   intel_execlists_ctx_id(head_req->ctx, engine));
+			seq_printf(m, "\tHead request context: %u\n",
+				   head_req->ctx->hw_id);
 			seq_printf(m, "\tHead request tail: %u\n",
 				   head_req->tail);
 		}
diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
index 5d8ee9059eee..ccabb688e049 100644
--- a/drivers/gpu/drm/i915/intel_lrc.c
+++ b/drivers/gpu/drm/i915/intel_lrc.c
@@ -224,6 +224,7 @@ enum {
 	FAULT_AND_CONTINUE /* Unsupported */
 };
 #define GEN8_CTX_ID_SHIFT 32
+#define GEN8_CTX_ID_WIDTH 21
 #define GEN8_CTX_RCS_INDIRECT_CTX_OFFSET_DEFAULT	0x17
 #define GEN9_CTX_RCS_INDIRECT_CTX_OFFSET_DEFAULT	0x26
 
@@ -307,7 +308,7 @@ logical_ring_init_platform_invariants(struct intel_engine_cs *engine)
  * This is what a descriptor looks like, from LSB to MSB:
  *    bits  0-11:    flags, GEN8_CTX_* (cached in ctx_desc_template)
  *    bits 12-31:    LRCA, GTT address of (the HWSP of) this context
- *    bits 32-52:    ctx ID, a globally unique tag (the LRCA again!)
+ *    bits 32-52:    ctx ID, a globally unique tag
  *    bits 53-54:    mbz, reserved for use by hardware
  *    bits 55-63:    group ID, currently unused and set to 0
  */
@@ -315,14 +316,14 @@ static void
 intel_lr_context_descriptor_update(struct intel_context *ctx,
 				   struct intel_engine_cs *engine)
 {
-	uint64_t lrca, desc;
+	u64 desc;
 
-	lrca = ctx->engine[engine->id].lrc_vma->node.start +
-	       LRC_PPHWSP_PN * PAGE_SIZE;
+	BUILD_BUG_ON(MAX_CONTEXT_HW_ID > (1<<GEN8_CTX_ID_WIDTH));
 
-	desc = engine->ctx_desc_template;		   /* bits  0-11 */
-	desc |= lrca;					   /* bits 12-31 */
-	desc |= (lrca >> PAGE_SHIFT) << GEN8_CTX_ID_SHIFT; /* bits 32-52 */
+	desc = engine->ctx_desc_template;			/* bits  0-11 */
+	desc |= ctx->engine[engine->id].lrc_vma->node.start +	/* bits 12-31 */
+	       LRC_PPHWSP_PN * PAGE_SIZE;
+	desc |= (u64)ctx->hw_id << GEN8_CTX_ID_SHIFT;		/* bits 32-52 */
 
 	ctx->engine[engine->id].lrc_desc = desc;
 }
@@ -333,28 +334,6 @@ uint64_t intel_lr_context_descriptor(struct intel_context *ctx,
 	return ctx->engine[engine->id].lrc_desc;
 }
 
-/**
- * intel_execlists_ctx_id() - get the Execlists Context ID
- * @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
- * they can refer to a context, and the new context ID we pass to the
- * ELSP so that the GPU can inform us of the context status via
- * interrupts.
- *
- * The context ID is a portion of the context descriptor, so we can
- * just extract the required part from the cached descriptor.
- *
- * Return: 20-bits globally unique context ID.
- */
-u32 intel_execlists_ctx_id(struct intel_context *ctx,
-			   struct intel_engine_cs *engine)
-{
-	return intel_lr_context_descriptor(ctx, engine) >> GEN8_CTX_ID_SHIFT;
-}
-
 static void execlists_elsp_write(struct drm_i915_gem_request *rq0,
 				 struct drm_i915_gem_request *rq1)
 {
@@ -500,7 +479,7 @@ execlists_check_remove_request(struct intel_engine_cs *engine, u32 request_id)
 	if (!head_req)
 		return 0;
 
-	if (unlikely(intel_execlists_ctx_id(head_req->ctx, engine) != request_id))
+	if (unlikely(head_req->ctx->hw_id != request_id))
 		return 0;
 
 	WARN(head_req->elsp_submitted == 0, "Never submitted head request\n");
diff --git a/drivers/gpu/drm/i915/intel_lrc.h b/drivers/gpu/drm/i915/intel_lrc.h
index 60a7385bc531..9510826f0d90 100644
--- a/drivers/gpu/drm/i915/intel_lrc.h
+++ b/drivers/gpu/drm/i915/intel_lrc.h
@@ -113,9 +113,6 @@ void intel_lr_context_reset(struct drm_i915_private *dev_priv,
 uint64_t intel_lr_context_descriptor(struct intel_context *ctx,
 				     struct intel_engine_cs *engine);
 
-u32 intel_execlists_ctx_id(struct intel_context *ctx,
-			   struct intel_engine_cs *engine);
-
 /* Execlists */
 int intel_sanitize_enable_execlists(struct drm_device *dev, int enable_execlists);
 struct i915_execbuffer_params;
-- 
2.8.1

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