[Intel-gfx] [PATCH] drm/i915/guc: Don't make assumptions while getting the lrca offset

[Michel Thierry]

Using the HWSP ggtt_offset to get the lrca offset is only correct if the
HWSP happens to be before it (when we reuse the PPHWSP of the kernel
context as the engine HWSP). Instead of making this assumption, get the
lrca offset from the kernel_context engine state.

And while looking at this part of the GuC interaction, it was also
noticed that the firmware expects the size of only the engine context
(context minus the execlist part, i.e. don't include the first 80
dwords), so pass the right size.

Reported-by: Daniele Ceraolo Spurio <daniele.ceraolospurio at intel.com>
Signed-off-by: Michel Thierry <michel.thierry at intel.com>
Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio at intel.com>
Cc: Michal Wajdeczko <michal.wajdeczko at intel.com>
Cc: Oscar Mateo <oscar.mateo at intel.com>
---
 drivers/gpu/drm/i915/i915_guc_submission.c | 15 ++++++++++++---
 1 file changed, 12 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_guc_submission.c b/drivers/gpu/drm/i915/i915_guc_submission.c
index 48a1e9349a2c..97ec11a7cc9a 100644
--- a/drivers/gpu/drm/i915/i915_guc_submission.c
+++ b/drivers/gpu/drm/i915/i915_guc_submission.c
@@ -1018,6 +1018,12 @@ static void guc_policies_init(struct guc_policies *policies)
 	policies->is_valid = 1;
 }
 
+/*
+ * The first 80 dwords of the register state context, containing the
+ * execlists and ppgtt registers.
+ */
+#define LR_HW_CONTEXT_SIZE	(80 * sizeof(u32))
+
 static int guc_ads_create(struct intel_guc *guc)
 {
 	struct drm_i915_private *dev_priv = guc_to_i915(guc);
@@ -1033,6 +1039,7 @@ static int guc_ads_create(struct intel_guc *guc)
 	struct intel_engine_cs *engine;
 	enum intel_engine_id id;
 	u32 base;
+	u32 lrca_offset = LRC_PPHWSP_PN * PAGE_SIZE;
 
 	GEM_BUG_ON(guc->ads_vma);
 
@@ -1062,13 +1069,15 @@ static int guc_ads_create(struct intel_guc *guc)
 	 * engines after a reset. Here we use the Render ring default
 	 * context, which must already exist and be pinned in the GGTT,
 	 * so its address won't change after we've told the GuC where
-	 * to find it.
+	 * to find it. GuC will skip the PPHWSP and 'Execlist Context',
+	 * thus reduce the size by 1 page (PPHWSP) and 80 dwords.
 	 */
 	blob->ads.golden_context_lrca =
-		dev_priv->engine[RCS]->status_page.ggtt_offset;
+		guc_ggtt_offset(dev_priv->kernel_context->engine[RCS].state) + lrca_offset;
 
+	/* context_size - PPHWSP - first 80 dwords */
 	for_each_engine(engine, dev_priv, id)
-		blob->ads.eng_state_size[engine->guc_id] = engine->context_size;
+		blob->ads.eng_state_size[engine->guc_id] = engine->context_size - lrca_offset - LR_HW_CONTEXT_SIZE;
 
 	base = guc_ggtt_offset(vma);
 	blob->ads.scheduler_policies = base + ptr_offset(blob, policies);
-- 
2.13.0