[PATCH 3/6] drm/i915/guc: Allocate separate shared data object for GuC communication

[Michel Thierry]

From: Michał Winiarski <michal.winiarski at intel.com>

We were using first page of kernel context render state for sharing data
with GuC. While it's justified by the fact that those pages are not used
(note, GuC still enforces this layout and refuses to work if we remove
the extra page in front), it's also confusing (why are we using this
particular page?). Let's allocate a separate object instead.

Suggested-by: Daniele Ceraolo Spurio <daniele.ceraolospurio at intel.com>
Signed-off-by: Michał Winiarski <michal.winiarski at intel.com>
Cc: Chris Wilson <chris at chris-wilson.co.uk>
Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio at intel.com>
Cc: Jeff McGee <jeff.mcgee at intel.com>
Cc: Michal Wajdeczko <michal.wajdeczko at intel.com>
Cc: Oscar Mateo <oscar.mateo at intel.com>
Reviewed-by: Daniele Ceraolo Spurio <daniele.ceraolospurio at intel.com>
---
 drivers/gpu/drm/i915/i915_guc_submission.c | 36 +++++++++++++++++++++++++++++-
 drivers/gpu/drm/i915/intel_guc.c           |  8 ++-----
 drivers/gpu/drm/i915/intel_guc.h           |  2 ++
 3 files changed, 39 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_guc_submission.c b/drivers/gpu/drm/i915/i915_guc_submission.c
index b0dda9d993ae..214e4ec3cfe7 100644
--- a/drivers/gpu/drm/i915/i915_guc_submission.c
+++ b/drivers/gpu/drm/i915/i915_guc_submission.c
@@ -437,6 +437,33 @@ static void guc_stage_desc_fini(struct intel_guc *guc,
 	memset(desc, 0, sizeof(*desc));
 }
 
+static int guc_shared_data_create(struct intel_guc *guc)
+{
+	struct i915_vma *vma;
+	void *vaddr;
+
+	vma = intel_guc_allocate_vma(guc, PAGE_SIZE);
+	if (IS_ERR(vma))
+		return PTR_ERR(vma);
+
+	vaddr = i915_gem_object_pin_map(vma->obj, I915_MAP_WB);
+	if (IS_ERR(vaddr)) {
+		i915_vma_unpin_and_release(&vma);
+		return PTR_ERR(vaddr);
+	}
+
+	guc->shared_data = vma;
+	guc->shared_data_vaddr = vaddr;
+
+	return 0;
+}
+
+static void guc_shared_data_destroy(struct intel_guc *guc)
+{
+	i915_gem_object_unpin_map(guc->shared_data->obj);
+	i915_vma_unpin_and_release(&guc->shared_data);
+}
+
 /* Construct a Work Item and append it to the GuC's Work Queue */
 static void guc_wq_item_append(struct i915_guc_client *client,
 			       struct drm_i915_gem_request *rq)
@@ -1011,9 +1038,13 @@ int i915_guc_submission_init(struct drm_i915_private *dev_priv)
 	if (ret)
 		return ret;
 
+	ret = guc_shared_data_create(guc);
+	if (ret)
+		goto err_stage_desc_pool;
+
 	ret = intel_guc_log_create(guc);
 	if (ret < 0)
-		goto err_stage_desc_pool;
+		goto err_shared_data;
 
 	ret = guc_ads_create(guc);
 	if (ret < 0)
@@ -1023,6 +1054,8 @@ int i915_guc_submission_init(struct drm_i915_private *dev_priv)
 
 err_log:
 	intel_guc_log_destroy(guc);
+err_shared_data:
+	guc_shared_data_destroy(guc);
 err_stage_desc_pool:
 	guc_stage_desc_pool_destroy(guc);
 	return ret;
@@ -1034,6 +1067,7 @@ void i915_guc_submission_fini(struct drm_i915_private *dev_priv)
 
 	guc_ads_destroy(guc);
 	intel_guc_log_destroy(guc);
+	guc_shared_data_destroy(guc);
 	guc_stage_desc_pool_destroy(guc);
 }
 
diff --git a/drivers/gpu/drm/i915/intel_guc.c b/drivers/gpu/drm/i915/intel_guc.c
index 9e18c4fb9909..eaad2781cc07 100644
--- a/drivers/gpu/drm/i915/intel_guc.c
+++ b/drivers/gpu/drm/i915/intel_guc.c
@@ -188,9 +188,7 @@ int intel_guc_suspend(struct drm_i915_private *dev_priv)
 	data[0] = INTEL_GUC_ACTION_ENTER_S_STATE;
 	/* any value greater than GUC_POWER_D0 */
 	data[1] = GUC_POWER_D1;
-	/* first page is shared data with GuC */
-	data[2] = guc_ggtt_offset(ctx->engine[RCS].state) +
-		  LRC_GUCSHR_PN * PAGE_SIZE;
+	data[2] = guc_ggtt_offset(guc->shared_data);
 
 	return intel_guc_send(guc, data, ARRAY_SIZE(data));
 }
@@ -215,9 +213,7 @@ int intel_guc_resume(struct drm_i915_private *dev_priv)
 
 	data[0] = INTEL_GUC_ACTION_EXIT_S_STATE;
 	data[1] = GUC_POWER_D0;
-	/* first page is shared data with GuC */
-	data[2] = guc_ggtt_offset(ctx->engine[RCS].state) +
-		  LRC_GUCSHR_PN * PAGE_SIZE;
+	data[2] = guc_ggtt_offset(guc->shared_data);
 
 	return intel_guc_send(guc, data, ARRAY_SIZE(data));
 }
diff --git a/drivers/gpu/drm/i915/intel_guc.h b/drivers/gpu/drm/i915/intel_guc.h
index aa9a7b55be6e..fdbb4428b88c 100644
--- a/drivers/gpu/drm/i915/intel_guc.h
+++ b/drivers/gpu/drm/i915/intel_guc.h
@@ -48,6 +48,8 @@ struct intel_guc {
 	struct i915_vma *stage_desc_pool;
 	void *stage_desc_pool_vaddr;
 	struct ida stage_ids;
+	struct i915_vma *shared_data;
+	void *shared_data_vaddr;
 
 	struct i915_guc_client *execbuf_client;
 
-- 
2.14.1