[Intel-gfx] [PATCH 12/13] drm/i915: find guilty batch buffer on ring resets

[Mika Kuoppala]

After hang check timer has declared gpu to be hang,
rings are reset. In ring reset, when clearing
request list, do post mortem analysis to find out
the guilty batch buffer.

Select requests for further analysis by inspecting
the completed sequence number which has been updated
into the HWS page. If request was completed, it can't
be related to the hang.

For noncompleted requests mark the batch as guilty
if the ring was not waiting and the ring head was
stuck inside the buffer object or in the flush region
right after the batch. For everything else, mark
them as innocents.

v2: Fixed a typo in commit message (Ville Syrjälä)

Signed-off-by: Mika Kuoppala <mika.kuoppala at intel.com>
---
 drivers/gpu/drm/i915/i915_gem.c |   91 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 91 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index ace482d..6380a50 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -2099,9 +2099,97 @@ i915_gem_request_remove_from_client(struct drm_i915_gem_request *request)
 	spin_unlock(&file_priv->mm.lock);
 }
 
+static bool i915_head_inside_object(u32 acthd, struct drm_i915_gem_object *obj)
+{
+	if (acthd >= obj->gtt_offset &&
+	    acthd < obj->gtt_offset + obj->base.size)
+		return true;
+
+	return false;
+}
+
+static bool i915_head_inside_request(u32 acthd, u32 rs, u32 re)
+{
+	if (rs < re) {
+		if (acthd >= rs && acthd < re)
+			return true;
+	} else if (rs > re) {
+		if (acthd >= rs || acthd < re)
+			return true;
+	}
+
+	return false;
+}
+
+static bool i915_request_guilty(struct drm_i915_gem_request *request,
+				const u32 acthd, bool *inside)
+{
+	if (request->batch_obj) {
+		if (i915_head_inside_object(acthd, request->batch_obj)) {
+			*inside = true;
+			return true;
+		}
+	}
+
+	if (i915_head_inside_request(acthd, request->head, request->tail)) {
+		*inside = false;
+		return true;
+	}
+
+	return false;
+}
+
+static void i915_set_reset_status(struct intel_ring_buffer *ring,
+				  struct drm_i915_gem_request *request,
+				  u32 acthd)
+{
+	bool inside;
+	struct ctx_reset_state *rs = NULL;
+	bool guilty;
+
+	/* Innocent until proven guilty */
+	guilty = false;
+
+	if (!ring->hangcheck_was_waiting &&
+	    i915_request_guilty(request, acthd, &inside)) {
+		DRM_ERROR("%s hung %s bo (0x%x ctx %d) at 0x%x\n",
+			  ring->name,
+			  inside ? "inside" : "flushing",
+			  request->batch_obj ?
+			  request->batch_obj->gtt_offset : 0,
+			  request->ctx ? request->ctx->id : 0,
+			  acthd);
+
+		guilty = true;
+	}
+
+	/* If contexts are disabled or this is the default context, use
+	 * file_priv->reset_state
+	 */
+	if (request->ctx && request->ctx->id != DEFAULT_CONTEXT_ID)
+		rs = &request->ctx->reset_state;
+	else if (request->file_priv)
+		rs = &request->file_priv->reset_state;
+
+	if (rs) {
+		rs->total++;
+
+		if (guilty)
+			rs->guilty++;
+		else
+			rs->innocent++;
+	}
+}
+
 static void i915_gem_reset_ring_lists(struct drm_i915_private *dev_priv,
 				      struct intel_ring_buffer *ring)
 {
+	u32 completed_seqno;
+	u32 acthd;
+
+	acthd = intel_ring_get_active_head(ring);
+	completed_seqno = ring->get_seqno(ring, false);
+
 	while (!list_empty(&ring->request_list)) {
 		struct drm_i915_gem_request *request;
 
@@ -2109,6 +2197,9 @@ static void i915_gem_reset_ring_lists(struct drm_i915_private *dev_priv,
 					   struct drm_i915_gem_request,
 					   list);
 
+		if (request->seqno > completed_seqno)
+			i915_set_reset_status(ring, request, acthd);
+
 		list_del(&request->list);
 		i915_gem_request_remove_from_client(request);
 
-- 
1.7.9.5