drm/i915: Include HW status page in error capture

Many times in the past we have concluded that the cause of the GPU hang
has been that the hw status page was stale, usually because the GPU and
CPU disagreed over the address of the page. Having stumbled across yet
another issue that seems to be related to the HWSP, it is time to
include that information in the GPU error dump.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_drv.h

@@ -306,6 +306,7 @@ struct drm_i915_error_state {
 	u32 tail[I915_NUM_RINGS];
 	u32 head[I915_NUM_RINGS];
 	u32 ctl[I915_NUM_RINGS];
+	u32 hws[I915_NUM_RINGS];
 	u32 ipeir[I915_NUM_RINGS];
 	u32 ipehr[I915_NUM_RINGS];
 	u32 instdone[I915_NUM_RINGS];
@@ -334,7 +335,7 @@ struct drm_i915_error_state {
 			int page_count;
 			u32 gtt_offset;
 			u32 *pages[0];
-		} *ringbuffer, *batchbuffer, *ctx;
+		} *ringbuffer, *batchbuffer, *ctx, *hws;
 		struct drm_i915_error_request {
 			long jiffies;
 			u32 seqno;

drivers/gpu/drm/i915/i915_gpu_error.c

@@ -243,6 +243,7 @@ static void i915_ring_error_state(struct drm_i915_error_state_buf *m,
 	err_printf(m, "  HEAD: 0x%08x\n", error->head[ring]);
 	err_printf(m, "  TAIL: 0x%08x\n", error->tail[ring]);
 	err_printf(m, "  CTL: 0x%08x\n", error->ctl[ring]);
+	err_printf(m, "  HWS: 0x%08x\n", error->hws[ring]);
 	err_printf(m, "  ACTHD: 0x%08x\n", error->acthd[ring]);
 	err_printf(m, "  IPEIR: 0x%08x\n", error->ipeir[ring]);
 	err_printf(m, "  IPEHR: 0x%08x\n", error->ipehr[ring]);
@@ -385,6 +386,22 @@ int i915_error_state_to_str(struct drm_i915_error_state_buf *m,
 			}
 		}
 
+		if ((obj = error->ring[i].hws)) {
+			err_printf(m, "%s --- HW Status = 0x%08x\n",
+				   dev_priv->ring[i].name,
+				   obj->gtt_offset);
+			offset = 0;
+			for (elt = 0; elt < PAGE_SIZE/16; elt += 4) {
+				err_printf(m, "[%04x] %08x %08x %08x %08x\n",
+					   offset,
+					   obj->pages[0][elt],
+					   obj->pages[0][elt+1],
+					   obj->pages[0][elt+2],
+					   obj->pages[0][elt+3]);
+					offset += 16;
+			}
+		}
+
 		obj = error->ring[i].ctx;
 		if (obj) {
 			err_printf(m, "%s --- HW Context = 0x%08x\n",
@@ -468,6 +485,7 @@ static void i915_error_state_free(struct kref *error_ref)
 	for (i = 0; i < ARRAY_SIZE(error->ring); i++) {
 		i915_error_object_free(error->ring[i].batchbuffer);
 		i915_error_object_free(error->ring[i].ringbuffer);
+		i915_error_object_free(error->ring[i].hws);
 		i915_error_object_free(error->ring[i].ctx);
 		kfree(error->ring[i].requests);
 	}
@@ -782,6 +800,35 @@ static void i915_record_ring_state(struct drm_device *dev,
 	error->tail[ring->id] = I915_READ_TAIL(ring);
 	error->ctl[ring->id] = I915_READ_CTL(ring);
 
+	if (I915_NEED_GFX_HWS(dev)) {
+		int mmio;
+
+		if (IS_GEN7(dev)) {
+			switch (ring->id) {
+			default:
+			case RCS:
+				mmio = RENDER_HWS_PGA_GEN7;
+				break;
+			case BCS:
+				mmio = BLT_HWS_PGA_GEN7;
+				break;
+			case VCS:
+				mmio = BSD_HWS_PGA_GEN7;
+				break;
+			case VECS:
+				mmio = VEBOX_HWS_PGA_GEN7;
+				break;
+			}
+		} else if (IS_GEN6(ring->dev)) {
+			mmio = RING_HWS_PGA_GEN6(ring->mmio_base);
+		} else {
+			/* XXX: gen8 returns to sanity */
+			mmio = RING_HWS_PGA(ring->mmio_base);
+		}
+
+		error->hws[ring->id] = I915_READ(mmio);
+	}
+
 	error->cpu_ring_head[ring->id] = ring->head;
 	error->cpu_ring_tail[ring->id] = ring->tail;
 
@@ -829,6 +876,9 @@ static void i915_gem_record_rings(struct drm_device *dev,
 		error->ring[i].ringbuffer =
 			i915_error_ggtt_object_create(dev_priv, ring->obj);
 
+		if (ring->status_page.obj)
+			error->ring[i].hws =
+				i915_error_ggtt_object_create(dev_priv, ring->status_page.obj);
 
 		i915_gem_record_active_context(ring, error, &error->ring[i]);