drm/i915: fix crash in error state readout on non-execlist platforms v2

Looks like this was introduced in:
commit d1675198ed1f21aec6e036336e4340c40b726497
Author: Alex Dai <yu.dai@intel.com>
Date:   Wed Aug 12 15:43:43 2015 +0100

    drm/i915: Integrate GuC-based command submission

This patch assumed LRC contexts and HWS layout, which is incorrect on
platforms without execlists.  This can lead to a crash in GPU error
state readout on those platforms.

I don't see a bug filed for this, but there may be one that I haven't
found.

v2: fixup offset handling for error capture fix (Dave)

Cc: Alex Dai <yu.dai@intel.com>
Reviewed-by: Dave Gordon <david.s.gordon@intel.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

diff --git a/drivers/gpu/drm/i915/i915_gpu_error.c b/drivers/gpu/drm/i915/i915_gpu_error.c
index 3379f9c1ef88a056481042cade8acb87ac78f15a..f95de05f793d176030521c86c17081baf34c7021 100644 (file)
--- a/drivers/gpu/drm/i915/i915_gpu_error.c
+++ b/drivers/gpu/drm/i915/i915_gpu_error.c
@@ -457,17 +457,23 @@ int i915_error_state_to_str(struct drm_i915_error_state_buf *m,
                }
 
                if ((obj = error->ring[i].hws_page)) {
+                       u64 hws_offset = obj->gtt_offset;
+                       u32 *hws_page = &obj->pages[0][0];
+
+                       if (i915.enable_execlists) {
+                               hws_offset += LRC_PPHWSP_PN * PAGE_SIZE;
+                               hws_page = &obj->pages[LRC_PPHWSP_PN][0];
+                       }
                        err_printf(m, "%s --- HW Status = 0x%08llx\n",
-                               dev_priv->ring[i].name,
-                               obj->gtt_offset + LRC_PPHWSP_PN * PAGE_SIZE);
+                                  dev_priv->ring[i].name, hws_offset);
                        offset = 0;
                        for (elt = 0; elt < PAGE_SIZE/16; elt += 4) {
                                err_printf(m, "[%04x] %08x %08x %08x %08x\n",
                                           offset,
-                                          obj->pages[LRC_PPHWSP_PN][elt],
-                                          obj->pages[LRC_PPHWSP_PN][elt+1],
-                                          obj->pages[LRC_PPHWSP_PN][elt+2],
-                                          obj->pages[LRC_PPHWSP_PN][elt+3]);
+                                          hws_page[elt],
+                                          hws_page[elt+1],
+                                          hws_page[elt+2],
+                                          hws_page[elt+3]);
                                        offset += 16;
                        }
                }