[Intel-gfx] ✗ Fi.CI.BAT: failure for series starting with [01/28] drm/i915/selftests: Add the usual batch vma managements to st_workarounds

[Chris Wilson]

Quoting Patchwork (2019-08-26 08:57:32)
>   * igt at i915_selftest@live_gem_contexts:
>     - fi-ivb-3770:        [PASS][3] -> [DMESG-FAIL][4]
>    [3]: https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_6783/fi-ivb-3770/igt@i915_selftest@live_gem_contexts.html
>    [4]: https://intel-gfx-ci.01.org/tree/drm-tip/Patchwork_14187/fi-ivb-3770/igt@i915_selftest@live_gem_contexts.html

ivb/hsw looked to be much more of a timing issue wrt to TLB
invalidation. Adding msleep() and whacking memory barriers around the
place appeared to improve the situation, but that may have just been
wishful thinking. Short term, I think we need to switch gen7 back to
aliasing-ppgtt until the TLB mess can be resolved (all we've changing in
this series is timing, so the same incorrect page access should be
possible in current kernels just harder to hit).
-Chris