i915 selftest hangcheck is causing the i915 driver timeouts, as reported by Intel CI bot:
http://gfx-ci.fi.intel.com/cibuglog-ng/issuefilterassoc/24297?query_key=42a9...
When such test runs, the only output is:
[ 68.811639] i915: Performing live selftests with st_random_seed=0xe138eac7 st_timeout=500 [ 68.811792] i915: Running hangcheck [ 68.811859] i915: Running intel_hangcheck_live_selftests/igt_hang_sanitycheck [ 68.816910] i915 0000:00:02.0: [drm] Cannot find any crtc or sizes [ 68.841597] i915: Running intel_hangcheck_live_selftests/igt_reset_nop [ 69.346347] igt_reset_nop: 80 resets [ 69.362695] i915: Running intel_hangcheck_live_selftests/igt_reset_nop_engine [ 69.863559] igt_reset_nop_engine(rcs0): 709 resets [ 70.364924] igt_reset_nop_engine(bcs0): 903 resets [ 70.866005] igt_reset_nop_engine(vcs0): 659 resets [ 71.367934] igt_reset_nop_engine(vcs1): 549 resets [ 71.869259] igt_reset_nop_engine(vecs0): 553 resets [ 71.882592] i915: Running intel_hangcheck_live_selftests/igt_reset_idle_engine [ 72.383554] rcs0: Completed 16605 idle resets [ 72.884599] bcs0: Completed 18641 idle resets [ 73.385592] vcs0: Completed 17517 idle resets [ 73.886658] vcs1: Completed 15474 idle resets [ 74.387600] vecs0: Completed 17983 idle resets [ 74.387667] i915: Running intel_hangcheck_live_selftests/igt_reset_active_engine [ 74.889017] rcs0: Completed 747 active resets [ 75.174240] intel_engine_reset(bcs0) failed, err:-110 [ 75.174301] bcs0: Completed 525 active resets
After that, the machine just silently hangs.
Bisecting the issue, the patch that introduced the regression is:
7938d61591d3 ("drm/i915: Flush TLBs before releasing backing store")
Reverting it fix the issues, but introduce other problems, as TLB won't be invalidated anymore. So, instead, let's fix the root cause.
It turns that the TLB flush logic ends conflicting with i915 reset, which is called during selftest hangcheck. So, the TLB cache should be serialized, but other TLB fix patches are required for this one to work.
Tested on an Intel NUC5i7RYB with an i7-5557U Broadwell CPU.
Chris Wilson (6): drm/i915/gt: Ignore TLB invalidations on idle engines drm/i915/gt: Invalidate TLB of the OA unit at TLB invalidations drm/i915/gt: Skip TLB invalidations once wedged drm/i915/gt: Only invalidate TLBs exposed to user manipulation drm/i915/gt: Serialize GRDOM access between multiple engine resets drm/i915/gt: Serialize TLB invalidates with GT resets
drivers/gpu/drm/i915/gem/i915_gem_pages.c | 10 +++--- drivers/gpu/drm/i915/gt/intel_gt.c | 43 +++++++++++++++++++---- drivers/gpu/drm/i915/gt/intel_gt_pm.h | 3 ++ drivers/gpu/drm/i915/gt/intel_reset.c | 37 ++++++++++++++----- drivers/gpu/drm/i915/i915_vma.c | 3 +- 5 files changed, 75 insertions(+), 21 deletions(-)