1. 14 May, 2019 15 commits
  2. 13 May, 2019 4 commits
  3. 09 May, 2019 9 commits
  4. 08 May, 2019 3 commits
    • Chris Wilson's avatar
      drm/i915: Seal races between async GPU cancellation, retirement and signaling · 0152b3b3
      Chris Wilson authored
      Currently there is an underlying assumption that i915_request_unsubmit()
      is synchronous wrt the GPU -- that is the request is no longer in flight
      as we remove it. In the near future that may change, and this may upset
      our signaling as we can process an interrupt for that request while it
      is no longer in flight.
      
      CPU0					CPU1
      intel_engine_breadcrumbs_irq
      (queue request completion)
      					i915_request_cancel_signaling
      ...					...
      					i915_request_enable_signaling
      dma_fence_signal
      
      Hence in the time it took us to drop the lock to signal the request, a
      preemption event may have occurred and re-queued the request. In the
      process, that request would have seen I915_FENCE_FLAG_SIGNAL clear and
      so reused the rq->signal_link that was in use on CPU0, leading to bad
      pointer chasing in intel_engine_breadcrumbs_irq.
      
      A related issue was that if someone started listening for a signal on a
      completed but no longer in-flight request, we missed the opportunity to
      immediately signal that request.
      
      Furthermore, as intel_contexts may be immediately released during
      request retirement, in order to be entirely sure that
      intel_engine_breadcrumbs_irq may no longer dereference the intel_context
      (ce->signals and ce->signal_link), we must wait for irq spinlock.
      
      In order to prevent the race, we use a bit in the fence.flags to signal
      the transfer onto the signal list inside intel_engine_breadcrumbs_irq.
      For simplicity, we use the DMA_FENCE_FLAG_SIGNALED_BIT as it then
      quickly signals to any outside observer that the fence is indeed signaled.
      
      v2: Sketch out potential dma-fence API for manual signaling
      v3: And the test_and_set_bit()
      
      Fixes: 52c0fdb2
      
       ("drm/i915: Replace global breadcrumbs with per-context interrupt tracking")
      Signed-off-by: default avatarChris Wilson <chris@chris-wilson.co.uk>
      Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
      Reviewed-by: default avatarTvrtko Ursulin <tvrtko.ursulin@intel.com>
      Link: https://patchwork.freedesktop.org/patch/msgid/20190508112452.18942-1-chris@chris-wilson.co.uk
      0152b3b3
    • Chris Wilson's avatar
      drm/i915/hangcheck: Replace hangcheck.seqno with RING_HEAD · 519a0194
      Chris Wilson authored
      
      
      After realising we need to sample RING_START to detect context switches
      from preemption events that do not allow for the seqno to advance, we
      can also realise that the seqno itself is just a distance along the ring
      and so can be replaced by sampling RING_HEAD.
      
      v2: Bonus comment for the mystery separate CS_STALL before MI_USER_INTERRUPT
      
      Signed-off-by: default avatarChris Wilson <chris@chris-wilson.co.uk>
      Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
      Reviewed-by: default avatarMika Kuoppala <mika.kuoppala@linux.intel.com>
      Link: https://patchwork.freedesktop.org/patch/msgid/20190508080704.24223-1-chris@chris-wilson.co.uk
      519a0194
    • Chris Wilson's avatar
      drm/i915: Reboot CI if forcewake fails · 18ecc6c5
      Chris Wilson authored
      
      
      If the HW fails to ack a change in forcewake status, the machine is as
      good as dead -- it may recover, but in reality it missed the mmio
      updates and is now in a very inconsistent state. If it happens, we can't
      trust the CI results (or at least the fails may be genuine but due to
      the HW being dead and not the actual test!) so reboot the machine (CI
      checks for a kernel taint in between each test and reboots if the
      machine is tainted).
      
      Signed-off-by: default avatarChris Wilson <chris@chris-wilson.co.uk>
      Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
      Cc: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
      Reviewed-by: default avatarMika Kuoppala <mika.kuoppala@linux.intel.com>
      Link: https://patchwork.freedesktop.org/patch/msgid/20190508115245.27790-1-chris@chris-wilson.co.uk
      18ecc6c5
  5. 07 May, 2019 9 commits