On Tue, Mar 21, 2023 at 05:18:03AM -0700, KernelCI bot wrote:
The KernelCI bisection bot found a boot bisection on one of the HP
ChromeBooks in v5.10.175 triggered by b5005605013d ("drm/i915: Don't use
BAR mappings for ring buffers with LLC"). The system appears to die
very early in boot with no output.
I've left the full report from the bot below, including links to full
boot logs such as they are and a tag for the bot, and the full web
dashboard for the test case fail is at:
https://linux.kernelci.org/test/plan/id/64147346939869e04b8c8694/
including details of the successful test on v5.10.174.
> * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
> * This automated bisection report was sent to you on the basis *
> * that you may be involved with the breaking commit it has *
> * found. No manual investigation has been done to verify it, *
> * and the root cause of the problem may be somewhere else. *
> * *
> * If you do send a fix, please include this trailer:*
> * Reported-by: "kernelci.org bot" *
> * *
> * Hope this helps! *
> * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
>
> stable-rc/linux-5.10.y bisection: baseline.login on hp-x360-14-G1-sona
>
> Summary:
> Start: de26e1b2103b Linux 5.10.175
> Plain log:
> https://storage.kernelci.org/stable-rc/linux-5.10.y/v5.10.175/x86_64/x86_64_defconfig+x86-chromebook/gcc-10/lab-collabora/baseline-hp-x360-14-G1-sona.txt
> HTML log:
> https://storage.kernelci.org/stable-rc/linux-5.10.y/v5.10.175/x86_64/x86_64_defconfig+x86-chromebook/gcc-10/lab-collabora/baseline-hp-x360-14-G1-sona.html
> Result: b5005605013d drm/i915: Don't use BAR mappings for ring buffers
> with LLC
>
> Checks:
> revert: PASS
> verify: PASS
>
> Parameters:
> Tree: stable-rc
> URL:
> https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable-rc.git
> Branch: linux-5.10.y
> Target: hp-x360-14-G1-sona
> CPU arch: x86_64
> Lab:lab-collabora
> Compiler: gcc-10
> Config: x86_64_defconfig+x86-chromebook
> Test case: baseline.login
>
> Breaking commit found:
>
> ---
> commit b5005605013d30ab27c303cbaeff60b7872234a3
> Author: John Harrison
> Date: Wed Feb 15 17:11:01 2023 -0800
>
> drm/i915: Don't use BAR mappings for ring buffers with LLC
>
> commit 85636167e3206c3fbd52254fc432991cc4e90194 upstream.
>
> Direction from hardware is that ring buffers should never be mapped
> via the BAR on systems with LLC. There are too many caching pitfalls
> due to the way BAR accesses are routed. So it is safest to just not
> use it.
>
> Signed-off-by: John Harrison
> Fixes: 9d80841ea4c9 ("drm/i915: Allow ringbuffers to be bound anywhere")
> Cc: Chris Wilson
> Cc: Joonas Lahtinen
> Cc: Jani Nikula
> Cc: Rodrigo Vivi
> Cc: Tvrtko Ursulin
> Cc: intel-...@lists.freedesktop.org
> Cc: # v4.9+
> Tested-by: Jouni Högander
> Reviewed-by: Daniele Ceraolo Spurio
> Link:
> https://patchwork.freedesktop.org/patch/msgid/20230216011101.1909009-3-john.c.harri...@intel.com
> (cherry picked from commit 65c08339db1ada87afd6cfe7db8e60bb4851d919)
> Signed-off-by: Jani Nikula
> Signed-off-by: John Harrison
> Signed-off-by: Greg Kroah-Hartman
>
> diff --git a/drivers/gpu/drm/i915/gt/intel_ring.c
> b/drivers/gpu/drm/i915/gt/intel_ring.c
> index 4034a4bac7f0..69b2e5509d67 100644
> --- a/drivers/gpu/drm/i915/gt/intel_ring.c
> +++ b/drivers/gpu/drm/i915/gt/intel_ring.c
> @@ -49,7 +49,7 @@ int intel_ring_pin(struct intel_ring *ring, struct
> i915_gem_ww_ctx *ww)
> if (unlikely(ret))
> goto err_unpin;
>
> - if (i915_vma_is_map_and_fenceable(vma))
> + if (i915_vma_is_map_and_fenceable(vma) && !HAS_LLC(vma->vm->i915))
> addr = (void __force *)i915_vma_pin_iomap(vma);
> else
> addr = i915_gem_object_pin_map(vma->obj,
> @@ -91,7 +91,7 @@ void intel_ring_unpin(struct intel_ring *ring)
> return;
>
> i915_vma_unset_ggtt_write(vma);
> - if (i915_vma_is_map_and_fenceable(vma))
> + if (i915_vma_is_map_and_fenceable(vma) && !HAS_LLC(vma->vm->i915))
> i915_vma_unpin_iomap(vma);
> else
> i915_gem_object_unpin_map(vma-&g
