Re: [RFC PATCH 0/3] drm/xe: diagnostics and workaround for GuC TLB invalidation ack stalls on ARL

[Matthew Brost <matthew.brost@intel.com>]

On Tue, Aug 04, 2026 at 01:34:19PM -0300, Tales A. Mendonça wrote:
> Patchwork reports my address is not on the CI allowlist, so CI was not
> triggered for this series:
> 
>     Series author address 'talesam@gmail.com' is not on the allowlist,
> which prevents CI from being automatically triggered.
> 
>   Could one of the project owners click 'retest' on the series (and/or
> add me to the allowlist)? Series URL:
> 
>     https://patchwork.freedesktop.org/series/171539/
> 

We'd have to resend this ourselves. I can do this, but I've requested
for you to be on our allow list as well. I'll ping here once that goes
through.

Matt 

>   Thanks!
>   Tales
> 
> 
> Em seg., 3 de ago. de 2026 às 23:14, Tales A. Mendonça
> <talesam@gmail.com> escreveu:
> >
> > Hi,
> >
> > This series is a follow-up to the TLB invalidation ack stall I have
> > been debugging on ARL, tracked in:
> >
> >   https://gitlab.freedesktop.org/drm/xe/kernel/-/work_items/8678
> >
> > Summary of the issue: with GuC 70.53.0 on ARL (reproduced on 7d51 and
> > 7dd1 machines here, plus an independent Arc Pro 130T report on the
> > issue above), TLB invalidation acks intermittently stall for ~2.3s.
> > The H2G request is consumed from the CTB immediately and the G2H CTB
> > is empty the whole time - the firmware simply does not send the ack
> > until much later. The fence timeout fires at 2.25s and the ack lands
> > tens of ms after it. Userspace blocked on the invalidation (compositor
> > buffer unmaps etc.) hitches for the full window.
> >
> > Patch 1 adds xe_devcoredump_gt() so this kind of hang - which has no
> > exec queue or job to blame - leaves a devcoredump with the GuC log and
> > CT state behind (Matt suggested capturing devcoredumps when we
> > discussed the issue; devcoredumps from both machines are attached to
> > the issue above).
> >
> > Patch 2 logs when the ack for a timed out invalidation finally
> > arrives. This is what established that the acks are late rather than
> > lost.
> >
> > Patch 3 is the RFC part: a delayed work that pokes the GuC (status
> > register read, CT flush, doorbell ring) every 250ms while an ack is
> > overdue. On my machines this converts the guaranteed 2.3s stall into a
> > sub-500ms hiccup for the majority of occurrences; a minority of severe
> > episodes ignore 8-9 consecutive doorbells, which points at the GuC
> > firmware being internally blocked for the whole window. Full data on
> > the issue. I am happy to rework the approach (different delay,
> > tying it to the G2H handler, dropping the status read, etc.) - mainly
> > I would like the firmware side investigated, since no host-side poke
> > can fix the severe cases.
> >
> > Based on drm-tip. Tested for several days on both ARL machines under
> > desktop and VM-heavy workloads.
> >
> > Thanks,
> > Tales
> >
> > Tales A. Mendonça (3):
> >   drm/xe: Capture devcoredump on TLB invalidation timeout
> >   drm/xe: Log when a timed out TLB invalidation ack finally arrives
> >   drm/xe: Kick GuC while TLB invalidation acks are overdue
> >
> >  drivers/gpu/drm/xe/xe_devcoredump.c     |  68 ++++++++++++
> >  drivers/gpu/drm/xe/xe_devcoredump.h     |   6 ++
> >  drivers/gpu/drm/xe/xe_tlb_inval.c       | 131 +++++++++++++++++++++++-
> >  drivers/gpu/drm/xe/xe_tlb_inval_types.h |  42 ++++++++
> >  4 files changed, 243 insertions(+), 4 deletions(-)
> >
> > --
> > 2.55.0
> >
> 
> 
> -- 
> Com os cumprimentos,
> 
> Tales A. Mendonça
> talesam.org
> communitybig.org