[PATCH v2 0/3] drm/xe: add wedged_mode=3 fault inspection

[Daniel Charles <daniel.charles@intel.com>]

This series adds wedged_mode=3, a best-effort inspection mode for examining
Xe after a fault without automatically restarting the GTs. An operator can
release inspection through debugfs by choosing to skip or continue into
permanent wedging.

The patches add the inspection framework, preserve pending TLB invalidation
fences while inspection is active, and request inspection for additional
fault paths while coordinating MMIO-enabled RAS reset requests.

Changes in v2:
- Make inspection one-shot after GT stopping or runtime-resume failure,
  close the teardown admission window, and handle aborted inspection without
  leaving stale TLB pause state.
- Extend the GuC submission timeout guard to recognize inspection startup
  before the execution queues are marked wedged.
- Clarify the power-management requirements and that SKIP leaves the GTs
  stopped; it does not restore normal operation.
- Document that TLB preservation is not a freeze of mapping activity or new
  invalidations. New requests may be canceled and signaled while older
  fences remain preserved, and GGTT invalidations may still program MMIO
  while CT is disabled. Cancellation signaling does not imply hardware
  completion; inspection is not an atomic snapshot.
- Document that preserved fences can block process exit, unbind, or unload,
  and that recovery may require a power cycle.

The TLB behavior does not prevent subsequent mapping changes or independent
reset/resume activity during inspection. Holding newly issued invalidation
fences could also block synchronous callers indefinitely, including callers
holding the GGTT mutex. The series documents these limitations rather than
claiming inspection is an atomic hardware snapshot.

Runtime validation of the specific inspection-startup timeout interleaving
remains pending.

Alan Previn (1):
  drm/xe/wedge: add fault inspection with debugfs release

Daniel Charles (2):
  drm/xe/wedge: preserve pending TLB invalidations during inspection
  drm/xe/wedge: request inspection for additional fault paths

 drivers/gpu/drm/xe/xe_debugfs.c         |  39 +++-
 drivers/gpu/drm/xe/xe_device.c          |  12 +-
 drivers/gpu/drm/xe/xe_gt.c              |  17 +-
 drivers/gpu/drm/xe/xe_gt.h              |   1 +
 drivers/gpu/drm/xe/xe_guc.c             |   2 +-
 drivers/gpu/drm/xe/xe_guc_ads.c         |   2 +-
 drivers/gpu/drm/xe/xe_guc_capture.c     |   2 +-
 drivers/gpu/drm/xe/xe_guc_submit.c      |  25 +-
 drivers/gpu/drm/xe/xe_pagefault.c       |   3 +
 drivers/gpu/drm/xe/xe_pci.c             |  16 +-
 drivers/gpu/drm/xe/xe_pci_error.c       |  11 +
 drivers/gpu/drm/xe/xe_tlb_inval.c       |  63 +++++
 drivers/gpu/drm/xe/xe_tlb_inval.h       |   1 +
 drivers/gpu/drm/xe/xe_tlb_inval_types.h |   4 +
 drivers/gpu/drm/xe/xe_uc.c              |   2 +-
 drivers/gpu/drm/xe/xe_wedge.c           | 292 ++++++++++++++++++++++--
 drivers/gpu/drm/xe/xe_wedge.h           |   4 +
 drivers/gpu/drm/xe/xe_wedge_types.h     |  48 ++++
 18 files changed, 512 insertions(+), 32 deletions(-)

-- 
2.43.0