[RFC 0/7] drm/xe/svm: Add MMU notifier-based madvise autoreset on munmap

[Arvind Yadav <arvind.yadav@intel.com>]

This series implements automatic reset of GPU memory attributes when userspace
unmaps memory (munmap), ensuring non-default attributes don't persist after
CPU mappings are freed.

The implementation uses MMU interval notifiers to detect munmap events on
CPU-only VMAs (not yet GPU-faulted). When detected, work is queued to reset
their attributes to defaults. GPU-touched VMAs continue using existing SVM
notifiers and are not affected by this series.

The autoreset is best-effort. The CPU_AUTORESET_ACTIVE flag serves as the
authoritative state - if notifier delivery fails, the GPU page table zapping
path checks this flag directly, ensuring correctness regardless of notifier
delivery.

Key aspects:
- CPU_AUTORESET_ACTIVE flag tracks CPU-only vs GPU-touched state
- Notifier callbacks queue work (cannot take vm->lock due to lock ordering)
- Workqueue processes resets under vm->lock, serializing with VM operations
- Mempool prevents allocation failures in atomic context
- Clean teardown: closing flag + SRCU sync + workqueue drain

Patch organization:
1. Add CPU_AUTORESET_ACTIVE flag definition
2. Propagate flag across GPUVA operations (map/remap/split)
3. Clear flag on GPU touch (one-way CPU-only → GPU-touched transition)
4. Add MMU notifier + workqueue infrastructure
5. Deactivate notifier optimization (avoid overhead after GPU touch)
6. Wire notifiers into VM lifecycle (init/fini/teardown)
7. Fix partial unmap attribute reset handling

Arvind Yadav (6):
  drm/xe/vm: Add CPU_AUTORESET_ACTIVE VMA flag
  drm/xe/vm: Preserve CPU_AUTORESET_ACTIVE across GPUVA operations
  drm/xe/svm: Clear CPU_AUTORESET_ACTIVE on first GPU fault
  drm/xe/vm: Add madvise autoreset interval notifier worker
    infrastructure
  drm/xe/vm: Deactivate madvise notifier on GPU touch
  drm/xe/vm: Wire MADVISE_AUTORESET notifiers into VM lifecycle

Himal Prasad Ghimiray (1):
  drm/xe/svm: Correct memory attribute reset for partial unmap

 drivers/gpu/drm/xe/xe_svm.c        |  78 +++-
 drivers/gpu/drm/xe/xe_svm.h        |  10 +
 drivers/gpu/drm/xe/xe_vm.c         |  50 ++-
 drivers/gpu/drm/xe/xe_vm.h         |  18 +
 drivers/gpu/drm/xe/xe_vm_madvise.c | 553 ++++++++++++++++++++++++++++-
 drivers/gpu/drm/xe/xe_vm_madvise.h |  10 +
 drivers/gpu/drm/xe/xe_vm_types.h   |  51 +++
 7 files changed, 749 insertions(+), 21 deletions(-)

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2.43.0