[v6,0/8] Add support for SVM atomics in Nouveau

Message

Alistair Popple March 12, 2021, 8:38 a.m. UTC

This is the sixth version of a series to add support to Nouveau for atomic
memory operations on OpenCL shared virtual memory (SVM) regions.

There are no significant changes for version six other than correcting a
minor s390 build and bisectability issue and removing a redundant call to
compound_page() when checking for PageLocked in patch 1.

Exclusive device access is implemented by adding a new swap entry type
(SWAP_DEVICE_EXCLUSIVE) which is similar to a migration entry. The main
difference is that on fault the original entry is immediately restored by
the fault handler instead of waiting.

Restoring the entry triggers calls to MMU notifers which allows a device
driver to revoke the atomic access permission from the GPU prior to the CPU
finalising the entry.

Patches 1 & 2 refactor existing migration and device private entry
functions.

Patches 3 & 4 rework try_to_unmap_one() by splitting out unrelated
functionality into separate functions - try_to_migrate_one() and
try_to_munlock_one(). These should not change any functionality, but any
help testing would be much appreciated as I have not been able to test
every usage of try_to_unmap_one().

Patch 5 contains the bulk of the implementation for device exclusive
memory.

Patch 6 contains some additions to the HMM selftests to ensure everything
works as expected.

Patch 7 is a cleanup for the Nouveau SVM implementation.

Patch 8 contains the implementation of atomic access for the Nouveau
driver.

This has been tested using the latest upstream Mesa userspace with a simple
OpenCL test program which checks the results of atomic GPU operations on a
SVM buffer whilst also writing to the same buffer from the CPU.

Alistair Popple (8):
  mm: Remove special swap entry functions
  mm/swapops: Rework swap entry manipulation code
  mm/rmap: Split try_to_munlock from try_to_unmap
  mm/rmap: Split migration into its own function
  mm: Device exclusive memory access
  mm: Selftests for exclusive device memory
  nouveau/svm: Refactor nouveau_range_fault
  nouveau/svm: Implement atomic SVM access

 Documentation/vm/hmm.rst                      |  19 +-
 arch/s390/mm/pgtable.c                        |   2 +-
 drivers/gpu/drm/nouveau/include/nvif/if000c.h |   1 +
 drivers/gpu/drm/nouveau/nouveau_svm.c         | 130 +++-
 drivers/gpu/drm/nouveau/nvkm/subdev/mmu/vmm.h |   1 +
 .../drm/nouveau/nvkm/subdev/mmu/vmmgp100.c    |   6 +
 fs/proc/task_mmu.c                            |  23 +-
 include/linux/mmu_notifier.h                  |  25 +-
 include/linux/rmap.h                          |   9 +-
 include/linux/swap.h                          |   8 +-
 include/linux/swapops.h                       | 123 ++--
 lib/test_hmm.c                                | 126 +++-
 lib/test_hmm_uapi.h                           |   2 +
 mm/debug_vm_pgtable.c                         |  12 +-
 mm/hmm.c                                      |  12 +-
 mm/huge_memory.c                              |  45 +-
 mm/hugetlb.c                                  |  10 +-
 mm/memcontrol.c                               |   2 +-
 mm/memory.c                                   | 127 +++-
 mm/migrate.c                                  |  41 +-
 mm/mprotect.c                                 |  18 +-
 mm/page_vma_mapped.c                          |  15 +-
 mm/rmap.c                                     | 597 +++++++++++++++---
 tools/testing/selftests/vm/hmm-tests.c        | 219 +++++++
 24 files changed, 1313 insertions(+), 260 deletions(-)