This is the fifth version of a series to add support to Nouveau for atomic memory operations on OpenCL shared virtual memory (SVM) regions.
The main changes since v4 are a rebase onto v5.12-rc2, the removal of check_device_exclusive_range() and the addition of MMU_NOTIFY_EXCLUSIVE which makes the extra check unnecessary. The driver can instead filter notifier updates called as part of make_device_exclusive_range().
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.
v5: * Rebased on v5.12-rc2. * Renamed range->migrate_pgmap_owner to range->owner. * Added MMU_NOTIFY_EXCLUSIVE to allow passing of a driver cookie which allows notifiers called as a result of make_device_exclusive_range() to be ignored. * Added a check to try_to_protect_one() to detect if the pages originally returned from get_user_pages() have been unmapped or not. * Removed check_device_exclusive_range() as it is no longer required with the other changes. * Documentation and comments.
v4: * Added pfn_swap_entry_to_page() and reinstated the migration entry page lock check. * Added check_device_exclusive_range() for use during mmu range notifier read side critical section when programming device page tables.
v3: * Refactored some existing functionality. * Switched to using get_user_pages_remote() instead of open-coding it. * Moved code out of hmm.
v2: * Changed implementation to use special swap entries instead of device private pages.
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(-)