[Nouveau] [PATCH v3 0/5] mm/hmm/nouveau: add PMD system memory mapping

[Ralph Campbell]

The goal for this series is to introduce the hmm_pfn_to_map_order()
function. This allows a device driver to know that a given 4K PFN is
actually mapped by the CPU using a larger sized CPU page table entry and
therefore the device driver can safely map system memory using larger
device MMU PTEs.
The series is based on 5.8.0-rc3 and is intended for Jason Gunthorpe's
hmm tree. These were originally part of a larger series:
https://lore.kernel.org/linux-mm/20200619215649.32297-1-rcampbell@nvidia.com/

Changes in v3:
Replaced the HMM_PFN_P[MU]D flags with hmm_pfn_to_map_order() to
indicate the size of the CPU mapping.

Changes in v2:
Make the hmm_range_fault() API changes into a separate series and add
  two output flags for PMD/PUD instead of a single compund page flag as
  suggested by Jason Gunthorpe.
Make the nouveau page table changes a separate patch as suggested by
  Ben Skeggs.
Only add support for 2MB nouveau mappings initially since changing the
1:1 CPU/GPU page table size assumptions requires a bigger set of changes.
Rebase to 5.8.0-rc3.

Ralph Campbell (5):
  nouveau/hmm: fault one page at a time
  mm/hmm: add hmm_mapping order
  nouveau: fix mapping 2MB sysmem pages
  nouveau/hmm: support mapping large sysmem pages
  hmm: add tests for HMM_PFN_PMD flag

 drivers/gpu/drm/nouveau/nouveau_svm.c         | 236 ++++++++----------
 drivers/gpu/drm/nouveau/nvkm/subdev/mmu/vmm.c |   5 +-
 .../drm/nouveau/nvkm/subdev/mmu/vmmgp100.c    |  82 ++++++
 include/linux/hmm.h                           |  24 +-
 lib/test_hmm.c                                |   4 +
 lib/test_hmm_uapi.h                           |   4 +
 mm/hmm.c                                      |  14 +-
 tools/testing/selftests/vm/hmm-tests.c        |  76 ++++++
 8 files changed, 299 insertions(+), 146 deletions(-)

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2.20.1