[PATCH 00/16] Add new DMA mapping operation for P2PDMA

[Logan Gunthorpe]

Hi,

This patchset continues my work to to add P2PDMA support to the common
dma map operations. This allows for creating SGLs that have both P2PDMA
and regular pages which is a necessary step to allowing P2PDMA pages in
userspace.

The earlier RFC[1] generated a lot of great feedback and I heard no show
stopping objections. Thus, I've incorporated all the feedback and have
decided to post this as a proper patch series with hopes of eventually
getting it in mainline.

I'm happy to do a few more passes if anyone has any further feedback
or better ideas.

This series is based on v5.12-rc6 and a git branch can be found here:

  https://github.com/sbates130272/linux-p2pmem/  p2pdma_map_ops_v1

Thanks,

Logan

[1] https://lore.kernel.org/linux-block/20210311233142.7900-1-logang@xxxxxxxxxxxx/


Changes since the RFC:
 * Added comment and fixed up the pci_get_slot patch. (per Bjorn)
 * Fixed glaring sg_phys() double offset bug. (per Robin)
 * Created a new map operation (dma_map_sg_p2pdma()) with a new calling
   convention instead of modifying the calling convention of
   dma_map_sg(). (per Robin)
 * Integrated the two similar pci_p2pdma_dma_map_type() and
   pci_p2pdma_map_type() functions into one (per Ira)
 * Reworked some of the logic in the map_sg() implementations into
   helpers in the p2pdma code. (per Christoph)
 * Dropped a bunch of unnecessary symbol exports (per Christoph)
 * Expanded the code in dma_pci_p2pdma_supported() for clarity. (per
   Ira and Christoph)
 * Finished off using the new dma_map_sg_p2pdma() call in rdma_rw
   and removed the old pci_p2pdma_[un]map_sg(). (per Jason)

--

Logan Gunthorpe (16):
  PCI/P2PDMA: Pass gfp_mask flags to upstream_bridge_distance_warn()
  PCI/P2PDMA: Avoid pci_get_slot() which sleeps
  PCI/P2PDMA: Attempt to set map_type if it has not been set
  PCI/P2PDMA: Refactor pci_p2pdma_map_type() to take pagmap and device
  dma-mapping: Introduce dma_map_sg_p2pdma()
  lib/scatterlist: Add flag for indicating P2PDMA segments in an SGL
  PCI/P2PDMA: Make pci_p2pdma_map_type() non-static
  PCI/P2PDMA: Introduce helpers for dma_map_sg implementations
  dma-direct: Support PCI P2PDMA pages in dma-direct map_sg
  dma-mapping: Add flags to dma_map_ops to indicate PCI P2PDMA support
  iommu/dma: Support PCI P2PDMA pages in dma-iommu map_sg
  nvme-pci: Check DMA ops when indicating support for PCI P2PDMA
  nvme-pci: Convert to using dma_map_sg_p2pdma for p2pdma pages
  nvme-rdma: Ensure dma support when using p2pdma
  RDMA/rw: use dma_map_sg_p2pdma()
  PCI/P2PDMA: Remove pci_p2pdma_[un]map_sg()

 drivers/infiniband/core/rw.c |  50 +++-------
 drivers/iommu/dma-iommu.c    |  66 ++++++++++--
 drivers/nvme/host/core.c     |   3 +-
 drivers/nvme/host/nvme.h     |   2 +-
 drivers/nvme/host/pci.c      |  39 ++++----
 drivers/nvme/target/rdma.c   |   3 +-
 drivers/pci/Kconfig          |   2 +-
 drivers/pci/p2pdma.c         | 188 +++++++++++++++++++----------------
 include/linux/dma-map-ops.h  |   3 +
 include/linux/dma-mapping.h  |  20 ++++
 include/linux/pci-p2pdma.h   |  53 ++++++----
 include/linux/scatterlist.h  |  49 ++++++++-
 include/rdma/ib_verbs.h      |  32 ++++++
 kernel/dma/direct.c          |  25 ++++-
 kernel/dma/mapping.c         |  70 +++++++++++--
 15 files changed, 416 insertions(+), 189 deletions(-)


base-commit: e49d033bddf5b565044e2abe4241353959bc9120
--
2.20.1