Re: [PATCH rdma-next 00/15] RDMA: Support HW requiring relaxed ordering and add Unordered access flag

[Leon Romanovsky <leon@kernel.org>]

On Sun, Jul 26, 2026 at 12:29:14PM +0300, Michael Gur wrote:
> This series prepares the mlx5 stack for hardware that restricts strong-
> ordered memory accesses, i.e. HW whose fabric doesn't guarantee memory
> operation ordering. The HW may choose to reject creation of an mkey that
> doesn't request relaxed ordering, so every mkey the driver creates -
> internal and user-facing - has to be handled accordingly.
> 
> The previously added 'ConnectX-10 NVLink-C2C' PCI device is such a device,
> as will be any future PCIe Gen7 UIO devices. 
> 
> The series does four things:
> 
> 1. Allow optional access flags on all memory registration
>    The uverbs ABI defines the optional access flags range as best-effort:
>    drivers must accept any flag in this range and treat support as
>    opportunistic, never failing registration. Several registration paths
>    (DM, DEVX UMEM, dmabuf ioctl, reg_mr ioctl) did not allow this range
>    and would reject such requests. These are fixed to allow newly added
>    optional access flag added later in the series and any future optional
>    access flag.
> 
> 2. Groundwork and internal mkeys
>    Rename the relaxed-ordering IFC fields to the new naming, add the new
>    ordering capability and mkey-context bits, and consolidate RO-setting
>    to a single helper in mlx5_core so all consumers share one cap-gated
>    implementation. Then enable relaxed ordering on the internal mkeys that
>    don't require strong ordering (resource dump, vfio live-migration data,
>    ODP null mkey, memory window mkey), so they keep working on strict-RO
>    HW.
> 
> 3. New Unordered access flag and enforcement
>    Add IB_ACCESS_UNORDERED, an optional access flag that additionally
>    allows read-after-write reordering, and wire up mlx5 support for it.
> 
> 4. Enforce no-strong-ordering in user MR registration on HW that requires
>    it.
> 
> Michael Gur (15):
>   RDMA/mlx5: Allow optional access flags in DM registration
>   RDMA/mlx5: Allow optional access flags in DEVX UMEM registration
>   RDMA/core: Allow optional access flags in dmabuf reg ioctl
>   RDMA/core: Allow optional access flags in reg mr ioctl
>   mlx5: Rename IFC bits of relaxed ordering fields
>   net/mlx5: Add IFC bits for new ordering caps
>   mlx5: Move RO setting helper to core and consolidate mlx5 consumers
>   net/mlx5: Enable relaxed ordering on resource dump mkey
>   vfio/mlx5: Enable relaxed ordering on the live migration data mkey
>   RDMA/mlx5: Enable relaxed ordering on ODP null mkey
>   RDMA/mlx5: Enable relaxed ordering on Memory Window mkey on strict-RO
>     HW
>   RDMA/mlx5: Converge UMR access-flag cap checks
>   RDMA/uverbs: Add new Unordered MR access flag
>   RDMA/mlx5: Support new Unordered access flag
>   RDMA/mlx5: Enforce relaxed ordering when HW requires it
> 
>  drivers/infiniband/core/umem.c                |  2 +-
>  drivers/infiniband/core/uverbs_std_types_mr.c |  4 +-
>  drivers/infiniband/hw/mlx5/devx.c             |  2 +-
>  drivers/infiniband/hw/mlx5/main.c             |  8 +-
>  drivers/infiniband/hw/mlx5/mlx5_ib.h          |  4 +-
>  drivers/infiniband/hw/mlx5/mr.c               | 79 ++++++++++---------
>  drivers/infiniband/hw/mlx5/odp.c              |  1 +
>  drivers/infiniband/hw/mlx5/umr.c              | 18 ++---
>  drivers/infiniband/hw/mlx5/umr.h              | 45 ++++++-----
>  .../mellanox/mlx5/core/diag/rsc_dump.c        |  1 +
>  drivers/net/ethernet/mellanox/mlx5/core/en.h  |  1 -
>  .../ethernet/mellanox/mlx5/core/en/params.c   |  2 +-
>  .../ethernet/mellanox/mlx5/core/en_common.c   | 13 +--
>  .../net/ethernet/mellanox/mlx5/core/en_main.c |  4 +-
>  drivers/net/ethernet/mellanox/mlx5/core/mr.c  | 21 +++++
>  drivers/vfio/pci/mlx5/cmd.c                   |  7 +-
>  include/linux/mlx5/driver.h                   |  1 +
>  include/linux/mlx5/mlx5_ifc.h                 | 24 ++++--
>  include/rdma/ib_verbs.h                       |  1 +
>  include/uapi/rdma/ib_user_ioctl_verbs.h       |  1 +
>  20 files changed, 134 insertions(+), 105 deletions(-)

Sashiko is not happy about this series.

Thanks

> 
> -- 
> 2.52.0
>