Re: [PATCH rdma-next v2 14/15] RDMA/mlx5: Support new Unordered access flag

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] RDMA/mlx5: missing IB_ACCESS_UNORDERED in _mlx5r_umr_update_mr_pas() for DD
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commit d54e400e3350128fbcd9fb5d5bce4f37dfe241bd
Author: Michael Gur <michaelgur@nvidia.com>

RDMA/mlx5: Support new Unordered access flag

This commit adds mlx5_ib support for the IB_ACCESS_UNORDERED flag by mapping
it to MLX5_MKEY_ORDER_UNORDERED, enabling ATS on DMABUF MRs with unordered
access, and marking the flag as unchangeable via UMR.

> diff --git a/drivers/infiniband/hw/mlx5/mlx5_ib.h b/drivers/infiniband/hw/mlx5/mlx5_ib.h
> index dd1fe8fd42206..75ea3f91e9314 100644
> --- a/drivers/infiniband/hw/mlx5/mlx5_ib.h
> +++ b/drivers/infiniband/hw/mlx5/mlx5_ib.h
> @@ -1672,11 +1672,13 @@ static inline bool mlx5_umem_needs_ats(struct mlx5_ib_dev *dev,
>  {
>  	if (!MLX5_CAP_GEN(dev->mdev, ats) || !umem->is_dmabuf)
>  		return false;
> -	return access_flags & IB_ACCESS_RELAXED_ORDERING;
> +	return access_flags & (IB_ACCESS_RELAXED_ORDERING | IB_ACCESS_UNORDERED);
>  }
>  
>  static inline enum mlx5_mkey_order mlx5r_access_to_mkey_order(int access_flags)
>  {
> +	if (access_flags & IB_ACCESS_UNORDERED)
> +		return MLX5_MKEY_ORDER_UNORDERED;
>  	if (access_flags & IB_ACCESS_RELAXED_ORDERING)
>  		return MLX5_MKEY_ORDER_RELAXED;
>  	return MLX5_MKEY_ORDER_STRICT;

[Severity: Medium]
As reported by Sashiko on v1 [1], when a Data-Direct DMABUF MR is registered
with IB_ACCESS_UNORDERED via mlx5_ib_reg_user_mr_dmabuf() ->
reg_user_mr_dmabuf_by_data_direct(), both crossed_mr and crossing_mr are
configured with MLX5_MKEY_ORDER_UNORDERED and ATS via
mlx5r_access_to_mkey_order() and mlx5_umem_needs_ats().

However, when populating the KSM entries in
drivers/infiniband/hw/mlx5/umr.c:_mlx5r_umr_update_mr_pas(), only
IB_ACCESS_RELAXED_ORDERING is checked when selecting between mdd->mkey_ro and
mdd->mkey:

		if (dd) {
			struct mlx5_data_direct *mdd = dev->mdev->data_direct;

			cur_ksm->va = cpu_to_be64(rdma_block_iter_dma_address(&biter));
			if (mr->access_flags & IB_ACCESS_RELAXED_ORDERING &&
			    mdd->mkey_ro_valid)
				cur_ksm->key = cpu_to_be32(mdd->mkey_ro);
			else
				cur_ksm->key = cpu_to_be32(mdd->mkey);

Similarly, in
drivers/infiniband/hw/mlx5/mr.c:reg_user_mr_dmabuf_by_data_direct(), when
mkey_ro_valid is false, only IB_ACCESS_RELAXED_ORDERING is masked out of
access_flags:

	if (!dev->mdev->data_direct->mkey_ro_valid)
		access_flags &= ~IB_ACCESS_RELAXED_ORDERING;

Should _mlx5r_umr_update_mr_pas() and reg_user_mr_dmabuf_by_data_direct()
also handle IB_ACCESS_UNORDERED so that Data-Direct KSM entries and
crossed_mr/crossing_mr ordering match the underlying Data-Direct mkey?

[1] https://lore.kernel.org/r/20260726092943.2880176-15-michaelgur@nvidia.com

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20261102223325.2115128-1-michaelgur@nvidia.com?part=14