Re: [PATCH rdma-next] RDMA/core: Rely on vendors to set right IOVA

From: Jason Gunthorpe <jgg@nvidia.com>
To: Leon Romanovsky <leon@kernel.org>
Cc: Doug Ledford <dledford@redhat.com>,
	Aharon Landau <aharonl@nvidia.com>,
	linux-kernel@vger.kernel.org, linux-rdma@vger.kernel.org
Subject: Re: [PATCH rdma-next] RDMA/core: Rely on vendors to set right IOVA
Date: Wed, 3 Nov 2021 09:51:44 -0300	[thread overview]
Message-ID: <20211103125144.GB1298412@nvidia.com> (raw)
In-Reply-To: <4b0a31bbc372842613286a10d7a8cbb0ee6069c7.1635400472.git.leonro@nvidia.com>

On Thu, Oct 28, 2021 at 08:55:22AM +0300, Leon Romanovsky wrote:
> From: Aharon Landau <aharonl@nvidia.com>
> 
> The vendors set the IOVA of newly created MRs in rereg_user_mr, so don't
> overwrite it. That ensures that this field is set only if IB_MR_REREG_TRANS
> flag is provided.
> 
> Fixes: 6e0954b11c05 ("RDMA/uverbs: Allow drivers to create a new HW object during rereg_mr")
> Signed-off-by: Aharon Landau <aharonl@nvidia.com>
> Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
> ---
>  drivers/infiniband/core/uverbs_cmd.c | 3 ---
>  1 file changed, 3 deletions(-)

I rewrote the commit message:

    RDMA/core: Require the driver to set the IOVA correctly during rereg_mr

    If the driver returns a new MR during rereg it has to fill it with the
    IOVA from the proper source. If IB_MR_REREG_TRANS is set then the IOVA is
    cmd.hca_va, otherwise the IOVA comes from the old MR. mlx5 for example has
    two calls inside rereg_mr:

                    return create_real_mr(new_pd, umem, mr->ibmr.iova,
                                          new_access_flags);
    and
                    return create_real_mr(new_pd, new_umem, iova, new_access_flags);

    Unconditionally overwriting the iova in the newly allocated MR will
    corrupt the iova if the first path is used.

    Remove the redundant initializations from ib_uverbs_rereg_mr().

    Fixes: 6e0954b11c05 ("RDMA/uverbs: Allow drivers to create a new HW object during rereg_mr")
    Link: https://lore.kernel.org/r/4b0a31bbc372842613286a10d7a8cbb0ee6069c7.1635400472.git.leonro@nvidia.com
    Signed-off-by: Aharon Landau <aharonl@nvidia.com>
    Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
    Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

Jason