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Date:   Sun, 30 May 2021 11:15:36 +0300
From:   Eli Cohen <elic@nvidia.com>
To:     "Michael S. Tsirkin" <mst@redhat.com>
CC:     <jasowang@redhat.com>, <virtualization@lists.linux-foundation.org>,
        <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 1/2] vdpa/mlx5: Fix umem sizes assignments on VQ create
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On Sun, May 30, 2021 at 04:05:16AM -0400, Michael S. Tsirkin wrote:
> On Sun, May 30, 2021 at 09:31:28AM +0300, Eli Cohen wrote:
> > Fix copy paste bug assigning umem1 size to umem2 and umem3.
> > 
> > Fixes: 1a86b377aa21 ("vdpa/mlx5: Add VDPA driver for supported mlx5 devices")
> > Signed-off-by: Eli Cohen <elic@nvidia.com>
> 
> could you clarify the impact of the bug please?
> 

I leads to firmware failure to create the virtqueue resource when you
try to use a 1:1 mapping MR. This kind of usage is presented in the
virtio_vdpa support I sent earlier.

> > ---
> >  drivers/vdpa/mlx5/net/mlx5_vnet.c | 4 ++--
> >  1 file changed, 2 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/vdpa/mlx5/net/mlx5_vnet.c b/drivers/vdpa/mlx5/net/mlx5_vnet.c
> > index 189e4385df40..53312f0460ad 100644
> > --- a/drivers/vdpa/mlx5/net/mlx5_vnet.c
> > +++ b/drivers/vdpa/mlx5/net/mlx5_vnet.c
> > @@ -828,9 +828,9 @@ static int create_virtqueue(struct mlx5_vdpa_net *ndev, struct mlx5_vdpa_virtque
> >  	MLX5_SET(virtio_q, vq_ctx, umem_1_id, mvq->umem1.id);
> >  	MLX5_SET(virtio_q, vq_ctx, umem_1_size, mvq->umem1.size);
> >  	MLX5_SET(virtio_q, vq_ctx, umem_2_id, mvq->umem2.id);
> > -	MLX5_SET(virtio_q, vq_ctx, umem_2_size, mvq->umem1.size);
> > +	MLX5_SET(virtio_q, vq_ctx, umem_2_size, mvq->umem2.size);
> >  	MLX5_SET(virtio_q, vq_ctx, umem_3_id, mvq->umem3.id);
> > -	MLX5_SET(virtio_q, vq_ctx, umem_3_size, mvq->umem1.size);
> > +	MLX5_SET(virtio_q, vq_ctx, umem_3_size, mvq->umem3.size);
> >  	MLX5_SET(virtio_q, vq_ctx, pd, ndev->mvdev.res.pdn);
> >  	if (MLX5_CAP_DEV_VDPA_EMULATION(ndev->mvdev.mdev, eth_frame_offload_type))
> >  		MLX5_SET(virtio_q, vq_ctx, virtio_version_1_0, 1);
> > -- 
> > 2.31.1
>