Re: [PATCH V2] vdpa/mlx5: preserve CVQ vringh index

[Eugenio Perez Martin]

On Wed, Nov 1, 2023 at 4:55 PM Steve Sistare <steven.sistare@xxxxxxxxxx> wrote:
>
> mlx5_vdpa does not preserve userland's view of vring base for the control
> queue in the following sequence:
>
> ioctl VHOST_SET_VRING_BASE
> ioctl VHOST_VDPA_SET_STATUS VIRTIO_CONFIG_S_DRIVER_OK
>   mlx5_vdpa_set_status()
>     setup_cvq_vring()
>       vringh_init_iotlb()
>         vringh_init_kern()
>           vrh->last_avail_idx = 0;
> ioctl VHOST_GET_VRING_BASE
>
> To fix, restore the value of cvq->vring.last_avail_idx after calling
> vringh_init_iotlb.
>

Fixes tag missing?

Apart from that,

Acked-by: Eugenio Pérez <eperezma@xxxxxxxxxx>

> Signed-off-by: Steve Sistare <steven.sistare@xxxxxxxxxx>
> ---
>  drivers/vdpa/mlx5/net/mlx5_vnet.c | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/vdpa/mlx5/net/mlx5_vnet.c b/drivers/vdpa/mlx5/net/mlx5_vnet.c
> index 946488b8989f..ca972af3c89a 100644
> --- a/drivers/vdpa/mlx5/net/mlx5_vnet.c
> +++ b/drivers/vdpa/mlx5/net/mlx5_vnet.c
> @@ -2795,13 +2795,18 @@ static int setup_cvq_vring(struct mlx5_vdpa_dev *mvdev)
>         struct mlx5_control_vq *cvq = &mvdev->cvq;
>         int err = 0;
>
> -       if (mvdev->actual_features & BIT_ULL(VIRTIO_NET_F_CTRL_VQ))
> +       if (mvdev->actual_features & BIT_ULL(VIRTIO_NET_F_CTRL_VQ)) {
> +               u16 idx = cvq->vring.last_avail_idx;
> +
>                 err = vringh_init_iotlb(&cvq->vring, mvdev->actual_features,
>                                         MLX5_CVQ_MAX_ENT, false,
>                                         (struct vring_desc *)(uintptr_t)cvq->desc_addr,
>                                         (struct vring_avail *)(uintptr_t)cvq->driver_addr,
>                                         (struct vring_used *)(uintptr_t)cvq->device_addr);
>
> +               if (!err)
> +                       cvq->vring.last_avail_idx = cvq->vring.last_used_idx = idx;
> +       }
>         return err;
>  }
>
> --
> 2.39.3
>