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From:   Eugenio Perez Martin <eperezma@redhat.com>
Date:   Thu, 2 Nov 2023 08:10:10 +0100
Message-ID: <CAJaqyWfpgQcYbvRgYkvVAq5SiFVVJdWF9PLfOnvd7ipGcjYghA@mail.gmail.com>
Subject: Re: [PATCH V2] vdpa/mlx5: preserve CVQ vringh index
To:     Steve Sistare <steven.sistare@oracle.com>
Cc:     virtualization@lists.linux-foundation.org,
        linux-kernel@vger.kernel.org,
        "Michael S. Tsirkin" <mst@redhat.com>,
        Jason Wang <jasowang@redhat.com>, Eli Cohen <elic@nvidia.com>,
        Si-Wei Liu <si-wei.liu@oracle.com>,
        Dragos Tatulea <dtatulea@nvidia.com>,
        Xuan Zhuo <xuanzhuo@linux.alibaba.com>
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On Wed, Nov 1, 2023 at 4:55=E2=80=AFPM Steve Sistare <steven.sistare@oracle=
.com> 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 =3D 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 P=C3=A9rez <eperezma@redhat.com>

> Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
> ---
>  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/ml=
x5_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 =3D &mvdev->cvq;
>         int err =3D 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 =3D cvq->vring.last_avail_idx;
> +
>                 err =3D vringh_init_iotlb(&cvq->vring, mvdev->actual_feat=
ures,
>                                         MLX5_CVQ_MAX_ENT, false,
>                                         (struct vring_desc *)(uintptr_t)c=
vq->desc_addr,
>                                         (struct vring_avail *)(uintptr_t)=
cvq->driver_addr,
>                                         (struct vring_used *)(uintptr_t)c=
vq->device_addr);
>
> +               if (!err)
> +                       cvq->vring.last_avail_idx =3D cvq->vring.last_use=
d_idx =3D idx;
> +       }
>         return err;
>  }
>
> --
> 2.39.3
>