Re: [PATCH V3] vdpa/mlx5: preserve CVQ vringh index

[Steven Sistare]

In V3 I added the fixes tag and the acks.  No other changes.

- Steve

On 11/3/2023 8:26 AM, Steve Sistare 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: 5262912ef3cf ("vdpa/mlx5: Add support for control VQ and MAC setting")
> 
> Signed-off-by: Steve Sistare <steven.sistare@xxxxxxxxxx>
> Acked-by: Eugenio Pérez <eperezma@xxxxxxxxxx>
> Acked-by: Jason Wang <jasowang@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;
>  }
>