Re: [PATCH v3 1/2] vdpa/mlx5: Set speed and duplex of vDPA devices to UNKNOWN

["Michael S. Tsirkin" <mst@redhat.com>]

On Wed, Sep 04, 2024 at 10:11:14AM -0500, Carlos Bilbao wrote:
> From: Carlos Bilbao <cbilbao@digitalocean.com>
> 
> Initialize the speed and duplex fields in virtio_net_config to UNKNOWN.
> This is needed because mlx5_vdpa vDPA devices currently do not support the
> VIRTIO_NET_F_SPEED_DUPLEX feature which reports speed and duplex.

I see no logic here. Without this feature bit, guests will not read
this field, why do we suddenly need to initialize it?

> Add
> needed helper cpu_to_mlx5vdpa32() to convert endianness of speed.
> 
> Signed-off-by: Carlos Bilbao <cbilbao@digitalocean.com>
> Reviewed-by: Dragos Tatulea <dtatulea@nvidia.com>
> ---
>  drivers/vdpa/mlx5/net/mlx5_vnet.c | 12 ++++++++++++
>  1 file changed, 12 insertions(+)
> 
> diff --git a/drivers/vdpa/mlx5/net/mlx5_vnet.c b/drivers/vdpa/mlx5/net/mlx5_vnet.c
> index b56aae3f7be3..41ca268d43ff 100644
> --- a/drivers/vdpa/mlx5/net/mlx5_vnet.c
> +++ b/drivers/vdpa/mlx5/net/mlx5_vnet.c
> @@ -173,6 +173,11 @@ static __virtio16 cpu_to_mlx5vdpa16(struct mlx5_vdpa_dev *mvdev, u16 val)
>  	return __cpu_to_virtio16(mlx5_vdpa_is_little_endian(mvdev), val);
>  }
>  
> +static __virtio32 cpu_to_mlx5vdpa32(struct mlx5_vdpa_dev *mvdev, u32 val)
> +{
> +	return __cpu_to_virtio32(mlx5_vdpa_is_little_endian(mvdev), val);
> +}
> +
>  static u16 ctrl_vq_idx(struct mlx5_vdpa_dev *mvdev)
>  {
>  	if (!(mvdev->actual_features & BIT_ULL(VIRTIO_NET_F_MQ)))
> @@ -3433,6 +3438,13 @@ static int mlx5_vdpa_dev_add(struct vdpa_mgmt_dev *v_mdev, const char *name,
>  	init_rwsem(&ndev->reslock);
>  	config = &ndev->config;
>  
> +	/*
> +	 * mlx5_vdpa vDPA devices currently don't support reporting or
> +	 * setting the speed or duplex.
> +	 */
> +	config->speed  = cpu_to_mlx5vdpa32(mvdev, SPEED_UNKNOWN);
> +	config->duplex = DUPLEX_UNKNOWN;
> +
>  	if (add_config->mask & BIT_ULL(VDPA_ATTR_DEV_NET_CFG_MTU)) {
>  		err = config_func_mtu(mdev, add_config->net.mtu);
>  		if (err)
> -- 
> 2.34.1