Re: [PATCH linux-next v3 0/6] vdpa: enable user to set mac, mtu

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

On Fri, Aug 06, 2021 at 10:50:27AM +0800, Jason Wang wrote:
> 
> 在 2021/8/5 下午5:57, Michael S. Tsirkin 写道:
> > On Wed, Jun 16, 2021 at 10:11:49PM +0300, Parav Pandit wrote:
> > > Currently user cannot set the mac address and mtu of the vdpa device.
> > > This patchset enables users to set the mac address and mtu of the vdpa
> > > device once the device is created.
> > > If a vendor driver supports such configuration user can set it otherwise
> > > user gets unsupported error.
> > This makes sense to me overall. People are used to
> > use netlink to set these parameters, and virtio does
> > not necessarily have a way to set all device
> > parameters - they can be RO in the config space.
> 
> 
> I don't get here, we need to care RO as well (e.g the max_virtqueue_pairs).

Point I tried to make is, a virtio transport will not allow writing
max_virtqueue_pairs, but when managing virtio VFs from a PF we do need
to set it.  Thus virtio devices need a new set of interfaces for
managing them, it is not just a virtio transport.

> And do we really want netlink uAPI for virtio like:
> 
>  enum vdpa_attr {
> @@ -33,6 +34,16 @@ enum vdpa_attr {
>  	VDPA_ATTR_DEV_MAX_VQS,			/* u32 */
>  	VDPA_ATTR_DEV_MAX_VQ_SIZE,		/* u16 */
> +	VDPA_ATTR_DEV_NET_CFG_MACADDR,		/* binary */
> +	VDPA_ATTR_DEV_NET_STATUS,		/* u8 */
> +	VDPA_ATTR_DEV_NET_CFG_MAX_VQP,		/* u16 */
> +	VDPA_ATTR_DEV_NET_CFG_MTU,		/* u16 */
> +	VDPA_ATTR_DEV_NET_CFG_SPEED,		/* u16 */
> +	VDPA_ATTR_DEV_NET_CFG_DUPLEX,		/* u16 */
> +	VDPA_ATTR_DEV_NET_CFG_RSS_MAX_KEY_LEN,	/* u8 */
> +	VDPA_ATTR_DEV_NET_CFG_RSS_MAX_IT_LEN,	/* u16 */
> +	VDPA_ATTR_DEV_NET_CFG_RSS_HASH_TYPES,	/* u32 */
> +
>  	/* new attributes must be added above here */
>  	VDPA_ATTR_MAX,
>  };

The point is to try and not reinvent a dedicated vpda interface
where a generic one exits.
E.g. for phy things such as mac speed etc, I think most people are using
ethtool things right?

> Or virtio uAPI and make netlink a transport?
> 
> I prefer the latter since we will meet the similar issue at the hardware
> level when we want to create and provision virtio device dynamically.
> 
> Thanks

Creating devices dynamically exists with e.g. vxlan.
That is using IFLA_MTU IFLA_ADDRESS etc.


> 
> > 
> > 

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