Re: [PATCH] vdpa/mlx5: Use random MAC for the vdpa net instance

[Jason Wang]

On 2020/12/2 下午9:07, Michael S. Tsirkin wrote:
> > > > Two questions here:
> > > > 1. Now we don't have support for control virtqueue. Yet, we must filter
> > > > packets based on MAC, what do you suggest to do here?
> > > How about an ioctl to pass the mac to the device?
> > > Maybe mirroring the control vq struct format ...
> > I think we'd better avoid such ad-hoc ioctls to make vhost-vDPA type
> > independent.
> Fundamentally this is about handling some VQs in QEMU, right?
> Maybe a generic ioctl along the lines of "CTRL_VQ" passing
> vq number and a command buffer from guest?
> Seems generic enough for you?

It looks to me you want to invent a synchronized API (or vDPA config 
ops) for submitting virtio descriptors.

Several issues I can think for this:

1) control vq allows the request to be handled asynchronously
2) we still need a way to isolate the DMA if there's a hardware 
virtqueue for the device that use DMA
3) new vDPA config operations need to be invented, new uAPI for 
vhost-vDPA, new virtio config ops for virtio-vDPA

It looks to me we can overcome 1) and 2) if we just stick to a virtqueue 
interface in vhost-vDPA as I proposed in [1]. For issue 3) it also 
requires much less work.

Thanks

[1] https://lkml.org/lkml/2020/9/23/1243