Re: [RFC] hypercall-vsock: add a new vsock transport

[Paolo Bonzini]

On 11/11/21 09:14, Wang, Wei W wrote:
> > Adding Andra and Sergio, because IIRC Firecracker and libkrun 
> > emulates virtio-vsock with virtio-mmio so the implementation
> > should be simple and also not directly tied to a specific VMM.
> OK. This would be OK for KVM based guests. For Hyperv and VMWare 
> based guests, they don't have virtio-mmio support. If the MigTD (a 
> special guest) we provide is based on virtio-mmio, it would not be 
> usable to them.

Hyper-V and VMware (and KVM) would have to add support for
hypercall-vsock anyway.  Why can't they just implement a subset of
virtio-mmio?  It's not hard and there's even plenty of permissively-
licensed code in the various VMMs for the *BSDs.

In fact, instead of defining your own transport for vsock, my first idea
would have been the opposite: reuse virtio-mmio for the registers and
the virtqueue format, and define your own virtio device for the MigTD!

Thanks,

Paolo