[transpute]

On Xen, QubeOS uses vchan for inter-VM shared memory communication, https://roscidus.com/blog/blog/2019/01/01/using-tla-plus-to-....

Virtio on Xen is still a work in progress, https://wiki.xenproject.org/wiki/Virtio_On_Xen

[kfreds]

Yes. I've used Qubes on and off since 2012. What I'd love to do is run Linux on top of seL4, and virtio-backends in VMs. There is a patch for ivshmemv2, but it seems abandoned.