Introduce vhost-user support in passt, to (optionally, depending on operation mode) replace the AF_UNIX interface with qemu and avoid two user/kernel copies. Further rationale and perspective was elaborated in:

https://issues.redhat.com/browse/CNV-11474

and this is tracked upstream at:

https://bugs.passt.top/show_bug.cgi?id=25

we'll add more details about a possible configuration options and what's critical for testing as we evaluate this.