Great! A few questions and comments:

How are configuration parameters passed in during device creation
(e.g. MAC address, number of queues)?

Can configuration parameters be changed at runtime (e.g. link up/down)?

Does the configuration parameter interface distinguish between
standard and vendor-specific parameters? Are they namespaced to
prevent naming collisions?

How are software-only parent drivers supported? It's kind of a shame
to modprobe unconditionally if they won't be used. Does vdpatool have
some way of requesting loading a parent driver? That way software
drivers can be loaded on demand.

What is the benefit of making it part of iproute2? If there is not a
significant advantage like sharing code, then I suggest using a
separate repository and package so vdpatool can be installed
separately (e.g. even on AF_VSOCK-only guests without Ethernet).

Stefan