VFIO is the real deal - if you can find the right hardware. Unfortunately, there isn't a master list of VFIO compatible hardware (that I know of). You have to scour reddit or the Red Hat VFIO mailing lists hoping someone has posted the motherboard/processor you're interested in.
Once you have hardware, there are lots of resources for pulling it off:
Once you have hardware, there are lots of resources for pulling it off:
https://www.kernel.org/doc/Documentation/vfio.txt
https://www.redhat.com/archives/vfio-users/
https://wiki.archlinux.org/index.php/PCI_passthrough_via_OVM...
https://www.reddit.com/r/VFIO/