KVM and VirtualBox (and BHyVe?) support virtio, and we finally have virtio drivers in base tree.
These virtualization technologies are sometimes used in resource restricted VPS and IaaS environments. For those environments, I made pre-built binary packages of virtio kernel loadble modules. You can activate virtio devices in your FreeBSD guests with only pkg_add, edit rc.conf/fstab, change host setting, and rebooting.
Currenly amd64 arch only.
(r234349 cannot be compiled on 8.2)