[Nullabillity]

As far as I can tell, VirtualBox supports KVM and Hyper-V personalities for its paravirtualization, presumably to be able to reuse virtio/hyperv guest drivers. The host side still seems to require their custom kernel module.

[jchw]

Yep. That said, Virtualbox still has some advantages mostly not related to the actual hypervisor and more related to the UI and other emulation details, so I use this patch to use Virtualbox on top of KVM on my machine.

https://github.com/cyberus-technology/virtualbox-kvm

From my PoV, it mainly is just missing support for more networking options. It's said that it isn't tested much on AMD, but I'm using it on multiple different AMD boxen with no issues.