linux59 5.9.0-1 from unstable a try. The virtualbox modules (dkms) do not compile for it. That is not realy a surprise.
gnome-boxes, which uses
libvirt, is not working either. It does not even show me the boxes I already have setup. When I boot back into kernel 5.8 the boxes are still there, but with kernel 5.9 I do not see them and I can not create new boxes.
This is for a Ryzen 7 processor and I had to set
options kvm ignore_msrs=1
to make gnome-boxes work even with kernel 5.8