I (accidentally1) did a software update on my laptop last night, and this morning when I needed my Win10 VM for something, VirtualBox threw an error like this at me:
VirtualBox can’t operate in VMX root mode. Please disable the KVM kernel extension, recompile your kernel and reboot (VERR_VMX_IN_VMX_ROOT_MODE).
A quick web search for “fedora update virtualbox vboxisomaker” gave me this forum post and consequently
this bug report, in which I found the solution: I just had to add the kernel parameter kvm.enable_virt_at_load=0 to disable KVM -
which comes enabled by default since Kernel 6.12. I accomplished that with grubby:
sudo grubby --update-kernel=ALL --args="kvm.enable_virt_at_load=0"
After a reboot, VirtualBox started again.
Given how often VirtualBox breaks for me on updates, long term I think I really need to find a different solution… And yes, I also really need to upgrade to Fedora 41, I know 😉
I needed to a quick reboot before an online call and promptly forgot to uncheck “install updates” on the reboot dialog. Which made me be late on the call. Meh. ↩︎