[SOLVED]VirtualBox VT-x stopped working since QEMU installed

[mailedfist]

Hello All.

I have been happily using VirtualBox for many years but thought I'd try using KVM through QEMU as I'd read some reports that it can be faster. This was a mistake as I now find that any VM I have in VirtualBox that is configured for multiple processors, and therefore needs to use VT-x, no longer works.

I get an error "VT-x is being used by another hypervisor". I presume this means that some part of QEMU/libvirt is still running even when I have nothing started in the Virtual Machine Manager. Do I have any options other than uninstalling QEMU?

[mailedfist]

Addendum: This is on Mageia 3

[ITA84]

It's probably the KVM kernel modules that are preventing those VM from working. I suppose blacklisting the modules would be a way to make things work; of course you wouldn't be able to use KVM and VirtualBox VMs at the same time.

The modules should be 'kvm' and either 'kvm_intel' or 'kvm_amd'. I can't remember if there's more.

[mailedfist]

This is what the VirtualBox error hints at, but I thought that was misleading. Surely KVM has been bundled into the kernel for some time? Just installing the QEMU module shouldn't make VirtualBox suddenly decide it can't handle the fact that kernel has KVM in surely?

[mailedfist]

Ah - see what you mean now. /sbin/rmmod kvm_intel does indeed solve the problem, so the module load list was changed by adding QEMU. Thank you.