Gnome Boxes on Ubuntu 18.04

I've recently tried to install Gnome Boxes on my computers. Mainly because I wanted to test how it performance against Virtualbox. Virtualbox is currently still owned by Oracle and they don't have a great track record with free software. Therefore it's a good idea to have an eye on alternatives to the products they provide.

While the main installation went fine I wasn't able to get a VM up and running. When I launched Boxes from the command line, it showed me this error message:

Failed to start windows-10: Unable to start domain: unsupported configuration: CPU mode 'custom' for x86_64 kvm domain on x86_64 host is not supported by hypervisor

After a bit of searching around I've found this bug report:

The last post from Stephen Matin contained the solution. You basically have to do the following:

Install Gnome Boxes and the qemu-kvm and libvirt-bin packages.

sudo apt install gnome-boxes qemu-kvm libvirt-bin

Add your user to the group kvm

sudo usermod -a -G kvm $USER

Allow users in the kvm group to start KVM virtual machines.

sudo sed -i -e 's/\#group\ =\ "root"/group=kvm/g' /etc/libvirt/qemu.conf


Now you can restart your computer and Gnome Boxes should work as expected.