I need a libvirt daemon running in order to use virt-manager

I want to use virt-manager because I want to use an Ubunu installation as a virtual machine, for reasons

I see there are 2 different services in gnu/services/virtualization.scm: a libvirt and a virtlog service

Because I don't now that much about virtualization, could anyone please give me an example of how I should configure such services in my conf file, in order to have an Ubuntu desktop ?

Thanks in advance