Comment # 12 on bug 1215984 from Charles Arnold

There are two main ways.
The first is as you mentioned. The role is selected at host installation for
KVM and tools. This should get users a functioning setup.

The second is after host installation. Users may run 'Install Hypervisor and
Tools' from a GUI menu or 'yast2 virtualization' from the command line and
there select their desired virtualization pattern (KVM server, KVM Tools,
or both).

Other ways of enabling KVM virtualization on the host such as using zypper
and systemctl are possible but not recommended.