So, installed cloudmin gpl on a centos 6 minimal install. All went ok, except, br0 was not active and cloudmin said no kvm could be created without a valid bridge interface. I looked over the network config in webmin, and found the issue. The netmask was blank on br0 so the network interface could not be activated. I set the netmask to the same netmask as eth0 and it came up.
Having never used cloudmin, hopefully, this is the correct solution.