Contirary to version PowerKVM 2.1, version 3.1 is a little endian Linux Distribution. It means host OS can not be upgraded. 

I installed PowerKVM 3.1 on top of version 2.1. It supposed to be  a fresh installation, but it did not work. The installer was exiting with a strange error. 

Here is my life saving recipe;    

-  Only when I wiped out the disk array setup with iprconfig* , I was able to finish the installation successfully.

-  Power 8 Firmware 830 does not support PowerKVM !! You should upgrade to 840.

-  Shutdown the OS and copy  VM's xml file and image files to an external disk system. You only need to do this, if you are working with local disks.

-  Reinstall PowerKVM 3.1, copy image file and define the VM with the xml file you exported earlier. I assume Host Configuration is not changed.

* https://www-01.ibm.com/support/knowledgecenter/linuxonibm/liaau/liaau-iprutils.htm