thanks to Cedric's hard work we have qemu 4.2 rc1 rpms with the powernv
machine type  available in my copr . It should be a drop-in
replacement of the qemu rpms from the virt-preview repo . The plan
is to follow virt-preview and update the "powernv" builds when they
update qemu to newer snaphots or releases. Long term plan is to have
powernv merged to the mainline qemu.