this sounds really,really good.
Under windows, my rx580 cards can achieve 31.9MH/s, but under Linux, I cannot get past 21.6MH/s.
I am trying to install this OS in libvirt, as my ubuntu box also does other tasks. It is working with Wn10 and Ubuntu, but I have issues with HiveOS.
I created a partition and used 'dd' to transfer the image.
about hashrate this seems to be related to PCI bus options in bios. try gen1 or something else.
About libvirt can't give you a good advice. The image you download is a full disk image, not just a partition. That disk has 2 partitions there.