Comment 20 for bug 1431473

Thanks Oleg. I guess it being canonistack we probably can assume Precise on the host. Based on that assumption I also did some tests. And there found that it is indeed a combination of host kernel / guest kernel which causes this. Looking at the kernel code there are many places that can actually exit with -EIO (sadly all without giving any hint about the specific mismatch that is causing the failure). Those mostly seem to be concerned with checking MSRs about correct configuration. So the cpuid flags may be different but at the same time could be just fluke. There should be ways to influence those in libvirt but now I think this may not help.

So my finding on the same Hashwell/Sharbay system:
- host 3.2: guest 3.2: ok
- host 3.2: guest 3.16: not ok
- host 3.13: guest: 3.16: ok

So this seems to be some mismatch in what the hosts kvm passes into the L1 guests vmx msr which in turn the L1 kvm module validates on load. But since I have now a setup combination that triggers the issue I can prepare a more verbose kvm-intel module to try locally.