[Libguestfs] [PATCH virt-v2v] v2v: windows: Install both legacy and modern virtio

[Richard W.M. Jones]

Hello Roman,

We have a bug with Windows 8 UEFI conversions failing with the usual
0x7B error:

  https://bugzilla.redhat.com/show_bug.cgi?id=1431579

There is a seemingly plausible theory that this happens because for
UEFI we use a qemu Q35 machine type.

Q35 machine type implies all-modern PCI-e devices, which implies the
use of virtio-1.0 and disabling of virtio legacy.

Virtio-1.0 uses different Windows registry keys: viostor changes from
VEN_1AF4&DEV_1001&SUBSYS_00021AF4&REV_00 ->
VEN_1AF4&DEV_1042&SUBSYS_11001AF4&REV_01, and vioscsi has a similar
change.

As we are only installing the virtio legacy key, but presenting
PCI-e virtio-1.0 (modern) devices to the guest, this may cause Windows
to fail to boot.

I have not gone beyond compile-testing the attached patch, but what do
you think?  I will try to actually test this tomorrow, but I wondered
if you have any comments.

Thanks,
Rich.