Open Stack

On 8/8/2018 2:42 PM, Chris Apsey wrote:
> qemu-system-arm, qemu-system-ppc64, etc. in our environment are all x86 
> packages, but they perform system-mode emulation (via dynamic 
> instruction translation) for those target environments.  So, you run 
> qemu-system-ppc64 on an x86 host in order to get a ppc64-emulated VM. 
> Our use case is specifically directed at reverse engineering binaries 
> and fuzzing for vulnerabilities inside of those architectures for things 
> that aren't built for x86, but there are others.
> 
> If you were to apt-get install qemu-system and then hit autocomplete, 
> you'd get a list of archiectures that qemu can emulate on x86 hardware - 
> that's what we're trying to do incorporate.  We still want to run normal 
> qemu-x86 with KVM virtualization extensions, but we ALSO want to run the 
> other emulators without the KVM virtualization extensions in order to 
> have more choice for target environments.
> 
> So to me, openstack would interpret this by checking to see if a target 
> host supports the architecture specified in the image (it does this 
> correctly), then it would choose the correct qemu-system-xx for spawning 
> the instance based on the architecture flag of the image, which it 
> currently does not (it always choose qemu-system-x86_64).
> 
> Does that make sense?

OK yeah now I'm following you - running ppc guests on an x86 host 
(virt_type=qemu rather than kvm right?).

I would have thought the hw_architecture image property was used for 
this somehow to configure the arch in the guest xml properly, like it's 
used in a few places [1][2][3].

See [4], I'd think we'd set the guest.arch but don't see that happening. 
We do set the guest.os_type though [5].

[1] 
https://github.com/openstack/nova/blob/c18b1c1bd646d7cefa3d3e4b25ce59460d1a6ebc/nova/virt/libvirt/driver.py#L4649
[2] 
https://github.com/openstack/nova/blob/c18b1c1bd646d7cefa3d3e4b25ce59460d1a6ebc/nova/virt/libvirt/driver.py#L4927
[3] 
https://github.com/openstack/nova/blob/c18b1c1bd646d7cefa3d3e4b25ce59460d1a6ebc/nova/virt/libvirt/blockinfo.py#L257
[4] https://libvirt.org/formatcaps.html#elementGuest
[5] 
https://github.com/openstack/nova/blob/c18b1c1bd646d7cefa3d3e4b25ce59460d1a6ebc/nova/virt/libvirt/driver.py#L5196

-- 

Thanks,

Matt