[ubuntu-cloud] Question- could an Ubuntu EC2 "host" instance detect use by a Qemu guest OS of XEN Paravirtualization Driver (GPLPV) I/O driver requests

[Scott Moser]

On Sat, 23 Oct 2010, brian mullan wrote:

>  Scott & Ahmed...
>
> The discussion about running UEC on EC2 is interesting because it relates
> somewhat to something I was looking at last month.
> A month ago I spent some time looking at the XEN Paravirtualization Drivers
> (GPLPV) <http://wiki.xensource.com/xenwiki/XenWindowsGplPv>.
>
> My initial thought was maybe I could somehow:
>
>    - using EC2 Ubuntu instance
>    - install a Windows OS on that instance using Qemu
>
> then ... Install in Windows install the Xen Paravirtualization drivers
> (GPLPV)
>
> It was actually a "Duh" moment because I soon realized that although I could
> install the GPLPV drivers on the Windows Qemu vm within
> the Ubuntu EC2 instance... that the Qemu Windows VM was still NOT going to
> be able to directly access the XEN environment
> *because the Qemu Windows was running inside Ubuntu* which was between
> Windows Qemu vm and EC2's XEN hypervisor environment.

Sorry for the slow response.  It seems that your general understanding is
correct.  To accomplish what you want, you'd have to modify qemu for sure.

A similar solution would be not to use the xen pv drivers but to use the
virtio drivers in the guest.  kvm and qemu get much better performance
when the guest uses virtio compared to emulated scsi or network devices.

I don't believe that nested vitalization has gotten any real interest.
It seems its generally considered to be "for development only".  Thus, you
don't see work like you're describing getting done, even though it could
be possible.  Additionally, you'd still have the cpu emulation (without
some paravirt-in-paravirt solution for cpu).