Re: [Xen-users] can svm and npt flags be enabled in dom-0.

[Alvin Starr <alvin@xxxxxxxxxx>]

I will punt this to the devel list.

But first.
There seems to be enough nested supported for AMD that I am able to run 
up several domUs that can run KVM VM.
Nested VMs are able to see SVM and NPT.

I was under the impression that dom0 is just a domU with more privileges.
But the theory and practice often diverge after a few years of coding.


On 06/05/2014 05:29 AM, Ian Campbell wrote:
> On Wed, 2014-06-04 at 12:05 -0400, Alvin Starr wrote:
> > I am trying to get cpuid flag manipulation working with libvirt and
> > libxl and it seems that libvirt expects to be able to see all the flags
> > that it hopes to pass or mask for a guest on the host system.
> >
> > Sadly the svm and npt flags are masked in dom-0
> Yes, since dom0 cannot use those features.
>
> Since svm/npt to a guest would imply the use of nested virt, I'd expect
> that enabling that feature would automatically expose those flags to the
> guest. Except I'm not sure that nested virt has been implemented for
> AMD, obviously without hypervisor side support just enabling those flags
> for a guest via the cpuid flag overrides isn't going to result in
> anything good happening ;-)
>
> AIUI there are ways for dom0 to get the raw hardware cpuid information,
> I'm not sure what the supported variant is though.
>
> If you want to keep going down this path then I think you should ask on
> xen-devel.
>
> Ian.

--
Alvin Starr                   ||   voice: (905)513-7688
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