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

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


Alvin Starr                   ||   voice: (905)513-7688
Netvel Inc.                   ||   Cell:  (416)806-0133
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