[libvirt] Support for kvm=off cpu option
Cole Robinson
crobinso at redhat.com
Fri Aug 15 14:38:23 UTC 2014
On 08/11/2014 05:54 PM, Alex Williamson wrote:
> As of QEMU 2.1 we now have a new -cpu option, kvm=on|off which controls
> whether we expose KVM as the hypervisor via the MSR hypervisor nodes.
> The default is on. The off state is meant to hide kvm from standard
> detection routines. This allows us to disable paravirtualization
> detection in the guest and can be used to bypass hypervisor checks in
> certain guest drivers[1].
>
> How would we like to enable this in libvirt? One option would be a
> processor feature, ex:
>
> <feature policy='disable' name='kvm'/>
>
> But since this doesn't map to a cpuid feature, I don't know if that
> would be acceptable.
>
> Another option might be to a domain feature, similar to some of the
> other hyper-v related flags.
>
> <domain type='kvm'>
> <features>
> <kvm>
> <kvm state='off'>
> </kvm>
> <hyperv>
> <relaxed state='on'>
> ...
> </hyperv>
> </features>
> ...
> </domain>
>
> Any other suggestions? Preference? Thanks,
IMO the latter suggestion makes the most sense.
However <kvm state='off'/> could cause confusion, sounds like it turns off kvm
acceleration. Maybe <signature state=on|off>, or hv_signature, something along
those lines.
- Cole
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