Re: [PATCH] qemu-kvm: Ask kernel about supported svm features

[Joerg Roedel <joro@8bytes.org>]

On Thu, Apr 22, 2010 at 03:13:14PM +0300, Avi Kivity wrote:
> On 04/22/2010 03:02 PM, Joerg Roedel wrote:

>> We can't just take the host-cpuid
>> because most of the additional svm features need special emulation in
>> the kernel. Or do you think this should better be handled in
>> target-i386/cpuid.c?
>>    
>
> Yes.  -cpu host should take KVM_GET_SUPPORTED_CPUID output and loop it  
> back to the vcpu configuration, others just take the qemu configuration,  
> mask it with supported bits, and pass it back (see  
> check_features_against_host()).

Hmm, the plan was to enable with -enable-nesting all kernel supported
svm features for the guest (and add switches later to remove them
individually)
If we activate nested svm with -cpu host in the future thats fine too
(closed-source hypervisors need that anyway). But we should also define
a cpu model in which we can migrate nested hypervisors between machines
were the cpu is not completly indentical.

> (need feature names for the bits, too, so you can enable or disable them  
> from the command line)

Yeah, I know. I omitted that for the first bring-up. It was planned for
a later patch.

	Joerg