[libvirt] looking again at add nested HVM to libxl

[Alvin Starr]

I have been looking at this once again and thinking about this whole 
implementation.

I can agree with Daniel's assesment of the SVM/NPT bit setting but the 
nested_hvm feature does not exist at all in  KVM at the libvirt level/
I could be wrong but when I last looked nested hvm could only be 
enabled/disabled in KVM at boot time and not on a per VM basis.

What is the accepted policy on features that are only available in a 
single VM engine?

I could remove the SVM/NPT bit twidling and resbumit the patch  if it is 
likely to go somewhere?

On 10/02/2015 02:44 PM, Alvin Starr wrote:
> I agree that it needs to be done the right way.
>
> I am willing to help where I can but my basic knowledge of the code is 
> badly lacking so there is no reasonable way for me to contribute in a 
> significant way.
>
> I am ok keeping my own hacks to the code that let me work along on my 
> projects and hope that some day this will get fixed.
>
>
> On 10/02/2015 10:03 AM, Daniel P. Berrange wrote:
>> On Fri, Oct 02, 2015 at 09:50:26AM -0400, Alvin Starr wrote:
>>> I wondered about this.
>>>
>>> I first looked at using the CPU feature bit manipulation but that 
>>> was, at
>>> the time, completely unimplemented.
>>> The CPU feature code also looked to be somewhat KVM centric.
>>>
>>> In the end I went for the simple implementation because the 
>>> complexity of
>>> implementing the feature code would mean that I would need to become a
>>> libvirt developer and I mostly just want to be a helpful libvirt user.
>> Yep, I can certainly understand that POV. Unfortunately I think in this
>> case we really do need to do it the right way. IIUC, Xen does indeed 
>> allow
>> the CPUID mask to be configured, so it ought to be possible to map from
>> the libvirt XML to the CPUID mask format. It would certainly be a 
>> non-negligble
>> bit of work though.
>>
>>
>> Regards,
>> Daniel
>
>


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