Re: Nested SVM and migration

Zachary Amsden
2010-02-24T20:21:50Z

On 02/24/2010 05:23 AM, Joerg Roedel wrote:
> On Sun, Feb 21, 2010 at 02:09:15PM +0100, Joerg Roedel wrote:
>
>> On Sun, Feb 21, 2010 at 02:54:01PM +0200, Avi Kivity wrote:
>>
>>> So, if some other cpu (or the guest itself, with appropriate
>>> permissions) modifies the msr permission bitmap, svm will not notice
>>> this? svm loads the bitmap during entry?
>>>
>> Yes.
>>
> Talked again with a few people about it and the architectural answer is
> a bit different. The right answer to that is:
>
> The cpu is allowed to load the msr permission map to internal state, but
> not required to do it by the architecture. The result of changing the
> msr permission map of a running vmcb is undefined.
>
> So we are fine with the way nested svm does it. And we don't need to
> care about that situation at all and just migrate whats in guest memory.
>

Awesome! Thanks for checking it out.