Re: Nested SVM and migration

Joerg Roedel
2010-02-24T15:23:40Z

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.

Thanks,

Joerg