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Re: [Xen-devel] treatment grant frames during save/restore

To: Jan Beulich <JBeulich@xxxxxxxxxx>
Subject: Re: [Xen-devel] treatment grant frames during save/restore
From: Keir Fraser <keir.fraser@xxxxxxxxxxxxx>
Date: Mon, 31 May 2010 16:29:25 +0100
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On 31/05/2010 15:58, "Jan Beulich" <JBeulich@xxxxxxxxxx> wrote:

>> Yep that would probably work. And also potentially gets rid of one lot of
>> "if-hvm-else-pv" branched code in xc_domain_save.c. I'd take a patch to do
>> that if you want to pick this item up.
> I'm afraid it won't: The live_p2m table gets created for pv guests only,
> but is needed as a prerequisite to calling XEN_DOMCTL_getpageframeinfo*
> (which wants MFNs as input). Hence while the hypervisor side patch is
> trivial, it doesn't get us any closer to a solution to the problem at hand.
> Unless we (re-)define the meaning of the input array to this domctl to
> specify gmfn-s rather than mfn-s (at least for the hvm case; for
> auto-translate pv guests, quite obviously the save code wouldn't
> work anyway, but for those passing in gmfn-s would seem the
> natural thing here).

This is fine. We can (re-)define the domctl interface as we like, and anyway
I'm pretty sure noone uses that particular domctl on HVM guests (yet).

 -- Keir

> Or unless we want to add code to libxc to create a live_p2m for all
> guests (which I wouldn't want to take on).

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