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Re: [Xen-devel] shadow2 corrupting PV guest state

To: <Doi.Tsunehisa@xxxxxxxxxxxxxx>, Tim Deegan <Tim.Deegan@xxxxxxxxxxxxx>
Subject: Re: [Xen-devel] shadow2 corrupting PV guest state
From: Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>
Date: Tue, 24 Oct 2006 10:44:52 +0100
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On 24/10/06 10:39, "Doi.Tsunehisa@xxxxxxxxxxxxxx"
<Doi.Tsunehisa@xxxxxxxxxxxxxx> wrote:

>> True, but we don't look at nd unless the page is allocated...
> 
>   Between domain_relinquish_resources() in domain_kill() and
> shadow_final_teadown() in domain_destroy(), nd might be looked
> with gnttab_copy(), I think.

Domain_destroy() is only called when the domain refcnt reaches zero. This
can only happen when all its page refcnts have reached zero. When a page's
refcnt reaches zero, get_page() no longer succeeds on it. So there is no
race between gnttab_copy() and domain_destroy().

 -- Keir



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