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Re: [Xen-devel] Swapping of PT pages

To: Mike Sun <msun@xxxxxxxxxx>
Subject: Re: [Xen-devel] Swapping of PT pages
From: Brendan Cully <brendan@xxxxxxxxx>
Date: Tue, 19 Feb 2008 12:49:29 -0800
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On Tuesday, 19 February 2008 at 15:27, Mike Sun wrote:
> Hi --
> In examining the domain save/migration code (xc_domain_save.c), I came
> across the step in which page table page frames in memory are
> canonicalized so that mfns are translated to pfns before those pages
> are written out to the saved image/destination host.  This makes me
> wonder if a PV host is allowed to swap out page table pages if it so
> decided; if swapping of PT pages were allowed, then wouldn't certain
> page table pages not be canonicalized (since they would be on disk,
> not in any of the machine frames).  This obviously be bad.
> Am I understanding things incorrectly?

Have a look at take_machine_down in

Before the suspend call is issued, the guest uses mm_pin_all to
prevent this scenario from happening.

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