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Re: [Xen-devel] More page-table questions.

To: "Petersson, Mats" <Mats.Petersson@xxxxxxx>, Keir Fraser <keir@xxxxxxxxxxxxx>, PUCCETTI Armand <armand.puccetti@xxxxxx>, <xen-devel@xxxxxxxxxxxxxxxxxxx>
Subject: Re: [Xen-devel] More page-table questions.
From: Keir Fraser <keir@xxxxxxxxxxxxx>
Date: Mon, 12 Mar 2007 16:32:21 +0000
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Thread-topic: [Xen-devel] More page-table questions.
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On 12/3/07 16:26, "Petersson, Mats" <Mats.Petersson@xxxxxxx> wrote:

> Are the page-tables ever updated directly by the guest, or is it all
> done via hyper-calls?

Leaf PTEs (i.e., really just PTEs, not PDEs) can be directly written from
the point-of-view of the guest. In fact they are trapped and emulated by
Xen. The guest is somewhat aware of this because it has explicitly
write-protected all its pagetables, so if it were to attempt the direct
write on native hardware in these circumstances it would receive a page

 -- Keir

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