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Re: [Xen-devel] page fault handling in Xen

To: jeet <jeet_sat12@xxxxxxxxxxx>, Tim Deegan <Tim.Deegan@xxxxxxxxxxxxx>
Subject: Re: [Xen-devel] page fault handling in Xen
From: Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>
Date: Mon, 05 Mar 2007 08:19:37 +0000
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On 5/3/07 06:29, "jeet" <jeet_sat12@xxxxxxxxxxx> wrote:

> Above code will execute and in inner unlikely condition will be true as PT
> table is read only and  error is write_access
> and control will go to not_a_shadow_fault?
> so when the emulation code would be executed for the write that has been
> performed on read only guest PT for adding entry in
> guest page table by guest?
> Have I missed some thing here in understanding

Yes: guest PTs are mapped with write permissions in the guest PTs. It's only
in the shadow PTs that the guest PTs are mapped read-only. The test on
accumulated_gflags is looking at the access permissions in the guest PTs.

 -- Keir

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