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Re: [Xen-devel] Questions on EPT dump and creation

To: Tim Deegan <Tim.Deegan@xxxxxxxxxx>
Subject: Re: [Xen-devel] Questions on EPT dump and creation
From: YAO <yffbrave@xxxxxxxxx>
Date: Wed, 20 Jul 2011 15:37:04 +0800
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2011/7/19 Tim Deegan <Tim.Deegan@xxxxxxxxxx>

At 18:57 +0800 on 19 Jul (1311101864), YAO wrote:
> I copied exactly every mapping one by one, but when I dumped the gfn->mfn
> mapping(I've modified ept_dump_p2m_table to find unequal entry),
> there are some strange output like this:
> (XEN) gfn: 200  mfn: 117def  my_mfn: 10d600
> (XEN) gfn: 400  mfn: 117dee  my_mfn: 111200
> (XEN) gfn: 600  mfn: 117ded  my_mfn: 111000
> (XEN) gfn: 800  mfn: 117dec  my_mfn: 10de00
> ......
> (XEN) gfn: 14a00  mfn: 1176bb  my_mfn: 10800
> (XEN) gfn: 14c00  mfn: 1176ba  my_mfn: 10600
> (XEN) gfn: 14e00  mfn: 1176b9  my_mfn: 10400
> (XEN) gfn: 15000  mfn: 1176b8  my_mfn: 10200
> ......
> (XEN) gfn: 1f600  mfn: 117b46  my_mfn: 4200
> (XEN) gfn: 1f800  mfn: 117b45  my_mfn: 4000
> It shouldn't have any unequal entry, I thought...and
> Every mismatch has a step of 0x200 until 0x1f800, which really confused me.

Hmmm.  The "my_mfn" values go up in 0x200s (which is the size of a
full EPT page) too but the "mfn" values go down 1 at a time.  I suspect
that your code is confused somewhere about the number of levels in the
EPT tables.


Tim Deegan <Tim.Deegan@xxxxxxxxxx>
Principal Software Engineer, Xen Platform Team
Citrix Systems UK Ltd.  (Company #02937203, SL9 0BG)

Hi, Tim
Many thanks for your tip, yes, I didn't cope with the levels properly. I have fixed it.
But here's another problem. Since I have a full ept copy, if I replace the system eptp with my eptp, 
the domU will still be running like nothing happened. Now the domU may be compromised, it didn't response to any keystroke or click...
Did I miss something when switching the eptp to and back?

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