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

[YAO <yffbrave@xxxxxxxxx>]

2011/7/19 Tim Deegan <Tim.Deegan@xxxxxxxxxx>

Hi,

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 Âmfn: 117def Âmy_mfn: 10d600
> (XEN) gfn: 400 Âmfn: 117dee Âmy_mfn: 111200
> (XEN) gfn: 600 Âmfn: 117ded Âmy_mfn: 111000
> (XEN) gfn: 800 Âmfn: 117dec Âmy_mfn: 10de00
> ......
> (XEN) gfn: 14a00 Âmfn: 1176bb Âmy_mfn: 10800
> (XEN) gfn: 14c00 Âmfn: 1176ba Âmy_mfn: 10600
> (XEN) gfn: 14e00 Âmfn: 1176b9 Âmy_mfn: 10400
> (XEN) gfn: 15000 Âmfn: 1176b8 Âmy_mfn: 10200
> ......
> (XEN) gfn: 1f600 Âmfn: 117b46 Âmy_mfn: 4200
> (XEN) gfn: 1f800 Âmfn: 117b45 Âmy_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. ÂThe "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. ÂI suspect
that your code is confused somewhere about the number of levels in the
EPT tables.

Tim.

--
Tim Deegan <Tim.Deegan@xxxxxxxxxx>
Principal Software Engineer, Xen Platform Team
Citrix Systems UK Ltd. Â(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,Â

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?

Thanks,

Yao

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