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Date: Tue, 31 Jan 2012 15:28:52 +0800
From: =?utf-8?B?6Zmz6Z+L5Lu7?= <chenwj@iis.sinica.edu.tw>
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Subject: Re: [Qemu-devel] nested page table translation for non-x86
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To: Xin Tong <xerox.time.tech@gmail.com>
Cc: qemu-devel <qemu-devel@nongnu.org>, =?utf-8?B?6Zmz6Z+L5Lu7?= <chenwj@iis.sinica.edu.tw>

On Fri, Jan 20, 2012 at 08:54:12AM -0500, Xin Tong wrote:
> On Fri, Jan 20, 2012 at 3:23 AM, =E9=99=B3=E9=9F=8B=E4=BB=BB <chenwj@ii=
s.sinica.edu.tw> wrote:
> >> 1.  The control of gCR3 and hCR3 needs kernel access. While they can
> >> be set with a device module as what is done in kvm. Trapping into th=
e
> >> kernel every time gCR3 is reseted might be too expensive.
> >
> >  Why the control of gCR3 needs kernel access? Isn't gCR3 just a field=
 of the
> > CPUX86State? QEMU should have the control of it. Or you mean the trap=
ping thing?
>=20
> I do not think gCR3 is a field in the CPUx86State. I think inorder to
> change the guest CR3, we need to trap into the kernel as kvm does.

  If your scenario is pure QEMU (without kvm), I think gCR3 is a field in=
 the
CPUx86State. See below,

typedef struct CPUX86State {

    ...

    target_ulong cr[5]; /* NOTE: cr1 is unused */

    ...
};

Or I misunderstand what you're trying to do?

Regards,
chenwj

--=20
Wei-Ren Chen (=E9=99=B3=E9=9F=8B=E4=BB=BB)
Computer Systems Lab, Institute of Information Science,
Academia Sinica, Taiwan (R.O.C.)
Tel:886-2-2788-3799 #1667
Homepage: http://people.cs.nctu.edu.tw/~chenwj