From mboxrd@z Thu Jan  1 00:00:00 1970
From: Jan Kiszka <jan.kiszka@web.de>
Subject: Re: CPU vendor in KVM
Date: Sat, 04 May 2013 10:05:31 +0200
Message-ID: <5184C14B.9040100@web.de>
References: <CABpY8MKmbU2Yj01x-Oa7GsLk1acf0q-iYDG8FHfY7zp_mFswwA@mail.gmail.com>
Mime-Version: 1.0
Content-Type: multipart/signed; micalg=pgp-sha1;
 protocol="application/pgp-signature";
 boundary="----enig2OLDGKQAKRAOEQSGKHLSW"
Cc: qemu-devel@nongnu.org, kvm <kvm@vger.kernel.org>
To: =?UTF-8?B?IuadjuaYpeWlhyA8QXJ0aHVyIENodW5xaSBMaT4i?=
	<yzt356@gmail.com>
Return-path: <kvm-owner@vger.kernel.org>
Received: from mout.web.de ([212.227.17.12]:64452 "EHLO mout.web.de"
	rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP
	id S1754507Ab3EDIFe (ORCPT <rfc822;kvm@vger.kernel.org>);
	Sat, 4 May 2013 04:05:34 -0400
In-Reply-To: <CABpY8MKmbU2Yj01x-Oa7GsLk1acf0q-iYDG8FHfY7zp_mFswwA@mail.gmail.com>
Sender: kvm-owner@vger.kernel.org
List-ID: <kvm.vger.kernel.org>

This is an OpenPGP/MIME signed message (RFC 4880 and 3156)
------enig2OLDGKQAKRAOEQSGKHLSW
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: quoted-printable

On 2013-05-04 09:50, =E6=9D=8E=E6=98=A5=E5=A5=87 <Arthur Chunqi Li> wrote=
:
> Hi Jan and All,
> I find that when enable KVM with qemu, vendor ID of simulated CPU will =
be
> set the same as host, but other features such as level, family, model,
> stepping are not changed. This may bring out a confusing result, the
> simulated CPU has a vendor name of "GenuineIntel" but with family numbe=
r
> "16".
>=20
> I disabled the related code in function cpu_x86_find_by_name:
> diff --git a/target-i386/cpu.c b/target-i386/cpu.c
> index e2302d8..df0e82e 100644
> --- a/target-i386/cpu.c
> +++ b/target-i386/cpu.c
> @@ -1295,7 +1295,8 @@ static int cpu_x86_find_by_name(x86_def_t
> *x86_cpu_def, const char *name)
>               * KVM's sysenter/syscall emulation in compatibility mode =
and
>               * when doing cross vendor migration
>               */
> -            if (kvm_enabled()) {
> +            //if (kvm_enabled()) {
> +            if (0) {
>                  uint32_t  ebx =3D 0, ecx =3D 0, edx =3D 0;
>                  host_cpuid(0, 0, NULL, &ebx, &ecx, &edx);
>                  x86_cpu_vendor_words2str(x86_cpu_def->vendor, ebx, edx=
,
> ecx);
>=20
> And the information of CPU remains consistent and the VM runs OK, even
> though with nested environment.
>=20
> Why should qemu set simulated cpu's vendor same as the host in KVM
> environment?

The reason (and a way out) is given in the comment above the cited code.

Jan



------enig2OLDGKQAKRAOEQSGKHLSW
Content-Type: application/pgp-signature; name="signature.asc"
Content-Description: OpenPGP digital signature
Content-Disposition: attachment; filename="signature.asc"

-----BEGIN PGP SIGNATURE-----
Version: GnuPG v2.0.16 (GNU/Linux)
Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/

iEYEARECAAYFAlGEwUsACgkQitSsb3rl5xRQlgCg4M70oAT1mEoScLNnyV0JDggt
i2YAni6ROATOXc2EwkU+nTEVJbuRr4uu
=zTr8
-----END PGP SIGNATURE-----

------enig2OLDGKQAKRAOEQSGKHLSW--