From mboxrd@z Thu Jan  1 00:00:00 1970
From: Jerone Young <jerone@gmail.com>
Subject: Re: VMX check in /xen/arch/x86/domain.c is invalid on
	x86-64 (at least AMD)
Date: Thu, 12 May 2005 00:58:05 -0500
Message-ID: <9f50a7a00505112258494d7688@mail.gmail.com>
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	<4282EE03.9080700@intel.com>
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To: Arun Sharma <arun.sharma@intel.com>
Cc: Jerone Young <jyoung5@us.ibm.com>, xen-devel@lists.xensource.com
List-Id: xen-devel@lists.xenproject.org

Yes I am actually. Sorry guy. I got that one screwed up in my head.
Pressed the send button too quickly. Thanks for the respsonses though.

On 5/12/05, Arun Sharma <arun.sharma@intel.com> wrote:
> Jerone Young wrote:
> > if (!(c->flags & ECF_VMX_GUEST))
> >         if ( ((c->cpu_ctxt.cs & 3) =3D=3D 0) ||
> >              ((c->cpu_ctxt.ss & 3) =3D=3D 0) )
> >                 return -EINVAL;
> >
> > This check in /xen/arch/x86/domain.c (line 394) is invalid for AMD
> > x86-64 as this field 1<<1 is a reserved field in the rflags (name for
> > 64bit eflags) that reads as 1. This can be found in the AMD x86-64
> > Programming manual vol 2 on page 65. Below is the code, I'm not sure ho=
w
> > to put an ifdef around since I'm not sure if Intel's EMT64 with VMX cpu=
s
> > have the same rflag reserved (which if this check is correct they do)?
> > This helps break x86-64 building domU domains.
> >
>=20
> It is a reserved bit on Intel as well. Look at:
>=20
> VMCS_EFLAGS_RESERVED_1 and the IA-32 vol1 Fig 3-7.
>=20
> Are you mixing up ctxt->user_regs.rflags and ctxt->flags in
> xc_linux_build.c?
>=20
>         -Arun
>=20
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