From mboxrd@z Thu Jan  1 00:00:00 1970
From: Arun Sharma <arun.sharma@intel.com>
Subject: Re: VMX check in /xen/arch/x86/domain.c is invalid on
	x86-64 (at least AMD)
Date: Wed, 11 May 2005 22:47:47 -0700
Message-ID: <4282EE03.9080700@intel.com>
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To: Jerone Young <jyoung5@us.ibm.com>
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Jerone Young wrote:
> if (!(c->flags & ECF_VMX_GUEST))
>         if ( ((c->cpu_ctxt.cs & 3) == 0) ||
>              ((c->cpu_ctxt.ss & 3) == 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 how
> to put an ifdef around since I'm not sure if Intel's EMT64 with VMX cpus
> have the same rflag reserved (which if this check is correct they do)?
> This helps break x86-64 building domU domains.
> 

It is a reserved bit on Intel as well. Look at:

VMCS_EFLAGS_RESERVED_1 and the IA-32 vol1 Fig 3-7.

Are you mixing up ctxt->user_regs.rflags and ctxt->flags in 
xc_linux_build.c?

	-Arun