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[Xen-devel] VMX check in /xen/arch/x86/domain.c is invalid on x86-64 (at least AMD)

  • To: xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxx>
  • From: Jerone Young <jyoung5@xxxxxxxxxx>
  • Date: Wed, 11 May 2005 22:55:56 -0500
  • Delivery-date: Thu, 12 May 2005 03:56:50 +0000
  • List-id: Xen developer discussion <xen-devel.lists.xensource.com>

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.

Jerone Young
IBM Linux Technology Center
512-838-1157 (T/L: 678-1157)

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