RE: [Xen-devel] VMX check in /xen/arch/x86/domain.c is invalid onx86-64 (at least AMD)

["Nakajima, Jun" <jun.nakajima@xxxxxxxxx>]

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.

This c-flags has nothing to do with the machine architecture, but it's
just a software field for the domain builder to specify the type of the
domain (i.e. VMX or not, for example). The rflags is in
execution_context_t.

Jun

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel