Re: CVS commit: src/sys/arch/x86/x86

[David Laight <david%l8s.co.uk@localhost>]

On Tue, Oct 14, 2014 at 03:16:56AM +0000, John Nemeth wrote:
> Module Name:	src
> Committed By:	jnemeth
> Date:		Tue Oct 14 03:16:56 UTC 2014
> 
> Modified Files:
> 	src/sys/arch/x86/x86: identcpu.c
> 
> Log Message:
> Force x86_xsave_features to 0 when running under XEN for AMD
> processors.  This prevents the use of xsave and xrstor thus fixing
> the problem in PR/49150.  The basic problem is that the way AMD
> implements those instructions means that information can leak
> between domains so XEN treats them as privileged.
> 
> XXX If anybody else comes up with a better / more "proper" fix, go
> for it.  However, this solves the problem I was having.  And, given
> that XEN being broken is pretty much a show-stopper for a release,
> something needed to be done.

One option would be to detect the fault at runtime.

	David

-- 
David Laight: david%l8s.co.uk@localhost