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Date: Wed, 30 May 2012 12:48:36 -0400
From: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
To: Jan Beulich <JBeulich@suse.com>
Cc: jeremy@goop.org, "H. Peter Anvin" <hpa@zytor.com>,
        Andre Przywara <andre.przywara@amd.com>, xen-devel@lists.xensource.com,
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        mingo@elte.hu, tglx@linutronix.de
Subject: Re: [Xen-devel] [PATCH] x86/amd: fix crash as Xen Dom0 on AMD
 Trinity systems
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On Wed, May 30, 2012 at 04:35:41PM +0100, Jan Beulich wrote:
> >>> On 30.05.12 at 17:15, "H. Peter Anvin" <hpa@zytor.com> wrote:
> > On 05/30/2012 08:08 AM, Jan Beulich wrote:
> >> 
> >> Xen does trap and emulate (possibly just ignore) both instructions.
> >> 
> > 
> > Then why the fsck is there paravirt_crap on this?
> 
> I have no clue. Jeremy, Konrad?

No idea. The git 132ec92f says:

Borislav Petkov <petkovbb@googlemail.com>
Date:   Mon Aug 31 09:50:09 2009 +0200

    x86, msr: Add rd/wrmsr interfaces with preset registers

    native_{rdmsr,wrmsr}_safe_regs are two new interfaces which allow
    presetting of a subset of eight x86 GPRs before executing the rd/wrmsr
    instructions. This is needed at least on AMD K8 for accessing an erratum
    workaround MSR.

    Originally based on an idea by H. Peter Anvin.