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Date: Wed, 30 May 2012 19:32:48 +0200
From: Borislav Petkov <bp@alien8.de>
To: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Jacob Shin <jacob.shin@amd.com>, Andre Przywara <andre.przywara@amd.com>,
        jeremy@goop.org, xen-devel@lists.xensource.com,
        linux-kernel@vger.kernel.org, Jan Beulich <JBeulich@suse.com>,
        hpa@zytor.com, 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 01:17:54PM -0400, Konrad Rzeszutek Wilk wrote:
> > Yes, the following patch also fixed the crash for us:
> > 
> > Implement rdmsr_regs and wrmsr_regs for Xen pvops.
> 
> That needs more data. Such as the reason for it, the crash
> tombstone, and an analysis of the bug.
> 
> But at this point I am not sure what we are going to do.
> 
> I think Peter leans towards ripping the .rdmsr_regs/wdmsr_regs
> function out altogether (so altering the amd_rdmsr... to use the
> .rdmsr/.wrdmsr). At which point I think this would all work
> just fine?

I wouldn't do that. Andre's patch switches to the
rdmsrl_safe/checking_wrmsrl functions so you don't need to implement the
_regs functions for pvops.

I'll send it now with corrected commit message.

> I am tempted to write a patch that checks all the pv-cpu-ops to see if
> there are any that are NULL and throw a warning so that this does not
> hit us in the future - to be at least more proactive about this sort
> of thing.

This could be a prudent thing to do.

-- 
Regards/Gruss,
Boris.