linux-kernel - Re: [Xen-devel] [PATCH] x86/amd: fix crash as Xen Dom0 on AMD Trinity systems

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Date:	Wed, 30 May 2012 19:32:48 +0200
From:	Borislav Petkov <bp@...en8.de>
To:	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
Cc:	Jacob Shin <jacob.shin@....com>,
	Andre Przywara <andre.przywara@....com>, jeremy@...p.org,
	xen-devel@...ts.xensource.com, linux-kernel@...r.kernel.org,
	Jan Beulich <JBeulich@...e.com>, hpa@...or.com, mingo@...e.hu,
	tglx@...utronix.de
Subject: Re: [Xen-devel] [PATCH] x86/amd: fix crash as Xen Dom0 on AMD
 Trinity systems

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.
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