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

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Message-ID: <20120530222356.GA28417@andromeda.dapyr.net>
Date:	Wed, 30 May 2012 18:23:56 -0400
From:	Konrad Rzeszutek Wilk <konrad@...nok.org>
To:	"H. Peter Anvin" <hpa@...or.com>
Cc:	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
	Andre Przywara <andre.przywara@....com>, jeremy@...p.org,
	xen-devel@...ts.xensource.com, Jacob Shin <jacob.shin@....com>,
	linux-kernel@...r.kernel.org, Jan Beulich <JBeulich@...e.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 10:31:41AM -0700, H. Peter Anvin wrote:
> On 05/30/2012 10:17 AM, 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?
> > 
> 
> No, you can't just do that.  Rip them out as in trap and emulate.

Then this should do it:

diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index 75f33b2..e74df95 100644
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -1116,7 +1116,10 @@ static const struct pv_cpu_ops xen_cpu_ops __initconst = {
 	.wbinvd = native_wbinvd,
 
 	.read_msr = native_read_msr_safe,
+	.rdmsr_regs = native_rdmsr_safe_regs,
 	.write_msr = xen_write_msr_safe,
+	.wrmsr_regs = native_wrmsr_safe_regs,
+
 	.read_tsc = native_read_tsc,
 	.read_pmc = native_read_pmc,

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