From mboxrd@z Thu Jan  1 00:00:00 1970
From: Paolo Bonzini <pbonzini@redhat.com>
Subject: Re: [PATCH 0/3] x86/paravirt: Fix baremetal paravirt MSR ops
Date: Thu, 17 Sep 2015 17:29:01 +0200
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Cc: Andy Lutomirski <luto@kernel.org>, X86 ML <x86@kernel.org>,
	Peter Zijlstra <peterz@infradead.org>,
	KVM list <kvm@vger.kernel.org>,
	xen-devel <Xen-devel@lists.xen.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Peter Zijlstra <a.p.zijlstra@chello.nl>,
	Andrew Morton <akpm@linux-foundation.org>,
	"H. Peter Anvin" <hpa@zytor.com>
To: Arjan van de Ven <arjan@linux.intel.com>,
	Andy Lutomirski <luto@amacapital.net>,
	Ingo Molnar <mingo@kernel.org>
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On 17/09/2015 17:27, Arjan van de Ven wrote:
>>
>>> ( We should double check that rdmsr()/wrmsr() results are never left
>>>    uninitialized, but are set to zero or so, for cases where the
>>> return code is not
>>>    checked. )
>>
>> It sure looks like native_read_msr_safe doesn't clear the output if
>> the rdmsr fails.
> 
> I'd suggest to return some poison not just 0...

What about 0 + WARN?

Paolo

> less likely to get interesting surprises that are insane hard to
> debug/diagnose