linux-kernel - Re: Perhaps a side effect regarding NMI returns

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Message-ID: <20111129203111.GQ24062@one.firstfloor.org>
Date:	Tue, 29 Nov 2011 21:31:11 +0100
From:	Andi Kleen <andi@...stfloor.org>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
Cc:	Andi Kleen <andi@...stfloor.org>,
	Steven Rostedt <rostedt@...dmis.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Ingo Molnar <mingo@...hat.com>,
	Peter Zijlstra <peterz@...radead.org>,
	"H. Peter Anvin" <hpa@...ux.intel.com>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Mathieu Desnoyers <mathieu.desnoyers@...ymtl.ca>,
	Paul Turner <pjt@...gle.com>
Subject: Re: Perhaps a side effect regarding NMI returns

On Tue, Nov 29, 2011 at 12:12:44PM -0800, Linus Torvalds wrote:
> The problem is that NMI's are blocked!
> 
> We're potentially switching to another process, there is no guarantee
> there will be an "iret" *anywhere* in any patch for a long time. So
> any subsequent NMI's will not be able to come in.

True. That's a bug that needs to be fixed.

As a simple fix your proposal of forcing IRET sounds good.

-Andi
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