linux-kernel - Re: [PATCH] x86, nmi: workaround sti; hlt race vs nmi; intr

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Date:	Mon, 27 Sep 2010 11:22:49 +0200
From:	Alexander Graf <agraf@...e.de>
To:	Avi Kivity <avi@...hat.com>
Cc:	x86@...nel.org, linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Subject: Re: [PATCH] x86, nmi: workaround sti; hlt race vs nmi; intr


On 27.09.2010, at 11:17, Avi Kivity wrote:

> On 09/27/2010 11:15 AM, Alexander Graf wrote:
>> >
>> >  Wow, this is incredibly ugly :). Can't we just mask NMIs when the interrupt shadow is active?
> 
> I plan to do that, for all the code that's out there relying on on STI interrupt shadow masking NMIs.
> 
>> Yeah, that's me writing without thinking. So this means that the race can also happen on real hardware?
>> 
> 
> Yes.  At least on documented hardware.  Some (most? all?) hardware does mask NMIs after STI.

If all hardware masks NMIs after STI, wouldn't it be better to update the spec and declare KVM buggy for injecting NMIs there?


Alex

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