linux-kernel - Re: [RFC PATCH] x86 NMI-safe INT3 and Page Fault (v2)

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Message-ID: <48086EBC.3070904@goop.org>
Date:	Fri, 18 Apr 2008 19:49:48 +1000
From:	Jeremy Fitzhardinge <jeremy@...p.org>
To:	Mathieu Desnoyers <compudj@...stal.dyndns.org>
CC:	Ingo Molnar <mingo@...e.hu>, Andi Kleen <andi@...stfloor.org>,
	akpm@...l.org, "H. Peter Anvin" <hpa@...or.com>,
	Steven Rostedt <rostedt@...dmis.org>,
	"Frank Ch. Eigler" <fche@...hat.com>, linux-kernel@...r.kernel.org,
	Rusty Russell <rusty@...tcorp.com.au>,
	Zachary Amsden <zach@...are.com>
Subject: Re: [RFC PATCH] x86 NMI-safe INT3 and Page Fault (v2)

Mathieu Desnoyers wrote:
> * Jeremy Fitzhardinge (jeremy@...p.org) wrote:
>   
>> Ingo Molnar wrote:
>>     
>>> * Ingo Molnar <mingo@...e.hu> wrote:
>>>
>>>   
>>>       
>>>> thanks Mathieu, i've picked this up into x86.git for more testing.
>>>>     
>>>>         
>>> ... but had to drop it due to missing PARAVIRT support which broke the 
>>> build. I guess on paravirt we could just initially define 
>>> INTERRUPT_RETURN_NMI_SAFE to iret, etc.?
>>>       
>> I have not yet implemented Xen's support for paravirtual NMI, so there's no 
>> scope for breaking anything from my perspective.  When I get around to NMI, 
>> I'll work around whatever's there.  I don't know if lguest or VMI has any 
>> guest NMI support.
>>
>>    J
>>
>>     
>
> I wonder if we could simply paravirtualize the popf instruction, which
> seems to be the only one requiring to run in ring 0.

Hm, I'd need to think about it more.  There's more to NMI's than just 
the popf.

    J

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