From: "Jan Beulich" <jbeulich@novell.com>
To: "Nick Piggin" <nickpiggin@yahoo.com.au>
Cc: "Keir Fraser" <Keir.Fraser@cl.cam.ac.uk>,
"Ingo Molnar" <mingo@elte.hu>,
"Harvey Harrison" <harvey.harrison@gmail.com>,
"Jeremy Fitzhardinge" <jeremy@goop.org>,
"Matt Mackall" <mpm@selenic.com>, "Andi Kleen" <ak@suse.de>,
"Linux Kernel Mailing List" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH UPDATE] x86: ignore spurious faults
Date: Fri, 25 Jan 2008 09:18:04 +0000 [thread overview]
Message-ID: <4799B75C.76E4.0078.0@novell.com> (raw)
In-Reply-To: <200801251938.39231.nickpiggin@yahoo.com.au>
>>> Nick Piggin <nickpiggin@yahoo.com.au> 25.01.08 09:38 >>>
>On Friday 25 January 2008 19:15, Jan Beulich wrote:
>> Actually, another thought: permitting (and handling) spurious faults for
>> kernel mappings conflicts with NMI handling, i.e. great care would be
>> needed to ensure the NMI path cannot touch any such mapping. So
>> even the present Xen/Linux Dom0 implementation may have some
>> (perhaps unlikely) problems here, and it would get worse if we added
>> e.g. a virtual watchdog NMI (something I am considering, which would
>> then extend the problem to DomU-s).
>
>Can you explain how they conflict?
In the same way as vmalloc faults do (which is why vmalloc_sync_all()
got introduced): a page fault nested inside an NMI will, by virtue of
executing IRET, prematurely tell the processor that NMI handling is
done (and specifically unmask further NMIs).
Jan
next prev parent reply other threads:[~2008-01-25 9:17 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-01-24 0:05 [PATCH] " Jeremy Fitzhardinge
2008-01-24 0:18 ` Harvey Harrison
2008-01-24 0:26 ` Jeremy Fitzhardinge
2008-01-24 0:28 ` [PATCH UPDATE] " Jeremy Fitzhardinge
2008-01-24 19:14 ` Matt Mackall
2008-01-24 19:21 ` Jeremy Fitzhardinge
2008-01-24 23:41 ` Nick Piggin
2008-01-25 0:26 ` Jeremy Fitzhardinge
2008-01-25 7:36 ` Keir Fraser
2008-01-25 8:15 ` Jan Beulich
2008-01-25 8:38 ` Nick Piggin
2008-01-25 9:11 ` Andi Kleen
2008-01-25 9:18 ` Keir Fraser
2008-01-25 9:51 ` Andi Kleen
2008-01-25 10:19 ` Andi Kleen
2008-01-25 13:17 ` Keir Fraser
2008-01-25 9:18 ` Jan Beulich [this message]
2008-01-25 15:30 ` Ingo Molnar
2008-01-25 15:54 ` Jeremy Fitzhardinge
2008-01-25 18:08 ` Ingo Molnar
2008-01-25 18:39 ` Jeremy Fitzhardinge
2008-01-24 6:49 ` [PATCH] " Andi Kleen
2008-01-24 7:02 ` Jeremy Fitzhardinge
2008-01-24 7:11 ` Andi Kleen
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