From: Borislav Petkov <bp@alien8.de>
To: Jiri Kosina <jkosina@suse.cz>
Cc: Steven Rostedt <rostedt@goodmis.org>,
"H. Peter Anvin" <hpa@linux.intel.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
linux-kernel@vger.kernel.org, x86@kernel.org,
Salman Qazi <sqazi@google.com>, Ingo Molnar <mingo@elte.hu>,
Michal Hocko <mhocko@suse.cz>, Vojtech Pavlik <vojtech@suse.cz>,
Petr Tesarik <ptesarik@suse.cz>, Petr Mladek <pmladek@suse.cz>,
Andy Lutomirski <luto@amacapital.net>
Subject: Re: 64bit x86: NMI nesting still buggy?
Date: Wed, 21 May 2014 16:20:55 +0200 [thread overview]
Message-ID: <20140521142055.GH21205@pd.tnic> (raw)
In-Reply-To: <alpine.LNX.2.00.1405211540080.20534@pobox.suse.cz>
On Wed, May 21, 2014 at 03:42:24PM +0200, Jiri Kosina wrote:
> Alright, Andy's iret optimization efforts do immediately bring a
> followup question -- why is this not a problem with iret-based return
> from #MC possibly interrupting NMI?
Yeah, and frankly, I don't see this nesting fun at all protected against
a #MC interrupting it at any point actually. Because once the #MC
handler returns, it goes into paranoid_exit and that place doesn't
account for NMIs at all, AFAICS.
Which would mean:
* NMI goes off
* MCE happens, we switch to machine_check which is paranoidzeroentry
* #MC handler is done -> paranoid_exit -> IRET
-> boom! Or if not "boom", at least, the NMI gets forgotten.
Am I missing something?
--
Regards/Gruss,
Boris.
Sent from a fat crate under my desk. Formatting is fine.
--
next prev parent reply other threads:[~2014-05-21 14:21 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-04-29 13:05 64bit x86: NMI nesting still buggy? Jiri Kosina
2014-04-29 13:29 ` H. Peter Anvin
2014-04-29 14:06 ` Steven Rostedt
2014-04-29 14:28 ` H. Peter Anvin
2014-04-29 14:31 ` Petr Tesarik
2014-04-30 22:10 ` Jiri Kosina
2014-04-30 22:46 ` H. Peter Anvin
2014-04-29 14:03 ` Steven Rostedt
2014-04-29 15:24 ` Jiri Kosina
2014-04-29 15:41 ` Vojtech Pavlik
2014-04-29 16:09 ` Steven Rostedt
2014-04-29 16:19 ` Steven Rostedt
2014-04-29 16:51 ` Jiri Kosina
2014-04-29 17:12 ` Steven Rostedt
2014-04-29 18:48 ` Jiri Kosina
2014-04-29 19:16 ` Steven Rostedt
2014-05-06 10:02 ` Ingo Molnar
2014-05-21 13:42 ` Jiri Kosina
2014-05-21 14:20 ` Borislav Petkov [this message]
2014-05-21 14:58 ` Vojtech Pavlik
2014-05-21 15:22 ` Andy Lutomirski
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