From: Steven Rostedt <rostedt@goodmis.org>
To: Jiri Kosina <jkosina@suse.cz>
Cc: "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>, Borislav Petkov <bp@alien8.de>,
Vojtech Pavlik <vojtech@suse.cz>, Petr Tesarik <ptesarik@suse.cz>,
Petr Mladek <pmladek@suse.cz>
Subject: Re: 64bit x86: NMI nesting still buggy?
Date: Tue, 29 Apr 2014 10:03:45 -0400 [thread overview]
Message-ID: <20140429100345.3f76a5bd@gandalf.local.home> (raw)
In-Reply-To: <alpine.LNX.2.00.1404291150200.8903@pobox.suse.cz>
On Tue, 29 Apr 2014 15:05:55 +0200 (CEST)
Jiri Kosina <jkosina@suse.cz> wrote:
> According to 38.4 of [1], when SMM mode is entered while the CPU is
> handling NMI, the end result might be that upon exit from SMM, NMIs will
> be re-enabled and latched NMI delivered as nested [2].
Note, if this were true, then the x86_64 hardware would be extremely
buggy. That's because NMIs are not made to be nested. If SMM's come in
during an NMI and re-enables the NMI, then *all* software would break.
That would basically make NMIs useless.
The only time I've ever witness problems (and I stress NMIs all the
time), is when the NMI itself does a fault. Which my patch set handles
properly. I've also stressed this on boxes that do have SMIs and SMMs.
Now, you can have a bad BIOS that does re-enable NMIs from SMMs or
SMIs, but then you need to take that up with your vendor.
-- Steve
next prev parent reply other threads:[~2014-04-29 14:03 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-04-29 13:05 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 [this message]
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
2014-05-21 14:58 ` Vojtech Pavlik
2014-05-21 15:22 ` Andy Lutomirski
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