From: Andy Lutomirski <luto@amacapital.net>
To: Borislav Petkov <bp@alien8.de>
Cc: "H. Peter Anvin" <hpa@linux.intel.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
X86 ML <x86@kernel.org>
Subject: Re: STI architectural question (and lretq -- I'm not even kidding)
Date: Wed, 23 Jul 2014 08:12:32 -0700 [thread overview]
Message-ID: <CALCETrVzKJZiEmxuVNv8_7dybh-4AQYRA5Yb5ms+vK9CKYEorA@mail.gmail.com> (raw)
In-Reply-To: <20140723104917.GB23102@pd.tnic>
On Jul 23, 2014 3:49 AM, "Borislav Petkov" <bp@alien8.de> wrote:
>
> On Tue, Jul 22, 2014 at 06:33:02PM -0700, Andy Lutomirski wrote:
> > Of course, this does nothing at all to protect us from #MC after sti
> > on return from #MC to userspace, but I think we're screwed regardless
> > -- we could just as easily get a second #MC before the sti. Machine
> > check broadcast was the worst idea ever.
>
> Please do not think that a raised #MC means the machine is gone. There
> are MC errors which are reported with the exception mechanism and from
> which we can and do recover, regardless of broadcasting or not.
>
How are we supposed to survive two machine checks in rapid succession?
The second will fire as soon as the first one is acked, I imagine.
Unless we switch stacks before acking the MCE, the return address of
the first one will be lost.
In any event, I'll do a manual fixup for this in my patch.
--Andy
next prev parent reply other threads:[~2014-07-23 15:12 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-07-23 0:10 STI architectural question (and lretq -- I'm not even kidding) Andy Lutomirski
2014-07-23 1:03 ` Linus Torvalds
2014-07-23 1:33 ` Andy Lutomirski
2014-07-23 10:49 ` Borislav Petkov
2014-07-23 15:12 ` Andy Lutomirski [this message]
2014-07-23 15:23 ` Borislav Petkov
2014-07-23 9:40 ` Borislav Petkov
2014-07-23 21:18 ` Andi Kleen
2014-07-23 21:52 ` Andy Lutomirski
2014-07-23 23:10 ` Andi Kleen
2014-07-24 22:15 ` H. Peter Anvin
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