From: Andy Lutomirski <luto@amacapital.net>
To: Henrique de Moraes Holschuh <hmh@hmh.eng.br>,
linux-kernel@vger.kernel.org
Cc: Borislav Petkov <bp@alien8.de>, H Peter Anvin <hpa@zytor.com>
Subject: Re: x86, microcode: BUG: microcode update that changes x86_capability
Date: Thu, 18 Sep 2014 12:14:59 -0700 [thread overview]
Message-ID: <541B2F33.8000002@amacapital.net> (raw)
In-Reply-To: <20140918135202.GA26038@khazad-dum.debian.net>
On 09/18/2014 06:52 AM, Henrique de Moraes Holschuh wrote:
> The new Haswell microcode update[1] removes the "hle" (hardware lock
> elision) processor capability. And it is not cosmetic, either: Intel TSX
> opcodes will cause an illegal opcode trap after the microcode update[2].
>
> This means cpu_info()->x86_capability becomes stale after the microcode
> update.
>
> We could add logic to compute the new x86_capability after a microcode
> update run, and OOPS the kernel if something too important (i.e. anything
> the kernel uses) went away. Otherwise, refresh cpu_info()->x86_capability.
>
> Is that doable?
>
>
> [1] sig 0x000306f2, pf mask 0x6f, 2014-09-03, rev 0x0029, size 28672
> sig 0x000306c3, pf mask 0x32, 2014-07-03, rev 0x001c, size 21504
> sig 0x00040651, pf mask 0x72, 2014-07-03, rev 0x001c, size 20480
> sig 0x00040661, pf mask 0x32, 2014-07-03, rev 0x0012, size 23552
This is HSD136, right? Do you have a link to where that ucode comes
from? Does it have release notes?
>
> [2] instantly segfaulting every running process using libpthread-2.19,
> as well as any other users of Intel TSX.
> https://bugs.launchpad.net/intel/+bug/1370352
>
> And yes, this means we will kill support for microcode updates
> outside of the initramfs/early-initramfs, at least in Debian,
> and likely in Ubuntu.
>
Given that there is exactly one microcode update like this (at least of
the sort that blows up userspace), I think that we should seriously
consider blacklisting just this particular microcode update once
userspace is running.
--Andy
next prev parent reply other threads:[~2014-09-18 19:15 UTC|newest]
Thread overview: 47+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-09-18 13:52 x86, microcode: BUG: microcode update that changes x86_capability Henrique de Moraes Holschuh
2014-09-18 19:14 ` Andy Lutomirski [this message]
2014-09-18 19:53 ` Chuck Ebbert
2014-09-18 19:55 ` H. Peter Anvin
2014-09-18 20:06 ` Henrique de Moraes Holschuh
2014-09-19 0:13 ` Henrique de Moraes Holschuh
2014-09-19 0:23 ` Andy Lutomirski
2014-09-19 0:28 ` H. Peter Anvin
2014-09-19 1:00 ` Andy Lutomirski
2014-09-19 8:03 ` Borislav Petkov
2014-09-19 11:00 ` Henrique de Moraes Holschuh
2014-09-19 11:29 ` Borislav Petkov
2014-09-19 12:54 ` Chuck Ebbert
2014-09-19 13:14 ` Josh Boyer
2014-09-19 13:37 ` Chuck Ebbert
2014-09-19 15:00 ` Borislav Petkov
2014-09-19 16:13 ` Andy Lutomirski
2014-09-19 16:54 ` Henrique de Moraes Holschuh
2014-09-19 16:42 ` Henrique de Moraes Holschuh
2014-09-23 20:00 ` Borislav Petkov
2014-09-24 14:56 ` Henrique de Moraes Holschuh
2014-09-24 15:00 ` Andy Lutomirski
2014-09-24 17:45 ` Henrique de Moraes Holschuh
2014-09-24 17:48 ` Andy Lutomirski
2014-09-24 18:59 ` Henrique de Moraes Holschuh
2014-09-24 19:34 ` Andy Lutomirski
2014-09-25 8:57 ` Borislav Petkov
2014-09-25 8:51 ` Borislav Petkov
2014-09-25 11:36 ` Henrique de Moraes Holschuh
2014-09-25 12:10 ` Borislav Petkov
2014-09-25 14:40 ` Henrique de Moraes Holschuh
2014-09-25 14:56 ` Borislav Petkov
2014-09-25 15:30 ` Henrique de Moraes Holschuh
2014-09-25 15:50 ` Borislav Petkov
2014-09-25 16:41 ` Henrique de Moraes Holschuh
2014-09-25 16:57 ` Borislav Petkov
2014-09-25 17:09 ` Henrique de Moraes Holschuh
2014-09-19 13:51 ` Henrique de Moraes Holschuh
2014-09-19 14:49 ` Borislav Petkov
2014-09-19 17:22 ` Henrique de Moraes Holschuh
2014-09-19 22:35 ` Henrique de Moraes Holschuh
2014-09-29 11:51 ` Henrique de Moraes Holschuh
2014-09-19 9:56 ` Henrique de Moraes Holschuh
2014-09-19 16:11 ` Henrique de Moraes Holschuh
2014-09-22 0:37 ` Andi Kleen
2014-09-22 0:51 ` H. Peter Anvin
2014-09-22 0:58 ` Andi Kleen
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