From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757108AbaIRT7i (ORCPT ); Thu, 18 Sep 2014 15:59:38 -0400 Received: from mail-ob0-f171.google.com ([209.85.214.171]:34378 "EHLO mail-ob0-f171.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756049AbaIRT7h (ORCPT ); Thu, 18 Sep 2014 15:59:37 -0400 Date: Thu, 18 Sep 2014 14:53:28 -0500 From: Chuck Ebbert To: Andy Lutomirski Cc: Henrique de Moraes Holschuh , linux-kernel@vger.kernel.org, Borislav Petkov , H Peter Anvin Subject: Re: x86, microcode: BUG: microcode update that changes x86_capability Message-ID: <20140918145328.0253f009@as> In-Reply-To: <541B2F33.8000002@amacapital.net> References: <20140918135202.GA26038@khazad-dum.debian.net> <541B2F33.8000002@amacapital.net> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 18 Sep 2014 12:14:59 -0700 Andy Lutomirski wrote: > 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? > https://downloadcenter.intel.com/Detail_Desc.aspx?DwnldID=24290&lang=eng I can't find any release notes. Haswell-EP is also affected, it appears: http://techreport.com/news/26911/errata-prompts-intel-to-disable-tsx-in-haswell-early-broadwell-cpus > > > > [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. > All future updates for these CPUs will have this problem.