From mboxrd@z Thu Jan 1 00:00:00 1970 From: Thomas Gleixner Subject: Re: [PATCH 06/18] x86, barrier: stop speculation for failed access_ok Date: Sun, 7 Jan 2018 21:56:39 +0100 (CET) Message-ID: References: <20180106183859.1ad9ae37@alans-desktop> <20180106185134.dzn2en4vw2hj3p6h@ast-mbp> <20180106195551.3207f75d@alans-desktop> <20180106200912.zhzdt4qmfrojeeqe@ast-mbp> <20180106202213.23e553fb@alans-desktop> <20180106211729.cp5oet3at3hyce4o@ast-mbp> <20180106230507.3547c9a0@alans-desktop> <20180107033812.awq3vz4gdkps7tix@ast-mbp> <20180107063356.GA9425@1wt.eu> <20180107201211.GA9996@1wt.eu> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Return-path: Received: from Galois.linutronix.de ([146.0.238.70]:47791 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750965AbeAGU5K (ORCPT ); Sun, 7 Jan 2018 15:57:10 -0500 In-Reply-To: Sender: linux-arch-owner@vger.kernel.org List-ID: To: Linus Torvalds Cc: Willy Tarreau , Alexei Starovoitov , Alan Cox , Dan Williams , Linux Kernel Mailing List , linux-arch@vger.kernel.org, Andi Kleen , Arnd Bergmann , Greg Kroah-Hartman , Peter Zijlstra , Network Development , Ingo Molnar , "H. Peter Anvin" On Sun, 7 Jan 2018, Linus Torvalds wrote: > We need to fix the security problem, but we need to do it *without* > these braindead arguments that performance is somehow secondary. I surely agree, but we have gone the way of PTI without the ability of exempting individual processes exactly for one reason: Lack of time It can be done on top of the PTI implementation and it won't take ages. For spectre_v1/2 we face the same problem simply because we got informed so much ahead of time and we were all twiddling thumbs, enjoying our christmas vacation and having a good time. The exploits are out in the wild and they are observed already, so we really have to make a decision whether we want to fix that in the most obvious ways even if it hurts performance right now and then take a break from all that hell and sit down and sort the performance mess or whether we want to discuss the right way to fix it for the next 3 month and leave all doors open until the last bit of performance is squeezed out. I totally can understand the anger of those who learned all of this a few days ago and are now grasping straws to avoid the obviously coming performance hit, but its not our fault that we have to make a decision which cannot make everyone happy tomorrow. If the general sentiment is that we have to fix the performance issue first, then please let me know and I take 3 weeks of vacation right now. Thanks, tglx