From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9C488C43331 for ; Thu, 2 Apr 2020 21:45:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 63AB420737 for ; Thu, 2 Apr 2020 21:45:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389053AbgDBVpN (ORCPT ); Thu, 2 Apr 2020 17:45:13 -0400 Received: from Galois.linutronix.de ([193.142.43.55]:39068 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388008AbgDBVpN (ORCPT ); Thu, 2 Apr 2020 17:45:13 -0400 Received: from p5de0bf0b.dip0.t-ipconnect.de ([93.224.191.11] helo=nanos.tec.linutronix.de) by Galois.linutronix.de with esmtpsa (TLS1.2:DHE_RSA_AES_256_CBC_SHA256:256) (Exim 4.80) (envelope-from ) id 1jK7e2-0003jo-Ii; Thu, 02 Apr 2020 23:45:02 +0200 Received: by nanos.tec.linutronix.de (Postfix, from userid 1000) id B3201100D52; Thu, 2 Apr 2020 23:45:01 +0200 (CEST) From: Thomas Gleixner To: Josh Poimboeuf , "Singh\, Balbir" Cc: "linux-kernel\@vger.kernel.org" , "tony.luck\@intel.com" , "keescook\@chromium.org" , "benh\@kernel.crashing.org" , "x86\@kernel.org" , "dave.hansen\@intel.com" Subject: Re: [PATCH 0/3] arch/x86: Optionally flush L1D on context switch In-Reply-To: <20200402204749.33ulub5jx66dktxg@treble> References: <20200402062401.29856-1-sblbir@amazon.com> <20200402201328.zqnxwaetpk4ubg56@treble> <31c9720eff18ce167378e9a0017dcd73e0552164.camel@amazon.com> <20200402204749.33ulub5jx66dktxg@treble> Date: Thu, 02 Apr 2020 23:45:01 +0200 Message-ID: <875zehmujm.fsf@nanos.tec.linutronix.de> MIME-Version: 1.0 Content-Type: text/plain X-Linutronix-Spam-Score: -1.0 X-Linutronix-Spam-Level: - X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required, ALL_TRUSTED=-1,SHORTCIRCUIT=-0.0001 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Josh Poimboeuf writes: > On Thu, Apr 02, 2020 at 08:35:46PM +0000, Singh, Balbir wrote: >> Yes, that CVE the motivation, the mitigation for CVE-2020-0550 does suggest >> flushing the cache on context switch. But in general, as we begin to find more >> ways of evicting data or snopping data, a generic mechanism is more useful and >> that is why I am making it an opt-in. > > Ok. I think it would be a good idea to expand on that justification > more precisely in the commit message. That would help both reviewers of > the code and users of the new option understand what level of paranoia > they're opting in to :-) The commit message is mostly useful for reviewers and people who have to do code archeaology. Documentation/admin-guide/hw-vuln/ has plenty of space to host a document with explanations. paranoia.rst comes to my mind. :) Thanks, tglx