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=-0.7 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 B6753C433E0 for ; Thu, 14 May 2020 19:29:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 86F6E20643 for ; Thu, 14 May 2020 19:29:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725975AbgENT30 (ORCPT ); Thu, 14 May 2020 15:29:26 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54198 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1725965AbgENT30 (ORCPT ); Thu, 14 May 2020 15:29:26 -0400 Received: from Galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D4CC8C061A0C; Thu, 14 May 2020 12:29:25 -0700 (PDT) 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 1jZJXe-0007Td-4a; Thu, 14 May 2020 21:29:14 +0200 Received: by nanos.tec.linutronix.de (Postfix, from userid 1000) id 5C81B1004CE; Thu, 14 May 2020 21:29:13 +0200 (CEST) From: Thomas Gleixner To: Borislav Petkov , Sean Christopherson Cc: "Dr. Greg" , Jarkko Sakkinen , torvalds@linux-foundation.org, linux-kernel@vger.kernel.org, x86@kernel.org, linux-sgx@vger.kernel.org, akpm@linux-foundation.org, dave.hansen@intel.com, nhorman@redhat.com, npmccallum@redhat.com, haitao.huang@intel.com, andriy.shevchenko@linux.intel.com, kai.svahn@intel.com, josh@joshtriplett.org, luto@kernel.org, kai.huang@intel.com, rientjes@google.com, cedric.xing@intel.com, puiterwijk@redhat.com Subject: Re: [PATCH v29 00/20] Intel SGX foundations In-Reply-To: <20200514162054.GE9266@zn.tnic> References: <20200421215316.56503-1-jarkko.sakkinen@linux.intel.com> <20200426165753.GA11046@wind.enjellic.com> <87d07gk24l.fsf@nanos.tec.linutronix.de> <20200508190226.GA31465@wind.enjellic.com> <20200508195635.GR27052@linux.intel.com> <20200514091637.GA25156@wind.enjellic.com> <20200514161559.GA15603@linux.intel.com> <20200514162054.GE9266@zn.tnic> Date: Thu, 14 May 2020 21:29:13 +0200 Message-ID: <87pnb6xqly.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-sgx-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-sgx@vger.kernel.org Borislav Petkov writes: > On Thu, May 14, 2020 at 09:15:59AM -0700, Sean Christopherson wrote: >> I'm not opposed to adding a kernel param to disable SGX. At one point >> there was a proposal to extend clearcpuid to allow disabling multiple >> feature bits, but it looks like that went the way of the dodo. clearcpuid is a trainwreck which should have never happened. >> Note, such a param would disable SGX entirely, e.g. clear the feature bit >> in /proc/cpuinfo and prevent any in-kernel SGX code from running. > > It is a usual practice for big features like SGX to add a > "nosgx" cmdline param to disable it in case something goes > south. We do this for all features - see all "no*" switches in > Documentation/admin-guide/kernel-parameters.txt Correct. Thanks, tglx