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 A4EFAC4332B for ; Tue, 24 Mar 2020 10:40:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7A2122070A for ; Tue, 24 Mar 2020 10:40:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727384AbgCXKk1 (ORCPT ); Tue, 24 Mar 2020 06:40:27 -0400 Received: from Galois.linutronix.de ([193.142.43.55]:44365 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727084AbgCXKk1 (ORCPT ); Tue, 24 Mar 2020 06:40:27 -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 1jGgyo-0001rl-RA; Tue, 24 Mar 2020 11:40:19 +0100 Received: by nanos.tec.linutronix.de (Postfix, from userid 1000) id 4616C100292; Tue, 24 Mar 2020 11:40:18 +0100 (CET) From: Thomas Gleixner To: Xiaoyao Li , Ingo Molnar , Borislav Petkov , hpa@zytor.com, Paolo Bonzini , Sean Christopherson , kvm@vger.kernel.org, x86@kernel.org, linux-kernel@vger.kernel.org Cc: Andy Lutomirski , Peter Zijlstra , Arvind Sankar , Fenghua Yu , Tony Luck , Vitaly Kuznetsov , Jim Mattson Subject: Re: [PATCH v5 3/9] x86/split_lock: Re-define the kernel param option for split_lock_detect In-Reply-To: References: <20200315050517.127446-1-xiaoyao.li@intel.com> <20200315050517.127446-4-xiaoyao.li@intel.com> <87r1xjov3a.fsf@nanos.tec.linutronix.de> Date: Tue, 24 Mar 2020 11:40:18 +0100 Message-ID: <87r1xidoj1.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 Xiaoyao Li writes: > On 3/24/2020 1:10 AM, Thomas Gleixner wrote: >> Xiaoyao Li writes: >> >>> Change sld_off to sld_disable, which means disabling feature split lock >>> detection and it cannot be used in kernel nor can kvm expose it guest. >>> Of course, the X86_FEATURE_SPLIT_LOCK_DETECT is not set. >>> >>> Add a new optioin sld_kvm_only, which means kernel turns split lock >>> detection off, but kvm can expose it to guest. >> >> What's the point of this? If the host is not clean, then you better fix >> the host first before trying to expose it to guests. > > It's not about whether or not host is clean. It's for the cases that > users just don't want it enabled on host, to not break the applications > or drivers that do have split lock issue. It's very much about whether the host is split lock clean. If your host kernel is not, then this wants to be fixed first. If your host application is broken, then either fix it or use "warn". Stop proliferating crap. Thanks, tglx