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=-1.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, HK_RANDOM_FROM,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 4F884C43331 for ; Tue, 24 Mar 2020 01:38:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2D71D20714 for ; Tue, 24 Mar 2020 01:38:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727163AbgCXBig (ORCPT ); Mon, 23 Mar 2020 21:38:36 -0400 Received: from mga11.intel.com ([192.55.52.93]:28454 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727102AbgCXBif (ORCPT ); Mon, 23 Mar 2020 21:38:35 -0400 IronPort-SDR: fptz7yYNEIC+i9q+pRreHWp5nBmNGQ80F8E60IJjFq5VjceYcMNeBXD2OEjV4OqX3I5/8nzzom T0cRm0fYCOVA== X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga004.fm.intel.com ([10.253.24.48]) by fmsmga102.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 23 Mar 2020 18:38:35 -0700 IronPort-SDR: Fp1vKMVheC0S+iVbmeEbtCgRPQYmeZ6Q4gBmT7xJ1Z6eA3qxqgXym6lxe3arpUuN6y/M6jSVHp 0qNSGsz04L3Q== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.72,298,1580803200"; d="scan'208";a="270169232" Received: from xiaoyaol-mobl.ccr.corp.intel.com (HELO [10.255.31.120]) ([10.255.31.120]) by fmsmga004.fm.intel.com with ESMTP; 23 Mar 2020 18:38:31 -0700 Subject: Re: [PATCH v5 3/9] x86/split_lock: Re-define the kernel param option for split_lock_detect To: Thomas Gleixner , 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 References: <20200315050517.127446-1-xiaoyao.li@intel.com> <20200315050517.127446-4-xiaoyao.li@intel.com> <87r1xjov3a.fsf@nanos.tec.linutronix.de> From: Xiaoyao Li Message-ID: Date: Tue, 24 Mar 2020 09:38:30 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.6.0 MIME-Version: 1.0 In-Reply-To: <87r1xjov3a.fsf@nanos.tec.linutronix.de> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. > Thanks, > > tglx >