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=-1.2 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 D8A94CA9ED0 for ; Fri, 18 Oct 2019 04:58:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B3FCD222C3 for ; Fri, 18 Oct 2019 04:58:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2407377AbfJRE6C (ORCPT ); Fri, 18 Oct 2019 00:58:02 -0400 Received: from mga04.intel.com ([192.55.52.120]:47341 "EHLO mga04.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730688AbfJRE6C (ORCPT ); Fri, 18 Oct 2019 00:58:02 -0400 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga005.jf.intel.com ([10.7.209.41]) by fmsmga104.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 17 Oct 2019 19:36:47 -0700 X-IronPort-AV: E=Sophos;i="5.67,310,1566889200"; d="scan'208";a="371328089" Received: from xiaoyaol-mobl.ccr.corp.intel.com (HELO [10.239.13.123]) ([10.239.13.123]) by orsmga005-auth.jf.intel.com with ESMTP/TLS/AES256-SHA; 17 Oct 2019 19:36:43 -0700 Subject: Re: [RFD] x86/split_lock: Request to Intel To: Thomas Gleixner , Paolo Bonzini Cc: Sean Christopherson , Fenghua Yu , Ingo Molnar , Borislav Petkov , H Peter Anvin , Peter Zijlstra , Andrew Morton , Dave Hansen , Radim Krcmar , Ashok Raj , Tony Luck , Dan Williams , Sai Praneeth Prakhya , Ravi V Shankar , linux-kernel , x86 , kvm@vger.kernel.org References: <1560897679-228028-1-git-send-email-fenghua.yu@intel.com> <1560897679-228028-10-git-send-email-fenghua.yu@intel.com> <20190626203637.GC245468@romley-ivt3.sc.intel.com> <20190925180931.GG31852@linux.intel.com> <3ec328dc-2763-9da5-28d6-e28970262c58@redhat.com> <57f40083-9063-5d41-f06d-fa1ae4c78ec6@redhat.com> <8808c9ac-0906-5eec-a31f-27cbec778f9c@intel.com> From: Xiaoyao Li Message-ID: <5da90713-9a0d-6466-64f7-db435ba07dbe@intel.com> Date: Fri, 18 Oct 2019 10:36:41 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.9.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On 10/17/2019 8:29 PM, Thomas Gleixner wrote: > The more I look at this trainwreck, the less interested I am in merging any > of this at all. > > The fact that it took Intel more than a year to figure out that the MSR is > per core and not per thread is yet another proof that this industry just > works by pure chance. > Whether it's per-core or per-thread doesn't affect much how we implement for host/native. And also, no matter it's per-core or per-thread, we always can do something in VIRT. Maybe what matters is below. > Seriously, this makes only sense when it's by default enabled and not > rendered useless by VIRT. Otherwise we never get any reports and none of > the issues are going to be fixed. > For VIRT, it doesn't want old guest to be killed due to #AC. But for native, it doesn't want VIRT to disable the #AC detection I think it's just about the default behavior that whether to disable the host's #AC detection or kill the guest (SIGBUS or something else) once there is an split-lock #AC in guest. So we can provide CONFIG option to set the default behavior and module parameter to let KVM set/change the default behavior.