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,URIBL_BLOCKED, 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 D258FC43331 for ; Thu, 26 Mar 2020 15:09:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A54C2206F8 for ; Thu, 26 Mar 2020 15:09:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728539AbgCZPJ2 (ORCPT ); Thu, 26 Mar 2020 11:09:28 -0400 Received: from mga11.intel.com ([192.55.52.93]:17880 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728269AbgCZPJ1 (ORCPT ); Thu, 26 Mar 2020 11:09:27 -0400 IronPort-SDR: 7x7LOdjTPs40A6ZKdaqVSeQFEbmalSDR3389wllgNs2T+t365kccNKU0rrNgXVAgF6rePud2GE KN6x0HIZxMoA== X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga004.jf.intel.com ([10.7.209.38]) by fmsmga102.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 26 Mar 2020 08:09:26 -0700 IronPort-SDR: 0olWpR3BrHOQAdLf02zYkwm6exIzj8RlT59MYX5rIQSqQ8WWjOXXO4S2Rk0kt1UhRQJefA2hw2 ZTFvsFleDGzg== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.72,308,1580803200"; d="scan'208";a="394014406" Received: from xiaoyaol-mobl.ccr.corp.intel.com (HELO [10.249.169.99]) ([10.249.169.99]) by orsmga004.jf.intel.com with ESMTP; 26 Mar 2020 08:09:22 -0700 Subject: Re: [PATCH v6 8/8] kvm: vmx: virtualize split lock detection To: Thomas Gleixner , Ingo Molnar , Borislav Petkov , hpa@zytor.com, Paolo Bonzini , Sean Christopherson Cc: x86@kernel.org, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Andy Lutomirski , Peter Zijlstra , Arvind Sankar , Fenghua Yu , Tony Luck References: <20200324151859.31068-1-xiaoyao.li@intel.com> <20200324151859.31068-9-xiaoyao.li@intel.com> <87eethz2p6.fsf@nanos.tec.linutronix.de> <88b01989-25cd-90af-bfe8-c236bd5d1dbf@intel.com> <87d08zxtgl.fsf@nanos.tec.linutronix.de> <1d98bddd-a6a4-2fcc-476b-c9b19f65c6b6@intel.com> <87a743xj0n.fsf@nanos.tec.linutronix.de> From: Xiaoyao Li Message-ID: Date: Thu, 26 Mar 2020 23:09:21 +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: <87a743xj0n.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 3/26/2020 10:55 PM, Thomas Gleixner wrote: > Xiaoyao Li writes: >> On 3/26/2020 7:10 PM, Thomas Gleixner wrote: >> If the host has it disabled, !split_lock_detect_on() is true, it skips >> following check due to || >> >> if (!boot_cpu_has(X86_FEATURE_SPLIT_LOCK)) { >> inject #AC back to guest and return 1; > > That'd be a regular #AC, right? Yes. >> } else { >> if (guest_alignment_check_enabled() || guest_sld_on()) >> inject #AC back to guest and return 1; > Here is clearly an else path missing. the else path is fall through. i.e. calling handle_user_split_lock(). If cannot handle, it falls through to report #AC to user space (QEMU) >> } > If there is no problem with the above. So what's the problem of the original?