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=-8.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT autolearn=ham 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 77601C43331 for ; Fri, 3 Apr 2020 18:25:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 461882166E for ; Fri, 3 Apr 2020 18:25:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2404076AbgDCSZJ (ORCPT ); Fri, 3 Apr 2020 14:25:09 -0400 Received: from serv1.kernkonzept.com ([159.69.200.6]:36311 "EHLO mx.kernkonzept.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728364AbgDCSZI (ORCPT ); Fri, 3 Apr 2020 14:25:08 -0400 Received: from muedsl-82-207-238-232.citykom.de ([82.207.238.232] helo=x1c.dd1.int.kernkonzept.com) by mx.kernkonzept.com with esmtpsa (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) id 1jKQMp-0001aj-2Q; Fri, 03 Apr 2020 19:44:31 +0200 From: Benjamin Lamowski To: xiaoyao.li@intel.com Cc: philipp.eppelt@kernkonzept.com, bp@alien8.de, fenghua.yu@intel.com, hpa@zytor.com, linux-kernel@vger.kernel.org, luto@kernel.org, mingo@redhat.com, nivedita@alum.mit.edu, pbonzini@redhat.com, peterz@infradead.org, sean.j.christopherson@intel.com, tglx@linutronix.de, tony.luck@intel.com, x86@kernel.org Subject: [PATCH 0/1] x86/split_lock: check split lock feature on initialization Date: Fri, 3 Apr 2020 19:44:02 +0200 Message-Id: <20200403174403.306363-1-benjamin.lamowski@kernkonzept.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20200325030924.132881-1-xiaoyao.li@intel.com> References: <20200325030924.132881-1-xiaoyao.li@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, During regression testing of our hypervisor[1] with the current git tip, we got writes to the TEST_CTRL MSR on hardware that does not support split lock detection. While the original split_lock implementation does not exhibit this behavior, the reworked initialization from dbaba47085b0c unconditionally calls split_lock_verify_msr() from split_lock_init(). After the elaborate checks in cpu_set_core_cap_bits() this seems like an oversight. The following simple patch fixes our regression by checking for X86_FEATURE_SPLIT_LOCK_DETECT before accessing the TEST_CTRL MSR. Please CC me on replies - I am not subscribed to the LKML. Kind regards, Ben [1] https://github.com/kernkonzept/uvmm -- Benjamin Lamowski - +49.351.41883235 Operating Systems Engineer - https://www.kernkonzept.com Kernkonzept GmbH. Sitz: Dresden. Amtsgericht Dresden, HRB 31129. Geschäftsführer: Dr.-Ing. Michael Hohmuth