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=-2.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_PASS,UNPARSEABLE_RELAY,USER_AGENT_MUTT 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 6B901C43381 for ; Mon, 4 Mar 2019 21:55:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 33C56206B6 for ; Mon, 4 Mar 2019 21:55:36 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b="eAN2RcKS" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726484AbfCDVze (ORCPT ); Mon, 4 Mar 2019 16:55:34 -0500 Received: from userp2130.oracle.com ([156.151.31.86]:41434 "EHLO userp2130.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726038AbfCDVze (ORCPT ); Mon, 4 Mar 2019 16:55:34 -0500 Received: from pps.filterd (userp2130.oracle.com [127.0.0.1]) by userp2130.oracle.com (8.16.0.27/8.16.0.27) with SMTP id x24LrW3i043085; Mon, 4 Mar 2019 21:55:08 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=date : from : to : cc : subject : message-id : references : mime-version : content-type : in-reply-to; s=corp-2018-07-02; bh=wjOWfKm74HnT1aTRV2qWh4NO3N9bZ5oJ8SNfdGHeTZ0=; b=eAN2RcKSBgXosBVT4O1KYtDPBTSN+ZbO0PxYs2hAmc+qXiYZd8gMmLZP4oZS6wokPK0M Jj2oE0Z+1ub/E9m686qwJsak5ych8x+e4cXhqYXjoPBtkpnxNBQF67WEAci8ydu/YzAl SsMneak0abbkjPtARoyBWzV6E3EhNb2Rf9NFpoVv+DNwaBLLjrM2WcQh710oZH1tgFfN pBQEOYqCHWdPm72KtJHd1Rm0opDWxgqkToP+bjWAJUgW/m3zgChJtrqcfOYx1kcQT2SI MWIJEPqMIlehEKJMjxv4sBdLZMpdzz3ull7LTgmM63XYRtw9HGHE8FqxSLkBxg3TGymV rQ== Received: from userv0021.oracle.com (userv0021.oracle.com [156.151.31.71]) by userp2130.oracle.com with ESMTP id 2qyh8u1h1a-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 04 Mar 2019 21:55:08 +0000 Received: from userv0122.oracle.com (userv0122.oracle.com [156.151.31.75]) by userv0021.oracle.com (8.14.4/8.14.4) with ESMTP id x24Lt8wo022137 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 4 Mar 2019 21:55:08 GMT Received: from abhmp0018.oracle.com (abhmp0018.oracle.com [141.146.116.24]) by userv0122.oracle.com (8.14.4/8.14.4) with ESMTP id x24Lt7VK009455; Mon, 4 Mar 2019 21:55:07 GMT Received: from char.us.oracle.com (/10.152.32.25) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Mon, 04 Mar 2019 13:55:06 -0800 Received: by char.us.oracle.com (Postfix, from userid 1000) id 81F916A012E; Mon, 4 Mar 2019 16:55:05 -0500 (EST) Date: Mon, 4 Mar 2019 16:55:05 -0500 From: Konrad Rzeszutek Wilk To: Fenghua Yu Cc: Thomas Gleixner , Ingo Molnar , Borislav Petkov , H Peter Anvin , Paolo Bonzini , Dave Hansen , Ashok Raj , Peter Zijlstra , Ravi V Shankar , Xiaoyao Li , linux-kernel , x86 , kvm@vger.kernel.org Subject: Re: [PATCH v4 00/17] x86/split_lock: Enable #AC exception for split locked accesses Message-ID: <20190304215505.GC30350@char.us.oracle.com> References: <1551494711-213533-1-git-send-email-fenghua.yu@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1551494711-213533-1-git-send-email-fenghua.yu@intel.com> User-Agent: Mutt/1.9.1 (2017-09-22) X-Proofpoint-Virus-Version: vendor=nai engine=5900 definitions=9185 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1011 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1903040153 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > This capability may also find usage in cloud. A user process with split > lock running in one guest can block other cores from accessing shared > memory during its split locked memory access. That may cause overall > system performance degradation. "shared memory" ? As in memory shared between two guests? > > Split lock may open a security hole where malicious user code may slow > down overall system by executing instructions with split lock. How much slowdown are we talking?