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=-2.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, 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 0CDC0CA9EAF for ; Mon, 21 Oct 2019 13:03:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D9E7920679 for ; Mon, 21 Oct 2019 13:03:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728846AbfJUNDO (ORCPT ); Mon, 21 Oct 2019 09:03:14 -0400 Received: from mx1.redhat.com ([209.132.183.28]:34856 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726767AbfJUNDO (ORCPT ); Mon, 21 Oct 2019 09:03:14 -0400 Received: from mail-wr1-f70.google.com (mail-wr1-f70.google.com [209.85.221.70]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id ECE6785536 for ; Mon, 21 Oct 2019 13:03:13 +0000 (UTC) Received: by mail-wr1-f70.google.com with SMTP id j14so6964700wrm.6 for ; Mon, 21 Oct 2019 06:03:13 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:openpgp:message-id :date:user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=SRsEP7MdZ/U/cm1kcGdYUO6agWlHXT6j/oNDoj6CtAE=; b=LqCyb3Fe/A3eYfU2Q2APKQ+H2myz+iuWsLcwxneiXuAjDGAgyv1LstoU3xslhFJLoJ dNGKtS/CLh3Ox3BqL071etJIdnXXmfrQ+EfAAzbhwHfP+I0Kb77jJ7i/9mN+IYCHj9Xx u+cQQgV8ftLofuNuEDVpGDWt9xlYmwMKgLGQ3/pWIHIhXftw6UNVrl4CdWFDGsBHqaNr QlnVRBrCd0UezBREFViEcqYueq9nDrPvpt78kH/U0lyKXXMtIzJK1zqnBBPSbj9H1Ifv Zcm4KB43N/4B+2xO3UR6FFTOfH48qiQUCiCL4MByyZCoBS5TCh2jxrjf5vwgiXpylll3 xRrQ== X-Gm-Message-State: APjAAAV8HNL65gowGML5Jsic9v1n6iarrKKXGtlO+LfkE7cKNfILtVyI u5oGw1Toi5NjNi3oThsxa9NXIT4eyk8LLonLX4IZYhL9yqy+Ik4YRhpm8VWGz4rUmWv8k3hGHuC NL6hHOex0lsourplZg69rt7Xu X-Received: by 2002:adf:ea83:: with SMTP id s3mr4300753wrm.43.1571662992511; Mon, 21 Oct 2019 06:03:12 -0700 (PDT) X-Google-Smtp-Source: APXvYqx0vfWrFJ17dOTpy0SjdT50aBC6AoFTEf08r3xOJ2JAlE1xg/YCfk4j4w2W0Kt7dxid70mggw== X-Received: by 2002:adf:ea83:: with SMTP id s3mr4300716wrm.43.1571662992251; Mon, 21 Oct 2019 06:03:12 -0700 (PDT) Received: from ?IPv6:2001:b07:6468:f312:566:fc24:94f2:2f13? ([2001:b07:6468:f312:566:fc24:94f2:2f13]) by smtp.gmail.com with ESMTPSA id l18sm19087044wrn.48.2019.10.21.06.03.09 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 21 Oct 2019 06:03:10 -0700 (PDT) Subject: Re: [PATCH v9 09/17] x86/split_lock: Handle #AC exception for split lock To: Sean Christopherson Cc: Xiaoyao Li , Thomas Gleixner , 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: <3ec328dc-2763-9da5-28d6-e28970262c58@redhat.com> <57f40083-9063-5d41-f06d-fa1ae4c78ec6@redhat.com> <3a12810b-1196-b70a-aa2e-9fe17dc7341a@redhat.com> <20191016154116.GA5866@linux.intel.com> <20191016162337.GC5866@linux.intel.com> <20191016174200.GF5866@linux.intel.com> From: Paolo Bonzini Openpgp: preference=signencrypt Message-ID: Date: Mon, 21 Oct 2019 15:03:12 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <20191016174200.GF5866@linux.intel.com> Content-Type: text/plain; charset=utf-8 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 16/10/19 19:42, Sean Christopherson wrote: > KVM uses a locked cmpxchg in emulator_cmpxchg_emulated() and the address > is guest controlled, e.g. a guest could coerce the host into disabling > split-lock detection via the host's #AC handler by triggering emulation > and inducing an #AC in the emulator. Yes, that's a possible issue. Paolo