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=-2.2 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 27714C433E3 for ; Thu, 18 Jun 2020 15:53:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0156D20732 for ; Thu, 18 Jun 2020 15:53:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731610AbgFRPw7 (ORCPT ); Thu, 18 Jun 2020 11:52:59 -0400 Received: from mga14.intel.com ([192.55.52.115]:58067 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727911AbgFRPw6 (ORCPT ); Thu, 18 Jun 2020 11:52:58 -0400 IronPort-SDR: zz43w2BAAasn4uYs6kw3LtkM3X323TZTDNMMY35jUR2bO0DDhj5n4j/NuluZmxsdce64e6hqCN ReScRyT47BAg== X-IronPort-AV: E=McAfee;i="6000,8403,9656"; a="141701484" X-IronPort-AV: E=Sophos;i="5.75,251,1589266800"; d="scan'208";a="141701484" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga006.jf.intel.com ([10.7.209.51]) by fmsmga103.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 18 Jun 2020 08:52:56 -0700 IronPort-SDR: Rz7wj+h3c6y5PnE7mt0HLs+WCimZP8shyO9jjYR92TH5XPP+l4Rs1D7su9MB1R/gF705XCWoaj /weqIcFrTVQg== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.75,251,1589266800"; d="scan'208";a="277665815" Received: from otcsectest.jf.intel.com (HELO 258ff54ff3c0) ([10.54.30.81]) by orsmga006.jf.intel.com with ESMTP; 18 Jun 2020 08:52:56 -0700 Date: Thu, 18 Jun 2020 15:49:32 +0000 From: "Andersen, John" To: Dave Hansen Cc: corbet@lwn.net, pbonzini@redhat.com, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, x86@kernel.org, hpa@zytor.com, shuah@kernel.org, sean.j.christopherson@intel.com, liran.alon@oracle.com, drjones@redhat.com, rick.p.edgecombe@intel.com, kristen@linux.intel.com, vkuznets@redhat.com, wanpengli@tencent.com, jmattson@google.com, joro@8bytes.org, mchehab+huawei@kernel.org, gregkh@linuxfoundation.org, paulmck@kernel.org, pawan.kumar.gupta@linux.intel.com, jgross@suse.com, mike.kravetz@oracle.com, oneukum@suse.com, luto@kernel.org, peterz@infradead.org, fenghua.yu@intel.com, reinette.chatre@intel.com, vineela.tummalapalli@intel.com, dave.hansen@linux.intel.com, arjan@linux.intel.com, caoj.fnst@cn.fujitsu.com, bhe@redhat.com, nivedita@alum.mit.edu, keescook@chromium.org, dan.j.williams@intel.com, eric.auger@redhat.com, aaronlewis@google.com, peterx@redhat.com, makarandsonare@google.com, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, linux-kselftest@vger.kernel.org, kernel-hardening@lists.openwall.com Subject: Re: [PATCH 4/4] X86: Use KVM CR pin MSRs Message-ID: <20200618154931.GD23@258ff54ff3c0> References: <20200617190757.27081-1-john.s.andersen@intel.com> <20200617190757.27081-5-john.s.andersen@intel.com> <20200618152649.GC23@258ff54ff3c0> <5706af0c-e426-91bc-4c38-d1203cf1b3b7@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <5706af0c-e426-91bc-4c38-d1203cf1b3b7@intel.com> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jun 18, 2020 at 08:38:06AM -0700, Dave Hansen wrote: > On 6/18/20 8:26 AM, Andersen, John wrote: > > On Thu, Jun 18, 2020 at 07:41:04AM -0700, Dave Hansen wrote: > >>> +config PARAVIRT_CR_PIN > >>> + bool "Paravirtual bit pinning for CR0 and CR4" > >>> + depends on KVM_GUEST > >>> + help > >>> + Select this option to have the virtualised guest request that the > >>> + hypervisor disallow it from disabling protections set in control > >>> + registers. The hypervisor will prevent exploits from disabling > >>> + features such as SMEP, SMAP, UMIP, and WP. > >> > >> I'm confused. Does this add support for ""Paravirtual bit pinning", or > >> actually tell the guest to request pinning by default? > >> > >> It says "Select this option to have the virtualised guest request...", > >> which makes it sound like it affects the default rather than the > >> availability of the option. > > > > How about this > > > > Select this option to request protection of SMEP, SMAP, UMIP, and WP > > control register bits when running paravirtualized under KVM. Protection will > > be active provided the feature is available host side and kexec is disabled via > > kconfig or the command line for the guest requesting protection. > > It still isn't very clear to me. > > Let's pull the config option out of this patch. Enable the feature by > default and do the command-line processing in this patch. > > If you still think a Kconfig option is helpful, add it in a separate > patch calling out the deficiencies with the boot-time options. That's right we're going to pull it out anyway and just disable if the disable_pv_cr_pin command line option is set. Oops. That solves that. Thank you very much for your review Dave