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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 66947C432C3 for ; Fri, 22 Nov 2019 20:15:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 38D022068F for ; Fri, 22 Nov 2019 20:15:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726655AbfKVUPi (ORCPT ); Fri, 22 Nov 2019 15:15:38 -0500 Received: from mga12.intel.com ([192.55.52.136]:54647 "EHLO mga12.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726187AbfKVUPi (ORCPT ); Fri, 22 Nov 2019 15:15:38 -0500 X-Amp-Result: UNKNOWN X-Amp-Original-Verdict: FILE UNKNOWN X-Amp-File-Uploaded: False Received: from orsmga007.jf.intel.com ([10.7.209.58]) by fmsmga106.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 22 Nov 2019 12:15:38 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.69,231,1571727600"; d="scan'208";a="197731025" Received: from sjchrist-coffee.jf.intel.com (HELO linux.intel.com) ([10.54.74.41]) by orsmga007.jf.intel.com with ESMTP; 22 Nov 2019 12:15:38 -0800 Date: Fri, 22 Nov 2019 12:15:38 -0800 From: Sean Christopherson To: Paolo Bonzini Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org, jmattson@google.com, stable@vger.kernel.org Subject: Re: [PATCH 1/5] KVM: x86: fix presentation of TSX feature in ARCH_CAPABILITIES Message-ID: <20191122201537.GD31235@linux.intel.com> References: <1574101067-5638-1-git-send-email-pbonzini@redhat.com> <1574101067-5638-2-git-send-email-pbonzini@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1574101067-5638-2-git-send-email-pbonzini@redhat.com> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org On Mon, Nov 18, 2019 at 07:17:43PM +0100, Paolo Bonzini wrote: > KVM does not implement MSR_IA32_TSX_CTRL, so it must not be presented > to the guests. It is also confusing to have !ARCH_CAP_TSX_CTRL_MSR && > !RTM && ARCH_CAP_TAA_NO: lack of MSR_IA32_TSX_CTRL suggests TSX was not > hidden (it actually was), yet the value says that TSX is not vulnerable > to microarchitectural data sampling. Fix both. > > Cc: stable@vger.kernel.org > Signed-off-by: Paolo Bonzini > --- > arch/x86/kvm/x86.c | 10 ++++++++-- > 1 file changed, 8 insertions(+), 2 deletions(-) > > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index 5d530521f11d..6ea735d632e9 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -1327,12 +1327,18 @@ static u64 kvm_get_arch_capabilities(void) > * If TSX is disabled on the system, guests are also mitigated against > * TAA and clear CPU buffer mitigation is not required for guests. > */ > - if (boot_cpu_has_bug(X86_BUG_TAA) && boot_cpu_has(X86_FEATURE_RTM) && > - (data & ARCH_CAP_TSX_CTRL_MSR)) > + if (!boot_cpu_has(X86_FEATURE_RTM)) > + data &= ~ARCH_CAP_TAA_NO; > + else if (!boot_cpu_has_bug(X86_BUG_TAA)) > + data |= ARCH_CAP_TAA_NO; > + else if (data & ARCH_CAP_TSX_CTRL_MSR) > data &= ~ARCH_CAP_MDS_NO; > > + /* KVM does not emulate MSR_IA32_TSX_CTRL. */ > + data &= ~ARCH_CAP_TSX_CTRL_MSR; > return data; > } > +EXPORT_SYMBOL_GPL(kvm_get_arch_capabilities); Whoever backports this patch should drop this spurious addition of EXPORT_SYMBOL_GPL, unless they also want to backport the cleanup :-).