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=-3.7 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 02430C35242 for ; Sat, 8 Feb 2020 18:34:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D212420661 for ; Sat, 8 Feb 2020 18:34:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727999AbgBHSem (ORCPT ); Sat, 8 Feb 2020 13:34:42 -0500 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:34176 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727874AbgBHS3p (ORCPT ); Sat, 8 Feb 2020 13:29:45 -0500 Received: from [192.168.4.242] (helo=deadeye) by shadbolt.decadent.org.uk with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.89) (envelope-from ) id 1j0UrK-0003fL-9B; Sat, 08 Feb 2020 18:29:38 +0000 Received: from ben by deadeye with local (Exim 4.93) (envelope-from ) id 1j0UrK-000CTo-3t; Sat, 08 Feb 2020 18:29:38 +0000 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, Denis Kirjanov , "Paolo Bonzini" , "Jim Mattson" Date: Sat, 08 Feb 2020 18:20:51 +0000 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) X-Patchwork-Hint: ignore Subject: [PATCH 3.16 112/148] KVM: x86: fix presentation of TSX feature in ARCH_CAPABILITIES In-Reply-To: X-SA-Exim-Connect-IP: 192.168.4.242 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.16.82-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Paolo Bonzini commit cbbaa2727aa3ae9e0a844803da7cef7fd3b94f2b upstream. 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. Tested-by: Jim Mattson Signed-off-by: Paolo Bonzini [bwh: Backported to 3.16: adjust context] Signed-off-by: Ben Hutchings --- --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -945,10 +945,15 @@ 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; }