From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752193AbZHaXh4 (ORCPT ); Mon, 31 Aug 2009 19:37:56 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751598AbZHaXhz (ORCPT ); Mon, 31 Aug 2009 19:37:55 -0400 Received: from hera.kernel.org ([140.211.167.34]:57069 "EHLO hera.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751431AbZHaXhx (ORCPT ); Mon, 31 Aug 2009 19:37:53 -0400 Date: Mon, 31 Aug 2009 23:37:40 GMT From: tip-bot for Borislav Petkov Cc: linux-kernel@vger.kernel.org, hpa@zytor.com, mingo@redhat.com, tglx@linutronix.de, borislav.petkov@amd.com Reply-To: mingo@redhat.com, hpa@zytor.com, linux-kernel@vger.kernel.org, tglx@linutronix.de, borislav.petkov@amd.com In-Reply-To: <1251705011-18636-3-git-send-email-petkovbb@gmail.com> References: <1251705011-18636-3-git-send-email-petkovbb@gmail.com> To: linux-tip-commits@vger.kernel.org Subject: [tip:x86/cpu] x86, AMD: Disable wrongly set X86_FEATURE_LAHF_LM CPUID bit Message-ID: Git-Commit-ID: 6b0f43ddfa358dc71ad2a2d57bce5906c1c5dc1a X-Mailer: tip-git-log-daemon MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.0 (hera.kernel.org [127.0.0.1]); Mon, 31 Aug 2009 23:37:41 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: 6b0f43ddfa358dc71ad2a2d57bce5906c1c5dc1a Gitweb: http://git.kernel.org/tip/6b0f43ddfa358dc71ad2a2d57bce5906c1c5dc1a Author: Borislav Petkov AuthorDate: Mon, 31 Aug 2009 09:50:11 +0200 Committer: H. Peter Anvin CommitDate: Mon, 31 Aug 2009 15:14:29 -0700 x86, AMD: Disable wrongly set X86_FEATURE_LAHF_LM CPUID bit fbd8b1819e80ac5a176d085fdddc3a34d1499318 turns off the bit for /proc/cpuinfo. However, a proper/full fix would be to additionally turn off the bit in the CPUID output so that future callers get correct CPU features info. Do that by basically reversing what the BIOS wrongfully does at boot. Signed-off-by: Borislav Petkov LKML-Reference: <1251705011-18636-3-git-send-email-petkovbb@gmail.com> Signed-off-by: H. Peter Anvin --- arch/x86/kernel/cpu/amd.c | 11 ++++++++++- 1 files changed, 10 insertions(+), 1 deletions(-) diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c index 63fddcd..0a717fc 100644 --- a/arch/x86/kernel/cpu/amd.c +++ b/arch/x86/kernel/cpu/amd.c @@ -404,9 +404,18 @@ static void __cpuinit init_amd(struct cpuinfo_x86 *c) /* * Some BIOSes incorrectly force this feature, but only K8 * revision D (model = 0x14) and later actually support it. + * (AMD Erratum #110, docId: 25759). */ - if (c->x86_model < 0x14) + if (c->x86_model < 0x14 && cpu_has(c, X86_FEATURE_LAHF_LM)) { + u64 val; + clear_cpu_cap(c, X86_FEATURE_LAHF_LM); + if (!rdmsrl_amd_safe(0xc001100d, &val)) { + val &= ~(1ULL << 32); + wrmsrl_amd_safe(0xc001100d, val); + } + } + } if (c->x86 == 0x10 || c->x86 == 0x11) set_cpu_cap(c, X86_FEATURE_REP_GOOD);