From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753958AbZHPGlp (ORCPT ); Sun, 16 Aug 2009 02:41:45 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753690AbZHPGlp (ORCPT ); Sun, 16 Aug 2009 02:41:45 -0400 Received: from mx2.mail.elte.hu ([157.181.151.9]:40665 "EHLO mx2.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753439AbZHPGlo (ORCPT ); Sun, 16 Aug 2009 02:41:44 -0400 Date: Sun, 16 Aug 2009 08:41:32 +0200 From: Ingo Molnar To: mingo@redhat.com, hpa@zytor.com, linux-kernel@vger.kernel.org, kjwinchester@gmail.com, tglx@linutronix.de, borislav.petkov@amd.com Cc: linux-tip-commits@vger.kernel.org Subject: Re: [tip:x86/urgent] x86, AMD: Disable wrongly set X86_FEATURE_LAHF_LM CPUID bit Message-ID: <20090816064132.GA16278@elte.hu> References: <1250251594-8348-2-git-send-email-borislav.petkov@amd.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/1.5.18 (2008-05-17) X-ELTE-SpamScore: -1.5 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-1.5 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.2.5 -1.5 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * tip-bot for Borislav Petkov wrote: > Commit-ID: c74cb13b94118ec89e48849806356b67caa5ff86 > Gitweb: http://git.kernel.org/tip/c74cb13b94118ec89e48849806356b67caa5ff86 > Author: Borislav Petkov > AuthorDate: Fri, 14 Aug 2009 14:06:34 +0200 > Committer: Ingo Molnar > CommitDate: Sat, 15 Aug 2009 18:43:59 +0200 > > 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. > > Tested-by: Kevin Winchester > Signed-off-by: Borislav Petkov > Cc: kjwinchester@gmail.com > Cc: mikpe@it.uu.se > Cc: brgerst@gmail.com > LKML-Reference: <1250251594-8348-2-git-send-email-borislav.petkov@amd.com> > Signed-off-by: Ingo Molnar > > > --- > arch/x86/kernel/cpu/amd.c | 12 +++++++++++- > 1 files changed, 11 insertions(+), 1 deletions(-) > > diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c > index 63fddcd..0ee63dd 100644 > --- a/arch/x86/kernel/cpu/amd.c > +++ b/arch/x86/kernel/cpu/amd.c > @@ -404,9 +404,19 @@ 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); > + wrmsr_amd_safe(0xc001100d, (u32) val, > + (u32)(val >> 32)); > + } > + } > + > } > if (c->x86 == 0x10 || c->x86 == 0x11) > set_cpu_cap(c, X86_FEATURE_REP_GOOD); -tip testing found this build bug caused by this patch: arch/x86/kernel/cpu/amd.c: In function ‘init_amd’: arch/x86/kernel/cpu/amd.c:417: error: implicit declaration of function ‘wrmsr_amd_safe’ Ingo