From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753396Ab1HCPrn (ORCPT ); Wed, 3 Aug 2011 11:47:43 -0400 Received: from DMZ-MAILSEC-SCANNER-5.MIT.EDU ([18.7.68.34]:57257 "EHLO dmz-mailsec-scanner-5.mit.edu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753634Ab1HCPr2 (ORCPT ); Wed, 3 Aug 2011 11:47:28 -0400 X-AuditID: 12074422-b7ba7ae000000a14-44-4e396d7aadf0 From: Andy Lutomirski To: x86@kernel.org, linux-kernel@vger.kernel.org Cc: Fenghua Yu , Andy Lutomirski Subject: [PATCH 1/2] x86: Enable fast strings on Intel if BIOS hasn't already Date: Wed, 3 Aug 2011 11:47:16 -0400 Message-Id: X-Mailer: git-send-email 1.7.6 In-Reply-To: References: In-Reply-To: References: X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFrrNIsWRmVeSWpSXmKPExsUixCmqrVuda+lncLuPw6LvylF2i7ZpjhaX d81hs/ix4TGrA4vHzll32T0W73nJ5LFpVSebx+dNcgEsUVw2Kak5mWWpRfp2CVwZ/xc+Yik4 KVBxc0crYwPjWd4uRk4OCQETiWdLWtggbDGJC/fWA9lcHEIC+xglHh2dyAzhrGeUWHrmJCuE 85RJom/rNnaQFjYBFYmOpQ+YQGwRAQOJLStfsILYzAKuEge2PWUEsYUFfCV6rt1kBrFZBFQl Vuw5B1bPKxAkcWFaKxPEajmJI5efg9mcQHOOty4Es4UE9CX+/l3Aikt8AqPAAkaGVYyyKblV urmJmTnFqcm6xcmJeXmpRbqmermZJXqpKaWbGEFhyO6itIPx50GlQ4wCHIxKPLyFSZZ+QqyJ ZcWVuYcYJTmYlER592UDhfiS8lMqMxKLM+KLSnNSiw8xSnAwK4nwtvMC5XhTEiurUovyYVLS HCxK4rwl3v99hQTSE0tSs1NTC1KLYLIyHBxKErybcoAaBYtS01Mr0jJzShDSTBycIMN5gIaD 1fAWFyTmFmemQ+RPMSpKifNOAkkIgCQySvPgemFp4hWjONArwryd8UBVPMAUA9f9CmgwE9Dg /+8tQAaXJCKkpBoYI046LxN96HLgrs+9gjtvWP8cPNdUccvN5SZrv3Tks50CMXpreWIDHLzq bpu3p1Xn/tE8ozTx/umYIIszHic2vPj2U9No2/yu/S1h/x3tq+6XzjBw0bty5MyUX9PKnqtt viK47e/h7/MPfDWbMFn88fvf/a6/XTdwHoi65xYUaNfcYivbsaUxRYmlOCPRUIu5qDgRAL+o u6ruAgAA Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org I have two Sandy Bridge systems and neither one enables fast strings in BIOS. I can't find anything in the manual that says that only BIOS should enable or disable the feature, so try to enable it at bootup. Signed-off-by: Andy Lutomirski --- arch/x86/kernel/cpu/intel.c | 17 +++++++++++++++-- 1 files changed, 15 insertions(+), 2 deletions(-) diff --git a/arch/x86/kernel/cpu/intel.c b/arch/x86/kernel/cpu/intel.c index ed6086e..6b20fef 100644 --- a/arch/x86/kernel/cpu/intel.c +++ b/arch/x86/kernel/cpu/intel.c @@ -30,6 +30,7 @@ static void __cpuinit early_init_intel(struct cpuinfo_x86 *c) { u64 misc_enable; + bool allow_fast_string = true; /* Unmask CPUID levels if masked: */ if (c->x86 > 6 || (c->x86 == 6 && c->x86_model >= 0xd)) { @@ -118,10 +119,11 @@ static void __cpuinit early_init_intel(struct cpuinfo_x86 *c) * (model 2) with the same problem. */ if (c->x86 == 15) { - rdmsrl(MSR_IA32_MISC_ENABLE, misc_enable); + allow_fast_string = false; + printk(KERN_INFO "kmemcheck: Disabling fast string operations\n"); + rdmsrl(MSR_IA32_MISC_ENABLE, misc_enable); if (misc_enable & MSR_IA32_MISC_ENABLE_FAST_STRING) { - printk(KERN_INFO "kmemcheck: Disabling fast string operations\n"); misc_enable &= ~MSR_IA32_MISC_ENABLE_FAST_STRING; wrmsrl(MSR_IA32_MISC_ENABLE, misc_enable); @@ -135,6 +137,17 @@ static void __cpuinit early_init_intel(struct cpuinfo_x86 *c) */ if (c->x86 > 6 || (c->x86 == 6 && c->x86_model >= 0xd)) { rdmsrl(MSR_IA32_MISC_ENABLE, misc_enable); + + if (allow_fast_string && + !(misc_enable & MSR_IA32_MISC_ENABLE_FAST_STRING)) { + misc_enable |= MSR_IA32_MISC_ENABLE_FAST_STRING; + wrmsrl(MSR_IA32_MISC_ENABLE, misc_enable); + printk(KERN_INFO "Enabled fast string operations\n"); + + /* Re-read to make sure it stuck. */ + rdmsrl(MSR_IA32_MISC_ENABLE, misc_enable); + } + if (!(misc_enable & MSR_IA32_MISC_ENABLE_FAST_STRING)) { printk(KERN_INFO "Disabled fast string operations\n"); setup_clear_cpu_cap(X86_FEATURE_REP_GOOD); -- 1.7.6