From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965461Ab1C3WV0 (ORCPT ); Wed, 30 Mar 2011 18:21:26 -0400 Received: from vms173013pub.verizon.net ([206.46.173.13]:38583 "EHLO vms173013pub.verizon.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933138Ab1C3WVY (ORCPT ); Wed, 30 Mar 2011 18:21:24 -0400 Date: Wed, 30 Mar 2011 18:21:02 -0400 (EDT) From: Len Brown X-X-Sender: lenb@x980 To: x86@kernel.org Cc: linux-pm@lists.linux-foundation.org, linux-kernel@vger.kernel.org Subject: [PATCH] x86 intel power: Initialize MSR_IA32_ENERGY_PERF_BIAS Message-id: User-Agent: Alpine 2.02 (LFD 1266 2009-07-14) MIME-version: 1.0 Content-type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Len Brown Since 2.6.35 (23016bf0d25), Linux prints the existence of "epb" in /proc/cpuinfo, Since 2.6.38 (d5532ee7b40), the x86_energy_perf_policy(8) utility is available in-tree to update MSR_IA32_ENERGY_PERF_BIAS. However, the typical BIOS fails to initialize the MSR, and the typical Linux distro neglects to invoke x86_energy_perf_policy(8). The result is that some modern hardware is running in hardware default, which is "performance" mode, rather than the intended design default of "normal" mode. Initialize the MSR to the "normal" setting during kernel boot. Of course, x86_energy_perf_policy(8) is available to change the default after boot, should the user have a policy preference. cc: stable@kernel.org Signed-off-by: Len Brown --- arch/x86/include/asm/msr-index.h | 3 +++ arch/x86/kernel/cpu/intel.c | 14 ++++++++++++++ 2 files changed, 17 insertions(+), 0 deletions(-) diff --git a/arch/x86/include/asm/msr-index.h b/arch/x86/include/asm/msr-index.h index 43a18c7..91fedd9 100644 --- a/arch/x86/include/asm/msr-index.h +++ b/arch/x86/include/asm/msr-index.h @@ -250,6 +250,9 @@ #define MSR_IA32_TEMPERATURE_TARGET 0x000001a2 #define MSR_IA32_ENERGY_PERF_BIAS 0x000001b0 +#define ENERGY_PERF_BIAS_PERFORMANCE 0 +#define ENERGY_PERF_BIAS_NORMAL 6 +#define ENERGY_PERF_BIAS_POWERSWAVE 15 #define MSR_IA32_PACKAGE_THERM_STATUS 0x000001b1 diff --git a/arch/x86/kernel/cpu/intel.c b/arch/x86/kernel/cpu/intel.c index d16c2c5..48cca4a 100644 --- a/arch/x86/kernel/cpu/intel.c +++ b/arch/x86/kernel/cpu/intel.c @@ -448,6 +448,20 @@ static void __cpuinit init_intel(struct cpuinfo_x86 *c) if (cpu_has(c, X86_FEATURE_VMX)) detect_vmx_virtcap(c); + + /* + * Initialize MSR_IA32_ENERGY_PERF_BIAS if BIOS did not. + * x86_energy_perf_policy(8) is available to change it at run-time + */ + if (cpu_has(c, X86_FEATURE_EPB)) { + u64 epb; + + rdmsrl(MSR_IA32_ENERGY_PERF_BIAS, epb); + if ((epb & 0xF) == 0) { + epb = (epb & ~0xF) | ENERGY_PERF_BIAS_NORMAL; + wrmsrl(MSR_IA32_ENERGY_PERF_BIAS, epb); + } + } } #ifdef CONFIG_X86_32 -- 1.7.4.2.406.gbe91