From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752349AbdATNXH (ORCPT ); Fri, 20 Jan 2017 08:23:07 -0500 Received: from mga11.intel.com ([192.55.52.93]:12648 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752294AbdATNXE (ORCPT ); Fri, 20 Jan 2017 08:23:04 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.33,258,1477983600"; d="scan'208";a="1096695936" From: Grzegorz Andrejczuk To: tglx@linutronix.de, mingo@redhat.com, hpa@zytor.com, x86@kernel.org Cc: linux-kernel@vger.kernel.org, Piotr.Luc@intel.com, dave.hansen@linux.intel.com, Grzegorz Andrejczuk Subject: [PATCH v12 4/5] x86/cpufeature: enable RING3MWAIT for Knights Landing Date: Fri, 20 Jan 2017 14:22:36 +0100 Message-Id: <1484918557-15481-5-git-send-email-grzegorz.andrejczuk@intel.com> X-Mailer: git-send-email 2.5.1 In-Reply-To: <1484918557-15481-1-git-send-email-grzegorz.andrejczuk@intel.com> References: <1484918557-15481-1-git-send-email-grzegorz.andrejczuk@intel.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Enable ring 3 MONITOR/MWAIT for Intel Xeon Phi x200 codenamed Knights Landing. Presence of this feature cannot be detected automatically (by reading any other MSR) therefore it is required to explicitly check for the family and model of the CPU before attempting to enable it. Signed-off-by: Grzegorz Andrejczuk --- Documentation/admin-guide/kernel-parameters.txt | 4 +++ arch/x86/kernel/cpu/intel.c | 37 +++++++++++++++++++++++++ 2 files changed, 41 insertions(+) diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index be7c0d9..cfbb3fc 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -3563,6 +3563,10 @@ rhash_entries= [KNL,NET] Set number of hash buckets for route cache + ring3mwait=disable + [KNL] Disable ring 3 MONITOR/MWAIT feature on supported + CPUs. + ro [KNL] Mount root device read-only on boot rodata= [KNL] diff --git a/arch/x86/kernel/cpu/intel.c b/arch/x86/kernel/cpu/intel.c index 203f860..213cbf0 100644 --- a/arch/x86/kernel/cpu/intel.c +++ b/arch/x86/kernel/cpu/intel.c @@ -15,6 +15,8 @@ #include #include #include +#include +#include #ifdef CONFIG_X86_64 #include @@ -62,6 +64,39 @@ void check_mpx_erratum(struct cpuinfo_x86 *c) } } +static int ring3mwait_disabled __read_mostly; + +static int __init ring3mwait_disable(char *__unused) +{ + ring3mwait_disabled = 1; + return 0; +} +__setup("ring3mwait=disable", ring3mwait_disable); + +static void probe_xeon_phi_r3mwait(struct cpuinfo_x86 *c) +{ + /* + * Ring 3 MONITOR/MWAIT feature cannot be detected without + * cpu model and family comparison. + */ + if (c->x86 != 6 || c->x86_model != INTEL_FAM6_XEON_PHI_KNL) + return; + + if (ring3mwait_disabled) { + msr_clear_bit(MSR_MISC_FEATURE_ENABLES, + MSR_MISC_FEATURE_ENABLES_RING3MWAIT_BIT); + return; + } + + msr_set_bit(MSR_MISC_FEATURE_ENABLES, + MSR_MISC_FEATURE_ENABLES_RING3MWAIT_BIT); + + set_cpu_cap(c, X86_FEATURE_RING3MWAIT); + + if (c == &boot_cpu_data) + ELF_HWCAP2 |= HWCAP2_RING3MWAIT; +} + static void early_init_intel(struct cpuinfo_x86 *c) { u64 misc_enable; @@ -560,6 +595,8 @@ static void init_intel(struct cpuinfo_x86 *c) detect_vmx_virtcap(c); init_intel_energy_perf(c); + + probe_xeon_phi_r3mwait(c); } #ifdef CONFIG_X86_32 -- 2.5.1