From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030206AbcJ0ODA (ORCPT ); Thu, 27 Oct 2016 10:03:00 -0400 Received: from mga11.intel.com ([192.55.52.93]:33317 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S935306AbcJ0OCT (ORCPT ); Thu, 27 Oct 2016 10:02:19 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.31,404,1473145200"; d="scan'208";a="1051135849" From: Grzegorz Andrejczuk To: tglx@linutronix.de, mingo@redhat.com, hpa@zytor.com, x86@kernel.org Cc: bp@suse.de, dave.hansen@linux.intel.com, lukasz.daniluk@intel.com, james.h.cownie@intel.com, jacob.jun.pan@intel.com, Piotr.Luc@intel.com, linux-kernel@vger.kernel.org, Grzegorz Andrejczuk Subject: [PATCH v6: 2/4] x86: Add enabling of the R3MWAIT during boot Date: Thu, 27 Oct 2016 16:02:01 +0200 Message-Id: <1477576923-3244-3-git-send-email-grzegorz.andrejczuk@intel.com> X-Mailer: git-send-email 2.5.1 In-Reply-To: <1477576923-3244-1-git-send-email-grzegorz.andrejczuk@intel.com> References: <1477576923-3244-1-git-send-email-grzegorz.andrejczuk@intel.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org If processor is Intel Xeon Phi x200 we enable user-level mwait feature. Enabling this feature suppresses invalid-opcode error, when MONITOR/MWAIT is called from ring 3. Signed-off-by: Grzegorz Andrejczuk --- Documentation/kernel-parameters.txt | 5 +++++ arch/x86/kernel/cpu/intel.c | 37 +++++++++++++++++++++++++++++++++++++ 2 files changed, 42 insertions(+) diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index a4f4d69..d58915b 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -3120,6 +3120,11 @@ bytes respectively. Such letter suffixes can also be entirely omitted. pg. [PARIDE] See Documentation/blockdev/paride.txt. + phir3mwait= [X86] Disable Intel Xeon Phi x200 ring 3 MONITOR/MWAIT + feature for all cpus. + Format: { disable } + See arch/x86/kernel/cpu/intel.c + pirq= [SMP,APIC] Manual mp-table setup See Documentation/x86/i386/IO-APIC.txt. diff --git a/arch/x86/kernel/cpu/intel.c b/arch/x86/kernel/cpu/intel.c index fcd484d..2140ed3 100644 --- a/arch/x86/kernel/cpu/intel.c +++ b/arch/x86/kernel/cpu/intel.c @@ -61,6 +61,36 @@ void check_mpx_erratum(struct cpuinfo_x86 *c) } } +#ifdef CONFIG_X86_64 +static int phi_r3mwait_disabled __read_mostly; + +static int __init phir3mwait_disable(char *__unused) +{ + phi_r3mwait_disabled = 1; + pr_warn("x86/phir3mwait: Disabled ring 3 MWAIT for Xeon Phi"); + return 1; +} +__setup("phir3mwait=disable", phir3mwait_disable); + +static void probe_xeon_phi_r3mwait(struct cpuinfo_x86 *c) +{ + u64 msr; + + rdmsrl(MSR_PHI_MISC_THD_FEATURE, msr); + + if (phi_r3mwait_disabled) { + msr &= ~MSR_PHI_MISC_THD_FEATURE_R3MWAIT; + wrmsrl(MSR_PHI_MISC_THD_FEATURE, msr); + } else { + msr |= MSR_PHI_MISC_THD_FEATURE_R3MWAIT; + wrmsrl(MSR_PHI_MISC_THD_FEATURE, msr); + } +} + +#else +static void probe_xeon_phi_r3mwait(struct cpuinfo_x86 *__unused) {} +#endif + static void early_init_intel(struct cpuinfo_x86 *c) { u64 misc_enable; @@ -565,6 +595,13 @@ static void init_intel(struct cpuinfo_x86 *c) detect_vmx_virtcap(c); init_intel_energy_perf(c); + + /* + * Setting ring 3 MONITOR/MWAIT for thread + * when CPU is Xeon Phi Family x200 (KnightsLanding). + */ + if (c->x86 == 6 && c->x86_model == INTEL_FAM6_XEON_PHI_KNL) + probe_xeon_phi_r3mwait(c); } #ifdef CONFIG_X86_32 -- 2.5.1