From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755789AbcJLRVT (ORCPT ); Wed, 12 Oct 2016 13:21:19 -0400 Received: from mga01.intel.com ([192.55.52.88]:48430 "EHLO mga01.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753659AbcJLRVO (ORCPT ); Wed, 12 Oct 2016 13:21:14 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.31,336,1473145200"; d="scan'208";a="1063905311" Subject: Re: [PATCH v2 2/4] Add enabling of the R3 MWAIT during boot for KNL To: Grzegorz Andrejczuk , tglx@linutronix.de, mingo@redhat.com, hpa@zytor.com, x86@kernel.org References: <1476274585-21679-1-git-send-email-grzegorz.andrejczuk@intel.com> <1476274585-21679-3-git-send-email-grzegorz.andrejczuk@intel.com> Cc: bp@suse.de, linux-kernel@vger.kernel.org, lukasz.daniluk@intel.com, james.h.cownie@intel.com From: Dave Hansen Message-ID: <57FE7104.6070608@linux.intel.com> Date: Wed, 12 Oct 2016 10:21:08 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.8.0 MIME-Version: 1.0 In-Reply-To: <1476274585-21679-3-git-send-email-grzegorz.andrejczuk@intel.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 10/12/2016 05:16 AM, Grzegorz Andrejczuk wrote: > @@ -211,6 +219,25 @@ static void early_init_intel(struct cpuinfo_x86 *c) > } > > check_mpx_erratum(c); > + > + /* > + * Setting ring 3 MONITOR/MWAIT for all threads > + * when CPU is Xeon Phi Family x200 > + * This can be disabled with phir3mwait=disable cmdline switch. > + * We preserve the reserved values and set only 2nd bit. > + * Ref: > + * https://software.intel.com/en-us/blogs/2016/10/06/intel-xeon-phi-product-family-x200-knl-user-mode-ring-3-monitor-and-mwait > + */ > + if (c->x86 == 6 && > + c->x86_model == INTEL_FAM6_XEON_PHI_KNL && > + phir3mwait) { > + u64 prev; > + > + rdmsrl(MSR_PHI_MISC_THD_FEATURE, prev); > + if ((prev & MSR_PHI_MISC_THD_FEATURE_R3MWAIT) == 0) > + wrmsrl(MSR_PHI_MISC_THD_FEATURE, > + prev | MSR_PHI_MISC_THD_FEATURE_R3MWAIT); > + } > } I'd really prefer that we put hunks like this into helpers just like the nice check_mpx_erratum(). I know early_init_intel() looks a lot like what you have here, but I think a little: probe_xeon_phi_mwait() would be a lot nicer. BTW, this hunk totally indicates how badly named 'phir3mwait' is. Could you please give it a sane name like 'phi_r3_mwait_disabled'?