From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751333AbcFRIO7 (ORCPT ); Sat, 18 Jun 2016 04:14:59 -0400 Received: from terminus.zytor.com ([198.137.202.10]:56588 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751299AbcFRIOr (ORCPT ); Sat, 18 Jun 2016 04:14:47 -0400 Date: Sat, 18 Jun 2016 01:13:49 -0700 From: tip-bot for Fenghua Yu Message-ID: Cc: brgerst@gmail.com, sai.praneeth.prakhya@intel.com, luto@kernel.org, tglx@linutronix.de, oleg@redhat.com, torvalds@linux-foundation.org, fenghua.yu@intel.com, quentin.casasnovas@oracle.com, yu-cheng.yu@intel.com, dave.hansen@intel.com, hpa@zytor.com, peterz@infradead.org, mingo@kernel.org, bp@alien8.de, ravi.v.shankar@intel.com, dvlasenk@redhat.com, linux-kernel@vger.kernel.org, dave.hansen@linux.intel.com Reply-To: fenghua.yu@intel.com, quentin.casasnovas@oracle.com, yu-cheng.yu@intel.com, brgerst@gmail.com, sai.praneeth.prakhya@intel.com, tglx@linutronix.de, luto@kernel.org, oleg@redhat.com, torvalds@linux-foundation.org, bp@alien8.de, mingo@kernel.org, ravi.v.shankar@intel.com, dvlasenk@redhat.com, linux-kernel@vger.kernel.org, dave.hansen@linux.intel.com, dave.hansen@intel.com, hpa@zytor.com, peterz@infradead.org In-Reply-To: <2fb4ec7f18b76e8cda057a8c0038def74a9b8044.1463760376.git.yu-cheng.yu@intel.com> References: <2fb4ec7f18b76e8cda057a8c0038def74a9b8044.1463760376.git.yu-cheng.yu@intel.com> To: linux-tip-commits@vger.kernel.org Subject: [tip:x86/fpu] x86/fpu/xstate: Keep init_fpstate.xsave.header.xfeatures as zero for init optimization Git-Commit-ID: 7d9370607d28afd454775c623d5447603473a3c3 X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: 7d9370607d28afd454775c623d5447603473a3c3 Gitweb: http://git.kernel.org/tip/7d9370607d28afd454775c623d5447603473a3c3 Author: Fenghua Yu AuthorDate: Fri, 20 May 2016 10:47:07 -0700 Committer: Ingo Molnar CommitDate: Sat, 18 Jun 2016 10:10:19 +0200 x86/fpu/xstate: Keep init_fpstate.xsave.header.xfeatures as zero for init optimization Keep init_fpstate.xsave.header.xfeatures as zero for init optimization. This is important for init optimization that is implemented in processor. If a bit corresponding to an xstate in xstate_bv is 0, it means the xstate is in init status and will not be read from memory to the processor during XRSTOR/XRSTORS instruction. This largely impacts context switch performance. Signed-off-by: Fenghua Yu Signed-off-by: Yu-cheng Yu Reviewed-by: Dave Hansen Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Brian Gerst Cc: Dave Hansen Cc: Denys Vlasenko Cc: H. Peter Anvin Cc: Linus Torvalds Cc: Oleg Nesterov Cc: Peter Zijlstra Cc: Quentin Casasnovas Cc: Ravi V. Shankar Cc: Sai Praneeth Prakhya Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/2fb4ec7f18b76e8cda057a8c0038def74a9b8044.1463760376.git.yu-cheng.yu@intel.com Signed-off-by: Ingo Molnar --- arch/x86/kernel/fpu/xstate.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-) diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c index 46abfaf..dbfef1b 100644 --- a/arch/x86/kernel/fpu/xstate.c +++ b/arch/x86/kernel/fpu/xstate.c @@ -329,13 +329,11 @@ static void __init setup_init_fpu_buf(void) setup_xstate_features(); print_xstate_features(); - if (boot_cpu_has(X86_FEATURE_XSAVES)) { + if (boot_cpu_has(X86_FEATURE_XSAVES)) init_fpstate.xsave.header.xcomp_bv = (u64)1 << 63 | xfeatures_mask; - init_fpstate.xsave.header.xfeatures = xfeatures_mask; - } /* - * Init all the features state with header_bv being 0x0 + * Init all the features state with header.xfeatures being 0x0 */ copy_kernel_to_xregs_booting(&init_fpstate.xsave);