From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759781AbcLAU4A (ORCPT ); Thu, 1 Dec 2016 15:56:00 -0500 Received: from mga09.intel.com ([134.134.136.24]:3523 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753817AbcLAUz7 (ORCPT ); Thu, 1 Dec 2016 15:55:59 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.33,726,1477983600"; d="scan'208";a="907744786" From: "Fenghua Yu" To: "Thomas Gleixner" Cc: "H. Peter Anvin" , "Ingo Molnar" , "Marcelo Tosatti" , "Tony Luck" , "Ravi V Shankar" , "Sai Prakhya" , "Vikas Shivappa" , "linux-kernel" , "x86" , "Fenghua Yu" Subject: [PATCH v2] x86/intel_rdt: Call intel_rdt_sched_in() with preemption disabled Date: Thu, 1 Dec 2016 12:55:14 -0800 Message-Id: <1480625714-54246-1-git-send-email-fenghua.yu@intel.com> X-Mailer: git-send-email 1.8.0.1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Fenghua Yu intel_rdt_sched_in() must be called with preemption disabled because the function accesses percpu variables (pqr_state and closid). If a task moves itself via move_myself() preemption is enabled, which violates the calling convention and can result in incorrect closid selection when the task gets preempted or migrated. Add the required protection and a comment about the calling convention. Signed-off-by: Fenghua Yu --- arch/x86/include/asm/intel_rdt.h | 2 ++ arch/x86/kernel/cpu/intel_rdt_rdtgroup.c | 2 ++ 2 files changed, 4 insertions(+) diff --git a/arch/x86/include/asm/intel_rdt.h b/arch/x86/include/asm/intel_rdt.h index 6e90e87..95ce5c8 100644 --- a/arch/x86/include/asm/intel_rdt.h +++ b/arch/x86/include/asm/intel_rdt.h @@ -192,6 +192,8 @@ int rdtgroup_schemata_show(struct kernfs_open_file *of, * resctrl file system. * - Caches the per cpu CLOSid values and does the MSR write only * when a task with a different CLOSid is scheduled in. + * + * Must be called with preemption disabled. */ static inline void intel_rdt_sched_in(void) { diff --git a/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c b/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c index fb8e03e..1afd3f3 100644 --- a/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c +++ b/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c @@ -326,8 +326,10 @@ static void move_myself(struct callback_head *head) kfree(rdtgrp); } + preempt_disable(); /* update PQR_ASSOC MSR to make resource group go into effect */ intel_rdt_sched_in(); + preempt_enable(); kfree(callback); } -- 2.5.0