From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-11.9 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SIGNED_OFF_BY,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7B4BBC67839 for ; Tue, 11 Dec 2018 21:13:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4AD2020851 for ; Tue, 11 Dec 2018 21:13:24 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 4AD2020851 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=zytor.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726312AbeLKVNX (ORCPT ); Tue, 11 Dec 2018 16:13:23 -0500 Received: from terminus.zytor.com ([198.137.202.136]:54491 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726134AbeLKVNW (ORCPT ); Tue, 11 Dec 2018 16:13:22 -0500 Received: from terminus.zytor.com (localhost [127.0.0.1]) by terminus.zytor.com (8.15.2/8.15.2) with ESMTPS id wBBLD7Df4154210 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NO); Tue, 11 Dec 2018 13:13:07 -0800 Received: (from tipbot@localhost) by terminus.zytor.com (8.15.2/8.15.2/Submit) id wBBLD5Qh4154207; Tue, 11 Dec 2018 13:13:05 -0800 Date: Tue, 11 Dec 2018 13:13:05 -0800 X-Authentication-Warning: terminus.zytor.com: tipbot set sender to tipbot@zytor.com using -f From: tip-bot for Reinette Chatre Message-ID: Cc: mingo@kernel.org, tglx@linutronix.de, linux-kernel@vger.kernel.org, reinette.chatre@intel.com, fenghua.yu@intel.com, mingo@redhat.com, hpa@zytor.com, bp@suse.de, tony.luck@intel.com, stable@vger.kernel.org, x86@kernel.org Reply-To: bp@suse.de, tony.luck@intel.com, stable@vger.kernel.org, x86@kernel.org, mingo@kernel.org, tglx@linutronix.de, linux-kernel@vger.kernel.org, reinette.chatre@intel.com, fenghua.yu@intel.com, mingo@redhat.com, hpa@zytor.com In-Reply-To: References: To: linux-tip-commits@vger.kernel.org Subject: [tip:x86/urgent] x86/intel_rdt: Ensure a CPU remains online for the region's pseudo-locking sequence Git-Commit-ID: 80b71c340f17705ec145911b9a193ea781811b16 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 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: 80b71c340f17705ec145911b9a193ea781811b16 Gitweb: https://git.kernel.org/tip/80b71c340f17705ec145911b9a193ea781811b16 Author: Reinette Chatre AuthorDate: Mon, 10 Dec 2018 13:21:54 -0800 Committer: Borislav Petkov CommitDate: Tue, 11 Dec 2018 21:59:01 +0100 x86/intel_rdt: Ensure a CPU remains online for the region's pseudo-locking sequence The user triggers the creation of a pseudo-locked region when writing the requested schemata to the schemata resctrl file. The pseudo-locking of a region is required to be done on a CPU that is associated with the cache on which the pseudo-locked region will reside. In order to run the locking code on a specific CPU, the needed CPU has to be selected and ensured to remain online during the entire locking sequence. At this time, the cpu_hotplug_lock is not taken during the pseudo-lock region creation and it is thus possible for a CPU to be selected to run the pseudo-locking code and then that CPU to go offline before the thread is able to run on it. Fix this by ensuring that the cpu_hotplug_lock is taken while the CPU on which code has to run needs to be controlled. Since the cpu_hotplug_lock is always taken before rdtgroup_mutex the lock order is maintained. Fixes: e0bdfe8e36f3 ("x86/intel_rdt: Support creation/removal of pseudo-locked region") Signed-off-by: Reinette Chatre Signed-off-by: Borislav Petkov Cc: "H. Peter Anvin" Cc: Fenghua Yu Cc: Ingo Molnar Cc: Thomas Gleixner Cc: Tony Luck Cc: gavin.hindman@intel.com Cc: jithu.joseph@intel.com Cc: stable Cc: x86-ml Link: https://lkml.kernel.org/r/b7b17432a80f95a1fa21a1698ba643014f58ad31.1544476425.git.reinette.chatre@intel.com --- arch/x86/kernel/cpu/intel_rdt_ctrlmondata.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/arch/x86/kernel/cpu/intel_rdt_ctrlmondata.c b/arch/x86/kernel/cpu/intel_rdt_ctrlmondata.c index 27937458c231..efa4a519f5e5 100644 --- a/arch/x86/kernel/cpu/intel_rdt_ctrlmondata.c +++ b/arch/x86/kernel/cpu/intel_rdt_ctrlmondata.c @@ -23,6 +23,7 @@ #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt +#include #include #include #include @@ -310,9 +311,11 @@ ssize_t rdtgroup_schemata_write(struct kernfs_open_file *of, return -EINVAL; buf[nbytes - 1] = '\0'; + cpus_read_lock(); rdtgrp = rdtgroup_kn_lock_live(of->kn); if (!rdtgrp) { rdtgroup_kn_unlock(of->kn); + cpus_read_unlock(); return -ENOENT; } rdt_last_cmd_clear(); @@ -367,6 +370,7 @@ ssize_t rdtgroup_schemata_write(struct kernfs_open_file *of, out: rdtgroup_kn_unlock(of->kn); + cpus_read_unlock(); return ret ?: nbytes; }