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=-16.7 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT 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 3CCCEC4361B for ; Thu, 17 Dec 2020 22:32:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 138592376F for ; Thu, 17 Dec 2020 22:32:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732244AbgLQWcj (ORCPT ); Thu, 17 Dec 2020 17:32:39 -0500 Received: from mga12.intel.com ([192.55.52.136]:41195 "EHLO mga12.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732093AbgLQWci (ORCPT ); Thu, 17 Dec 2020 17:32:38 -0500 IronPort-SDR: 8zMSzPp/zNQrnfzFU3nvBZAhIOeb/Ilj4AeXFYfn1y+LK1lzH/2u1LgHtW4A02TK0h4gvTiLBb HTYPtYynjY5A== X-IronPort-AV: E=McAfee;i="6000,8403,9838"; a="154567848" X-IronPort-AV: E=Sophos;i="5.78,428,1599548400"; d="scan'208";a="154567848" Received: from fmsmga002.fm.intel.com ([10.253.24.26]) by fmsmga106.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 17 Dec 2020 14:31:43 -0800 IronPort-SDR: V+bt6X4JGWOuRyhkI25MFTX4y+NdpKXpbg2T9yyl/o7yUvxPEShenYR4k/vmfDxV0/NbCPA8MQ dwPKRfL9Y1oA== X-IronPort-AV: E=Sophos;i="5.78,428,1599548400"; d="scan'208";a="387836645" Received: from rchatre-mobl1.jf.intel.com ([10.54.70.7]) by fmsmga002-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 17 Dec 2020 14:31:42 -0800 From: Reinette Chatre To: tglx@linutronix.de, fenghua.yu@intel.com, bp@alien8.de, tony.luck@intel.com Cc: kuo-lang.tseng@intel.com, shakeelb@google.com, valentin.schneider@arm.com, mingo@redhat.com, babu.moger@amd.com, james.morse@arm.com, hpa@zytor.com, x86@kernel.org, linux-kernel@vger.kernel.org, Reinette Chatre Subject: [PATCH V2 4/4] x86/resctrl: Apply READ_ONCE/WRITE_ONCE to task_struct .rmid & .closid Date: Thu, 17 Dec 2020 14:31:21 -0800 Message-Id: <9921fda88ad81afb9885b517fbe864a2bc7c35a9.1608243147.git.reinette.chatre@intel.com> X-Mailer: git-send-email 2.26.2 In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Valentin Schneider A CPU's current task can have its {closid, rmid} fields read locally while they are being concurrently written to from another CPU. This can happen anytime __resctrl_sched_in() races with either __rdtgroup_move_task() or rdt_move_group_tasks(). Prevent load / store tearing for those accesses by giving them the READ_ONCE() / WRITE_ONCE() treatment. Signed-off-by: Valentin Schneider Signed-off-by: Reinette Chatre --- V1->V2: * Subject line prefix x86/intel_rdt -> x86/resctrl. (Reinette) arch/x86/include/asm/resctrl.h | 11 +++++++---- arch/x86/kernel/cpu/resctrl/rdtgroup.c | 10 +++++----- 2 files changed, 12 insertions(+), 9 deletions(-) diff --git a/arch/x86/include/asm/resctrl.h b/arch/x86/include/asm/resctrl.h index 07603064df8f..d60ed0668a59 100644 --- a/arch/x86/include/asm/resctrl.h +++ b/arch/x86/include/asm/resctrl.h @@ -56,19 +56,22 @@ static void __resctrl_sched_in(void) struct resctrl_pqr_state *state = this_cpu_ptr(&pqr_state); u32 closid = state->default_closid; u32 rmid = state->default_rmid; + u32 tmp; /* * If this task has a closid/rmid assigned, use it. * Else use the closid/rmid assigned to this cpu. */ if (static_branch_likely(&rdt_alloc_enable_key)) { - if (current->closid) - closid = current->closid; + tmp = READ_ONCE(current->closid); + if (tmp) + closid = tmp; } if (static_branch_likely(&rdt_mon_enable_key)) { - if (current->rmid) - rmid = current->rmid; + tmp = READ_ONCE(current->rmid); + if (tmp) + rmid = tmp; } if (closid != state->cur_closid || rmid != state->cur_rmid) { diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c index 9bd36210d220..5aeb4fb91228 100644 --- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c +++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c @@ -569,11 +569,11 @@ static int __rdtgroup_move_task(struct task_struct *tsk, */ if (rdtgrp->type == RDTCTRL_GROUP) { - tsk->closid = rdtgrp->closid; - tsk->rmid = rdtgrp->mon.rmid; + WRITE_ONCE(tsk->closid, rdtgrp->closid); + WRITE_ONCE(tsk->rmid, rdtgrp->mon.rmid); } else if (rdtgrp->type == RDTMON_GROUP) { if (rdtgrp->mon.parent->closid == tsk->closid) { - tsk->rmid = rdtgrp->mon.rmid; + WRITE_ONCE(tsk->rmid, rdtgrp->mon.rmid); } else { rdt_last_cmd_puts("Can't move task to different control group\n"); return -EINVAL; @@ -2316,8 +2316,8 @@ static void rdt_move_group_tasks(struct rdtgroup *from, struct rdtgroup *to, for_each_process_thread(p, t) { if (!from || is_closid_match(t, from) || is_rmid_match(t, from)) { - t->closid = to->closid; - t->rmid = to->mon.rmid; + WRITE_ONCE(t->closid, to->closid); + WRITE_ONCE(t->rmid, to->mon.rmid); /* * If the task is on a CPU, set the CPU in the mask. -- 2.26.2