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=-10.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable 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 92CEFC433DF for ; Thu, 25 Jun 2020 20:19:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 72F33206FA for ; Thu, 25 Jun 2020 20:19:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2436622AbgFYUTN (ORCPT ); Thu, 25 Jun 2020 16:19:13 -0400 Received: from mga18.intel.com ([134.134.136.126]:20502 "EHLO mga18.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2436565AbgFYUSm (ORCPT ); Thu, 25 Jun 2020 16:18:42 -0400 IronPort-SDR: fs6VCpu+SklCtNdeekw2jwfY8KXjM7IRYXn4Qutvdw1BBKYn6FZln881fDDHvL+P7n6fdCJSDw SwY2vnSMIfYg== X-IronPort-AV: E=McAfee;i="6000,8403,9663"; a="132505292" X-IronPort-AV: E=Sophos;i="5.75,280,1589266800"; d="scan'208";a="132505292" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga005.jf.intel.com ([10.7.209.41]) by orsmga106.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 25 Jun 2020 13:18:40 -0700 IronPort-SDR: Kk6DpyVQJqAJXF++AIe3VPnRKebmX+PgrOYJgnscvOreJgLE8bb0i59wzBc9avcmxFaKZX9Cqu akUboyEUtnoA== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.75,280,1589266800"; d="scan'208";a="453132247" Received: from romley-ivt3.sc.intel.com ([172.25.110.60]) by orsmga005.jf.intel.com with ESMTP; 25 Jun 2020 13:18:40 -0700 From: Fenghua Yu To: "Thomas Gleixner" , "Joerg Roedel" , "Ingo Molnar" , "Borislav Petkov" , "Peter Zijlstra" , "H Peter Anvin" , "David Woodhouse" , "Lu Baolu" , "Dave Hansen" , "Tony Luck" , "Jean-Philippe Brucker" , "Christoph Hellwig" , "Ashok Raj" , "Jacob Jun Pan" , "Dave Jiang" , "Sohil Mehta" , "Ravi V Shankar" Cc: "linux-kernel" , "x86" , iommu@lists.linux-foundation.org, Fenghua Yu Subject: [PATCH v4 09/12] x86/process: Clear PASID state for a newly forked/cloned thread Date: Thu, 25 Jun 2020 13:17:19 -0700 Message-Id: <1593116242-31507-10-git-send-email-fenghua.yu@intel.com> X-Mailer: git-send-email 2.5.0 In-Reply-To: <1593116242-31507-1-git-send-email-fenghua.yu@intel.com> References: <1593116242-31507-1-git-send-email-fenghua.yu@intel.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The PASID state has to be cleared on forks, since the child has a different address space. The PASID is also cleared for thread clone. While it would be correct to inherit the PASID in this case, it is unknown whether the new task will use ENQCMD. Giving it the PASID "just in case" would have the downside of increased context switch overhead to setting the PASID MSR. Since #GP faults have to be handled on any threads that were created before the PASID was assigned to the mm of the process, newly created threads might as well be treated in a consistent way. Suggested-by: Thomas Gleixner Signed-off-by: Fenghua Yu Reviewed-by: Tony Luck --- v2: - Modify init_task_pasid(). arch/x86/kernel/process.c | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c index f362ce0d5ac0..1b1492e337a6 100644 --- a/arch/x86/kernel/process.c +++ b/arch/x86/kernel/process.c @@ -121,6 +121,21 @@ static int set_new_tls(struct task_struct *p, unsigned long tls) return do_set_thread_area_64(p, ARCH_SET_FS, tls); } +/* Initialize the PASID state for the forked/cloned thread. */ +static void init_task_pasid(struct task_struct *task) +{ + struct ia32_pasid_state *ppasid; + + /* + * Initialize the PASID state so that the PASID MSR will be + * initialized to its initial state (0) by XRSTORS when the task is + * scheduled for the first time. + */ + ppasid = get_xsave_addr(&task->thread.fpu.state.xsave, XFEATURE_PASID); + if (ppasid) + ppasid->pasid = INIT_PASID; +} + int copy_thread_tls(unsigned long clone_flags, unsigned long sp, unsigned long arg, struct task_struct *p, unsigned long tls) { @@ -174,6 +189,9 @@ int copy_thread_tls(unsigned long clone_flags, unsigned long sp, task_user_gs(p) = get_user_gs(current_pt_regs()); #endif + if (static_cpu_has(X86_FEATURE_ENQCMD)) + init_task_pasid(p); + /* Set a new TLS for the child thread? */ if (clone_flags & CLONE_SETTLS) ret = set_new_tls(p, tls); -- 2.19.1