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=-13.0 required=3.0 tests=BAYES_00, 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 2C0F9C43457 for ; Mon, 13 Jul 2020 23:49:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0D69F21582 for ; Mon, 13 Jul 2020 23:49:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727834AbgGMXtQ (ORCPT ); Mon, 13 Jul 2020 19:49:16 -0400 Received: from mga03.intel.com ([134.134.136.65]:36776 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727085AbgGMXss (ORCPT ); Mon, 13 Jul 2020 19:48:48 -0400 IronPort-SDR: RkoJcZnBZq6XTDuVV0bz0iXP7efgUiEzS+0uSXQ6flLS8bwk7KokX6HPL85XbvV5ojYHS9/dTw 1ihj5jCG2LpQ== X-IronPort-AV: E=McAfee;i="6000,8403,9681"; a="148748424" X-IronPort-AV: E=Sophos;i="5.75,349,1589266800"; d="scan'208";a="148748424" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga003.jf.intel.com ([10.7.209.27]) by orsmga103.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 13 Jul 2020 16:48:46 -0700 IronPort-SDR: tV81P1EHE6ArAwCH7kXPVlxq4xceAQw5O+9OlkyrmpfO6wxzUFCly09pwe6KFnrxhA62MNEgS8 BWC0+8tcEbYw== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.75,349,1589266800"; d="scan'208";a="281570462" Received: from romley-ivt3.sc.intel.com ([172.25.110.60]) by orsmga003.jf.intel.com with ESMTP; 13 Jul 2020 16:48:45 -0700 From: Fenghua Yu To: "Thomas Gleixner" , "Joerg Roedel" , "Ingo Molnar" , "Borislav Petkov" , "Peter Zijlstra" , "H Peter Anvin" , "David Woodhouse" , "Lu Baolu" , "Felix Kuehling" , "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, "amd-gfx" , Fenghua Yu Subject: [PATCH v6 09/12] x86/process: Clear PASID state for a newly forked/cloned thread Date: Mon, 13 Jul 2020 16:48:04 -0700 Message-Id: <1594684087-61184-10-git-send-email-fenghua.yu@intel.com> X-Mailer: git-send-email 2.5.0 In-Reply-To: <1594684087-61184-1-git-send-email-fenghua.yu@intel.com> References: <1594684087-61184-1-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