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=-9.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, 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 C514BC2D0F3 for ; Mon, 30 Mar 2020 20:38:10 +0000 (UTC) Received: from whitealder.osuosl.org (smtp1.osuosl.org [140.211.166.138]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id A5D46216FD for ; Mon, 30 Mar 2020 20:38:10 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A5D46216FD Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=intel.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=iommu-bounces@lists.linux-foundation.org Received: from localhost (localhost [127.0.0.1]) by whitealder.osuosl.org (Postfix) with ESMTP id 7AE1087C8A; Mon, 30 Mar 2020 20:38:10 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from whitealder.osuosl.org ([127.0.0.1]) by localhost (.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id xMm29hbp1DJ8; Mon, 30 Mar 2020 20:38:09 +0000 (UTC) Received: from lists.linuxfoundation.org (lf-lists.osuosl.org [140.211.9.56]) by whitealder.osuosl.org (Postfix) with ESMTP id CD90F87CB4; Mon, 30 Mar 2020 20:38:09 +0000 (UTC) Received: from lf-lists.osuosl.org (localhost [127.0.0.1]) by lists.linuxfoundation.org (Postfix) with ESMTP id BC6E7C1D7E; Mon, 30 Mar 2020 20:38:09 +0000 (UTC) Received: from silver.osuosl.org (smtp3.osuosl.org [140.211.166.136]) by lists.linuxfoundation.org (Postfix) with ESMTP id F25F0C1D7E for ; Mon, 30 Mar 2020 20:38:04 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by silver.osuosl.org (Postfix) with ESMTP id DC13722E96 for ; Mon, 30 Mar 2020 20:38:04 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from silver.osuosl.org ([127.0.0.1]) by localhost (.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id HL9VbTY9vAUC for ; Mon, 30 Mar 2020 20:38:04 +0000 (UTC) X-Greylist: domain auto-whitelisted by SQLgrey-1.7.6 Received: from mga05.intel.com (mga05.intel.com [192.55.52.43]) by silver.osuosl.org (Postfix) with ESMTPS id 3F9F622851 for ; Mon, 30 Mar 2020 20:38:04 +0000 (UTC) IronPort-SDR: 70rI+twmkz4wT0hZJg0auIouZPakGog63jd+HwsJvDQsQkFJb8sRm1Wv+R8WjFweGH+neSKPec VKmnckCq6niQ== X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga008.jf.intel.com ([10.7.209.65]) by fmsmga105.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 30 Mar 2020 13:38:04 -0700 IronPort-SDR: CSSoTcScmVyPfUPOOfY3YTLN4JfQ2LiwNlB2QAn9UO0ffbWgKcWZRt0i4Q2gqsAMKLfRElPSQA soFSCKE/xZRQ== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.72,325,1580803200"; d="scan'208";a="242143905" Received: from romley-ivt3.sc.intel.com ([172.25.110.60]) by orsmga008.jf.intel.com with ESMTP; 30 Mar 2020 13:38:03 -0700 From: Fenghua Yu To: "Thomas Gleixner" , "Ingo Molnar" , "Borislav Petkov" , "H Peter Anvin" , "David Woodhouse" , "Lu Baolu" , "Dave Hansen" , "Tony Luck" , "Ashok Raj" , "Jacob Jun Pan" , "Dave Jiang" , "Sohil Mehta" , "Ravi V Shankar" Subject: [PATCH 7/7] x86/process: Clear PASID state for a newly forked/cloned thread Date: Mon, 30 Mar 2020 12:33:08 -0700 Message-Id: <1585596788-193989-8-git-send-email-fenghua.yu@intel.com> X-Mailer: git-send-email 2.5.0 In-Reply-To: <1585596788-193989-1-git-send-email-fenghua.yu@intel.com> References: <1585596788-193989-1-git-send-email-fenghua.yu@intel.com> Cc: Fenghua Yu , iommu@lists.linux-foundation.org, x86 , linux-kernel X-BeenThere: iommu@lists.linux-foundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Development issues for Linux IOMMU support List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: iommu-bounces@lists.linux-foundation.org Sender: "iommu" 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 --- arch/x86/kernel/process.c | 13 +++++++++++++ 1 file changed, 13 insertions(+) diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c index 87de18c64cf5..cefdc8f7fc13 100644 --- a/arch/x86/kernel/process.c +++ b/arch/x86/kernel/process.c @@ -122,6 +122,16 @@ static int set_new_tls(struct task_struct *p, unsigned long tls) return do_set_thread_area_64(p, ARCH_SET_FS, tls); } +/* Clear PASID MSR/state for the forked/cloned thread. */ +static void clear_task_pasid(struct task_struct *task) +{ + /* + * Clear the xfeatures bit in the PASID state so that the MSR will be + * initialized to its init state (0) by XRSTORS. + */ + task->thread.fpu.state.xsave.header.xfeatures &= ~XFEATURE_MASK_PASID; +} + int copy_thread_tls(unsigned long clone_flags, unsigned long sp, unsigned long arg, struct task_struct *p, unsigned long tls) { @@ -175,6 +185,9 @@ 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)) + clear_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 _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu