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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED 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 8CC2DC4321E for ; Thu, 6 Sep 2018 23:41:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 31F7C2075B for ; Thu, 6 Sep 2018 23:41:22 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 31F7C2075B Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=intel.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 S1727748AbeIGETN (ORCPT ); Fri, 7 Sep 2018 00:19:13 -0400 Received: from mga18.intel.com ([134.134.136.126]:8981 "EHLO mga18.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725926AbeIGETN (ORCPT ); Fri, 7 Sep 2018 00:19:13 -0400 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga002.jf.intel.com ([10.7.209.21]) by orsmga106.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 06 Sep 2018 16:41:19 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.53,340,1531810800"; d="scan'208";a="89648597" Received: from jacob-builder.jf.intel.com (HELO jacob-builder) ([10.7.199.155]) by orsmga002.jf.intel.com with ESMTP; 06 Sep 2018 16:41:17 -0700 Date: Thu, 6 Sep 2018 16:43:17 -0700 From: Jacob Pan To: Lu Baolu Cc: "Tian, Kevin" , Joerg Roedel , David Woodhouse , "Raj, Ashok" , "Kumar, Sanjay K" , "Liu, Yi L" , "Sun, Yi Y" , "peterx@redhat.com" , Jean-Philippe Brucker , "iommu@lists.linux-foundation.org" , "linux-kernel@vger.kernel.org" , Jacob Pan , jacob.jun.pan@intel.com Subject: Re: [PATCH v2 02/12] iommu/vt-d: Manage scalalble mode PASID tables Message-ID: <20180906164317.786bbdda@jacob-builder> In-Reply-To: <44298d5c-5720-a382-07d1-a90a072ff24b@linux.intel.com> References: <20180830013524.28743-1-baolu.lu@linux.intel.com> <20180830013524.28743-3-baolu.lu@linux.intel.com> <44298d5c-5720-a382-07d1-a90a072ff24b@linux.intel.com> Organization: OTC X-Mailer: Claws Mail 3.13.2 (GTK+ 2.24.30; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 6 Sep 2018 10:46:03 +0800 Lu Baolu wrote: > >> @@ -224,7 +271,14 @@ struct pasid_entry > >> *intel_pasid_get_entry(struct device *dev, int pasid) > >> */ > >> static inline void pasid_clear_entry(struct pasid_entry *pe) > >> { > >> - WRITE_ONCE(pe->val, 0); > >> + WRITE_ONCE(pe->val[0], 0); > >> + WRITE_ONCE(pe->val[1], 0); > >> + WRITE_ONCE(pe->val[2], 0); > >> + WRITE_ONCE(pe->val[3], 0); > >> + WRITE_ONCE(pe->val[4], 0); > >> + WRITE_ONCE(pe->val[5], 0); > >> + WRITE_ONCE(pe->val[6], 0); > >> + WRITE_ONCE(pe->val[7], 0); > > > > memset? > > The order is important here. Otherwise, the PRESENT bit of this pasid > entry might still set while other fields contains invalid values. WRITE_ONCE/READ_ONCE will switch to __builtin_memcpy() in if the size exceeds word size, ie. 64bit in this case. I don;t think compiler will reorder built-in function. Beside, we only need to clear present and FDP bit, right?