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=-5.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 ABAEDC33C9E for ; Sat, 18 Jan 2020 02:15:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 80D602192A for ; Sat, 18 Jan 2020 02:15:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730613AbgARCPi (ORCPT ); Fri, 17 Jan 2020 21:15:38 -0500 Received: from mga09.intel.com ([134.134.136.24]:25928 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727033AbgARCPi (ORCPT ); Fri, 17 Jan 2020 21:15:38 -0500 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga007.jf.intel.com ([10.7.209.58]) by orsmga102.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 17 Jan 2020 18:15:37 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.70,332,1574150400"; d="scan'208";a="214686218" Received: from allen-box.sh.intel.com (HELO [10.239.159.138]) ([10.239.159.138]) by orsmga007.jf.intel.com with ESMTP; 17 Jan 2020 18:15:35 -0800 Cc: baolu.lu@linux.intel.com, ashok.raj@intel.com, jacob.jun.pan@intel.com, kevin.tian@intel.com, iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/1] iommu/vt-d: Remove unnecessary WARN_ON_ONCE() To: Joerg Roedel References: <20200116015236.4458-1-baolu.lu@linux.intel.com> <20200117095953.GB15760@8bytes.org> From: Lu Baolu Message-ID: Date: Sat, 18 Jan 2020 10:14:11 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.2.2 MIME-Version: 1.0 In-Reply-To: <20200117095953.GB15760@8bytes.org> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Joerg, On 1/17/20 5:59 PM, Joerg Roedel wrote: > On Thu, Jan 16, 2020 at 09:52:36AM +0800, Lu Baolu wrote: >> Address field in device TLB invalidation descriptor is qualified >> by the S field. If S field is zero, a single page at page address >> specified by address [63:12] is requested to be invalidated. If S >> field is set, the least significant bit in the address field with >> value 0b (say bit N) indicates the invalidation address range. The >> spec doesn't require the address [N - 1, 0] to be cleared, hence >> remove the unnecessary WARN_ON_ONCE(). >> >> Otherwise, the caller might set "mask = MAX_AGAW_PFN_WIDTH" in order >> to invalidating all the cached mappings on an endpoint, and below >> overflow error will be triggered. >> >> [...] >> UBSAN: Undefined behaviour in drivers/iommu/dmar.c:1354:3 >> shift exponent 64 is too large for 64-bit type 'long long unsigned int' >> [...] >> >> Reported-and-tested-by: Frank >> Signed-off-by: Lu Baolu > > Does this need a Fixes and/or stable tag? > This doesn't cause any errors, just an unnecessary checking of "0 & ((1UL << 64) - 1)" in some cases. > > Regards, > > Joerg Best regards, baolu