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=-15.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, 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 D4743C4361B for ; Wed, 16 Dec 2020 12:11:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 752F223109 for ; Wed, 16 Dec 2020 12:11:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725806AbgLPMLM (ORCPT ); Wed, 16 Dec 2020 07:11:12 -0500 Received: from foss.arm.com ([217.140.110.172]:49160 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725283AbgLPMLM (ORCPT ); Wed, 16 Dec 2020 07:11:12 -0500 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id A86551FB; Wed, 16 Dec 2020 04:10:26 -0800 (PST) Received: from [10.57.34.90] (unknown [10.57.34.90]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 09D3C3F66E; Wed, 16 Dec 2020 04:10:23 -0800 (PST) Subject: Re: [PATCH v3 4/7] iommu: Switch gather->end to unsigned long long To: Yong Wu , Joerg Roedel , Will Deacon Cc: youlin.pei@mediatek.com, anan.sun@mediatek.com, Nicolas Boichat , srv_heupstream@mediatek.com, chao.hao@mediatek.com, linux-kernel@vger.kernel.org, Krzysztof Kozlowski , Tomasz Figa , iommu@lists.linux-foundation.org, linux-mediatek@lists.infradead.org, Matthias Brugger , Greg Kroah-Hartman , kernel-team@android.com, linux-arm-kernel@lists.infradead.org References: <20201216103607.23050-1-yong.wu@mediatek.com> <20201216103607.23050-5-yong.wu@mediatek.com> From: Robin Murphy Message-ID: <16a9565e-5b01-e1c2-0f4a-d06db7f3b093@arm.com> Date: Wed, 16 Dec 2020 12:10:22 +0000 User-Agent: Mozilla/5.0 (Windows NT 10.0; rv:78.0) Gecko/20100101 Thunderbird/78.5.1 MIME-Version: 1.0 In-Reply-To: <20201216103607.23050-5-yong.wu@mediatek.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-GB Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2020-12-16 10:36, Yong Wu wrote: > Currently gather->end is "unsigned long" which may be overflow in > arch32 in the corner case: 0xfff00000 + 0x100000(iova + size). > Although it doesn't affect the size(end - start), it affects the checking > "gather->end < end" This won't help the same situation at the top of a 64-bit address space, though, and now that we have TTBR1 support for AArch64 format that is definitely a thing. Better to just encode the end address as the actual end address, i.e. iova + size - 1. We don't lose anything other than the ability to encode zero-sized invalidations that don't make sense anyway. Robin. > Fixes: a7d20dc19d9e ("iommu: Introduce struct iommu_iotlb_gather for batching TLB flushes") > Signed-off-by: Yong Wu > --- > include/linux/iommu.h | 5 +++-- > 1 file changed, 3 insertions(+), 2 deletions(-) > > diff --git a/include/linux/iommu.h b/include/linux/iommu.h > index 794d4085edd3..6e907a95d981 100644 > --- a/include/linux/iommu.h > +++ b/include/linux/iommu.h > @@ -178,7 +178,7 @@ enum iommu_dev_features { > */ > struct iommu_iotlb_gather { > unsigned long start; > - unsigned long end; > + unsigned long long end; > size_t pgsize; > }; > > @@ -537,7 +537,8 @@ static inline void iommu_iotlb_gather_add_page(struct iommu_domain *domain, > struct iommu_iotlb_gather *gather, > unsigned long iova, size_t size) > { > - unsigned long start = iova, end = start + size; > + unsigned long start = iova; > + unsigned long long end = start + size; > > /* > * If the new page is disjoint from the current range or is mapped at >