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=-5.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=no 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 392D1C433DB for ; Wed, 27 Jan 2021 09:43:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 13C4220644 for ; Wed, 27 Jan 2021 09:43:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235312AbhA0Jm7 (ORCPT ); Wed, 27 Jan 2021 04:42:59 -0500 Received: from foss.arm.com ([217.140.110.172]:35176 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233844AbhA0Jk0 (ORCPT ); Wed, 27 Jan 2021 04:40:26 -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 8957131B; Wed, 27 Jan 2021 01:39:40 -0800 (PST) Received: from [10.57.46.236] (unknown [10.57.46.236]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 65DC03F66B; Wed, 27 Jan 2021 01:39:39 -0800 (PST) Subject: Re: [PATCH 1/1] iommu/arm-smmu-v3: add support for BBML To: Keqian Zhu , Will Deacon Cc: Jean-Philippe Brucker , linux-kernel , iommu , Yang Yingliang , linux-arm-kernel References: <20201126034230.777-1-thunder.leizhen@huawei.com> <20210122125132.GB24102@willie-the-truck> <1bfd1ca0-953e-e943-f87e-144d5537bd0c@arm.com> <20210126101230.GA29204@willie-the-truck> <8a9685ec-67aa-824f-5429-f408bf79c5ab@huawei.com> <32f4752f-6954-183a-a0c1-b5d719c85b67@huawei.com> From: Robin Murphy Message-ID: <319e3532-4555-7431-9d6f-3c3b7c11a5d9@arm.com> Date: Wed, 27 Jan 2021 09:39:38 +0000 User-Agent: Mozilla/5.0 (Windows NT 10.0; rv:78.0) Gecko/20100101 Thunderbird/78.6.1 MIME-Version: 1.0 In-Reply-To: <32f4752f-6954-183a-a0c1-b5d719c85b67@huawei.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 2021-01-27 07:36, Keqian Zhu wrote: > > > On 2021/1/27 10:01, Leizhen (ThunderTown) wrote: >> >> >> On 2021/1/26 18:12, Will Deacon wrote: >>> On Mon, Jan 25, 2021 at 08:23:40PM +0000, Robin Murphy wrote: >>>> Now we probably will need some degreee of BBML feature awareness for the >>>> sake of SVA if and when we start using it for CPU pagetables, but I still >>>> cannot see any need to consider it in io-pgtable. >>> >>> Agreed; I don't think this is something that io-pgtable should have to care >>> about. > Hi, > > I have a question here :-). > If the old table is not live, then the break procedure seems unnecessary. Do I miss something? The MMU is allowed to prefetch translations at any time, so not following the proper update procedure could still potentially lead to a TLB conflict, even if there's no device traffic to worry about disrupting. Robin. > Thanks, > Keqian > >> >> Yes, the SVA works in stall mode, and the failed device access requests are not >> discarded. >> >> Let me look for examples. The BBML usage scenario was told by a former colleague. >> >>> >>> Will >>> >>> . >>> >> >> >> _______________________________________________ >> linux-arm-kernel mailing list >> linux-arm-kernel@lists.infradead.org >> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel >> . >> > _______________________________________________ > iommu mailing list > iommu@lists.linux-foundation.org > https://lists.linuxfoundation.org/mailman/listinfo/iommu >