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=-4.3 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE, SPF_PASS,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 C4E19C433C1 for ; Mon, 29 Mar 2021 19:31:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 99BDA6196E for ; Mon, 29 Mar 2021 19:31:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230213AbhC2TbI (ORCPT ); Mon, 29 Mar 2021 15:31:08 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54242 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230346AbhC2Tas (ORCPT ); Mon, 29 Mar 2021 15:30:48 -0400 Received: from mail-pl1-x630.google.com (mail-pl1-x630.google.com [IPv6:2607:f8b0:4864:20::630]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B3787C061574 for ; Mon, 29 Mar 2021 12:30:48 -0700 (PDT) Received: by mail-pl1-x630.google.com with SMTP id e14so4899159plj.2 for ; Mon, 29 Mar 2021 12:30:48 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=obZ+GpJjqBDtqxvYFyMbZyPSIXXyagLFH5qtJ8HsExQ=; b=HHhQPWAK96gQvI6JJPOnIFVc/FznBCpCUgJanyhV1/94rYU1ByXo2ua2XSsY0qQgmp KIaZTSyo5SuA6seJ5a/O7TcMaCc8Ha00PbefwymFFN6Bh4SozydEAVhqPLhRmlGm00ka lScMH+FJN19u14o2jaisyvXsm3zBEVeZY+xULE8uu7a5h6oH+HAG77+RU3KPPteH9R6B WYiKhCcxB/ecADLL2AoxhTy/NQbZ1fI6E7lpLVdSZ9SlfLS0OYYmiVb21b6R9Bvt3FBZ 41HDs14NdrUmwSNuMRWHhJisDMdHRjsyzIaX26cb0dW7YCSZj0e5a/nwIBZO9C/Xvcjp DOkw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=obZ+GpJjqBDtqxvYFyMbZyPSIXXyagLFH5qtJ8HsExQ=; b=SvahDJZeZmqos8Ab1ilm/o8AxkkY2PRgXEzT62NxIHeXc9BcBrP2JAfZjEVcDCTRr+ J9+QoAfPS7/L8X291UM8WNyYPFXJTBMiVbDWuJydwo5A4c3e1mTSPnX+iBLZ2TuCd/CT QE+kU+C6+72hw9hRvBO90oWUcAWqxqdXio6eBKs5NFr3EXxTR3mg8/KqGj+bilI4KExm P8qqci3JpeBq5UVP1H6IHzRsBYU0hCKYqHsX0BOVnJaUnnRpWAzJwFYsyRP+YX8+FHHu 8nudM1KG5JttbyxxOrRRdurRVd3U/BhrWf5JRH6BZwhFpILGdFS0sU9wg5amgUB8/WJa jx9g== X-Gm-Message-State: AOAM530d332JGiewfMrMStFCTE3hsoiqXfr3NJ55r5UmIQ+7awOnkIQn xBGtNuXL/g/bmUh7QKo4RRF3OV3VeWI= X-Google-Smtp-Source: ABdhPJxy4vuS0N+tsZKwReXwZHG1+vd1B7r82n2+XtMrMVGst8TxZghuZ5z5ETykyH/7joqAlbYfUA== X-Received: by 2002:a17:90b:10a:: with SMTP id p10mr668776pjz.148.1617046248127; Mon, 29 Mar 2021 12:30:48 -0700 (PDT) Received: from [10.67.49.104] ([192.19.223.252]) by smtp.googlemail.com with ESMTPSA id t19sm18375620pfg.38.2021.03.29.12.30.46 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 29 Mar 2021 12:30:47 -0700 (PDT) Subject: Re: [PATCH] ARM: Qualify enabling of swiotlb_init() To: Stefano Stabellini , Konrad Rzeszutek Wilk Cc: Christoph Hellwig , xen-devel@lists.xensource.com, linux-arm-kernel@lists.infradead.org, Marek Szyprowski , Robin Murphy , "open list:SWIOTLB SUBSYSTEM" , open list , Russell King , Mike Rapoport , Andrew Morton , Ard Biesheuvel , Max Filippov , Catalin Marinas , opendmb@gmail.com References: <20210319040333.183827-1-f.fainelli@gmail.com> <20210319130731.GB2624@lst.de> <20210319195929.GA1346384@konrad-char-us-oracle-com.allregionaliads.osdevelopmeniad.oraclevcn.com> From: Florian Fainelli Message-ID: <3db926f4-6047-cc62-8654-a965b8570e75@gmail.com> Date: Mon, 29 Mar 2021 12:30:42 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.7.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 3/19/21 5:22 PM, Stefano Stabellini wrote: > On Fri, 19 Mar 2021, Konrad Rzeszutek Wilk wrote: >> On Fri, Mar 19, 2021 at 02:07:31PM +0100, Christoph Hellwig wrote: >>> On Thu, Mar 18, 2021 at 09:03:33PM -0700, Florian Fainelli wrote: >>>> #ifdef CONFIG_ARM_LPAE >>>> + if (swiotlb_force == SWIOTLB_FORCE || >>>> + max_pfn > arm_dma_pfn_limit) >>> >>> Does arm_dma_pfn_limit do the right thing even with the weirdest >>> remapping ranges? Maybe a commen here would be useful. >>> >>>> + swiotlb_init(1); >>>> + else >>>> + swiotlb_force = SWIOTLB_NO_FORCE; >>> >>> Konrad: what do you think of setting swiotlb_force to SWIOTLB_NO_FORCE >>> and only switching it to SWIOTLB_NORMAL when swiotlb_init* is called? >>> That kind makes more sense than forcing the callers to do it. >>> >>> While we're at it, I think swiotlb_force should probably be renamed to >>> swiotlb_mode or somethng like that. >> >> swiotlb_mode sounds good. >> >> Also it got me thinking - ARM on Xen at some point was a bit strange, so not sure how >> the logic works here, Stefano? > > There is nothing strange in regards to swiotlb_force. swiotlb_force is only used > in swiotlb-xen map_page to figure out whether: > > - we actually have to use the swiotlb bounce buffer (this is the > swiotlb_xen == SWIOTLB_FORCE case) > - or we can use the provided page directly for dma if other conditions > are met (dma_capable, !range_straddles_page_boundary, ...) > > > I don't think that switching to "swiotlb_mode" would cause any issues. > Should I toss this in Russell's patch tracker or do you need me to make some changes to the patch? -- Florian