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[121.45.221.81]) by smtp.gmail.com with ESMTPSA id a185sm15138421pfa.27.2020.03.23.20.38.01 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 23 Mar 2020 20:38:05 -0700 (PDT) Subject: Re: [PATCH 1/2] dma-mapping: add a dma_ops_bypass flag to struct device To: Christoph Hellwig Cc: iommu@lists.linux-foundation.org, linuxppc-dev@lists.ozlabs.org, Lu Baolu , Greg Kroah-Hartman , Joerg Roedel , Robin Murphy , linux-kernel@vger.kernel.org, "Aneesh Kumar K.V" References: <20200320141640.366360-1-hch@lst.de> <20200320141640.366360-2-hch@lst.de> <2f31d0dd-aa7e-8b76-c8a1-5759fda5afc9@ozlabs.ru> <20200323083705.GA31245@lst.de> <37ce1b7e-264d-292d-32b1-093b24b3525c@ozlabs.ru> <20200323172014.GA31269@lst.de> From: Alexey Kardashevskiy Autocrypt: addr=aik@ozlabs.ru; keydata= mQINBE+rT0sBEADFEI2UtPRsLLvnRf+tI9nA8T91+jDK3NLkqV+2DKHkTGPP5qzDZpRSH6mD EePO1JqpVuIow/wGud9xaPA5uvuVgRS1q7RU8otD+7VLDFzPRiRE4Jfr2CW89Ox6BF+q5ZPV 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Zd44XWqUu7FzVOYaSgIvTP0hNrBYm/E6M7yrLbs3JY74fGzPWGRbBUHTZXQEqQnZglXaVB5V ZhSFtHopZnBSCUSNDbB+QGy4B/E++Bb02IBTGl/JxmOwG+kZUnymsPvTtnNIeTLHxN/H/ae0 c7E5M+/NpslPCmYnDjs5qg0/3ihh6XuOGggZQOqrYPC3PnsNs3NxirwOkVPQgO6mXxpuifvJ DG9EMkK8IBXnLulqVk54kf7fE0jT/d8RTtJIA92GzsgdK2rpT1MBKKVffjRFGwN7nQVOzi4T XrB5p+6ML7Bd84xOEGsj/vdaXmz1esuH7BOZAGEZfLRCHJ0GVCSssg== Message-ID: Date: Tue, 24 Mar 2020 14:37:59 +1100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.5.0 MIME-Version: 1.0 In-Reply-To: <20200323172014.GA31269@lst.de> Content-Type: text/plain; charset=utf-8 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 On 24/03/2020 04:20, Christoph Hellwig wrote: > On Mon, Mar 23, 2020 at 07:58:01PM +1100, Alexey Kardashevskiy wrote: >>>> 0x100.0000.0000 .. 0x101.0000.0000 >>>> >>>> 2x4G, each is 1TB aligned. And we can map directly only the first 4GB >>>> (because of the maximum IOMMU table size) but not the other. And 1:1 on >>>> that "pseries" is done with offset=0x0800.0000.0000.0000. >>>> >>>> So we want to check every bus address against dev->bus_dma_limit, not >>>> dev->coherent_dma_mask. In the example above I'd set bus_dma_limit to >>>> 0x0800.0001.0000.0000 and 1:1 mapping for the second 4GB would not be >>>> tried. Does this sound reasonable? Thanks, >>> >>> bus_dma_limit is just another limiting factor applied on top of >>> coherent_dma_mask or dma_mask respectively. >> >> This is not enough for the task: in my example, I'd set bus limit to >> 0x0800.0001.0000.0000 but this would disable bypass for all RAM >> addresses - the first and the second 4GB blocks. > > So what about something like the version here: > > http://git.infradead.org/users/hch/misc.git/shortlog/refs/heads/dma-bypass.3 dma_alloc_direct() and dma_map_direct() do the same thing now which is good, did I miss anything else? This lets us disable bypass automatically if this weird memory appears in the system but does not let us have 1:1 after that even for normal RAM. Thanks, -- Alexey 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=-7.1 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=unavailable 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 526CDC10DCE for ; Tue, 24 Mar 2020 03:39:59 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [203.11.71.2]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id BEA08205ED for ; Tue, 24 Mar 2020 03:39:58 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=ozlabs-ru.20150623.gappssmtp.com header.i=@ozlabs-ru.20150623.gappssmtp.com header.b="Hwmk7YeW" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org BEA08205ED Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=ozlabs.ru Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Received: from lists.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) by lists.ozlabs.org (Postfix) with ESMTP id 48mcSr1z2DzDqtp for ; Tue, 24 Mar 2020 14:39:56 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=ozlabs.ru (client-ip=2607:f8b0:4864:20::441; helo=mail-pf1-x441.google.com; envelope-from=aik@ozlabs.ru; receiver=) Authentication-Results: lists.ozlabs.org; dmarc=none (p=none dis=none) header.from=ozlabs.ru Authentication-Results: lists.ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=ozlabs-ru.20150623.gappssmtp.com header.i=@ozlabs-ru.20150623.gappssmtp.com header.a=rsa-sha256 header.s=20150623 header.b=Hwmk7YeW; dkim-atps=neutral Received: from mail-pf1-x441.google.com (mail-pf1-x441.google.com [IPv6:2607:f8b0:4864:20::441]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 48mcQn3cgFzDqjG for ; Tue, 24 Mar 2020 14:38:07 +1100 (AEDT) Received: by mail-pf1-x441.google.com with SMTP id l184so8599975pfl.7 for ; Mon, 23 Mar 2020 20:38:07 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ozlabs-ru.20150623.gappssmtp.com; s=20150623; h=subject:to:cc:references:from:autocrypt:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=EoHFVfVTHKDj3wA1Pgr7GAuawqBtohTxYrc3sgAwjww=; b=Hwmk7YeWhBR+bPT1gb5RzoUAqlgbKKsPNpeRYQ/mz2LUvzbQr9qBK4j2pJF2V9FcnQ hj9w27FSzgAg2S1NXDkkdYugd4QIdIg5Z2lTtwYpGfz+PGFujG7mexZ7uokW+4X0hVzf aL37xaDDprybYy5jKwSsalWxISoQzvlJMFYU0giGF0q8lsdhLJ5W+Hd+H5uwImLXA7Xi lp5qJN8sc5pwwihOM7AAj+At18+jJA+M9BruQFDT2JrY/HYEIvhIg1XPlIPmHn5KvlhZ LRYvAfITHWJ6eSm0kNT5HMfSisKBPNNORQREtLzc2ZvHXAbsTMz0CohVZbcdgo3p13cq IuZw== 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:autocrypt :message-id:date:user-agent:mime-version:in-reply-to :content-language:content-transfer-encoding; bh=EoHFVfVTHKDj3wA1Pgr7GAuawqBtohTxYrc3sgAwjww=; b=btYbt4LNMd5jsYL40PzVooOJG3OiWxytEUtfEyAzEcmnP6cbmC925m6XpaeI/SkiRS 7kHxZRUggr181LapB9T/sqtR0XgfklLmzWlXrCXzVi4cOO8HHxu2AFtnHq63UZmV0578 bSriFp36ChE9E9JTciR0Qs9RQtiEfxKIuPCwumfpgMkor3SafMI6A19eV2+E87vPMdKE hp414I9M4S7Zvy7D4fy5HDC2aWYJEZlNxktZoV5H5KD8n0FOyimbzjgz7xU9BCbXAqQq MNWH0YlExsFSmHs79OhxorjsAW3Lsb9XvgEUt4eAzN4WDfJsGVSVEA50muo2z6FDwM1R UxOg== X-Gm-Message-State: ANhLgQ0HRshVEkUbqxdHOso7qp4vL22XgsblK2FNj9/dM6Cgu1WvfgIC P3xeT28X66UytNKpf/e4HTtljg== X-Google-Smtp-Source: ADFU+vtUqBrBYpWGQT0F6qG4VH8WBvkLR2SPKKB9qgPmtRoXxqJJFq2PsqIAfuhTww49jsdZsgx7TQ== X-Received: by 2002:a63:1c4d:: with SMTP id c13mr24608158pgm.4.1585021085960; Mon, 23 Mar 2020 20:38:05 -0700 (PDT) Received: from [192.168.10.21] (ppp121-45-221-81.bras1.cbr2.internode.on.net. [121.45.221.81]) by smtp.gmail.com with ESMTPSA id a185sm15138421pfa.27.2020.03.23.20.38.01 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 23 Mar 2020 20:38:05 -0700 (PDT) Subject: Re: [PATCH 1/2] dma-mapping: add a dma_ops_bypass flag to struct device To: Christoph Hellwig References: <20200320141640.366360-1-hch@lst.de> <20200320141640.366360-2-hch@lst.de> <2f31d0dd-aa7e-8b76-c8a1-5759fda5afc9@ozlabs.ru> <20200323083705.GA31245@lst.de> <37ce1b7e-264d-292d-32b1-093b24b3525c@ozlabs.ru> <20200323172014.GA31269@lst.de> From: Alexey Kardashevskiy Autocrypt: addr=aik@ozlabs.ru; keydata= mQINBE+rT0sBEADFEI2UtPRsLLvnRf+tI9nA8T91+jDK3NLkqV+2DKHkTGPP5qzDZpRSH6mD EePO1JqpVuIow/wGud9xaPA5uvuVgRS1q7RU8otD+7VLDFzPRiRE4Jfr2CW89Ox6BF+q5ZPV /pS4v4G9eOrw1v09lEKHB9WtiBVhhxKK1LnUjPEH3ifkOkgW7jFfoYgTdtB3XaXVgYnNPDFo PTBYsJy+wr89XfyHr2Ev7BB3Xaf7qICXdBF8MEVY8t/UFsesg4wFWOuzCfqxFmKEaPDZlTuR tfLAeVpslNfWCi5ybPlowLx6KJqOsI9R2a9o4qRXWGP7IwiMRAC3iiPyk9cknt8ee6EUIxI6 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DG9EMkK8IBXnLulqVk54kf7fE0jT/d8RTtJIA92GzsgdK2rpT1MBKKVffjRFGwN7nQVOzi4T XrB5p+6ML7Bd84xOEGsj/vdaXmz1esuH7BOZAGEZfLRCHJ0GVCSssg== Message-ID: Date: Tue, 24 Mar 2020 14:37:59 +1100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.5.0 MIME-Version: 1.0 In-Reply-To: <20200323172014.GA31269@lst.de> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Greg Kroah-Hartman , Joerg Roedel , linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org, "Aneesh Kumar K.V" , Robin Murphy , Lu Baolu Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On 24/03/2020 04:20, Christoph Hellwig wrote: > On Mon, Mar 23, 2020 at 07:58:01PM +1100, Alexey Kardashevskiy wrote: >>>> 0x100.0000.0000 .. 0x101.0000.0000 >>>> >>>> 2x4G, each is 1TB aligned. And we can map directly only the first 4GB >>>> (because of the maximum IOMMU table size) but not the other. And 1:1 on >>>> that "pseries" is done with offset=0x0800.0000.0000.0000. >>>> >>>> So we want to check every bus address against dev->bus_dma_limit, not >>>> dev->coherent_dma_mask. In the example above I'd set bus_dma_limit to >>>> 0x0800.0001.0000.0000 and 1:1 mapping for the second 4GB would not be >>>> tried. Does this sound reasonable? Thanks, >>> >>> bus_dma_limit is just another limiting factor applied on top of >>> coherent_dma_mask or dma_mask respectively. >> >> This is not enough for the task: in my example, I'd set bus limit to >> 0x0800.0001.0000.0000 but this would disable bypass for all RAM >> addresses - the first and the second 4GB blocks. > > So what about something like the version here: > > http://git.infradead.org/users/hch/misc.git/shortlog/refs/heads/dma-bypass.3 dma_alloc_direct() and dma_map_direct() do the same thing now which is good, did I miss anything else? This lets us disable bypass automatically if this weird memory appears in the system but does not let us have 1:1 after that even for normal RAM. Thanks, -- Alexey 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=-7.1 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING, 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 9E45BC10DCE for ; Tue, 24 Mar 2020 03:45:41 +0000 (UTC) Received: from fraxinus.osuosl.org (smtp4.osuosl.org [140.211.166.137]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 601D7206F8 for ; Tue, 24 Mar 2020 03:45:41 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=ozlabs-ru.20150623.gappssmtp.com header.i=@ozlabs-ru.20150623.gappssmtp.com header.b="Hwmk7YeW" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 601D7206F8 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=ozlabs.ru Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=iommu-bounces@lists.linux-foundation.org Received: from localhost (localhost [127.0.0.1]) by fraxinus.osuosl.org (Postfix) with ESMTP id 3806586398; Tue, 24 Mar 2020 03:45:41 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from fraxinus.osuosl.org ([127.0.0.1]) by localhost (.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id B8rGjkGQ7Tof; Tue, 24 Mar 2020 03:45:40 +0000 (UTC) Received: from lists.linuxfoundation.org (lf-lists.osuosl.org [140.211.9.56]) by fraxinus.osuosl.org (Postfix) with ESMTP id 37C7F85F60; Tue, 24 Mar 2020 03:45:40 +0000 (UTC) Received: from lf-lists.osuosl.org (localhost [127.0.0.1]) by lists.linuxfoundation.org (Postfix) with ESMTP id 2E217C1AE2; Tue, 24 Mar 2020 03:45:40 +0000 (UTC) Received: from fraxinus.osuosl.org (smtp4.osuosl.org [140.211.166.137]) by lists.linuxfoundation.org (Postfix) with ESMTP id EA41EC0177 for ; Tue, 24 Mar 2020 03:45:37 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by fraxinus.osuosl.org (Postfix) with ESMTP id E0E1085F60 for ; Tue, 24 Mar 2020 03:45:37 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from fraxinus.osuosl.org ([127.0.0.1]) by localhost (.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id bUCxss7TmtHG for ; Tue, 24 Mar 2020 03:45:36 +0000 (UTC) X-Greylist: delayed 00:07:30 by SQLgrey-1.7.6 Received: from mail-pg1-f193.google.com (mail-pg1-f193.google.com [209.85.215.193]) by fraxinus.osuosl.org (Postfix) with ESMTPS id BE01B85F4C for ; Tue, 24 Mar 2020 03:45:36 +0000 (UTC) Received: by mail-pg1-f193.google.com with SMTP id t24so8337820pgj.7 for ; Mon, 23 Mar 2020 20:45:36 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ozlabs-ru.20150623.gappssmtp.com; s=20150623; h=subject:to:cc:references:from:autocrypt:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=EoHFVfVTHKDj3wA1Pgr7GAuawqBtohTxYrc3sgAwjww=; b=Hwmk7YeWhBR+bPT1gb5RzoUAqlgbKKsPNpeRYQ/mz2LUvzbQr9qBK4j2pJF2V9FcnQ hj9w27FSzgAg2S1NXDkkdYugd4QIdIg5Z2lTtwYpGfz+PGFujG7mexZ7uokW+4X0hVzf aL37xaDDprybYy5jKwSsalWxISoQzvlJMFYU0giGF0q8lsdhLJ5W+Hd+H5uwImLXA7Xi lp5qJN8sc5pwwihOM7AAj+At18+jJA+M9BruQFDT2JrY/HYEIvhIg1XPlIPmHn5KvlhZ LRYvAfITHWJ6eSm0kNT5HMfSisKBPNNORQREtLzc2ZvHXAbsTMz0CohVZbcdgo3p13cq IuZw== 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:autocrypt :message-id:date:user-agent:mime-version:in-reply-to :content-language:content-transfer-encoding; bh=EoHFVfVTHKDj3wA1Pgr7GAuawqBtohTxYrc3sgAwjww=; b=lA60RyRfAQAyIjyyO4gpcgTpuM2ifta9jVda3+icXxl3+wZGpNx7mlAbL4L/yU5nly jF3pqS+HY8TSCUH9flRNYr4Ss6lp/LVoP2NIWjLUvNKwKY0rDCLr5+UE+P/+9oIsyyUK X0AxrUpb8PVaeKqpj0bwEnHmpSHmfngyhUiFXuOInSOQbaq0zwjWIk4K3PaybAMT2o4M TBdGpPuZUeJjKsKhILrx7V6t3gZ2NGhLPGEJvXeb+P8wSigyu5kHQ+O+paqsZ9m0YDGg V3jk5GJjbI531/GHxfPE9s1CTTq/22QmFecd5WFOYfTBZ1CWMLmpnGVQgriay4AwIwAK FnHg== X-Gm-Message-State: ANhLgQ0KL7FTmo5E9lJzfN0SlV6iM58ChUew2A25KUasfSJRcv9LpZKr jKLcmbpNrzQuuK2NdHeumeY1R6Mhg8I= X-Google-Smtp-Source: ADFU+vtUqBrBYpWGQT0F6qG4VH8WBvkLR2SPKKB9qgPmtRoXxqJJFq2PsqIAfuhTww49jsdZsgx7TQ== X-Received: by 2002:a63:1c4d:: with SMTP id c13mr24608158pgm.4.1585021085960; Mon, 23 Mar 2020 20:38:05 -0700 (PDT) Received: from [192.168.10.21] (ppp121-45-221-81.bras1.cbr2.internode.on.net. [121.45.221.81]) by smtp.gmail.com with ESMTPSA id a185sm15138421pfa.27.2020.03.23.20.38.01 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 23 Mar 2020 20:38:05 -0700 (PDT) Subject: Re: [PATCH 1/2] dma-mapping: add a dma_ops_bypass flag to struct device To: Christoph Hellwig References: <20200320141640.366360-1-hch@lst.de> <20200320141640.366360-2-hch@lst.de> <2f31d0dd-aa7e-8b76-c8a1-5759fda5afc9@ozlabs.ru> <20200323083705.GA31245@lst.de> <37ce1b7e-264d-292d-32b1-093b24b3525c@ozlabs.ru> <20200323172014.GA31269@lst.de> From: Alexey Kardashevskiy Autocrypt: addr=aik@ozlabs.ru; keydata= mQINBE+rT0sBEADFEI2UtPRsLLvnRf+tI9nA8T91+jDK3NLkqV+2DKHkTGPP5qzDZpRSH6mD EePO1JqpVuIow/wGud9xaPA5uvuVgRS1q7RU8otD+7VLDFzPRiRE4Jfr2CW89Ox6BF+q5ZPV /pS4v4G9eOrw1v09lEKHB9WtiBVhhxKK1LnUjPEH3ifkOkgW7jFfoYgTdtB3XaXVgYnNPDFo PTBYsJy+wr89XfyHr2Ev7BB3Xaf7qICXdBF8MEVY8t/UFsesg4wFWOuzCfqxFmKEaPDZlTuR tfLAeVpslNfWCi5ybPlowLx6KJqOsI9R2a9o4qRXWGP7IwiMRAC3iiPyk9cknt8ee6EUIxI6 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DG9EMkK8IBXnLulqVk54kf7fE0jT/d8RTtJIA92GzsgdK2rpT1MBKKVffjRFGwN7nQVOzi4T XrB5p+6ML7Bd84xOEGsj/vdaXmz1esuH7BOZAGEZfLRCHJ0GVCSssg== Message-ID: Date: Tue, 24 Mar 2020 14:37:59 +1100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.5.0 MIME-Version: 1.0 In-Reply-To: <20200323172014.GA31269@lst.de> Content-Language: en-US Cc: Greg Kroah-Hartman , linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org, "Aneesh Kumar K.V" , Robin Murphy X-BeenThere: iommu@lists.linux-foundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Development issues for Linux IOMMU support List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: iommu-bounces@lists.linux-foundation.org Sender: "iommu" On 24/03/2020 04:20, Christoph Hellwig wrote: > On Mon, Mar 23, 2020 at 07:58:01PM +1100, Alexey Kardashevskiy wrote: >>>> 0x100.0000.0000 .. 0x101.0000.0000 >>>> >>>> 2x4G, each is 1TB aligned. And we can map directly only the first 4GB >>>> (because of the maximum IOMMU table size) but not the other. And 1:1 on >>>> that "pseries" is done with offset=0x0800.0000.0000.0000. >>>> >>>> So we want to check every bus address against dev->bus_dma_limit, not >>>> dev->coherent_dma_mask. In the example above I'd set bus_dma_limit to >>>> 0x0800.0001.0000.0000 and 1:1 mapping for the second 4GB would not be >>>> tried. Does this sound reasonable? Thanks, >>> >>> bus_dma_limit is just another limiting factor applied on top of >>> coherent_dma_mask or dma_mask respectively. >> >> This is not enough for the task: in my example, I'd set bus limit to >> 0x0800.0001.0000.0000 but this would disable bypass for all RAM >> addresses - the first and the second 4GB blocks. > > So what about something like the version here: > > http://git.infradead.org/users/hch/misc.git/shortlog/refs/heads/dma-bypass.3 dma_alloc_direct() and dma_map_direct() do the same thing now which is good, did I miss anything else? This lets us disable bypass automatically if this weird memory appears in the system but does not let us have 1:1 after that even for normal RAM. Thanks, -- Alexey _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu