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=-2.7 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT 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 1E552C282DD for ; Thu, 18 Apr 2019 23:42:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id DFFF22171F for ; Thu, 18 Apr 2019 23:42:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1555630966; bh=JEAOgYJlOvZdMdVyDXHifM67i+2PUhKtJ1YzNTJp9lo=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=cE6Xy9GfGgrISIhXMmw8NOdDC31EV0FwRs9rBjHe5NdQYs+FrUMRjA8rQ22hU1P53 iqM7WYjal5FxPviGs1vQ1BNu5WPgiKNmw0XlNFSch7ZDrqy5OjwXp40UfPUKd8xK9T BACvHPrWxomCcwHC5buTlLvfuhho9ikjOVNx3hJo= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726394AbfDRXmp (ORCPT ); Thu, 18 Apr 2019 19:42:45 -0400 Received: from mail.kernel.org ([198.145.29.99]:34446 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725855AbfDRXmo (ORCPT ); Thu, 18 Apr 2019 19:42:44 -0400 Received: from localhost (unknown [69.71.4.100]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 4953920675; Thu, 18 Apr 2019 23:42:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1555630963; bh=JEAOgYJlOvZdMdVyDXHifM67i+2PUhKtJ1YzNTJp9lo=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=E/qBST9ORsR60kh4OyKwZYSNPLU1KtkPCKOL2msKqvW3FvPnRVcysWhpIFE8F4jnK Bcc1w4IWiGv3jVOdq+RBcREQuURZ/9F+kvZtdPtL8nCOrd5kkKoTpYUdzS2ZZgkRyq Og5o5Esmo8zurb+diXzEdBOfP6V4B5PxeOi4MEZs= Date: Thu, 18 Apr 2019 18:42:41 -0500 From: Bjorn Helgaas To: Srinath Mannam Cc: Robin Murphy , Joerg Roedel , Lorenzo Pieralisi , poza@codeaurora.org, Ray Jui , BCM Kernel Feedback , linux-pci@vger.kernel.org, iommu@lists.linux-foundation.org, Linux Kernel Mailing List Subject: Re: [PATCH v4 0/3] PCIe Host request to reserve IOVA Message-ID: <20190418234241.GF126710@google.com> References: <1555038815-31916-1-git-send-email-srinath.mannam@broadcom.com> <20190412223409.GB126710@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Apr 16, 2019 at 05:28:36PM +0530, Srinath Mannam wrote: > On Sat, Apr 13, 2019 at 4:04 AM Bjorn Helgaas wrote: > > On Fri, Apr 12, 2019 at 08:43:32AM +0530, Srinath Mannam wrote: > > > Few SOCs have limitation that their PCIe host can't allow few inbound > > > address ranges. Allowed inbound address ranges are listed in dma-ranges > > > DT property and this address ranges are required to do IOVA mapping. > > > Remaining address ranges have to be reserved in IOVA mapping. > > > If I understand correctly, devices below these PCIe host bridges can > > DMA only to the listed address ranges, and you prevent devices from > > doing DMA to the holes between the listed ranges by reserving the > > holes in dma-iommu. > > Yes, devices below these PCIe host bridges can DMA only to the listed > address ranges, > and this patch prevents to allocate DMA(IOVA) addresses in the holes > of listed ranges. > > > Apparently there's something that makes sure driver dma_map_*() always > > goes through dma-iommu? I traced as far as seeing that dma-iommu > > depends on CONFIG_IOMMU_DMA, and that arm64 selects CONFIG_IOMMU_DMA > > if CONFIG_IOMMU_SUPPORT, but then the trail got cold. I didn't see > > what selects CONFIG_IOMMU_SUPPORT. > > IOMMU_SUPPORT depends on MMU. Yes, I see that IOMMU_SUPPORT depends on MMU (in drivers/iommu/Kconfig). But that doesn't *select* IOMMU_SUPPORT; it only means you *can't* select it unless MMU has already been selected. I think you only get dma-iommu if you choose to select IOMMU_SUPPORT via menuconfig or whatever, and the current config rules allow you to turn that off. Maybe that's OK, I dunno. If you do turn it off, I guess we'll ignore the holes in "dma-ranges" and devices will be able to DMA to the holes. > > This does look like what Robin suggested, as far as I can tell. > > Hopefully he'll take a look and give his reviewed-by. Thanks for > > persevering! > Thank you. > > Regards, > Srinath. > > > > > PCIe Host driver of those SOCs has to list resource entries of allowed > > > address ranges given in dma-ranges DT property in sorted order. This > > > sorted list of resources will be processed and reserve IOVA address for > > > inaccessible address holes while initializing IOMMU domain. > > > > > > This patch set is based on Linux-5.0-rc2. > > > > > > Changes from v3: > > > - Addressed Robin Murphy review comments. > > > - pcie-iproc: parse dma-ranges and make sorted resource list. > > > - dma-iommu: process list and reserve gaps between entries > > > > > > Changes from v2: > > > - Patch set rebased to Linux-5.0-rc2 > > > > > > Changes from v1: > > > - Addressed Oza review comments. > > > > > > Srinath Mannam (3): > > > PCI: Add dma_ranges window list > > > iommu/dma: Reserve IOVA for PCIe inaccessible DMA address > > > PCI: iproc: Add sorted dma ranges resource entries to host bridge > > > > > > drivers/iommu/dma-iommu.c | 19 ++++++++++++++++ > > > drivers/pci/controller/pcie-iproc.c | 44 ++++++++++++++++++++++++++++++++++++- > > > drivers/pci/probe.c | 3 +++ > > > include/linux/pci.h | 1 + > > > 4 files changed, 66 insertions(+), 1 deletion(-) > > > > > > -- > > > 2.7.4 > > >