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=-2.5 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,MAILING_LIST_MULTI,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 E9286C43332 for ; Wed, 18 Mar 2020 22:48:49 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (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 B3E3B20752 for ; Wed, 18 Mar 2020 22:48:49 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="a0V7E4ec"; dkim=fail reason="signature verification failed" (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="jaM0G/5t" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B3E3B20752 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=eOYwffPCIAX9j/4n9gs1AasHcWafQfyuP014oew/wzw=; b=a0V7E4ecyMuA1b gkxKjvsNuUfQoo0wPQ10/tg35yCCX4y6h3Npa64WfPJXnsasq8MEP+6Y31k/S08FYyyyiMSWW0+5W Pcfg0/KdGSMRaTwh8oFWNnZvGq5E832BcRiiai6eMaV2sbjhdb8HoTZiwPYNvv3mFGNK8yfL0Zq5/ YZ8KDkOhMwRFu/NHp8dlqf5ZJs2t3fOcp4BjFrcpEUruMXMpnFxgz21QuYLiaY/kVsISj7UqCdumj J8BQ4ZbL4BSRCAfOM8D3o9Wn/OBE1CRsHBOdZ6SbzAixpzGK61Nk6w8lIFtnzoExJOUWSUUb2GqRQ zP/J145wrRZ/mXphXcrg==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1jEhUV-0001kE-Vk; Wed, 18 Mar 2020 22:48:47 +0000 Received: from mail.kernel.org ([198.145.29.99]) by bombadil.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1jEhUT-0001js-IS for linux-arm-kernel@lists.infradead.org; Wed, 18 Mar 2020 22:48:46 +0000 Received: from willie-the-truck (236.31.169.217.in-addr.arpa [217.169.31.236]) (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 E7DC020752; Wed, 18 Mar 2020 22:48:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1584571725; bh=sxbtUTf11iJytMzmHFkvIe4CnT3yrC6BYKS3V/0Z0Fk=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=jaM0G/5trMtdFkV2/vhMxNOFWaSGhrrs52HK2xDjUYl+JI3hUsWXm6CPYojhT/ldL j3jQDJn+SmUHKWEmCw8/fOnx7X2yRYKJ3RXUvmhvhVIUEaKPQzUP3rG1mL4eh2B5sb HN/0wISxOh2nwOxnShOj3pxzI9FpXy/K2iWAVTrY= Date: Wed, 18 Mar 2020 22:48:40 +0000 From: Will Deacon To: Jordan Crouse Subject: Re: [PATCH v1 2/6] arm/smmu: Add auxiliary domain support for arm-smmuv2 Message-ID: <20200318224840.GA10796@willie-the-truck> References: <1580249770-1088-1-git-send-email-jcrouse@codeaurora.org> <1580249770-1088-3-git-send-email-jcrouse@codeaurora.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <1580249770-1088-3-git-send-email-jcrouse@codeaurora.org> User-Agent: Mutt/1.10.1 (2018-07-13) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200318_154845_631694_9F3C978C X-CRM114-Status: GOOD ( 16.88 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-arm-msm@vger.kernel.org, Joerg Roedel , linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org, robin.murphy@arm.com, linux-arm-kernel@lists.infradead.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Tue, Jan 28, 2020 at 03:16:06PM -0700, Jordan Crouse wrote: > Support auxiliary domains for arm-smmu-v2 to initialize and support > multiple pagetables for a single SMMU context bank. Since the smmu-v2 > hardware doesn't have any built in support for switching the pagetable > base it is left as an exercise to the caller to actually use the pagetable. > > Aux domains are supported if split pagetable (TTBR1) support has been > enabled on the master domain. Each auxiliary domain will reuse the > configuration of the master domain. By default the a domain with TTBR1 > support will have the TTBR0 region disabled so the first attached aux > domain will enable the TTBR0 region in the hardware and conversely the > last domain to be detached will disable TTBR0 translations. All subsequent > auxiliary domains create a pagetable but not touch the hardware. > > The leaf driver will be able to query the physical address of the > pagetable with the DOMAIN_ATTR_PTBASE attribute so that it can use the > address with whatever means it has to switch the pagetable base. > > Following is a pseudo code example of how a domain can be created > > /* Check to see if aux domains are supported */ > if (iommu_dev_has_feature(dev, IOMMU_DEV_FEAT_AUX)) { > iommu = iommu_domain_alloc(...); > > if (iommu_aux_attach_device(domain, dev)) > return FAIL; > > /* Save the base address of the pagetable for use by the driver > iommu_domain_get_attr(domain, DOMAIN_ATTR_PTBASE, &ptbase); > } I'm not really understanding what the pagetable base gets used for here and, to be honest with you, the whole thing feels like a huge layering violation with the way things are structured today. Why doesn't the caller just interface with io-pgtable directly? Finally, if we need to support context-switching TTBR0 for a live domain then that code really needs to live inside the SMMU driver because the ASID and TLB management necessary to do that safely doesn't belong anywhere else. Will _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel