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 DACFBC433ED for ; Wed, 19 May 2021 15:23:33 +0000 (UTC) Received: from smtp2.osuosl.org (smtp2.osuosl.org [140.211.166.133]) (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 7B914611B0 for ; Wed, 19 May 2021 15:23:33 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7B914611B0 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=iommu-bounces@lists.linux-foundation.org Received: from localhost (localhost [127.0.0.1]) by smtp2.osuosl.org (Postfix) with ESMTP id 456C8403ED; Wed, 19 May 2021 15:23:33 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from smtp2.osuosl.org ([127.0.0.1]) by localhost (smtp2.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 1iBs0LgwDFGx; Wed, 19 May 2021 15:23:32 +0000 (UTC) Received: from lists.linuxfoundation.org (lf-lists.osuosl.org [140.211.9.56]) by smtp2.osuosl.org (Postfix) with ESMTP id 3E848400FA; Wed, 19 May 2021 15:23:32 +0000 (UTC) Received: from lf-lists.osuosl.org (localhost [127.0.0.1]) by lists.linuxfoundation.org (Postfix) with ESMTP id 1EE5DC000E; Wed, 19 May 2021 15:23:32 +0000 (UTC) Received: from smtp3.osuosl.org (smtp3.osuosl.org [IPv6:2605:bc80:3010::136]) by lists.linuxfoundation.org (Postfix) with ESMTP id 30E2FC0001 for ; Wed, 19 May 2021 15:23:31 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by smtp3.osuosl.org (Postfix) with ESMTP id 10DA860719 for ; Wed, 19 May 2021 15:23:31 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from smtp3.osuosl.org ([127.0.0.1]) by localhost (smtp3.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id JdhUx54SjGhp for ; Wed, 19 May 2021 15:23:30 +0000 (UTC) X-Greylist: domain auto-whitelisted by SQLgrey-1.8.0 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp3.osuosl.org (Postfix) with ESMTP id 17E3360710 for ; Wed, 19 May 2021 15:23:29 +0000 (UTC) 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 34EF511D4; Wed, 19 May 2021 08:23:29 -0700 (PDT) Received: from [10.57.66.179] (unknown [10.57.66.179]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 7E1C63F73D; Wed, 19 May 2021 08:23:27 -0700 (PDT) Subject: Re: [PATCH 3/6] vfio: remove the unused mdev iommu hook To: Joerg Roedel , Jason Gunthorpe References: <20210513120058.GG1096940@ziepe.ca> <20210514121925.GI1096940@ziepe.ca> <20210514133143.GK1096940@ziepe.ca> <20210517123010.GO1096940@ziepe.ca> <20210517133500.GP1096940@ziepe.ca> From: Robin Murphy Message-ID: <131327e3-5066-7a88-5b3c-07013585eb01@arm.com> Date: Wed, 19 May 2021 16:23:21 +0100 User-Agent: Mozilla/5.0 (Windows NT 10.0; rv:78.0) Gecko/20100101 Thunderbird/78.10.1 MIME-Version: 1.0 In-Reply-To: Content-Language: en-GB Cc: "Tian, Kevin" , "kvm@vger.kernel.org" , David Woodhouse , "iommu@lists.linux-foundation.org" , Kirti Wankhede , Alex Williamson , Will Deacon , Christoph Hellwig , "linux-arm-kernel@lists.infradead.org" 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-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Errors-To: iommu-bounces@lists.linux-foundation.org Sender: "iommu" On 2021-05-17 16:35, Joerg Roedel wrote: > On Mon, May 17, 2021 at 10:35:00AM -0300, Jason Gunthorpe wrote: >> Well, I'm sorry, but there is a huge other thread talking about the >> IOASID design in great detail and why this is all needed. Jumping into >> this thread without context and basically rejecting all the >> conclusions that were reached over the last several weeks is really >> not helpful - especially since your objection is not technical. >> >> I think you should wait for Intel to put together the /dev/ioasid uAPI >> proposal and the example use cases it should address then you can give >> feedback there, with proper context. > > Yes, I think the next step is that someone who read the whole thread > writes up the conclusions and a rough /dev/ioasid API proposal, also > mentioning the use-cases it addresses. Based on that we can discuss the > implications this needs to have for IOMMU-API and code. > > From the use-cases I know the mdev concept is just fine. But if there is > a more generic one we can talk about it. Just to add another voice here, I have some colleagues working on drivers where they want to use SMMU Substream IDs for a single hardware block to operate on multiple iommu_domains managed entirely within the kernel. Using an mdev-like approach with aux domains is pretty much the ideal fit for this use-case, while all the IOASID discussion appears centred on SVA and userspace interfaces, and as such barely relevant if at all. I seem to recall a non-trivial amount of effort going into the aux domain design too, so the promise of replacing it with "a big TBD" just because vfio-mdev turned out to be awful hardly fills me with enthusiasm either :/ Robin. _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu