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=-6.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SPF_PASS 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 DB2A2C169C4 for ; Tue, 29 Jan 2019 18:54:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id AAC4920844 for ; Tue, 29 Jan 2019 18:54:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729158AbfA2Syr (ORCPT ); Tue, 29 Jan 2019 13:54:47 -0500 Received: from mx1.redhat.com ([209.132.183.28]:35132 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727229AbfA2Syq (ORCPT ); Tue, 29 Jan 2019 13:54:46 -0500 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id E3075C05D41E; Tue, 29 Jan 2019 18:54:45 +0000 (UTC) Received: from redhat.com (ovpn-123-79.rdu2.redhat.com [10.10.123.79]) by smtp.corp.redhat.com (Postfix) with SMTP id 6977D53; Tue, 29 Jan 2019 18:54:43 +0000 (UTC) Date: Tue, 29 Jan 2019 13:54:42 -0500 From: "Michael S. Tsirkin" To: Jean-Philippe Brucker Cc: mark.rutland@arm.com, virtio-dev@lists.oasis-open.org, kevin.tian@intel.com, tnowicki@caviumnetworks.com, devicetree@vger.kernel.org, marc.zyngier@arm.com, linux-pci@vger.kernel.org, will.deacon@arm.com, robin.murphy@arm.com, virtualization@lists.linux-foundation.org, iommu@lists.linux-foundation.org, robh+dt@kernel.org, kvmarm@lists.cs.columbia.edu, bhelgaas@google.com, frowand.list@gmail.com, jasowang@redhat.com, linuxppc-dev@lists.ozlabs.org, Thiago Jung Bauermann Subject: Re: [PATCH v7 0/7] Add virtio-iommu driver Message-ID: <20190129135345-mutt-send-email-mst@kernel.org> References: <20190115121959.23763-1-jean-philippe.brucker@arm.com> <20190118103235-mutt-send-email-mst@kernel.org> <0ba215f5-e856-bf31-8dd9-a85710714a7a@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <0ba215f5-e856-bf31-8dd9-a85710714a7a@arm.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.32]); Tue, 29 Jan 2019 18:54:46 +0000 (UTC) Sender: linux-pci-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org On Mon, Jan 21, 2019 at 11:29:05AM +0000, Jean-Philippe Brucker wrote: > Hi, > > On 18/01/2019 15:51, Michael S. Tsirkin wrote: > > > > On Tue, Jan 15, 2019 at 12:19:52PM +0000, Jean-Philippe Brucker wrote: > >> Implement the virtio-iommu driver, following specification v0.9 [1]. > >> > >> This is a simple rebase onto Linux v5.0-rc2. We now use the > >> dev_iommu_fwspec_get() helper introduced in v5.0 instead of accessing > >> dev->iommu_fwspec, but there aren't any functional change from v6 [2]. > >> > >> Our current goal for virtio-iommu is to get a paravirtual IOMMU working > >> on Arm, and enable device assignment to guest userspace. In this > >> use-case the mappings are static, and don't require optimal performance, > >> so this series tries to keep things simple. However there is plenty more > >> to do for features and optimizations, and having this base in v5.1 would > >> be good. Given that most of the changes are to drivers/iommu, I believe > >> the driver and future changes should go via the IOMMU tree. > >> > >> You can find Linux driver and kvmtool device on v0.9.2 branches [3], > >> module and x86 support on virtio-iommu/devel. Also tested with Eric's > >> QEMU device [4]. Please note that the series depends on Robin's > >> probe-deferral fix [5], which will hopefully land in v5.0. > >> > >> [1] Virtio-iommu specification v0.9, sources and pdf > >> git://linux-arm.org/virtio-iommu.git virtio-iommu/v0.9 > >> http://jpbrucker.net/virtio-iommu/spec/v0.9/virtio-iommu-v0.9.pdf > >> > >> [2] [PATCH v6 0/7] Add virtio-iommu driver > >> https://lists.linuxfoundation.org/pipermail/iommu/2018-December/032127.html > >> > >> [3] git://linux-arm.org/linux-jpb.git virtio-iommu/v0.9.2 > >> git://linux-arm.org/kvmtool-jpb.git virtio-iommu/v0.9.2 > >> > >> [4] [RFC v9 00/17] VIRTIO-IOMMU device > >> https://www.mail-archive.com/qemu-devel@nongnu.org/msg575578.html > >> > >> [5] [PATCH] iommu/of: Fix probe-deferral > >> https://www.spinics.net/lists/arm-kernel/msg698371.html > > > > Thanks for the work! > > So really my only issue with this is that there's no > > way for the IOMMU to describe the devices that it > > covers. > > > > As a result that is then done in a platform-specific way. > > > > And this means that for example it does not solve the problem that e.g. > > some power people have in that their platform simply does not have a way > > to specify which devices are covered by the IOMMU. > > Isn't power using device tree? I haven't looked much at power because I > was told a while ago that they already paravirtualize their IOMMU and > don't need virtio-iommu, except perhaps for some legacy platforms. Or > something along those lines. But I would certainly be interested in > enabling the IOMMU for more architectures. I have CC'd the relevant ppc developers, let's see what do they think. > As for the enumeration problem, I still don't think we can get much > better than DT and ACPI as solutions (and IMO they are necessary to make > this device portable). But I believe that getting DT and ACPI support is > just a one-off inconvenience. That is, once the required bindings are > accepted, any future extension can then be done at the virtio level with > feature bits and probe requests, without having to update ACPI or DT. > > Thanks, > Jean > > > Solving that problem would make me much more excited about > > this device. > > > > On the other hand I can see that while there have been some > > developments most of the code has been stable for quite a while now. > > > > So what I am trying to do right about now, is making a small module that > > loads early and pokes at the IOMMU sufficiently to get the data about > > which devices use the IOMMU out of it using standard virtio config > > space. IIUC it's claimed to be impossible without messy changes to the > > boot sequence. > > > > If I succeed at least on some platforms I'll ask that this design is > > worked into this device, minimizing info that goes through DT/ACPI. If > > I see I can't make it in time to meet the next merge window, I plan > > merging the existing patches using DT (barring surprises). > > > > As I only have a very small amount of time to spend on this attempt, If > > someone else wants to try doing that in parallel, that would be great! > > > > > >> Jean-Philippe Brucker (7): > >> dt-bindings: virtio-mmio: Add IOMMU description > >> dt-bindings: virtio: Add virtio-pci-iommu node > >> of: Allow the iommu-map property to omit untranslated devices > >> PCI: OF: Initialize dev->fwnode appropriately > >> iommu: Add virtio-iommu driver > >> iommu/virtio: Add probe request > >> iommu/virtio: Add event queue > >> > >> .../devicetree/bindings/virtio/iommu.txt | 66 + > >> .../devicetree/bindings/virtio/mmio.txt | 30 + > >> MAINTAINERS | 7 + > >> drivers/iommu/Kconfig | 11 + > >> drivers/iommu/Makefile | 1 + > >> drivers/iommu/virtio-iommu.c | 1158 +++++++++++++++++ > >> drivers/of/base.c | 10 +- > >> drivers/pci/of.c | 7 + > >> include/uapi/linux/virtio_ids.h | 1 + > >> include/uapi/linux/virtio_iommu.h | 161 +++ > >> 10 files changed, 1449 insertions(+), 3 deletions(-) > >> create mode 100644 Documentation/devicetree/bindings/virtio/iommu.txt > >> create mode 100644 drivers/iommu/virtio-iommu.c > >> create mode 100644 include/uapi/linux/virtio_iommu.h > >> > >> -- > >> 2.19.1 > > _______________________________________________ > > iommu mailing list > > iommu@lists.linux-foundation.org > > https://lists.linuxfoundation.org/mailman/listinfo/iommu > >