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Subject: Re: [PATCH RFC v1 00/15] iommu/virtio: Nested stage support with Arm
To:     Vivek Gautam <vivek.gautam@arm.com>, linux-kernel@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org,
        iommu@lists.linux-foundation.org,
        virtualization@lists.linux-foundation.org
Cc:     joro@8bytes.org, will.deacon@arm.com, mst@redhat.com,
        robin.murphy@arm.com, jean-philippe@linaro.org,
        alex.williamson@redhat.com, kevin.tian@intel.com,
        jacob.jun.pan@linux.intel.com, yi.l.liu@intel.com,
        lorenzo.pieralisi@arm.com, shameerali.kolothum.thodi@huawei.com
References: <20210115121342.15093-1-vivek.gautam@arm.com>
From:   Auger Eric <eric.auger@redhat.com>
Message-ID: <a8fd0176-3888-44cf-d659-2e2213a59969@redhat.com>
Date:   Tue, 19 Jan 2021 10:03:22 +0100
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Hi Vivek,

On 1/15/21 1:13 PM, Vivek Gautam wrote:
> This patch-series aims at enabling Nested stage translation in guests
> using virtio-iommu as the paravirtualized iommu. The backend is supported
> with Arm SMMU-v3 that provides nested stage-1 and stage-2 translation.
> 
> This series derives its purpose from various efforts happening to add
> support for Shared Virtual Addressing (SVA) in host and guest. On Arm,
> most of the support for SVA has already landed. The support for nested
> stage translation and fault reporting to guest has been proposed [1].
> The related changes required in VFIO [2] framework have also been put
> forward.
> 
> This series proposes changes in virtio-iommu to program PASID tables
> and related stage-1 page tables. A simple iommu-pasid-table library
> is added for this purpose that interacts with vendor drivers to
> allocate and populate PASID tables.
> In Arm SMMUv3 we propose to pull the Context Descriptor (CD) management
> code out of the arm-smmu-v3 driver and add that as a glue vendor layer
> to support allocating CD tables, and populating them with right values.
> These CD tables are essentially the PASID tables and contain stage-1
> page table configurations too.
> A request to setup these CD tables come from virtio-iommu driver using
> the iommu-pasid-table library when running on Arm. The virtio-iommu
> then pass these PASID tables to the host using the right virtio backend
> and support in VMM.
> 
> For testing we have added necessary support in kvmtool. The changes in
> kvmtool are based on virtio-iommu development branch by Jean-Philippe
> Brucker [3].
> 
> The tested kernel branch contains following in the order bottom to top
> on the git hash -
> a) v5.11-rc3
> b) arm-smmu-v3 [1] and vfio [2] changes from Eric to add nested page
>    table support for Arm.
> c) Smmu test engine patches from Jean-Philippe's branch [4]
> d) This series
> e) Domain nesting info patches [5][6][7].
> f) Changes to add arm-smmu-v3 specific nesting info (to be sent to
>    the list).
> 
> This kernel is tested on Neoverse reference software stack with
> Fixed virtual platform. Public version of the software stack and
> FVP is available here[8][9].
> 
> A big thanks to Jean-Philippe for his contributions towards this work
> and for his valuable guidance.
> 
> [1] https://lore.kernel.org/linux-iommu/20201118112151.25412-1-eric.auger@redhat.com/T/
> [2] https://lore.kernel.org/kvmarm/20201116110030.32335-12-eric.auger@redhat.com/T/
> [3] https://jpbrucker.net/git/kvmtool/log/?h=virtio-iommu/devel
> [4] https://jpbrucker.net/git/linux/log/?h=sva/smmute
> [5] https://lore.kernel.org/kvm/1599734733-6431-2-git-send-email-yi.l.liu@intel.com/
> [6] https://lore.kernel.org/kvm/1599734733-6431-3-git-send-email-yi.l.liu@intel.com/
> [7] https://lore.kernel.org/kvm/1599734733-6431-4-git-send-email-yi.l.liu@intel.com/
> [8] https://developer.arm.com/tools-and-software/open-source-software/arm-platforms-software/arm-ecosystem-fvps
> [9] https://git.linaro.org/landing-teams/working/arm/arm-reference-platforms.git/about/docs/rdn1edge/user-guide.rst

Could you share a public branch where we could find all the kernel pieces.

Thank you in advance

Best Regards

Eric
> 
> Jean-Philippe Brucker (6):
>   iommu/virtio: Add headers for table format probing
>   iommu/virtio: Add table format probing
>   iommu/virtio: Add headers for binding pasid table in iommu
>   iommu/virtio: Add support for INVALIDATE request
>   iommu/virtio: Attach Arm PASID tables when available
>   iommu/virtio: Add support for Arm LPAE page table format
> 
> Vivek Gautam (9):
>   iommu/arm-smmu-v3: Create a Context Descriptor library
>   iommu: Add a simple PASID table library
>   iommu/arm-smmu-v3: Update drivers to work with iommu-pasid-table
>   iommu/arm-smmu-v3: Update CD base address info for user-space
>   iommu/arm-smmu-v3: Set sync op from consumer driver of cd-lib
>   iommu: Add asid_bits to arm smmu-v3 stage1 table info
>   iommu/virtio: Update table format probing header
>   iommu/virtio: Prepare to add attach pasid table infrastructure
>   iommu/virtio: Update fault type and reason info for viommu fault
> 
>  drivers/iommu/arm/arm-smmu-v3/Makefile        |   2 +-
>  .../arm/arm-smmu-v3/arm-smmu-v3-cd-lib.c      | 283 +++++++
>  .../iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c   |  16 +-
>  drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c   | 268 +------
>  drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h   |   4 +-
>  drivers/iommu/iommu-pasid-table.h             | 140 ++++
>  drivers/iommu/virtio-iommu.c                  | 692 +++++++++++++++++-
>  include/uapi/linux/iommu.h                    |   2 +-
>  include/uapi/linux/virtio_iommu.h             | 158 +++-
>  9 files changed, 1303 insertions(+), 262 deletions(-)
>  create mode 100644 drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-cd-lib.c
>  create mode 100644 drivers/iommu/iommu-pasid-table.h
>