Message-ID: <ba4c30b9-1f31-f6b2-e69a-7bb71ce74d57@arm.com>
Date:   Thu, 21 Jan 2021 23:04:29 +0530
From:   Vivek Kumar Gautam <vivek.gautam@....com>
To:     Auger Eric <eric.auger@...hat.com>, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        iommu@...ts.linux-foundation.org,
        virtualization@...ts.linux-foundation.org
Cc:     joro@...tes.org, will.deacon@....com, mst@...hat.com,
        robin.murphy@....com, jean-philippe@...aro.org,
        alex.williamson@...hat.com, kevin.tian@...el.com,
        jacob.jun.pan@...ux.intel.com, yi.l.liu@...el.com,
        lorenzo.pieralisi@....com, shameerali.kolothum.thodi@...wei.com
Subject: Re: [PATCH RFC v1 00/15] iommu/virtio: Nested stage support with Arm

Hi Eric,


On 1/19/21 2:33 PM, Auger Eric wrote:
> 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

Apologies for the delay. It took a bit of time to sort things out for a 
public branch.
The branch is available in my github now. Please have a look.

https://github.com/vivek-arm/linux/tree/5.11-rc3-nested-pgtbl-arm-smmuv3-virtio-iommu


Thanks and regards
Vivek

> 
> 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
>>
> 

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