RE: [PATCH RFC v1 00/15] iommu/virtio: Nested stage support with Arm

Shameerali Kolothum Thodi
2021-01-22T15:56:44Z

Hi Vivek,

> -----Original Message-----
> From: Vivek Kumar Gautam [mailto:vivek.gautam@arm.com]
> Sent: 21 January 2021 17:34
> To: Auger Eric <eric.auger@redhat.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 <shameerali.kolothum.thodi@huawei.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@red
> >> hat.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-platfo
> >> rms.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-vi
> rtio-iommu

Thanks for this. Do you have a corresponding kvmtool branch mentioned above as public?

Thanks,
Shameer