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    SubjectRe: [PATCH v2 0/8] Host1x context isolation support
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    Will, Joerg, Rob,

    On 08/11/2021 10:36, Mikko Perttunen wrote:
    > On 9/16/21 5:32 PM, Mikko Perttunen wrote:
    >> Hi all,
    >>
    >> ***
    >> New in v2:
    >>
    >> Added support for Tegra194
    >> Use standard iommu-map property instead of custom mechanism
    >> ***
    >>
    >> this series adds support for Host1x 'context isolation'. Since
    >> when programming engines through Host1x, userspace can program in
    >> any addresses it wants, we need some way to isolate the engines'
    >> memory spaces. Traditionally this has either been done imperfectly
    >> with a single shared IOMMU domain, or by copying and verifying the
    >> programming command stream at submit time (Host1x firewall).
    >>
    >> Since Tegra186 there is a privileged (only usable by kernel)
    >> Host1x opcode that allows setting the stream ID sent by the engine
    >> to the SMMU. So, by allocating a number of context banks and stream
    >> IDs for this purpose, and using this opcode at the beginning of
    >> each job, we can implement isolation. Due to the limited number of
    >> context banks only each process gets its own context, and not
    >> each channel.
    >>
    >> This feature also allows sharing engines among multiple VMs when
    >> used with Host1x's hardware virtualization support - up to 8 VMs
    >> can be configured with a subset of allowed stream IDs, enforced
    >> at hardware level.
    >>
    >> To implement this, this series adds a new host1x context bus, which
    >> will contain the 'struct device's corresponding to each context
    >> bank / stream ID, changes to device tree and SMMU code to allow
    >> registering the devices and using the bus, as well as the Host1x
    >> stream ID programming code and support in TegraDRM.
    >>
    >> Device tree bindings are not updated yet pending consensus that the
    >> proposed changes make sense.
    >>
    >> Thanks,
    >> Mikko
    >>
    >> Mikko Perttunen (8):
    >>    gpu: host1x: Add context bus
    >>    gpu: host1x: Add context device management code
    >>    gpu: host1x: Program context stream ID on submission
    >>    iommu/arm-smmu: Attach to host1x context device bus
    >>    arm64: tegra: Add Host1x context stream IDs on Tegra186+
    >>    drm/tegra: falcon: Set DMACTX field on DMA transactions
    >>    drm/tegra: vic: Implement get_streamid_offset
    >>    drm/tegra: Support context isolation
    >>
    >>   arch/arm64/boot/dts/nvidia/tegra186.dtsi  |  12 ++
    >>   arch/arm64/boot/dts/nvidia/tegra194.dtsi  |  12 ++
    >>   drivers/gpu/Makefile                      |   3 +-
    >>   drivers/gpu/drm/tegra/drm.h               |   2 +
    >>   drivers/gpu/drm/tegra/falcon.c            |   8 +
    >>   drivers/gpu/drm/tegra/falcon.h            |   1 +
    >>   drivers/gpu/drm/tegra/submit.c            |  13 ++
    >>   drivers/gpu/drm/tegra/uapi.c              |  34 ++++-
    >>   drivers/gpu/drm/tegra/vic.c               |  38 +++++
    >>   drivers/gpu/host1x/Kconfig                |   5 +
    >>   drivers/gpu/host1x/Makefile               |   2 +
    >>   drivers/gpu/host1x/context.c              | 174 ++++++++++++++++++++++
    >>   drivers/gpu/host1x/context.h              |  27 ++++
    >>   drivers/gpu/host1x/context_bus.c          |  31 ++++
    >>   drivers/gpu/host1x/dev.c                  |  12 +-
    >>   drivers/gpu/host1x/dev.h                  |   2 +
    >>   drivers/gpu/host1x/hw/channel_hw.c        |  52 ++++++-
    >>   drivers/gpu/host1x/hw/host1x06_hardware.h |  10 ++
    >>   drivers/gpu/host1x/hw/host1x07_hardware.h |  10 ++
    >>   drivers/iommu/arm/arm-smmu/arm-smmu.c     |  13 ++
    >>   include/linux/host1x.h                    |  21 +++
    >>   include/linux/host1x_context_bus.h        |  15 ++
    >>   22 files changed, 488 insertions(+), 9 deletions(-)
    >>   create mode 100644 drivers/gpu/host1x/context.c
    >>   create mode 100644 drivers/gpu/host1x/context.h
    >>   create mode 100644 drivers/gpu/host1x/context_bus.c
    >>   create mode 100644 include/linux/host1x_context_bus.h
    >>
    >
    > IOMMU/DT folks, any thoughts about this approach? The patches that are
    > of interest outside of Host1x/TegraDRM specifics are patches 1, 2, 4,
    > and 5.


    Any feedback on this?

    Jon

    --
    nvpublic

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