linux-kernel - Re: [PATCH v2 0/8] Host1x context isolation support

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Date:   Tue, 14 Dec 2021 08:05:44 +0000
From:   Jon Hunter <jonathanh@...dia.com>
To:     joro@...tes.org, will@...nel.org, robh+dt@...nel.org,
        robin.murphy@....com
Cc:     linux-tegra@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        iommu@...ts.linux-foundation.org, linux-kernel@...r.kernel.org,
        devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        Mikko Perttunen <cyndis@...si.fi>,
        Mikko Perttunen <mperttunen@...dia.com>,
        thierry.reding@...il.com
Subject: Re: [PATCH v2 0/8] Host1x context isolation support

Hi all,

Still no response on this :-(

On 06/12/2021 09:55, Jon Hunter wrote:
> 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
> 

-- 
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