On 2021-11-08 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.
FWIW it looks fairly innocuous to me. I don't understand host1x - neither hardware nor driver abstractions - well enough to meaningfully review it all (e.g. maybe it's deliberate that the bus .dma_configure method isn't used?), but the SMMU patch seems fine given the Kconfig solution to avoid module linkage problems.
Cheers, Robin.