[PATCH v10 0/7] Linux RISC-V IOMMU Support

[Palmer Dabbelt]

On Tue, 15 Oct 2024 23:52:12 PDT (-0700), tjeznach at rivosinc.com wrote:
> This patch series introduces support for RISC-V IOMMU architected
> hardware into the Linux kernel.
>
> The RISC-V IOMMU specification, which this series is based on, is
> ratified and available at GitHub/riscv-non-isa [1].
>
> At a high level, the RISC-V IOMMU specification defines:
>
> 1) Data structures:
>   - Device-context: Associates devices with address spaces and holds
>     per-device parameters for address translations.
>   - Process-contexts: Associates different virtual address spaces based
>     on device-provided process identification numbers.
>   - MSI page table configuration used to direct an MSI to a guest
>     interrupt file in an IMSIC.
> 2) In-memory queue interface:
>   - Command-queue for issuing commands to the IOMMU.
>   - Fault/event queue for reporting faults and events.
>   - Page-request queue for reporting "Page Request" messages received
>     from PCIe devices.
>   - Message-signaled and wire-signaled interrupt mechanisms.
> 3) Memory-mapped programming interface:
>   - Mandatory and optional register layout and description.
>   - Software guidelines for device initialization and capabilities discovery.
>
>
> This series introduces RISC-V IOMMU hardware initialization and complete
> single-stage translation with paging domain support.
>
> The patches are organized as follows:
>
> Patch 1: Introduces minimal required device tree bindings for the driver.
> Patch 2: Defines RISC-V IOMMU data structures, hardware programming interface
>          registers layout, and minimal initialization code for enabling global
>          pass-through for all connected masters.
> Patch 3: Implements the device driver for PCIe implementation of RISC-V IOMMU
>          architected hardware.
> Patch 4: Introduces IOMMU interfaces to the kernel subsystem.
> Patch 5: Implements device directory management with discovery sequences for
>          I/O mapped or in-memory device directory table location, hardware
>          capabilities discovery, and device to domain attach implementation.
> Patch 6: Implements command and fault queue, and introduces directory cache
>          invalidation sequences.
> Patch 7: Implements paging domain, using highest page-table mode advertised
>          by the hardware. This series enables only 4K mappings; complete support
>          for large page mappings will be introduced in follow-up patch series.
>
> Follow-up patch series providing MSI interrupt remapping, complete ATS/PRI/SVA
> and VFIO/IOMMUFD support are available at the GitHub [2], and has been tested
> with published QEMU RISC-V IOMMU device model [3].
>
> Changes from v9:
> - rebase on v6.12-rc3
> - #6 Memory ordering fix and updated commentary, based on Will’s suggestions.
> - #7 Remove riscv_iommu_device_domain_type() and use head-less kfree_rcu in
>      riscv_iommu_release_device(), based on Jason's suggestions.
>
> Best regards,
>  Tomasz Jeznach
>
> [1] link: https://github.com/riscv-non-isa/riscv-iommu
> [2] link: https://github.com/tjeznach/linux/riscv_iommu.next
> [3] link: https://lore.kernel.org/qemu-devel/20241004155721.2154626-1-dbarboza@ventanamicro.com/
> v9 link:  https://lore.kernel.org/linux-iommu/cover.1728579958.git.tjeznach@rivosinc.com/
> v8 link:  https://lore.kernel.org/linux-iommu/cover.1718388908.git.tjeznach@rivosinc.com/
> v7 link:  https://lore.kernel.org/linux-iommu/cover.1717612298.git.tjeznach@rivosinc.com/
> v6 link:  https://lore.kernel.org/linux-iommu/cover.1716578450.git.tjeznach@rivosinc.com/
> v5 link:  https://lore.kernel.org/linux-iommu/cover.1715708679.git.tjeznach@rivosinc.com/
> v4 link:  https://lore.kernel.org/linux-iommu/cover.1714752293.git.tjeznach@rivosinc.com/
> v3 link:  https://lore.kernel.org/linux-iommu/cover.1714494653.git.tjeznach@rivosinc.com/
> v2 link:  https://lore.kernel.org/linux-iommu/cover.1713456597.git.tjeznach@rivosinc.com/
> v1 link:  https://lore.kernel.org/linux-iommu/cover.1689792825.git.tjeznach@rivosinc.com/
>
> Tomasz Jeznach (7):
>   dt-bindings: iommu: riscv: Add bindings for RISC-V IOMMU
>   iommu/riscv: Add RISC-V IOMMU platform device driver
>   iommu/riscv: Add RISC-V IOMMU PCIe device driver
>   iommu/riscv: Enable IOMMU registration and device probe.
>   iommu/riscv: Device directory management.
>   iommu/riscv: Command and fault queue support
>   iommu/riscv: Paging domain support
>
>  .../bindings/iommu/riscv,iommu.yaml           |  147 ++
>  MAINTAINERS                                   |    9 +
>  drivers/iommu/Kconfig                         |    1 +
>  drivers/iommu/Makefile                        |    2 +-
>  drivers/iommu/riscv/Kconfig                   |   20 +
>  drivers/iommu/riscv/Makefile                  |    3 +
>  drivers/iommu/riscv/iommu-bits.h              |  784 ++++++++
>  drivers/iommu/riscv/iommu-pci.c               |  120 ++
>  drivers/iommu/riscv/iommu-platform.c          |   92 +
>  drivers/iommu/riscv/iommu.c                   | 1661 +++++++++++++++++
>  drivers/iommu/riscv/iommu.h                   |   88 +
>  11 files changed, 2926 insertions(+), 1 deletion(-)
>  create mode 100644 Documentation/devicetree/bindings/iommu/riscv,iommu.yaml
>  create mode 100644 drivers/iommu/riscv/Kconfig
>  create mode 100644 drivers/iommu/riscv/Makefile
>  create mode 100644 drivers/iommu/riscv/iommu-bits.h
>  create mode 100644 drivers/iommu/riscv/iommu-pci.c
>  create mode 100644 drivers/iommu/riscv/iommu-platform.c
>  create mode 100644 drivers/iommu/riscv/iommu.c
>  create mode 100644 drivers/iommu/riscv/iommu.h
>
>
> base-commit: 8e929cb546ee42c9a61d24fae60605e9e3192354

Acked-by: Palmer Dabbelt <palmer at rivosinc.com>

if anyone was waiting on me.  IIUC the plan here was to aim this at the 
IOMMU tree, but I'm happy to look closer and take it through the RISC-V 
tree if people want.  Just LMK, for now I'm  going to do nothing ;)