[PATCH v3 0/7] Linux RISC-V IOMMU Support

[Tomasz Jeznach]

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, with page table using the same format as the
         CPU’s MMU. This patch series enables only 4K mappings; complete support
         for large page mappings will be introduced in follow-up patch series.

Follow-up patch series, providing large page support and updated walk cache
management based on the revised specification, and complete ATS/PRI/SVA support,
will be posted to GitHub [2].

Changes from v2:
- rebase on top of v6.9-rc6 and applied series for iommu-next:
  IOMMU memory observability, v6 [3]
  iommu, dma-mapping: Simplify arch_setup_dma_ops(), v4 [4]
- dt-bindings: compatible string
- Kconfig: optional built-in driver; removed module info
- kdump support added, interrupts and binding fixes, pcim_*
- use iommu allocation accounting wrappers
- use new dma-mapping setup, removed probe_finalize
- release domain added, memory allocations moved to domain alloc
- updated domain attach flow, fixes for domain to device bond locking
- fixed alignment check, fixed non-leaf page release
- driver warnings cleaned up


Best regards,
 Tomasz Jeznach

[1] link: https://github.com/riscv-non-isa/riscv-iommu
[2] link: https://github.com/tjeznach/linux
[3] link: https://lore.kernel.org/linux-iommu/20240413002522.1101315-1-pasha.tatashin@xxxxxxxxxx/
[4] link: https://lore.kernel.org/linux-iommu/cover.1713523152.git.robin.murphy@xxxxxxx/
v2 link:  https://lore.kernel.org/linux-iommu/cover.1713456597.git.tjeznach@xxxxxxxxxxxx/
v1 link:  https://lore.kernel.org/linux-iommu/cover.1689792825.git.tjeznach@xxxxxxxxxxxx/

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           |  150 ++
 MAINTAINERS                                   |    8 +
 drivers/iommu/Kconfig                         |    1 +
 drivers/iommu/Makefile                        |    2 +-
 drivers/iommu/riscv/Kconfig                   |   20 +
 drivers/iommu/riscv/Makefile                  |    3 +
 drivers/iommu/riscv/iommu-bits.h              |  782 +++++++++
 drivers/iommu/riscv/iommu-pci.c               |  119 ++
 drivers/iommu/riscv/iommu-platform.c          |   92 +
 drivers/iommu/riscv/iommu.c                   | 1549 +++++++++++++++++
 drivers/iommu/riscv/iommu.h                   |   88 +
 11 files changed, 2813 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: e67572cd2204894179d89bd7b984072f19313b03
message-id: 20240413002522.1101315-1-pasha.tatashin@xxxxxxxxxx
message-id: cover.1713523152.git.robin.murphy@xxxxxxx
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2.34.1