Re: [PATCH 00/13] Linux RISC-V IOMMU Support

[Zong Li <zong.li@sifive.com>]

On Fri, Apr 5, 2024 at 1:37 AM Tomasz Jeznach <tjeznach@rivosinc.com> wrote:
>
> On Fri, Feb 23, 2024 at 6:04 AM Zong Li <zong.li@sifive.com> wrote:
> >
> > >
> > > The RISC-V IOMMU specification is now ratified as-per the RISC-V international
> > > process [1]. The latest frozen specifcation can be found at:
> > > https://github.com/riscv-non-isa/riscv-iommu/releases/download/v1.0/riscv-iommu.pdf
> > >
> > > At a high-level, the RISC-V IOMMU specification defines:
> > > 1) Memory-mapped programming interface
> > >    - Mandatory and optional registers layout and description.
> > >    - Software guidelines for device initialization and capabilities discovery.
> > > 2) In-memory queue interface
> > >    - A command-queue used by software to queue commands to the IOMMU.
> > >    - A fault/event queue used to bring faults and events to software’s attention.
> > >    - A page-request queue used to report “Page Request” messages received from
> > >      PCIe devices.
> > >    - Message-signalled and wire-signaled interrupt mechanism.
> > > 3) In-memory data structures
> > >    - Device-context: used to associate a device with an address space and to hold
> > >      other per-device parameters used by the IOMMU to perform address translations.
> > >    - Process-contexts: used to associate a different virtual address space based on
> > >      device provided process identification number.
> > >    - MSI page table configuration used to direct an MSI to a guest interrupt file
> > >      in an IMSIC. The MSI page table formats are defined by the Advanced Interrupt
> > >      Architecture specification [2].
> > >
> > > This series introduces complete single-level translation support, including shared
> > > virtual address (SVA), ATS/PRI interfaces in the kernel driver. Patches adding MSI
> > > identity remapping and G-Stage translation (GPA to SPA) are added only to excercise
> > > hardware interfaces, to be complemented with AIA/KVM bindings in follow-up series.
> > >
> > > This series is a logical regrouping of series of incremental patches based on
> > > RISC-V International IOMMU Task Group discussions and specification development
> > > process. Original series can be found at the maintainer's repository branch [3].
> > >
> > > These patches can also be found in the riscv_iommu_v1 branch at:
> > > https://github.com/tjeznach/linux/tree/riscv_iommu_v1
> > >
> > > To test this series, use QEMU/OpenSBI with RISC-V IOMMU implementation available in
> > > the riscv_iommu_v1 branch at:
> > > https://github.com/tjeznach/qemu/tree/riscv_iommu_v1
> > >
> > > References:
> > > [1] - https://wiki.riscv.org/display/HOME/Specification+Status
> > > [2] - https://github.com/riscv/riscv-aia/releases/download/1.0/riscv-interrupts-1.0.pdf
> > > [3] - https://github.com/tjeznach/qemu/tree/tjeznach/riscv-iommu-20230719
> > >
> > >
> > > Anup Patel (1):
> > >   dt-bindings: Add RISC-V IOMMU bindings
> > >
> > > Tomasz Jeznach (10):
> > >   RISC-V: drivers/iommu: Add RISC-V IOMMU - Ziommu support.
> > >   RISC-V: arch/riscv/config: enable RISC-V IOMMU support
> > >   MAINTAINERS: Add myself for RISC-V IOMMU driver
> > >   RISC-V: drivers/iommu/riscv: Add sysfs interface
> > >   RISC-V: drivers/iommu/riscv: Add command, fault, page-req queues
> > >   RISC-V: drivers/iommu/riscv: Add device context support
> > >   RISC-V: drivers/iommu/riscv: Add page table support
> > >   RISC-V: drivers/iommu/riscv: Add SVA with PASID/ATS/PRI support.
> > >   RISC-V: drivers/iommu/riscv: Add MSI identity remapping
> > >   RISC-V: drivers/iommu/riscv: Add G-Stage translation support
> > >
> > >  .../bindings/iommu/riscv,iommu.yaml           |  146 ++
> > >  MAINTAINERS                                   |    7 +
> > >  arch/riscv/configs/defconfig                  |    1 +
> > >  drivers/iommu/Kconfig                         |    1 +
> > >  drivers/iommu/Makefile                        |    2 +-
> > >  drivers/iommu/io-pgtable.c                    |    3 +
> > >  drivers/iommu/riscv/Kconfig                   |   22 +
> > >  drivers/iommu/riscv/Makefile                  |    1 +
> > >  drivers/iommu/riscv/io_pgtable.c              |  266 ++
> > >  drivers/iommu/riscv/iommu-bits.h              |  704 ++++++
> > >  drivers/iommu/riscv/iommu-pci.c               |  206 ++
> > >  drivers/iommu/riscv/iommu-platform.c          |  160 ++
> > >  drivers/iommu/riscv/iommu-sysfs.c             |  183 ++
> > >  drivers/iommu/riscv/iommu.c                   | 2130 +++++++++++++++++
> > >  drivers/iommu/riscv/iommu.h                   |  165 ++
> > >  include/linux/io-pgtable.h                    |    2 +
> > >  16 files changed, 3998 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/io_pgtable.c
> > >  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-sysfs.c
> > >  create mode 100644 drivers/iommu/riscv/iommu.c
> > >  create mode 100644 drivers/iommu/riscv/iommu.h
> > >
> > > --
> > > 2.34.1
> > >
> > >
> > > _______________________________________________
> > > linux-riscv mailing list
> > > linux-riscv@lists.infradead.org
> > > http://lists.infradead.org/mailman/listinfo/linux-riscv
> >
> > Hi Tomasz,
> > Could I know if you have a plan for the next version and if you have
> > any estimates for when the v2 patch will be ready? We have some
> > patches based on top of your old implementation, and it would be great
> > if we can rebase them onto your next version. Thanks.
>
> Hi Zong,
>
> Thank you for your interest. Next version of the iommu/riscv is almost ready to
> be sent in next few days.

Hi Tomasz,
Thanks you for the update, I would help to review the v2 series as well.

> There is a number of bug fixes and design changes based on the testing and
> great feedback after v1 was published.
> Upcoming patch set will be smaller, with core functionality only, hopefully to
> make the review easier. Functionality related to the MSI remapping, shared
> virtual addressing, nested translations will be moved to separate patch sets.
>
> Complete, up to date revision is always available at
> https://github.com/tjeznach/linux/
>
> regards,
> - Tomasz