[PATCH v4 00/23] iommufd: Add vIOMMU infrastructure (Part-4 HW QUEUE)

[Nicolin Chen <nicolinc@nvidia.com>]

The vIOMMU object is designed to represent a slice of an IOMMU HW for its
virtualization features shared with or passed to user space (a VM mostly)
in a way of HW acceleration. This extended the HWPT-based design for more
advanced virtualization feature.

HW QUEUE introduced by this series as a part of the vIOMMU infrastructure
represents a HW accelerated queue/buffer for VM to use exclusively, e.g.
 - NVIDIA's Virtual Command Queue
 - AMD vIOMMU's Command Buffer, Event Log Buffer, and PPR Log Buffer
each of which allows its IOMMU HW to directly access a queue memory owned
by a guest VM and allows a guest OS to control the HW queue direclty, to
avoid VM Exit overheads to improve the performance.

Introduce IOMMUFD_OBJ_HW_QUEUE and its pairing IOMMUFD_CMD_HW_QUEUE_ALLOC
allowing VMM to forward the IOMMU-specific queue info, such as queue base
address, size, and etc.

Meanwhile, a guest-owned queue needs the guest kernel to control the queue
by reading/writing its consumer and producer indexes, via MMIO acceses to
the hardware MMIO registers. Introduce an mmap infrastructure for iommufd
to support passing through a piece of MMIO region from the host physical
address space to the guest physical address space. The mmap info (offset/
length) used by an mmap syscall must be pre-allocated and returned to the
user space via an output driver-data during an IOMMUFD_CMD_HW_QUEUE_ALLOC
call. Thus, it requires a driver-specific user data support in the vIOMMU
allocation flow.

As a real-world use case, this series implements a HW QUEUE support in the
tegra241-cmdqv driver for VCMDQs on NVIDIA Grace CPU. In another word, it
is also the Tegra CMDQV series Part-2 (user-space support), reworked from
Previous RFCv1:
    https://lore.kernel.org/all/cover.1712978212.git.nicolinc@nvidia.com/
This enables the HW accelerated feature for NVIDIA Grace CPU. Compared to
the standard SMMUv3 operating in the nested translation mode trapping CMDQ
for TLBI and ATC_INV commands, this gives a huge performance improvement:
70% to 90% reductions of invalidation time were measured by various DMA
unmap tests running in a guest OS.

// Unmap latencies from "dma_map_benchmark -g @granule -t @threads",
// by toggling "/sys/kernel/debug/iommu/tegra241_cmdqv/bypass_vcmdq"
@granule | @threads | bypass_vcmdq=1 | bypass_vcmdq=0
    4KB        1          35.7 us          5.3 us
   16KB        1          41.8 us          6.8 us
   64KB        1          68.9 us          9.9 us
  128KB        1         109.0 us         12.6 us
  256KB        1         187.1 us         18.0 us
    4KB        2          96.9 us          6.8 us
   16KB        2          97.8 us          7.5 us
   64KB        2         151.5 us         10.7 us
  128KB        2         257.8 us         12.7 us
  256KB        2         443.0 us         17.9 us

This is on Github:
https://github.com/nicolinc/iommufd/commits/iommufd_hw_queue-v4

Paring QEMU branch for testing:
https://github.com/nicolinc/qemu/commits/wip/for_iommufd_hw_queue-v4

Changelog
v4
 * Rebase on v6.15-rc5
 * Add Reviewed-by from Vasant
 * Rename "vQUEUE" to "HW QUEUE"
 * Use "offset" and "length" for all mmap-related variables
 * [iommufd] Use u64 for guest PA
 * [iommufd] Fix typo in uAPI doc
 * [iommufd] Rename immap_id to offset
 * [iommufd] Drop the partial-size mmap support
 * [iommufd] Do not replace WARN_ON with WARN_ON_ONCE
 * [iommufd] Use "u64 base_addr" for queue base address
 * [iommufd] Use u64 base_pfn/num_pfns for immap structure
 * [iommufd] Correct the size passed in to mtree_alloc_range()
 * [iommufd] Add IOMMUFD_VIOMMU_FLAG_HW_QUEUE_READS_PA to viommu_ops
v3
 https://lore.kernel.org/all/cover.1746139811.git.nicolinc@nvidia.com/
 * Add Reviewed-by from Baolu, Pranjal, and Alok
 * Revise kdocs, uAPI docs, and commit logs
 * Rename "vCMDQ" back to "vQUEUE" for AMD cases
 * [tegra] Add tegra241_vcmdq_hw_flush_timeout()
 * [tegra] Rename vsmmu_alloc to alloc_vintf_user
 * [tegra] Use writel for SID replacement registers
 * [tegra] Move mmap removal call to vsmmu_destroy op
 * [tegra] Fix revert in tegra241_vintf_alloc_lvcmdq_user()
 * [iommufd] Replace "& ~PAGE_MASK" with PAGE_ALIGNED()
 * [iommufd] Add an object-type "owner" to immap structure
 * [iommufd] Drop the ictx input in the new for-driver APIs
 * [iommufd] Add iommufd_vma_ops to keep track of mmap lifecycle
 * [iommufd] Add viommu-based iommufd_viommu_alloc/destroy_mmap helpers
 * [iommufd] Rename iommufd_ctx_alloc/free_mmap to
             _iommufd_alloc/destroy_mmap
v2
 https://lore.kernel.org/all/cover.1745646960.git.nicolinc@nvidia.com/
 * Add Reviewed-by from Jason
 * [smmu] Fix vsmmu initial value
 * [smmu] Support impl for hw_info
 * [tegra] Rename "slot" to "vsid"
 * [tegra] Update kdocs and commit logs
 * [tegra] Map/unmap LVCMDQ dynamically
 * [tegra] Refcount the previous LVCMDQ
 * [tegra] Return -EEXIST if LVCMDQ exists
 * [tegra] Simplify VINTF cleanup routine
 * [tegra] Use vmid and s2_domain in vsmmu
 * [tegra] Rename "mmap_pgoff" to "immap_id"
 * [tegra] Add more addr and length validation
 * [iommufd] Add more narrative to mmap's kdoc
 * [iommufd] Add iommufd_struct_depend/undepend()
 * [iommufd] Rename vcmdq_free op to vcmdq_destroy
 * [iommufd] Fix bug in iommu_copy_struct_to_user()
 * [iommufd] Drop is_io from iommufd_ctx_alloc_mmap()
 * [iommufd] Test the queue memory for its contiguity
 * [iommufd] Return -ENXIO if address or length fails
 * [iommufd] Do not change @min_last in mock_viommu_alloc()
 * [iommufd] Generalize TEGRA241_VCMDQ data in core structure
 * [iommufd] Add selftest coverage for IOMMUFD_CMD_VCMDQ_ALLOC
 * [iommufd] Add iopt_pin_pages() to prevent queue memory from unmapping
v1
 https://lore.kernel.org/all/cover.1744353300.git.nicolinc@nvidia.com/

Thanks
Nicolin

Nicolin Chen (23):
  iommufd/viommu: Add driver-allocated vDEVICE support
  iommu: Pass in a driver-level user data structure to viommu_alloc op
  iommufd/viommu: Allow driver-specific user data for a vIOMMU object
  iommu: Add iommu_copy_struct_to_user helper
  iommufd/driver: Let iommufd_viommu_alloc helper save ictx to
    viommu->ictx
  iommufd/driver: Add iommufd_struct_destroy to revert
    iommufd_viommu_alloc
  iommufd/selftest: Support user_data in mock_viommu_alloc
  iommufd/selftest: Add covearge for viommu data
  iommufd: Abstract iopt_pin_pages and iopt_unpin_pages helpers
  iommufd/viommu: Introduce IOMMUFD_OBJ_HW_QUEUE and its related struct
  iommufd/viommu: Add IOMMUFD_CMD_HW_QUEUE_ALLOC ioctl
  iommufd/driver: Add iommufd_hw_queue_depend/undepend() helpers
  iommufd/selftest: Add coverage for IOMMUFD_CMD_HW_QUEUE_ALLOC
  iommufd: Add mmap interface
  iommufd/selftest: Add coverage for the new mmap interface
  Documentation: userspace-api: iommufd: Update HW QUEUE
  iommu/arm-smmu-v3-iommufd: Add vsmmu_alloc impl op
  iommu/arm-smmu-v3-iommufd: Support implementation-defined hw_info
  iommu/tegra241-cmdqv: Use request_threaded_irq
  iommu/tegra241-cmdqv: Simplify deinit flow in
    tegra241_cmdqv_remove_vintf()
  iommu/tegra241-cmdqv: Do not statically map LVCMDQs
  iommu/tegra241-cmdqv: Add user-space use support
  iommu/tegra241-cmdqv: Add IOMMU_VEVENTQ_TYPE_TEGRA241_CMDQV support

 drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h   |  25 +-
 drivers/iommu/iommufd/io_pagetable.h          |   8 +
 drivers/iommu/iommufd/iommufd_private.h       |  28 +-
 drivers/iommu/iommufd/iommufd_test.h          |  20 +
 include/linux/iommu.h                         |  43 +-
 include/linux/iommufd.h                       | 186 ++++++-
 include/uapi/linux/iommufd.h                  | 116 ++++-
 tools/testing/selftests/iommu/iommufd_utils.h |  52 +-
 .../arm/arm-smmu-v3/arm-smmu-v3-iommufd.c     |  43 +-
 .../iommu/arm/arm-smmu-v3/tegra241-cmdqv.c    | 490 +++++++++++++++++-
 drivers/iommu/iommufd/device.c                | 117 +----
 drivers/iommu/iommufd/driver.c                |  94 ++++
 drivers/iommu/iommufd/io_pagetable.c          |  95 ++++
 drivers/iommu/iommufd/main.c                  |  80 ++-
 drivers/iommu/iommufd/selftest.c              | 133 ++++-
 drivers/iommu/iommufd/viommu.c                | 121 ++++-
 tools/testing/selftests/iommu/iommufd.c       |  97 +++-
 .../selftests/iommu/iommufd_fail_nth.c        |  11 +-
 Documentation/userspace-api/iommufd.rst       |  12 +
 19 files changed, 1577 insertions(+), 194 deletions(-)


base-commit: 92a09c47464d040866cf2b4cd052bc60555185fb
-- 
2.43.0