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    Subject[PATCH v3 00/17] iommufd: Add nesting infrastructure
    Date
    Nested translation is a hardware feature that is supported by many modern
    IOMMU hardwares. It has two stages (stage-1, stage-2) address translation
    to get access to the physical address. stage-1 translation table is owned
    by userspace (e.g. by a guest OS), while stage-2 is owned by kernel. Changes
    to stage-1 translation table should be followed by an IOTLB invalidation.

    Take Intel VT-d as an example, the stage-1 translation table is I/O page
    table. As the below diagram shows, guest I/O page table pointer in GPA
    (guest physical address) is passed to host and be used to perform the stage-1
    address translation. Along with it, modifications to present mappings in the
    guest I/O page table should be followed with an IOTLB invalidation.

    .-------------. .---------------------------.
    | vIOMMU | | Guest I/O page table |
    | | '---------------------------'
    .----------------/
    | PASID Entry |--- PASID cache flush --+
    '-------------' |
    | | V
    | | I/O page table pointer in GPA
    '-------------'
    Guest
    ------| Shadow |---------------------------|--------
    v v v
    Host
    .-------------. .------------------------.
    | pIOMMU | | FS for GIOVA->GPA |
    | | '------------------------'
    .----------------/ |
    | PASID Entry | V (Nested xlate)
    '----------------\.----------------------------------.
    | | | SS for GPA->HPA, unmanaged domain|
    | | '----------------------------------'
    '-------------'
    Where:
    - FS = First stage page tables
    - SS = Second stage page tables
    <Intel VT-d Nested translation>

    In IOMMUFD, all the translation tables are tracked by hw_pagetable (hwpt)
    and each has an iommu_domain allocated from iommu driver. So in this series
    hw_pagetable and iommu_domain means the same thing if no special note.
    IOMMUFD has already supported allocating hw_pagetable that is linked with
    an IOAS. However, nesting requires IOMMUFD to allow allocating hw_pagetable
    with driver specific parameters and interface to sync stage-1 IOTLB as user
    owns the stage-1 translation table.

    This series is based on the iommu hw info reporting series [1]. It first
    introduces new iommu op for allocating domains with user data and the op
    for invalidate stage-1 IOTLB, and then extend the IOMMUFD internal infrastructure
    to accept user_data and parent hwpt, then relay the data to iommu core to
    allocate user iommu_domain. After it, extends the ioctl IOMMU_HWPT_ALLOC to
    accept user data and stage-2 hwpt ID to allocate hwpt. Along with it, ioctl
    IOMMU_HWPT_INVALIDATE is added to invalidate stage-1 IOTLB. This is needed
    for user-managed hwpts. Selftest is added as well to cover the new ioctls.

    Complete code can be found in [2], QEMU could can be found in [3].

    At last, this is a team work together with Nicolin Chen, Lu Baolu. Thanks
    them for the help. ^_^. Look forward to your feedbacks.

    [1] https://lore.kernel.org/linux-iommu/20230724105936.107042-1-yi.l.liu@intel.com/
    [2] https://github.com/yiliu1765/iommufd/tree/iommufd_nesting
    [3] https://github.com/yiliu1765/qemu/tree/wip/iommufd_rfcv4_nesting

    Change log:

    v3:
    - Add new uAPI things in alphabetical order
    - Pass in "enum iommu_hwpt_type hwpt_type" to op->domain_alloc_user for
    sanity, replacing the previous op->domain_alloc_user_data_len solution
    - Return ERR_PTR from domain_alloc_user instead of NULL
    - Only add IOMMU_RESV_SW_MSI to kernel-managed HWPT in nested translation (Kevin)
    - Add IOMMU_RESV_IOVA_RANGES to report resv iova ranges to userspace hence
    userspace is able to exclude the ranges in the stage-1 HWPT (e.g. guest I/O
    page table). (Kevin)
    - Add selftest coverage for the new IOMMU_RESV_IOVA_RANGES ioctl
    - Minor changes per Kevin's inputs

    v2: https://lore.kernel.org/linux-iommu/20230511143844.22693-1-yi.l.liu@intel.com/
    - Add union iommu_domain_user_data to include all user data structures to avoid
    passing void * in kernel APIs.
    - Add iommu op to return user data length for user domain allocation
    - Rename struct iommu_hwpt_alloc::data_type to be hwpt_type
    - Store the invalidation data length in iommu_domain_ops::cache_invalidate_user_data_len
    - Convert cache_invalidate_user op to be int instead of void
    - Remove @data_type in struct iommu_hwpt_invalidate
    - Remove out_hwpt_type_bitmap in struct iommu_hw_info hence drop patch 08 of v1

    v1: https://lore.kernel.org/linux-iommu/20230309080910.607396-1-yi.l.liu@intel.com/

    Thanks,
    Yi Liu

    Lu Baolu (2):
    iommu: Add new iommu op to create domains owned by userspace
    iommu: Add nested domain support

    Nicolin Chen (6):
    iommufd/hw_pagetable: Do not populate user-managed hw_pagetables
    iommufd: Only enforce IOMMU_RESV_SW_MSI when attaching user-managed
    HWPT
    iommufd/selftest: Add domain_alloc_user() support in iommu mock
    iommufd/selftest: Add coverage for IOMMU_HWPT_ALLOC with user data
    iommufd/selftest: Add IOMMU_TEST_OP_MD_CHECK_IOTLB test op
    iommufd/selftest: Add coverage for IOMMU_HWPT_INVALIDATE ioctl

    Yi Liu (9):
    iommufd/hw_pagetable: Use domain_alloc_user op for domain allocation
    iommufd: Pass in hwpt_type/parent/user_data to
    iommufd_hw_pagetable_alloc()
    iommufd: Add IOMMU_RESV_IOVA_RANGES
    iommufd: IOMMU_HWPT_ALLOC allocation with user data
    iommufd: Add IOMMU_HWPT_INVALIDATE
    iommufd/selftest: Add a helper to get test device
    iommufd/selftest: Add IOMMU_TEST_OP_DEV_[ADD|DEL]_RESERVED to add/del
    reserved regions to selftest device
    iommufd/selftest: Add .get_resv_regions() for mock_dev
    iommufd/selftest: Add coverage for IOMMU_RESV_IOVA_RANGES

    drivers/iommu/iommufd/device.c | 9 +-
    drivers/iommu/iommufd/hw_pagetable.c | 181 +++++++++++-
    drivers/iommu/iommufd/io_pagetable.c | 5 +-
    drivers/iommu/iommufd/iommufd_private.h | 20 +-
    drivers/iommu/iommufd/iommufd_test.h | 36 +++
    drivers/iommu/iommufd/main.c | 59 +++-
    drivers/iommu/iommufd/selftest.c | 266 ++++++++++++++++--
    include/linux/iommu.h | 34 +++
    include/uapi/linux/iommufd.h | 96 ++++++-
    tools/testing/selftests/iommu/iommufd.c | 224 ++++++++++++++-
    tools/testing/selftests/iommu/iommufd_utils.h | 70 +++++
    11 files changed, 958 insertions(+), 42 deletions(-)

    --
    2.34.1

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