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    Subject[PATCH 00/12] iommufd: Add nesting infrastructure
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    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 syncing 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 iommu_domain. After it, extend 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. ioctl IOMMU_DEVICE_GET_HW_INFO is extended to report
    the supported hwpt types bitmap to user. 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.

    base-commit: 3dfe670c94c7fc4af42e5c08cdd8a110b594e18e

    [1] https://lore.kernel.org/linux-iommu/20230309075358.571567-1-yi.l.liu@intel.com/
    [2] https://github.com/yiliu1765/iommufd/tree/iommufd_nesting
    [3] https://github.com/yiliu1765/qemu/tree/wip/iommufd_rfcv3%2Bnesting

    Thanks,
    Yi Liu

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

    Nicolin Chen (5):
    iommufd/hw_pagetable: Do not populate user-managed hw_pagetables
    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 (5):
    iommufd/hw_pagetable: Use domain_alloc_user op for domain allocation
    iommufd: Pass parent hwpt and user_data to
    iommufd_hw_pagetable_alloc()
    iommufd: IOMMU_HWPT_ALLOC allocation with user data
    iommufd: Add IOMMU_HWPT_INVALIDATE
    iommufd/device: Report supported hwpt_types

    drivers/iommu/iommufd/device.c | 9 +-
    drivers/iommu/iommufd/hw_pagetable.c | 242 +++++++++++++++++-
    drivers/iommu/iommufd/iommufd_private.h | 16 +-
    drivers/iommu/iommufd/iommufd_test.h | 30 +++
    drivers/iommu/iommufd/main.c | 7 +-
    drivers/iommu/iommufd/selftest.c | 104 +++++++-
    include/linux/iommu.h | 11 +
    include/uapi/linux/iommufd.h | 65 +++++
    tools/testing/selftests/iommu/iommufd.c | 126 ++++++++-
    tools/testing/selftests/iommu/iommufd_utils.h | 71 +++++
    10 files changed, 654 insertions(+), 27 deletions(-)

    --
    2.34.1

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