[v3,00/17] iommufd: Add nesting infrastructure

Message

Yi Liu July 24, 2023, 11:03 a.m. UTC

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/[e-mail]/
[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/[e-mail]/
 - 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/[e-mail]/

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(-)