[v5,0/6] iommufd: Add nesting infrastructure (part 2/2)

Message

Yi Liu Oct. 20, 2023, 9:24 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>

This series adds the cache invalidation path for the userspace to invalidate
cache after modifying the stage-1 page table. This is based on the first part
of nesting [1]

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/zhenzhong/wip/iommufd_nesting_rfcv1

Change log:

v5:
 - Split the iommufd nesting series into two parts of alloc_user and
   invalidation (Jason)
 - Split IOMMUFD_OBJ_HW_PAGETABLE to IOMMUFD_OBJ_HWPT_PAGING/_NESTED, and
   do the same with the structures/alloc()/abort()/destroy(). Reworked the
   selftest accordingly too. (Jason)
 - Move hwpt/data_type into struct iommu_user_data from standalone op
   arguments. (Jason)
 - Rename hwpt_type to be data_type, the HWPT_TYPE to be HWPT_ALLOC_DATA,
   _TYPE_DEFAULT to be _ALLOC_DATA_NONE (Jason, Kevin)
 - Rename iommu_copy_user_data() to iommu_copy_struct_from_user() (Kevin)
 - Add macro to the iommu_copy_struct_from_user() to calculate min_size
   (Jason)
 - Fix two bugs spotted by ZhaoYan

v4: https://lore.kernel.org/linux-iommu/[e-mail]/
 - Separate HWPT alloc/destroy/abort functions between user-managed HWPTs
   and kernel-managed HWPTs
 - Rework invalidate uAPI to be a multi-request array-based design
 - Add a struct iommu_user_data_array and a helper for driver to sanitize
   and copy the entry data from user space invalidation array
 - Add a patch fixing TEST_LENGTH() in selftest program
 - Drop IOMMU_RESV_IOVA_RANGES patches
 - Update kdoc and inline comments
 - Drop the code to add IOMMU_RESV_SW_MSI to kernel-managed HWPT in nested translation,
   this does not change the rule that resv regions should only be added to the
   kernel-managed HWPT. The IOMMU_RESV_SW_MSI stuff will be added in later series
   as it is needed only by SMMU so far.

v3: https://lore.kernel.org/linux-iommu/[e-mail]/
 - 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 (1):
  iommu: Add cache_invalidate_user op

Nicolin Chen (4):
  iommu: Add iommu_copy_struct_from_user_array helper
  iommufd/selftest: Add mock_domain_cache_invalidate_user support
  iommufd/selftest: Add IOMMU_TEST_OP_MD_CHECK_IOTLB test op
  iommufd/selftest: Add coverage for IOMMU_HWPT_INVALIDATE ioctl

Yi Liu (1):
  iommufd: Add IOMMU_HWPT_INVALIDATE

 drivers/iommu/iommufd/hw_pagetable.c          | 35 ++++++++
 drivers/iommu/iommufd/iommufd_private.h       |  9 ++
 drivers/iommu/iommufd/iommufd_test.h          | 22 +++++
 drivers/iommu/iommufd/main.c                  |  3 +
 drivers/iommu/iommufd/selftest.c              | 69 +++++++++++++++
 include/linux/iommu.h                         | 84 +++++++++++++++++++
 include/uapi/linux/iommufd.h                  | 36 ++++++++
 tools/testing/selftests/iommu/iommufd.c       | 75 +++++++++++++++++
 tools/testing/selftests/iommu/iommufd_utils.h | 63 ++++++++++++++
 9 files changed, 396 insertions(+)