[PATCH v6 00/10] iommufd: Add nesting infrastructure (part 1/2)

Yi Liu
2023-10-24T15:09:33Z

Nested translation is a hardware feature that is supported by many modern
IOMMU hardwares. It has two stages of address translations to get access
to the physical address. A stage-1 translation table is owned by userspace
(e.g. by a guest OS), while a stage-2 is owned by kernel. Any change to a
stage-1 translation table should be followed by an IOTLB invalidation.

Take Intel VT-d as an example, the stage-1 translation table is guest I/O
page table. As the below diagram shows, the guest I/O page table pointer
in GPA (guest physical address) is passed to host and be used to perform
a stage-1 translation. Along with it, a modification to present mappings
in the guest I/O page table should be followed by 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 hwpt is backed by an iommu_domain allocated from an 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 linked
with an IOAS. However, a nesting case 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] and nested
parent domain allocation [2]. It first extends domain_alloc_user to allocate
hwpt with user data by allowing the IOMMUFD internal infrastructure to accept
user_data and parent hwpt, relaying the user_data/parent to the iommu core
to allocate IOMMU_DOMAIN_NESTED. And it then extends the IOMMU_HWPT_ALLOC
ioctl to accept user data and a parent hwpt ID.

Note that this series is the part-1 set of a two-part nesting series. It
does not include the cache invalidation interface, which will be added in
the part 2.

Complete code can be found in [3], it is on top of Joao's dirty page tracking
v6 series and fix patches. QEMU could can be found in [4].

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/20230818101033.4100-1-yi.l.liu@intel.com/#r - merged
[2] https://lore.kernel.org/linux-iommu/20230928071528.26258-1-yi.l.liu@intel.com/ - merged
[3] https://github.com/yiliu1765/iommufd/tree/iommufd_nesting
[4] https://github.com/yiliu1765/qemu/tree/zhenzhong/wip/iommufd_nesting_rfcv1

Change log:

v6:
- Rebase on top of Joao's dirty tracking series:
https://lore.kernel.org/linux-iommu/20231024135109.73787-1-joao.m.martins@oracle.com/
- Rebase on top of the enforce_cache_coherency removal patch:
https://lore.kernel.org/linux-iommu/ZTcAhwYjjzqM0A5M@Asurada-Nvidia/
- Add parent and user_data check in iommu driver before the driver actually
supports the two input. This can make better bisect support, the change is
in patch 02.

v5: https://lore.kernel.org/linux-iommu/20231020091946.12173-1-yi.l.liu@intel.com/
- 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/20230921075138.124099-1-yi.l.liu@intel.com/
- 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/20230724110406.107212-1-yi.l.liu@intel.com/
- 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

Jason Gunthorpe (2):
iommufd: Rename IOMMUFD_OBJ_HW_PAGETABLE to IOMMUFD_OBJ_HWPT_PAGING
iommufd/device: Wrap IOMMUFD_OBJ_HWPT_PAGING-only configurations

Lu Baolu (1):
iommu: Add IOMMU_DOMAIN_NESTED

Nicolin Chen (6):
iommufd: Derive iommufd_hwpt_paging from iommufd_hw_pagetable
iommufd: Share iommufd_hwpt_alloc with IOMMUFD_OBJ_HWPT_NESTED
iommufd: Add a nested HW pagetable object
iommu: Add iommu_copy_struct_from_user helper
iommufd/selftest: Add nested domain allocation for mock domain
iommufd/selftest: Add coverage for IOMMU_HWPT_ALLOC with nested HWPTs

Yi Liu (1):
iommu: Pass in parent domain with user_data to domain_alloc_user op

drivers/iommu/intel/iommu.c | 7 +-
drivers/iommu/iommufd/device.c | 157 +++++++---
drivers/iommu/iommufd/hw_pagetable.c | 271 +++++++++++++-----
drivers/iommu/iommufd/iommufd_private.h | 73 +++--
drivers/iommu/iommufd/iommufd_test.h | 18 ++
drivers/iommu/iommufd/main.c | 10 +-
drivers/iommu/iommufd/selftest.c | 151 ++++++++--
drivers/iommu/iommufd/vfio_compat.c | 6 +-
include/linux/iommu.h | 72 ++++-
include/uapi/linux/iommufd.h | 31 +-
tools/testing/selftests/iommu/iommufd.c | 120 ++++++++
.../selftests/iommu/iommufd_fail_nth.c | 3 +-
tools/testing/selftests/iommu/iommufd_utils.h | 31 +-
13 files changed, 768 insertions(+), 182 deletions(-)

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2.34.1