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@xxxxxxxxx/
[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@xxxxxxxxx/
- 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@xxxxxxxxx/
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
