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], 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... - merged [2] https://lore.kernel.org/linux-iommu/20230928071528.26258-1-yi.l.liu@intel.co... - merged [3] https://github.com/yiliu1765/iommufd/tree/iommufd_nesting [4] 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/20230921075138.124099-1-yi.l.liu@intel.c... - 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.c... - 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.co... - 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.c...
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 | 4 +- drivers/iommu/iommufd/device.c | 184 +++++++++----- drivers/iommu/iommufd/hw_pagetable.c | 237 ++++++++++++++---- drivers/iommu/iommufd/iommufd_private.h | 67 +++-- drivers/iommu/iommufd/iommufd_test.h | 18 ++ drivers/iommu/iommufd/main.c | 10 +- drivers/iommu/iommufd/selftest.c | 137 ++++++++-- 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, 752 insertions(+), 168 deletions(-)