IOMMU hardwares that support nested translation would have two stages address translation (normally mentioned as stage-1 and stage-2). The page table formats of the stage-1 and stage-2 can be different. e.g., VT-d has different page table formats for stage-1 and stage-2. Nested parent domain is the iommu domain used to represent the stage-2 translation. In IOMMUFD, both stage-1 and stage-2 translation are tracked as HWPT (a.k.a. iommu domain). Stage-2 HWPT is parent of stage-1 HWPT as stage-1 cannot work alone in nested translation. In the cases of stage-1 and stage-2 page table format are different, the parent HWPT should use exactly the stage-2 page table format. However, the existing kernel hides the format selection in iommu drivers, so the domain allocated via IOMMU_HWPT_ALLOC can use either stage-1 page table format or stage-2 page table format, there is no guarantees for it. To enforce the page table format of the nested parent domain, this series introduces a new iommu op (domain_alloc_user) which can accept user flags to allocate domain as userspace requires. It also converts IOMMUFD to use the new domain_alloc_user op for domain allocation if supported, then extends the IOMMU_HWPT_ALLOC ioctl to pass down a NEST_PARENT flag to allocate a HWPT which can be used as parent. This series implements the new op in Intel iommu driver to have a complete picture. It is a preparation for adding nesting support in IOMMUFD/IOMMU. Complete code can be found: https://github.com/yiliu1765/iommufd/tree/iommufd_alloc_user_v2 Change log: v2: - Require domain_alloc_user op if IOMMU_HWPT_ALLOC passes non-zero flags (Kevin) - IOMMUFD core should check kernel known flags while iommu driver needs to check supported flags as well (Jason) - Minor tweaks per Baolu's comment v1: https://lore.kernel.org/linux-iommu/20230919092523.39286-1-yi.l.liu@xxxxxxxxx/ Regards, Yi Liu Yi Liu (6): iommu: Add new iommu op to create domains owned by userspace iommufd/hw_pagetable: Use domain_alloc_user op for domain allocation iommufd/hw_pagetable: Accepts user flags for domain allocation iommufd/hw_pagetable: Support allocating nested parent domain iommufd/selftest: Add domain_alloc_user() support in iommu mock iommu/vt-d: Add domain_alloc_user op drivers/iommu/intel/iommu.c | 28 +++++++++++++++++ drivers/iommu/iommufd/device.c | 2 +- drivers/iommu/iommufd/hw_pagetable.c | 31 ++++++++++++++----- drivers/iommu/iommufd/iommufd_private.h | 3 +- drivers/iommu/iommufd/selftest.c | 19 ++++++++++++ include/linux/iommu.h | 11 ++++++- include/uapi/linux/iommufd.h | 12 ++++++- tools/testing/selftests/iommu/iommufd.c | 24 +++++++++++--- .../selftests/iommu/iommufd_fail_nth.c | 2 +- tools/testing/selftests/iommu/iommufd_utils.h | 11 +++++-- 10 files changed, 124 insertions(+), 19 deletions(-) -- 2.34.1
