| Message ID | 20230309080910.607396-1-yi.l.liu@intel.com (mailing list archive) |
|---|---|
| Headers | show |
| Series | iommufd: Add nesting infrastructure | expand |
On 2023/3/9 16:08, Yi Liu wrote: > 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. The last sentence is not always true. If any entry of the stage-1 translation table is changed from non-present to present, the IOTLB has no chance to cache it yet. Hence there's no need for invalidation. Best regards, baolu
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 syncing 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 iommu_domain. After it, extend 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. ioctl IOMMU_DEVICE_GET_HW_INFO is extended to report the supported hwpt types bitmap to user. 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. base-commit: 3dfe670c94c7fc4af42e5c08cdd8a110b594e18e [1] https://lore.kernel.org/linux-iommu/20230309075358.571567-1-yi.l.liu@intel.com/ [2] https://github.com/yiliu1765/iommufd/tree/iommufd_nesting [3] https://github.com/yiliu1765/qemu/tree/wip/iommufd_rfcv3%2Bnesting Thanks, Yi Liu Lu Baolu (2): iommu: Add new iommu op to create domains owned by userspace iommu: Add nested domain support Nicolin Chen (5): iommufd/hw_pagetable: Do not populate user-managed hw_pagetables 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 (5): iommufd/hw_pagetable: Use domain_alloc_user op for domain allocation iommufd: Pass parent hwpt and user_data to iommufd_hw_pagetable_alloc() iommufd: IOMMU_HWPT_ALLOC allocation with user data iommufd: Add IOMMU_HWPT_INVALIDATE iommufd/device: Report supported hwpt_types drivers/iommu/iommufd/device.c | 9 +- drivers/iommu/iommufd/hw_pagetable.c | 242 +++++++++++++++++- drivers/iommu/iommufd/iommufd_private.h | 16 +- drivers/iommu/iommufd/iommufd_test.h | 30 +++ drivers/iommu/iommufd/main.c | 7 +- drivers/iommu/iommufd/selftest.c | 104 +++++++- include/linux/iommu.h | 11 + include/uapi/linux/iommufd.h | 65 +++++ tools/testing/selftests/iommu/iommufd.c | 126 ++++++++- tools/testing/selftests/iommu/iommufd_utils.h | 71 +++++ 10 files changed, 654 insertions(+), 27 deletions(-)