RE: [PATCH v5 00/13] iommufd: Add vIOMMU infrastructure (Part-2: vDEVICE)

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> From: Nicolin Chen <nicolinc@xxxxxxxxxx>
> Sent: Saturday, October 26, 2024 7:50 AM
> 
> Following the previous vIOMMU series, this adds another vDEVICE structure,
> representing the association from an iommufd_device to an
> iommufd_viommu.
> This gives the whole architecture a new "v" layer:
> 
> ________________________________________________________________
> _______
>  |                      iommufd (with vIOMMU/vDEVICE)                    |
>  |                        _____________      _____________               |
>  |                       |             |    |             |              |
>  |      |----------------|    vIOMMU   |<---|   vDEVICE   |<------|      |
>  |      |                |             |    |_____________|       |      |
>  |      |     ______     |             |     _____________     ___|____  |
>  |      |    |      |    |             |    |             |   |        | |
>  |      |    | IOAS |<---|(HWPT_PAGING)|<---| HWPT_NESTED |<--| DEVICE | |
>  |      |    |______|    |_____________|    |_____________|   |________| |
> 
> |______|________|______________|__________________|_____________
> __|_____|
>         |        |              |                  |               |
>   ______v_____   |        ______v_____       ______v_____       ___v__
>  |   struct   |  |  PFN  |  (paging)  |     |  (nested)  |     |struct|
>  |iommu_device|  |------>|iommu_domain|<----|iommu_domain|<----
> |device|
>  |____________|   storage|____________|     |____________|     |______|
> 
> This vDEVICE object is used to collect and store all vIOMMU-related device
> information/attributes in a VM. As an initial series for vDEVICE, add only
> the virt_id to the vDEVICE, which is a vIOMMU specific device ID in a VM:
> e.g. vSID of ARM SMMUv3, vDeviceID of AMD IOMMU, and vID of Intel VT-d

s/vID/vRID/ for VT-d

> to
> a Context Table. This virt_id helps IOMMU drivers to link the vID to a pID
> of the device against the physical IOMMU instance. This is essential for a
> vIOMMU-based invalidation, where the request contains a device's vID for a
> device cache flush, e.g. ATC invalidation.

probably connect this to vCMDQ passthrough? otherwise for sw-based
invalidation the userspace can always replace vID with pID before
submitting the request.

> 
> Therefore, with this vDEVICE object, support a vIOMMU-based invalidation,
> by reusing IOMMUFD_CMD_HWPT_INVALIDATE for a vIOMMU object to
> flush cache
> with a given driver data.
> 
> As for the implementation of the series, add driver support in ARM SMMUv3
> for a real world use case.
> 
> This series is on Github:
> https://github.com/nicolinc/iommufd/commits/iommufd_viommu_p2-v5
> 
> For testing, try this "with-rmr" branch:
> https://github.com/nicolinc/iommufd/commits/iommufd_viommu_p2-v5-
> with-rmr
> Paring QEMU branch for testing:
> https://github.com/nicolinc/qemu/commits/wip/for_iommufd_viommu_p2-
> v5
> 
> Changelog
> v5
>  * Dropped driver-allocated vDEVICE support
>  * Changed vdev_to_dev helper to iommufd_viommu_find_dev
> v4
>  https://lore.kernel.org/all/cover.1729555967.git.nicolinc@xxxxxxxxxx/
>  * Added missing brackets in switch-case
>  * Fixed the unreleased idev refcount issue
>  * Reworked the iommufd_vdevice_alloc allocator
>  * Dropped support for IOMMU_VIOMMU_TYPE_DEFAULT
>  * Added missing TEST_LENGTH and fail_nth coverages
>  * Added a verification to the driver-allocated vDEVICE object
>  * Added an iommufd_vdevice_abort for a missing mutex protection
>  * Added a u64 structure arm_vsmmu_invalidation_cmd for user command
>    conversion
> v3
>  https://lore.kernel.org/all/cover.1728491532.git.nicolinc@xxxxxxxxxx/
>  * Added Jason's Reviewed-by
>  * Split this invalidation part out of the part-1 series
>  * Repurposed VDEV_ID ioctl to a wider vDEVICE structure and ioctl
>  * Reduced viommu_api functions by allowing drivers to access viommu
>    and vdevice structure directly
>  * Dropped vdevs_rwsem by using xa_lock instead
>  * Dropped arm_smmu_cache_invalidate_user
> v2
>  https://lore.kernel.org/all/cover.1724776335.git.nicolinc@xxxxxxxxxx/
>  * Limited vdev_id to one per idev
>  * Added a rw_sem to protect the vdev_id list
>  * Reworked driver-level APIs with proper lockings
>  * Added a new viommu_api file for IOMMUFD_DRIVER config
>  * Dropped useless iommu_dev point from the viommu structure
>  * Added missing index numnbers to new types in the uAPI header
>  * Dropped IOMMU_VIOMMU_INVALIDATE uAPI; Instead, reuse the HWPT
> one
>  * Reworked mock_viommu_cache_invalidate() using the new iommu helper
>  * Reordered details of set/unset_vdev_id handlers for proper lockings
> v1
>  https://lore.kernel.org/all/cover.1723061377.git.nicolinc@xxxxxxxxxx/
> 
> Thanks!
> Nicolin
> 
> Jason Gunthorpe (2):
>   iommu: Add iommu_copy_struct_from_full_user_array helper
>   iommu/arm-smmu-v3: Allow ATS for IOMMU_DOMAIN_NESTED
> 
> Nicolin Chen (11):
>   iommufd/viommu: Add IOMMUFD_OBJ_VDEVICE and
> IOMMU_VDEVICE_ALLOC ioctl
>   iommufd/selftest: Add IOMMU_VDEVICE_ALLOC test coverage
>   iommu/viommu: Add cache_invalidate to iommufd_viommu_ops
>   iommufd/hw_pagetable: Enforce invalidation op on vIOMMU-based
>     hwpt_nested
>   iommufd: Allow hwpt_id to carry viommu_id for
> IOMMU_HWPT_INVALIDATE
>   iommufd/viommu: Add iommufd_viommu_find_dev helper
>   iommufd/selftest: Add mock_viommu_cache_invalidate
>   iommufd/selftest: Add IOMMU_TEST_OP_DEV_CHECK_CACHE test
> command
>   iommufd/selftest: Add vIOMMU coverage for IOMMU_HWPT_INVALIDATE
> ioctl
>   Documentation: userspace-api: iommufd: Update vDEVICE
>   iommu/arm-smmu-v3: Add arm_vsmmu_cache_invalidate
> 
>  drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h   |   9 +-
>  drivers/iommu/iommufd/iommufd_private.h       |  20 ++
>  drivers/iommu/iommufd/iommufd_test.h          |  30 +++
>  include/linux/iommu.h                         |  48 ++++-
>  include/linux/iommufd.h                       |  21 ++
>  include/uapi/linux/iommufd.h                  |  61 +++++-
>  tools/testing/selftests/iommu/iommufd_utils.h |  83 +++++++
>  .../arm/arm-smmu-v3/arm-smmu-v3-iommufd.c     | 161 +++++++++++++-
>  drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c   |  32 ++-
>  drivers/iommu/iommufd/device.c                |  11 +
>  drivers/iommu/iommufd/driver.c                |  13 ++
>  drivers/iommu/iommufd/hw_pagetable.c          |  36 +++-
>  drivers/iommu/iommufd/main.c                  |   7 +
>  drivers/iommu/iommufd/selftest.c              |  98 ++++++++-
>  drivers/iommu/iommufd/viommu.c                | 101 +++++++++
>  tools/testing/selftests/iommu/iommufd.c       | 204 +++++++++++++++++-
>  .../selftests/iommu/iommufd_fail_nth.c        |   4 +
>  Documentation/userspace-api/iommufd.rst       |  41 +++-
>  18 files changed, 942 insertions(+), 38 deletions(-)
> 
> --
> 2.43.0






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