> From: Nicolin Chen <nicolinc@xxxxxxxxxx> > Sent: Tuesday, October 22, 2024 8:19 AM > > This series introduces a new vIOMMU infrastructure and related ioctls. > > IOMMUFD has been using the HWPT infrastructure for all cases, including a > nested IO page table support. Yet, there're limitations for an HWPT-based > structure to support some advanced HW-accelerated features, such as > CMDQV > on NVIDIA Grace, and HW-accelerated vIOMMU on AMD. Even for a multi- > IOMMU > environment, it is not straightforward for nested HWPTs to share the same > parent HWPT (stage-2 IO pagetable), with the HWPT infrastructure alone: a > parent HWPT typically hold one stage-2 IO pagetable and tag it with only > one ID in the cache entries. When sharing one large stage-2 IO pagetable > across physical IOMMU instances, that one ID may not always be available > across all the IOMMU instances. In other word, it's ideal for SW to have > a different container for the stage-2 IO pagetable so it can hold another > ID that's available. Just holding multiple IDs doesn't require a different container. This is just a side effect when vIOMMU will be required for other said reasons. If we have to put more words here I'd prefer to adding a bit more for CMDQV which is more compelling. not a big deal though. 😊 > > For this "different container", add vIOMMU, an additional layer to hold > extra virtualization information: > > ________________________________________________________________ > _______ > | iommufd (with vIOMMU) | > | | > | [5] | > | _____________ | > | | | | > | |----------------| vIOMMU | | > | | | | | > | | | | | > | | [1] | | [4] [2] | > | | ______ | | _____________ ________ | > | | | | | [3] | | | | | | > | | | IOAS |<---|(HWPT_PAGING)|<---| HWPT_NESTED |<--| DEVICE | | > | | |______| |_____________| |_____________| |________| | > | | | | | | | > > |______|________|______________|__________________|_____________ > __|_____| > | | | | | > ______v_____ | ______v_____ ______v_____ ___v__ > | struct | | PFN | (paging) | | (nested) | |struct| > |iommu_device| |------>|iommu_domain|<----|iommu_domain|<---- > |device| > |____________| storage|____________| |____________| |______| > nit - [1] ... [5] can be removed. > The vIOMMU object should be seen as a slice of a physical IOMMU instance > that is passed to or shared with a VM. That can be some HW/SW resources: > - Security namespace for guest owned ID, e.g. guest-controlled cache tags > - Access to a sharable nesting parent pagetable across physical IOMMUs > - Virtualization of various platforms IDs, e.g. RIDs and others > - Delivery of paravirtualized invalidation > - Direct assigned invalidation queues > - Direct assigned interrupts > - Non-affiliated event reporting sorry no idea about 'non-affiliated event'. Can you elaborate? > > On a multi-IOMMU system, the vIOMMU object must be instanced to the > number > of the physical IOMMUs that are passed to (via devices) a guest VM, while 'to the number of the physical IOMMUs that have a slice passed to ..." > being able to hold the shareable parent HWPT. Each vIOMMU then just > needs > to allocate its own individual ID to tag its own cache: > ---------------------------- > ---------------- | | paging_hwpt0 | > | hwpt_nested0 |--->| viommu0 ------------------ > ---------------- | | IDx | > ---------------------------- > ---------------------------- > ---------------- | | paging_hwpt0 | > | hwpt_nested1 |--->| viommu1 ------------------ > ---------------- | | IDy | > ---------------------------- > > As an initial part-1, add IOMMUFD_CMD_VIOMMU_ALLOC ioctl for an > allocation > only. And implement it in arm-smmu-v3 driver as a real world use case. > > More vIOMMU-based structs and ioctls will be introduced in the follow-up > series to support vDEVICE, vIRQ (vEVENT) and vQUEUE objects. Although we > repurposed the vIOMMU object from an earlier RFC, just for a referece: > https://lore.kernel.org/all/cover.1712978212.git.nicolinc@xxxxxxxxxx/ > > This series is on Github: > https://github.com/nicolinc/iommufd/commits/iommufd_viommu_p1-v4 > (paring QEMU branch for testing will be provided with the part2 series) > > Changelog > v4 > * Added "Reviewed-by" from Jason > * Dropped IOMMU_VIOMMU_TYPE_DEFAULT support > * Dropped iommufd_object_alloc_elm renamings > * Renamed iommufd's viommu_api.c to driver.c > * Reworked iommufd_viommu_alloc helper > * Added a separate iommufd_hwpt_nested_alloc_for_viommu function for > hwpt_nested allocations on a vIOMMU, and added comparison between > viommu->iommu_dev->ops and dev_iommu_ops(idev->dev) > * Replaced s2_parent with vsmmu in arm_smmu_nested_domain > * Replaced domain_alloc_user in iommu_ops with domain_alloc_nested in > viommu_ops > * Replaced wait_queue_head_t with a completion, to delay the unplug of > mock_iommu_dev > * Corrected documentation graph that was missing struct iommu_device > * Added an iommufd_verify_unfinalized_object helper to verify driver- > allocated vIOMMU/vDEVICE objects > * Added missing test cases for TEST_LENGTH and fail_nth > v3 > https://lore.kernel.org/all/cover.1728491453.git.nicolinc@xxxxxxxxxx/ > * Rebased on top of Jason's nesting v3 series > https://lore.kernel.org/all/0-v3-e2e16cd7467f+2a6a1- > smmuv3_nesting_jgg@xxxxxxxxxx/ > * Split the series into smaller parts > * Added Jason's Reviewed-by > * Added back viommu->iommu_dev > * Added support for driver-allocated vIOMMU v.s. core-allocated > * Dropped arm_smmu_cache_invalidate_user > * Added an iommufd_test_wait_for_users() in selftest > * Reworked test code to make viommu an individual FIXTURE > * Added missing TEST_LENGTH case for the new ioctl command > 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 > > Nicolin Chen (11): > iommufd: Move struct iommufd_object to public iommufd header > iommufd: Introduce IOMMUFD_OBJ_VIOMMU and its related struct > iommufd: Add iommufd_verify_unfinalized_object > iommufd/viommu: Add IOMMU_VIOMMU_ALLOC ioctl > iommufd: Add domain_alloc_nested op to iommufd_viommu_ops > iommufd: Allow pt_id to carry viommu_id for IOMMU_HWPT_ALLOC > iommufd/selftest: Add refcount to mock_iommu_device > iommufd/selftest: Add IOMMU_VIOMMU_TYPE_SELFTEST > iommufd/selftest: Add IOMMU_VIOMMU_ALLOC test coverage > Documentation: userspace-api: iommufd: Update vIOMMU > iommu/arm-smmu-v3: Add IOMMU_VIOMMU_TYPE_ARM_SMMUV3 > support > > drivers/iommu/iommufd/Makefile | 5 +- > drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h | 26 +++--- > drivers/iommu/iommufd/iommufd_private.h | 36 ++------ > drivers/iommu/iommufd/iommufd_test.h | 2 + > include/linux/iommu.h | 14 +++ > include/linux/iommufd.h | 89 +++++++++++++++++++ > include/uapi/linux/iommufd.h | 56 ++++++++++-- > tools/testing/selftests/iommu/iommufd_utils.h | 28 ++++++ > .../arm/arm-smmu-v3/arm-smmu-v3-iommufd.c | 79 ++++++++++------ > drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 9 +- > drivers/iommu/iommufd/driver.c | 38 ++++++++ > drivers/iommu/iommufd/hw_pagetable.c | 69 +++++++++++++- > drivers/iommu/iommufd/main.c | 58 ++++++------ > drivers/iommu/iommufd/selftest.c | 73 +++++++++++++-- > drivers/iommu/iommufd/viommu.c | 85 ++++++++++++++++++ > tools/testing/selftests/iommu/iommufd.c | 78 ++++++++++++++++ > .../selftests/iommu/iommufd_fail_nth.c | 11 +++ > Documentation/userspace-api/iommufd.rst | 69 +++++++++++++- > 18 files changed, 701 insertions(+), 124 deletions(-) > create mode 100644 drivers/iommu/iommufd/driver.c > create mode 100644 drivers/iommu/iommufd/viommu.c > > -- > 2.43.0 >
