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.
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|____________| |____________| |______|
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
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
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
