Extend the selftest tool to add coverage of testing IOPF handling. This
would include the following tests:
- Allocating and destorying an iommufd fault object.
- Allocating and destroying an IOPF-capable HWPT.
- Attaching/detaching/replacing an IOPF-capable HWPT on a device.
- Triggering an IOPF
Extend the selftest mock device to support generating and responding to
an IOPF. Also add an ioctl interface to userspace applications to trigger
the IOPF on the mock device. This would allow userspace applications to
test the IOMMUFD's handling of IOPFs without having to rely on any real
The iopf-capable hw page table attach/detach/replace should use the iommu
iopf-specific interfaces. The pointer to iommufd_device is stored in the
private field of the attachment cookie, so that it can be easily retrieved
in the fault handling paths. The references to iommufd_device and
When allocating a user iommufd_hw_pagetable, the user space is allowed to
associate a fault object with the hw_pagetable by specifying the fault
object ID in the page table allocation data and setting the
IOMMU_HWPT_FAULT_ID_VALID flag bit.
On a successful return of hwpt allocation, the user can
An iommufd fault object provides an interface for delivering I/O page
faults to user space. These objects are created and destroyed by user
space, and they can be associated with or dissociated from hardware page
table objects during page table allocation or destruction.
User space interacts with
iommu_hwpt_pgfaults represent fault messages that the userspace can
retrieve. Multiple iommu_hwpt_pgfaults might be put in an iopf group,
with the IOMMU_PGFAULT_FLAGS_LAST_PAGE flag set only for the last
iommu_hwpt_pgfault.
An iommu_hwpt_page_response is a response message that the userspace
The iommu sva implementation relies on iopf handling. Allocate an
attachment cookie and use the iopf domain attach/detach interface.
The SVA domain is guaranteed to be released after all outstanding
page faults are handled.
In the fault delivering path, the attachment cookie is retrieved,
instead
There is a slight difference between iopf domains and non-iopf domains.
In the latter, references to domains occur between attach and detach;
While in the former, due to the existence of asynchronous iopf handling
paths, references to the domain may occur after detach, which leads to
potential UAF
This series implements the functionality of delivering IO page faults to
user space through the IOMMUFD framework. One feasible use case is the
nested translation. Nested translation is a hardware feature that
supports two-stage translation tables for IOMMU. The second-stage
translation table is
