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For SMMUv3 a IOMMU_DOMAIN_NESTED is composed of a S2 iommu_domain acting as the parent and a user provided STE fragment that defines the CD table and related data with addresses translated by the S2 iommu_domain. The kernel only permits userspace to control certain allowed bits of the STE that are safe for user/guest control. IOTLB maintenance is a bit subtle here, the S1 implicitly includes the S2 translation, but there is no way of knowing which S1 entries refer to a range of S2. For the IOTLB we follow ARM's guidance and issue a CMDQ_OP_TLBI_NH_ALL to flush all ASIDs from the VMID after flushing the S2 on any change to the S2. The IOMMU_DOMAIN_NESTED can only be created from inside a VIOMMU as the invalidation path relies on the VIOMMU to translate virtual stream ID used in the invalidation commands for the CD table and ATS. Link: https://patch.msgid.link/r/9-v4-9e99b76f3518+3a8-smmuv3_nesting_jgg@nvidia.com Reviewed-by: Nicolin Chen <nicolinc@nvidia.com> Reviewed-by: Kevin Tian <kevin.tian@intel.com> Reviewed-by: Jerry Snitselaar <jsnitsel@redhat.com> Reviewed-by: Donald Dutile <ddutile@redhat.com> Signed-off-by: Nicolin Chen <nicolinc@nvidia.com> Tested-by: Nicolin Chen <nicolinc@nvidia.com> Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.