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SW_MSI supports IOMMU to translate an MSI message before the MSI message is delivered to the interrupt controller. On such systems, an iommu_domain must have a translation for the MSI message for interrupts to work. The IRQ subsystem will call into IOMMU to request that a physical page be set up to receive MSI messages, and the IOMMU then sets an IOVA that maps to that physical page. Ultimately the IOVA is programmed into the device via the msi_msg. Generalize this by allowing iommu_domain owners to provide implementations of this mapping. Add a function pointer in struct iommu_domain to allow a domain owner to provide its own implementation. Have dma-iommu supply its implementation for IOMMU_DOMAIN_DMA types during the iommu_get_dma_cookie() path. For IOMMU_DOMAIN_UNMANAGED types used by VFIO (and iommufd for now), have the same iommu_dma_sw_msi set as well in the iommu_get_msi_cookie() path. Hold the group mutex while in iommu_dma_prepare_msi() to ensure the domain doesn't change or become freed while running. Races with IRQ operations from VFIO and domain changes from iommufd are possible here. Replace the msi_prepare_lock with a lockdep assertion for the group mutex as documentation. For the dmau_iommu.c each iommu_domain is unique to a group. Link: https://patch.msgid.link/r/4ca696150d2baee03af27c4ddefdb7b0b0280e7b.1740014950.git.nicolinc@nvidia.com Signed-off-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.