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When connected to VFIO, the only DMABUF exporter that is accepted, the move_notify callback will be made when VFIO wants to remove access to the MMIO. This is being called revoke. Wire up revoke to go through all the iommu_domain's that have mapped the DMABUF and unmap them. The locking here is unpleasant, since the existing locking scheme was designed to come from the iopt through the area to the pages we cannot use pages as starting point for the locking. There is no way to obtain the domains_rwsem before obtaining the pages mutex to reliably use the existing domains_itree. Solve this problem by adding a new tracking structure just for DMABUF revoke. Record a linked list of areas and domains inside the pages mutex. Clean the entries on the list during revoke. The map/unmaps are now all done under a pages mutex while updating the tracking linked list so nothing can get out of sync. Only one lock is required for revoke processing. Link: https://patch.msgid.link/r/4-v2-b2c110338e3f+5c2-iommufd_dmabuf_jgg@nvidia.com Reviewed-by: Nicolin Chen <nicolinc@nvidia.com> Reviewed-by: Kevin Tian <kevin.tian@intel.com> Tested-by: Nicolin Chen <nicolinc@nvidia.com> Tested-by: Shuai Xue <xueshuai@linux.alibaba.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.