9c57cde0dc
In preparation for provisioning CXL regions, add accounting for the DPA space consumed by existing regions / decoders. Recall, a CXL region is a memory range comprised from one or more endpoint devices contributing a mapping of their DPA into HPA space through a decoder. Record the DPA ranges covered by committed decoders at initial probe of endpoint ports relative to a per-device resource tree of the DPA type (pmem or volatile-ram). The cxl_dpa_rwsem semaphore is introduced to globally synchronize DPA state across all endpoints and their decoders at once. The vast majority of DPA operations are reads as region creation is expected to be as rare as disk partitioning and volume creation. The device_lock() for this synchronization is specifically avoided for concern of entangling with sysfs attribute removal. Co-developed-by: Ben Widawsky <bwidawsk@kernel.org> Signed-off-by: Ben Widawsky <bwidawsk@kernel.org> Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com> Link: https://lore.kernel.org/r/165784327682.1758207.7914919426043855876.stgit@dwillia2-xfh.jf.intel.com Signed-off-by: Dan Williams <dan.j.williams@intel.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 Restructured Text 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.