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Secondary Bus Reset (SBR) is equivalent to a device being hot removed and inserted again. Doing a SBR on a CXL type 3 device is problematic if the exported device memory is part of system memory that cannot be offlined. The event is equivalent to violently ripping out that range of memory from the kernel. While the hardware requires the "Unmask SBR" bit set in the Port Control Extensions register and the kernel currently does not unmask it, user can unmask this bit via setpci or similar tool. The driver does not have a way to detect whether a reset coming from the PCI subsystem is a Function Level Reset (FLR) or SBR. The only way to detect is to note if a decoder is marked as enabled in software but the decoder control register indicates it's not committed. Add a helper function to find discrepancy between the decoder software state versus the hardware register state. Suggested-by: Dan Williams <dan.j.williams@intel.com> Link: https://lore.kernel.org/r/20240502165851.1948523-6-dave.jiang@intel.com Signed-off-by: Dave Jiang <dave.jiang@intel.com> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com> Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com> Reviewed-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 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.