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Robert Richter
0cab687205
The Linux CXL subsystem is built on the assumption that HPA == SPA.
That is, the host physical address (HPA) the HDM decoder registers are
programmed with are system physical addresses (SPA).
During HDM decoder setup, the DVSEC CXL range registers (cxl-3.1,
8.1.3.8) are checked if the memory is enabled and the CXL range is in
a HPA window that is described in a CFMWS structure of the CXL host
bridge (cxl-3.1, 9.18.1.3).
Now, if the HPA is not an SPA, the CXL range does not match a CFMWS
window and the CXL memory range will be disabled then. The HDM decoder
stops working which causes system memory being disabled and further a
system hang during HDM decoder initialization, typically when a CXL
enabled kernel boots.
Prevent a system hang and do not disable the HDM decoder if the
decoder's CXL range is not found in a CFMWS window.
Note the change only fixes a hardware hang, but does not implement
HPA/SPA translation. Support for this can be added in a follow on
patch series.
Signed-off-by: Robert Richter <rrichter@amd.com>
Fixes: 34e37b4c43 ("cxl/port: Enable HDM Capability after validating DVSEC Ranges")
Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20240216160113.407141-1-rrichter@amd.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.