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x86 systems identify traffic using the CLOSID and RMID. The CLOSID is used to lookup the control policy, the RMID is used for monitoring. For x86 these are independent numbers. Arm's MPAM has equivalent features PARTID and PMG, where the PARTID is used to lookup the control policy. The PMG in contrast is a small number of bits that are used to subdivide PARTID when monitoring. The cache-occupancy monitors require the PARTID to be specified when monitoring. This means MPAM's PMG field is not unique. There are multiple PMG-0, one per allocated CLOSID/PARTID. If PMG is treated as equivalent to RMID, it cannot be allocated as an independent number. Bitmaps like rmid_busy_llc need to be sized by the number of unique entries for this resource. Treat the combined CLOSID and RMID as an index, and provide architecture helpers to pack and unpack an index. This makes the MPAM values unique. The domain's rmid_busy_llc and rmid_ptrs[] are then sized by index, as are domain mbm_local[] and mbm_total[]. x86 can ignore the CLOSID field when packing and unpacking an index, and report as many indexes as RMID. Signed-off-by: James Morse <james.morse@arm.com> Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de> Reviewed-by: Shaopeng Tan <tan.shaopeng@fujitsu.com> Reviewed-by: Babu Moger <babu.moger@amd.com> Reviewed-by: Reinette Chatre <reinette.chatre@intel.com> Tested-by: Shaopeng Tan <tan.shaopeng@fujitsu.com> Tested-by: Peter Newman <peternewman@google.com> Tested-by: Babu Moger <babu.moger@amd.com> Tested-by: Carl Worth <carl@os.amperecomputing.com> # arm64 Link: https://lore.kernel.org/r/20240213184438.16675-7-james.morse@arm.com Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
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.