[PATCH 0/2] CXL: Apply SRAT defined PXM to entire CFMWS window

[alison . schofield]

From: Alison Schofield <alison.schofield@xxxxxxxxx>

The CXL subsystem requires the creation of NUMA nodes for CFMWS
Windows not described in the SRAT. The existing implementation
only addresses windows that the SRAT describes completely or
not at all. This work addresses the case of partially described
CFMWS Windows by extending proximity domains in a portion of
a CFMWS window to the entire window.

Introduce a NUMA helper, numa_fill_memblks(), to fill gaps in
a numa_meminfo memblk address range. Update the CFMWS parsing
in the ACPI driver to use numa_fill_memblks() to extend SRAT
defined proximity domains to entire CXL windows.

An RFC of this patchset was previously posted for CXL folks
review.[1] The RFC feedback led to the implementation here,
extending existing memblks (Dan). Also, both Jonathan and
Dan influenced the changelog comments in the ACPI patch, with
regards to setting expectations on this evolving heuristic.

Repeating here to set reviewer expectations:
*Note that this heuristic will evolve when CFMWS Windows present
a wider range of characteristics. The extension of the proximity
domain, implemented here, is likely a step in developing a more
sophisticated performance profile in the future.

[1] https://lore.kernel.org/linux-cxl/cover.1683742429.git.alison.schofield@xxxxxxxxx/

Alison Schofield (2):
  x86/numa: Introduce numa_fill_memblks()
  ACPI: NUMA: Apply SRAT proximity domain to entire CFMWS window

 arch/x86/include/asm/sparsemem.h |  2 +
 arch/x86/mm/numa.c               | 82 ++++++++++++++++++++++++++++++++
 drivers/acpi/numa/srat.c         | 11 +++--
 include/linux/numa.h             |  7 +++
 4 files changed, 99 insertions(+), 3 deletions(-)


base-commit: f81d8f759e7f80c643027e631c586369836aac90
-- 
2.37.3