ACPI/NUMA: Apply SRAT proximity domain to entire CFMWS window

Commit fd49f99 ("ACPI: NUMA: Add a node and memblk for each
CFMWS not in SRAT") did not account for the case where the BIOS
only partially describes a CFMWS Window in the SRAT. That means
the omitted address ranges, of a partially described CFMWS Window,
do not get assigned to a NUMA node.

Replace the call to phys_to_target_node() with numa_add_memblks().
Numa_add_memblks() searches an HPA range for existing memblk(s)
and extends those memblk(s) to fill the entire CFMWS Window.

Extending the existing memblks is a simple strategy that reuses
SRAT defined proximity domains from part of a window to fill out
the entire window, based on the knowledge* that all of a CFMWS
window is of a similar performance class.

*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.

There is no change in behavior when the SRAT does not describe
the CFMWS Window at all. In that case, a new NUMA node with a
single memblk covering the entire CFMWS Window is created.

Fixes: fd49f99 ("ACPI: NUMA: Add a node and memblk for each CFMWS not in SRAT")
Reported-by: Derick Marks <[email protected]>
Suggested-by: Dan Williams <[email protected]>
Signed-off-by: Alison Schofield <[email protected]>
Signed-off-by: Dave Hansen <[email protected]>
Reviewed-by: Dan Williams <[email protected]>
Tested-by: Derick Marks <[email protected]>
Link: https://lore.kernel.org/all/eaa0b7cffb0951a126223eef3cbe7b55b8300ad9.1689018477.git.alison.schofield%40intel.com

Author: AlisonSchofield

drivers/acpi/numa/srat.c

@@ -310,11 +310,16 @@ static int __init acpi_parse_cfmws(union acpi_subtable_headers *header,
 	start = cfmws->base_hpa;
 	end = cfmws->base_hpa + cfmws->window_size;
 
-	/* Skip if the SRAT already described the NUMA details for this HPA */
-	node = phys_to_target_node(start);
-	if (node != NUMA_NO_NODE)
+	/*
+	 * The SRAT may have already described NUMA details for all,
+	 * or a portion of, this CFMWS HPA range. Extend the memblks
+	 * found for any portion of the window to cover the entire
+	 * window.
+	 */
+	if (!numa_fill_memblks(start, end))
 		return 0;
 
+	/* No SRAT description. Create a new node. */
 	node = acpi_map_pxm_to_node(*fake_pxm);
 
 	if (node == NUMA_NO_NODE) {