acpi: numa: Add support to enumerate and store extended linear address mode

Store the address mode as part of the cache attriutes. Export the mode
attribute to sysfs as all other cache attributes.

Link: https://lore.kernel.org/linux-cxl/[email protected]/
Reviewed-by: Jonathan Cameron <[email protected]>
Reviewed-by: Li Ming <[email protected]>
Reviewed-by: Alison Schofield <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Dave Jiang <[email protected]>

Author: davejiang

Documentation/ABI/stable/sysfs-devices-node

@@ -177,6 +177,12 @@ Description:
 		The cache write policy: 0 for write-back, 1 for write-through,
 		other or unknown.
 
+What:		/sys/devices/system/node/nodeX/memory_side_cache/indexY/address_mode
+Date:		March 2025
+Contact:	Dave Jiang <[email protected]>
+Description:
+		The address mode: 0 for reserved, 1 for extended-linear.
+
 What:		/sys/devices/system/node/nodeX/x86/sgx_total_bytes
 Date:		November 2021
 Contact:	Jarkko Sakkinen <[email protected]>

drivers/acpi/numa/hmat.c

@@ -506,6 +506,11 @@ static __init int hmat_parse_cache(union acpi_subtable_headers *header,
 	switch ((attrs & ACPI_HMAT_CACHE_ASSOCIATIVITY) >> 8) {
 	case ACPI_HMAT_CA_DIRECT_MAPPED:
 		tcache->cache_attrs.indexing = NODE_CACHE_DIRECT_MAP;
+		/* Extended Linear mode is only valid if cache is direct mapped */
+		if (cache->address_mode == ACPI_HMAT_CACHE_MODE_EXTENDED_LINEAR) {
+			tcache->cache_attrs.address_mode =
+				NODE_CACHE_ADDR_MODE_EXTENDED_LINEAR;
+		}
 		break;
 	case ACPI_HMAT_CA_COMPLEX_CACHE_INDEXING:
 		tcache->cache_attrs.indexing = NODE_CACHE_INDEXED;

drivers/base/node.c

@@ -244,12 +244,14 @@ CACHE_ATTR(size, "%llu")
 CACHE_ATTR(line_size, "%u")
 CACHE_ATTR(indexing, "%u")
 CACHE_ATTR(write_policy, "%u")
+CACHE_ATTR(address_mode, "%#x")
 
 static struct attribute *cache_attrs[] = {
 	&dev_attr_indexing.attr,
 	&dev_attr_size.attr,
 	&dev_attr_line_size.attr,
 	&dev_attr_write_policy.attr,
+	&dev_attr_address_mode.attr,
 	NULL,
 };
 ATTRIBUTE_GROUPS(cache);

include/linux/node.h

@@ -57,6 +57,11 @@ enum cache_write_policy {
 	NODE_CACHE_WRITE_OTHER,
 };
 
+enum cache_mode {
+	NODE_CACHE_ADDR_MODE_RESERVED,
+	NODE_CACHE_ADDR_MODE_EXTENDED_LINEAR,
+};
+
 /**
  * struct node_cache_attrs - system memory caching attributes
  *
@@ -65,13 +70,15 @@ enum cache_write_policy {
  * @size:		Total size of cache in bytes
  * @line_size:		Number of bytes fetched on a cache miss
  * @level:		The cache hierarchy level
+ * @address_mode:		The address mode
  */
 struct node_cache_attrs {
 	enum cache_indexing indexing;
 	enum cache_write_policy write_policy;
 	u64 size;
 	u16 line_size;
 	u8 level;
+	u16 address_mode;
 };
 
 #ifdef CONFIG_HMEM_REPORTING