[RFC PATCH v2 1/5] acpi: numa: Add support to enumerate and store extended linear address mode

[Dave Jiang <dave.jiang@intel.com>]

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/668333b17e4b2_5639294fd@dwillia2-xfh.jf.intel.com.notmuch/
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
---
v2:
- Fix spelling errors (Jonathan)
- Change UNKNOWN to RESERVED (Jonathan)
---
 Documentation/ABI/stable/sysfs-devices-node | 6 ++++++
 drivers/acpi/numa/hmat.c                    | 3 +++
 drivers/base/node.c                         | 2 ++
 include/linux/node.h                        | 7 +++++++
 4 files changed, 18 insertions(+)

diff --git a/Documentation/ABI/stable/sysfs-devices-node b/Documentation/ABI/stable/sysfs-devices-node
index 402af4b2b905..725ef0e1e01f 100644
--- a/Documentation/ABI/stable/sysfs-devices-node
+++ b/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/mode
+Date:		September 2024
+Contact:	Dave Jiang <dave.jiang@intel.com>
+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 <jarkko@kernel.org>
diff --git a/drivers/acpi/numa/hmat.c b/drivers/acpi/numa/hmat.c
index 1a902a02390f..39524f36be5b 100644
--- a/drivers/acpi/numa/hmat.c
+++ b/drivers/acpi/numa/hmat.c
@@ -506,6 +506,9 @@ 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.mode = NODE_CACHE_MODE_EXTENDED_LINEAR;
 		break;
 	case ACPI_HMAT_CA_COMPLEX_CACHE_INDEXING:
 		tcache->cache_attrs.indexing = NODE_CACHE_INDEXED;
diff --git a/drivers/base/node.c b/drivers/base/node.c
index eb72580288e6..744be5470728 100644
--- a/drivers/base/node.c
+++ b/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(mode, "%u")
 
 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_mode.attr,
 	NULL,
 };
 ATTRIBUTE_GROUPS(cache);
diff --git a/include/linux/node.h b/include/linux/node.h
index 9a881c2208b3..fdecb760ef49 100644
--- a/include/linux/node.h
+++ b/include/linux/node.h
@@ -57,6 +57,11 @@ enum cache_write_policy {
 	NODE_CACHE_WRITE_OTHER,
 };
 
+enum cache_mode {
+	NODE_CACHE_MODE_RESERVED,
+	NODE_CACHE_MODE_EXTENDED_LINEAR,
+};
+
 /**
  * struct node_cache_attrs - system memory caching attributes
  *
@@ -65,6 +70,7 @@ 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
+ * @mode:		The address mode
  */
 struct node_cache_attrs {
 	enum cache_indexing indexing;
@@ -72,6 +78,7 @@ struct node_cache_attrs {
 	u64 size;
 	u16 line_size;
 	u8 level;
+	u16 mode;
 };
 
 #ifdef CONFIG_HMEM_REPORTING
-- 
2.47.0