acpi/hmat / cxl: Add extended linear cache support for CXL

The current cxl region size only indicates the size of the CXL memory
region without accounting for the extended linear cache size. Retrieve the
cache size from HMAT and append that to the cxl region size for the cxl
region range that matches the SRAT range that has extended linear cache
enabled.

The SRAT defines the whole memory range that includes the extended linear
cache and the CXL memory region. The new HMAT ECN/ECR to the Memory Side
Cache Information Structure defines the size of the extended linear cache
size and matches to the SRAT Memory Affinity Structure by the memory
proxmity domain. Add a helper to match the cxl range to the SRAT memory
range in order to retrieve the cache size.

There are several places that checks the cxl region range against the
decoder range. Use new helper to check between the two ranges and address
the new cache size.

Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Li Ming <ming.li@zohomail.com>
Reviewed-by: Alison Schofield <alison.schofield@intel.com>
Link: https://patch.msgid.link/20250226162224.3633792-3-dave.jiang@intel.com
Signed-off-by: Dave Jiang <dave.jiang@intel.com>

1 files changed, 39 insertions, 0 deletions

diff --git a/drivers/acpi/numa/hmat.c b/drivers/acpi/numa/hmat.c
index 2630511937f5..9d9052258e92 100644
--- a/drivers/acpi/numa/hmat.c
+++ b/drivers/acpi/numa/hmat.c
@@ -108,6 +108,45 @@ static struct memory_target *find_mem_target(unsigned int mem_pxm)
 	return NULL;
 }
 
+/**
+ * hmat_get_extended_linear_cache_size - Retrieve the extended linear cache size
+ * @backing_res: resource from the backing media
+ * @nid: node id for the memory region
+ * @cache_size: (Output) size of extended linear cache.
+ *
+ * Return: 0 on success. Errno on failure.
+ *
+ */
+int hmat_get_extended_linear_cache_size(struct resource *backing_res, int nid,
+					resource_size_t *cache_size)
+{
+	unsigned int pxm = node_to_pxm(nid);
+	struct memory_target *target;
+	struct target_cache *tcache;
+	struct resource *res;
+
+	target = find_mem_target(pxm);
+	if (!target)
+		return -ENOENT;
+
+	list_for_each_entry(tcache, &target->caches, node) {
+		if (tcache->cache_attrs.address_mode !=
+				NODE_CACHE_ADDR_MODE_EXTENDED_LINEAR)
+			continue;
+
+		res = &target->memregions;
+		if (!resource_contains(res, backing_res))
+			continue;
+
+		*cache_size = tcache->cache_attrs.size;
+		return 0;
+	}
+
+	*cache_size = 0;
+	return 0;
+}
+EXPORT_SYMBOL_NS_GPL(hmat_get_extended_linear_cache_size, "CXL");
+
 static struct memory_target *acpi_find_genport_target(u32 uid)
 {
 	struct memory_target *target;