cxl/region: Deal with numa nodes not enumerated by SRAT

For the numa nodes that are not created by SRAT, no memory_target is
allocated and is not managed by the HMAT_REPORTING code. Therefore
hmat_callback() memory hotplug notifier will exit early on those NUMA
nodes. The CXL memory hotplug notifier will need to call
node_set_perf_attrs() directly in order to setup the access sysfs
attributes.

In acpi_numa_init(), the last proximity domain (pxm) id created by SRAT is
stored. Add a helper function acpi_node_backed_by_real_pxm() in order to
check if a NUMA node id is defined by SRAT or created by CFMWS.

node_set_perf_attrs() symbol is exported to allow update of perf attribs
for a node. The sysfs path of
/sys/devices/system/node/nodeX/access0/initiators/* is created by
node_set_perf_attrs() for the various attributes where nodeX is matched
to the NUMA node of the CXL region.

Cc: Rafael J. Wysocki <rafael@kernel.org>
Reviewed-by: Alison Schofield <alison.schofield@intel.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Tested-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Link: https://lore.kernel.org/r/20240308220055.2172956-13-dave.jiang@intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

Author: davejiang

drivers/acpi/numa/srat.c

@@ -29,6 +29,8 @@ static int node_to_pxm_map[MAX_NUMNODES]
 unsigned char acpi_srat_revision __initdata;
 static int acpi_numa __initdata;
 
+static int last_real_pxm;
+
 void __init disable_srat(void)
 {
 	acpi_numa = -1;
@@ -536,6 +538,7 @@ int __init acpi_numa_init(void)
 		if (node_to_pxm_map[i] > fake_pxm)
 			fake_pxm = node_to_pxm_map[i];
 	}
+	last_real_pxm = fake_pxm;
 	fake_pxm++;
 	acpi_table_parse_cedt(ACPI_CEDT_TYPE_CFMWS, acpi_parse_cfmws,
 			      &fake_pxm);
@@ -547,6 +550,14 @@ int __init acpi_numa_init(void)
 	return 0;
 }
 
+bool acpi_node_backed_by_real_pxm(int nid)
+{
+	int pxm = node_to_pxm(nid);
+
+	return pxm <= last_real_pxm;
+}
+EXPORT_SYMBOL_GPL(acpi_node_backed_by_real_pxm);
+
 static int acpi_get_pxm(acpi_handle h)
 {
 	unsigned long long pxm;

drivers/base/node.c

@@ -215,6 +215,7 @@ void node_set_perf_attrs(unsigned int nid, struct access_coordinate *coord,
 		}
 	}
 }
+EXPORT_SYMBOL_GPL(node_set_perf_attrs);
 
 /**
  * struct node_cache_info - Internal tracking for memory node caches

drivers/cxl/core/cdat.c

@@ -586,3 +586,8 @@ int cxl_update_hmat_access_coordinates(int nid, struct cxl_region *cxlr,
 {
 	return hmat_update_target_coordinates(nid, &cxlr->coord[access], access);
 }
+
+bool cxl_need_node_perf_attrs_update(int nid)
+{
+	return !acpi_node_backed_by_real_pxm(nid);
+}

drivers/cxl/core/core.h

@@ -92,5 +92,6 @@ long cxl_pci_get_latency(struct pci_dev *pdev);
 
 int cxl_update_hmat_access_coordinates(int nid, struct cxl_region *cxlr,
 				       enum access_coordinate_class access);
+bool cxl_need_node_perf_attrs_update(int nid);
 
 #endif /* __CXL_CORE_H__ */

drivers/cxl/core/region.c

@@ -2279,7 +2279,12 @@ static bool cxl_region_update_coordinates(struct cxl_region *cxlr, int nid)
 
 	for (int i = 0; i < ACCESS_COORDINATE_MAX; i++) {
 		if (cxlr->coord[i].read_bandwidth) {
-			rc = cxl_update_hmat_access_coordinates(nid, cxlr, i);
+			rc = 0;
+			if (cxl_need_node_perf_attrs_update(nid))
+				node_set_perf_attrs(nid, &cxlr->coord[i], i);
+			else
+				rc = cxl_update_hmat_access_coordinates(nid, cxlr, i);
+
 			if (rc == 0)
 				cset++;
 		}

include/linux/acpi.h

@@ -1559,4 +1559,13 @@ static inline int hmat_update_target_coordinates(int nid,
 }
 #endif
 
+#ifdef CONFIG_ACPI_NUMA
+bool acpi_node_backed_by_real_pxm(int nid);
+#else
+static inline bool acpi_node_backed_by_real_pxm(int nid)
+{
+	return false;
+}
+#endif
+
 #endif	/*_LINUX_ACPI_H*/