Merge: cxl/mem: Fix no cxl_nvd during pmem region auto-assembling

MR: https://gitlab.com/redhat/centos-stream/src/kernel/centos-stream-9/-/merge_requests/4936

## Summary of Changes

cxl/mem: Fix no cxl_nvd during pmem region auto-assembling

## Approved Development Ticket
JIRA: https://issues.redhat.com/browse/RHEL-51364

CVE: CVE-2024-41085

Signed-off-by: John W. Linville <linville@redhat.com>

Approved-by: Myron Stowe <mstowe@redhat.com>
Approved-by: Charles Mirabile <cmirabil@redhat.com>
Approved-by: CKI KWF Bot <cki-ci-bot+kwf-gitlab-com@redhat.com>

Merged-by: Lucas Zampieri <lzampier@redhat.com>

Author: zampierilucas

drivers/cxl/core/pmem.c

@@ -62,16 +62,21 @@ static int match_nvdimm_bridge(struct device *dev, void *data)
 	return is_cxl_nvdimm_bridge(dev);
 }
 
-struct cxl_nvdimm_bridge *cxl_find_nvdimm_bridge(struct cxl_memdev *cxlmd)
+/**
+ * cxl_find_nvdimm_bridge() - find a bridge device relative to a port
+ * @port: any descendant port of an nvdimm-bridge associated
+ *        root-cxl-port
+ */
+struct cxl_nvdimm_bridge *cxl_find_nvdimm_bridge(struct cxl_port *port)
 {
-	struct cxl_port *port = find_cxl_root(cxlmd->endpoint);
+	struct cxl_port *root_port = find_cxl_root(port);
 	struct device *dev;
 
-	if (!port)
+	if (!root_port)
 		return NULL;
 
-	dev = device_find_child(&port->dev, NULL, match_nvdimm_bridge);
-	put_device(&port->dev);
+	dev = device_find_child(&root_port->dev, NULL, match_nvdimm_bridge);
+	put_device(&root_port->dev);
 
 	if (!dev)
 		return NULL;
@@ -242,18 +247,20 @@ static void cxlmd_release_nvdimm(void *_cxlmd)
 
 /**
  * devm_cxl_add_nvdimm() - add a bridge between a cxl_memdev and an nvdimm
+ * @parent_port: parent port for the (to be added) @cxlmd endpoint port
  * @cxlmd: cxl_memdev instance that will perform LIBNVDIMM operations
  *
  * Return: 0 on success negative error code on failure.
  */
-int devm_cxl_add_nvdimm(struct cxl_memdev *cxlmd)
+int devm_cxl_add_nvdimm(struct cxl_port *parent_port,
+			struct cxl_memdev *cxlmd)
 {
 	struct cxl_nvdimm_bridge *cxl_nvb;
 	struct cxl_nvdimm *cxl_nvd;
 	struct device *dev;
 	int rc;
 
-	cxl_nvb = cxl_find_nvdimm_bridge(cxlmd);
+	cxl_nvb = cxl_find_nvdimm_bridge(parent_port);
 	if (!cxl_nvb)
 		return -ENODEV;
 

drivers/cxl/core/region.c

@@ -2547,7 +2547,7 @@ static struct cxl_pmem_region *cxl_pmem_region_alloc(struct cxl_region *cxlr)
 		 * bridge for one device is the same for all.
 		 */
 		if (i == 0) {
-			cxl_nvb = cxl_find_nvdimm_bridge(cxlmd);
+			cxl_nvb = cxl_find_nvdimm_bridge(cxlmd->endpoint);
 			if (!cxl_nvb) {
 				kfree(cxlr_pmem);
 				cxlr_pmem = ERR_PTR(-ENODEV);

drivers/cxl/cxl.h

@@ -798,8 +798,8 @@ struct cxl_nvdimm_bridge *devm_cxl_add_nvdimm_bridge(struct device *host,
 struct cxl_nvdimm *to_cxl_nvdimm(struct device *dev);
 bool is_cxl_nvdimm(struct device *dev);
 bool is_cxl_nvdimm_bridge(struct device *dev);
-int devm_cxl_add_nvdimm(struct cxl_memdev *cxlmd);
-struct cxl_nvdimm_bridge *cxl_find_nvdimm_bridge(struct cxl_memdev *cxlmd);
+int devm_cxl_add_nvdimm(struct cxl_port *parent_port, struct cxl_memdev *cxlmd);
+struct cxl_nvdimm_bridge *cxl_find_nvdimm_bridge(struct cxl_port *port);
 
 #ifdef CONFIG_CXL_REGION
 bool is_cxl_pmem_region(struct device *dev);

drivers/cxl/mem.c

@@ -152,6 +152,15 @@ static int cxl_mem_probe(struct device *dev)
 		return -ENXIO;
 	}
 
+	if (resource_size(&cxlds->pmem_res) && IS_ENABLED(CONFIG_CXL_PMEM)) {
+		rc = devm_cxl_add_nvdimm(parent_port, cxlmd);
+		if (rc) {
+			if (rc == -ENODEV)
+				dev_info(dev, "PMEM disabled by platform\n");
+			return rc;
+		}
+	}
+
 	if (dport->rch)
 		endpoint_parent = parent_port->uport_dev;
 	else
@@ -174,14 +183,6 @@ static int cxl_mem_probe(struct device *dev)
 	if (rc)
 		return rc;
 
-	if (resource_size(&cxlds->pmem_res) && IS_ENABLED(CONFIG_CXL_PMEM)) {
-		rc = devm_cxl_add_nvdimm(cxlmd);
-		if (rc == -ENODEV)
-			dev_info(dev, "PMEM disabled by platform\n");
-		else
-			return rc;
-	}
-
 	/*
 	 * The kernel may be operating out of CXL memory on this device,
 	 * there is no spec defined way to determine whether this device