Using these attributes region label is added/deleted into LSA. These
attributes are called from userspace (ndctl) after region creation.

Signed-off-by: Neeraj Kumar <s.neeraj@samsung.com>
---
 Documentation/ABI/testing/sysfs-bus-cxl | 22 ++++++
 drivers/cxl/core/pmem_region.c          | 94 ++++++++++++++++++++++++-
 drivers/cxl/cxl.h                       |  1 +
 3 files changed, 116 insertions(+), 1 deletion(-)

diff --git a/Documentation/ABI/testing/sysfs-bus-cxl b/Documentation/ABI/testing/sysfs-bus-cxl
index 6b4e8c7a963d..5b47a02a99ef 100644
--- a/Documentation/ABI/testing/sysfs-bus-cxl
+++ b/Documentation/ABI/testing/sysfs-bus-cxl
@@ -615,3 +615,25 @@ Description:
 		The count is persistent across power loss and wraps back to 0
 		upon overflow. If this file is not present, the device does not
 		have the necessary support for dirty tracking.
+
+
+What:		/sys/bus/cxl/devices/regionZ/pmem_regionZ/region_label_update
+Date:		July, 2025
+KernelVersion:	v6.16
+Contact:	linux-cxl@vger.kernel.org
+Description:
+		(RW) Write a boolean 'true' string value to this attribute to
+		update cxl region information into LSA as region label. It
+		uses nvdimm nd_region_label_update() to update cxl region
+		information saved during cxl region creation into LSA. This
+		attribute must be called at last during cxl region creation.
+
+
+What:		/sys/bus/cxl/devices/regionZ/pmem_regionZ/region_label_delete
+Date:		July, 2025
+KernelVersion:	v6.16
+Contact:	linux-cxl@vger.kernel.org
+Description:
+		(WO) When a boolean 'true' is written to this attribute then
+		pmem_region driver deletes cxl region label from LSA using
+		nvdimm nd_region_label_delete()
diff --git a/drivers/cxl/core/pmem_region.c b/drivers/cxl/core/pmem_region.c
index cd1177d345e6..cc9ef2f9a2b3 100644
--- a/drivers/cxl/core/pmem_region.c
+++ b/drivers/cxl/core/pmem_region.c
@@ -45,9 +45,101 @@ static void cxl_pmem_region_release(struct device *dev)
 	kfree(cxlr_pmem);
 }
 
+static ssize_t region_label_update_store(struct device *dev,
+					 struct device_attribute *attr,
+					 const char *buf, size_t len)
+{
+	struct cxl_pmem_region *cxlr_pmem = to_cxl_pmem_region(dev);
+	struct cxl_region *cxlr = cxlr_pmem->cxlr;
+	struct cxl_region_params *p = &cxlr->params;
+	ssize_t rc;
+	bool update;
+
+	rc = kstrtobool(buf, &update);
+	if (rc)
+		return rc;
+
+	ACQUIRE(rwsem_write_kill, rwsem)(&cxl_rwsem.region);
+	rc = ACQUIRE_ERR(rwsem_write_kill, &rwsem);
+	if (rc)
+		return rc;
+
+	/* Region not yet committed */
+	if (update && p->state != CXL_CONFIG_COMMIT) {
+		dev_dbg(dev, "region not committed, can't update into LSA\n");
+		return -ENXIO;
+	}
+
+	if (cxlr && cxlr->cxlr_pmem && cxlr->cxlr_pmem->nd_region) {
+		rc = nd_region_label_update(cxlr->cxlr_pmem->nd_region);
+		if (!rc)
+			p->region_label_state = 1;
+	}
+
+	if (rc)
+		return rc;
+
+	return len;
+}
+
+static ssize_t region_label_update_show(struct device *dev,
+		struct device_attribute *attr,
+		char *buf)
+{
+	struct cxl_pmem_region *cxlr_pmem = to_cxl_pmem_region(dev);
+	struct cxl_region *cxlr = cxlr_pmem->cxlr;
+	struct cxl_region_params *p = &cxlr->params;
+	ssize_t rc;
+
+	ACQUIRE(rwsem_read_intr, rwsem)(&cxl_rwsem.region);
+	rc = ACQUIRE_ERR(rwsem_read_intr, &rwsem);
+	if (rc)
+		return rc;
+
+	return sysfs_emit(buf, "%d\n", p->region_label_state);
+}
+static DEVICE_ATTR_RW(region_label_update);
+
+static ssize_t region_label_delete_store(struct device *dev,
+				   struct device_attribute *attr,
+				   const char *buf, size_t len)
+{
+	struct cxl_pmem_region *cxlr_pmem = to_cxl_pmem_region(dev);
+	struct cxl_region *cxlr = cxlr_pmem->cxlr;
+	struct cxl_region_params *p = &cxlr->params;
+	ssize_t rc;
+
+	ACQUIRE(rwsem_write_kill, rwsem)(&cxl_rwsem.region);
+	rc = ACQUIRE_ERR(rwsem_write_kill, &rwsem);
+	if (rc)
+		return rc;
+
+	if (cxlr && cxlr->cxlr_pmem && cxlr->cxlr_pmem->nd_region) {
+		rc = nd_region_label_delete(cxlr->cxlr_pmem->nd_region);
+		if (rc)
+			return rc;
+	}
+
+	p->region_label_state = 0;
+
+	return len;
+}
+DEVICE_ATTR_WO(region_label_delete);
+
+static struct attribute *cxl_pmem_region_attrs[] = {
+	&dev_attr_region_label_update.attr,
+	&dev_attr_region_label_delete.attr,
+	NULL
+};
+
+struct attribute_group cxl_pmem_region_group = {
+	.attrs = cxl_pmem_region_attrs,
+};
+
 static const struct attribute_group *cxl_pmem_region_attribute_groups[] = {
 	&cxl_base_attribute_group,
-	NULL,
+	&cxl_pmem_region_group,
+	NULL
 };
 
 const struct device_type cxl_pmem_region_type = {
diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h
index b7592cc76192..f3faa419ddc5 100644
--- a/drivers/cxl/cxl.h
+++ b/drivers/cxl/cxl.h
@@ -475,6 +475,7 @@ enum cxl_config_state {
  */
 struct cxl_region_params {
 	enum cxl_config_state state;
+	int region_label_state;
 	uuid_t uuid;
 	int interleave_ways;
 	int interleave_granularity;
-- 
2.34.1

Hi Neeraj,

kernel test robot noticed the following build warnings:

[auto build test WARNING on f11a5f89910a7ae970fbce4fdc02d86a8ba8570f]

url:    https://github.com/intel-lab-lkp/linux/commits/Neeraj-Kumar/nvdimm-label-Introduce-NDD_CXL_LABEL-flag-to-set-cxl-label-format/20250730-202209
base:   f11a5f89910a7ae970fbce4fdc02d86a8ba8570f
patch link:    https://lore.kernel.org/r/20250730121209.303202-21-s.neeraj%40samsung.com
patch subject: [PATCH V2 20/20] cxl/pmem_region: Add sysfs attribute cxl region label updation/deletion
config: i386-randconfig-062-20250731 (https://download.01.org/0day-ci/archive/20250731/202507311814.ngKmd10b-lkp@intel.com/config)
compiler: gcc-12 (Debian 12.2.0-14+deb12u1) 12.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250731/202507311814.ngKmd10b-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202507311814.ngKmd10b-lkp@intel.com/

sparse warnings: (new ones prefixed by >>)
>> drivers/cxl/core/pmem_region.c:127:1: sparse: sparse: symbol 'dev_attr_region_label_delete' was not declared. Should it be static?
>> drivers/cxl/core/pmem_region.c:135:24: sparse: sparse: symbol 'cxl_pmem_region_group' was not declared. Should it be static?

vim +/dev_attr_region_label_delete +127 drivers/cxl/core/pmem_region.c

   102	
   103	static ssize_t region_label_delete_store(struct device *dev,
   104					   struct device_attribute *attr,
   105					   const char *buf, size_t len)
   106	{
   107		struct cxl_pmem_region *cxlr_pmem = to_cxl_pmem_region(dev);
   108		struct cxl_region *cxlr = cxlr_pmem->cxlr;
   109		struct cxl_region_params *p = &cxlr->params;
   110		ssize_t rc;
   111	
   112		ACQUIRE(rwsem_write_kill, rwsem)(&cxl_rwsem.region);
   113		rc = ACQUIRE_ERR(rwsem_write_kill, &rwsem);
   114		if (rc)
   115			return rc;
   116	
   117		if (cxlr && cxlr->cxlr_pmem && cxlr->cxlr_pmem->nd_region) {
   118			rc = nd_region_label_delete(cxlr->cxlr_pmem->nd_region);
   119			if (rc)
   120				return rc;
   121		}
   122	
   123		p->region_label_state = 0;
   124	
   125		return len;
   126	}
 > 127	DEVICE_ATTR_WO(region_label_delete);
   128	
   129	static struct attribute *cxl_pmem_region_attrs[] = {
   130		&dev_attr_region_label_update.attr,
   131		&dev_attr_region_label_delete.attr,
   132		NULL
   133	};
   134	
 > 135	struct attribute_group cxl_pmem_region_group = {
   136		.attrs = cxl_pmem_region_attrs,
   137	};
   138	

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki