[PATCH V3 19/20] cxl/pmem_region: Add sysfs attribute cxl region label updation/deletion

Neeraj Kumar
2025-09-17T13:42:15Z

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 | 91 ++++++++++++++++++++++++-
drivers/cxl/cxl.h | 1 +
3 files changed, 113 insertions(+), 1 deletion(-)

diff --git a/Documentation/ABI/testing/sysfs-bus-cxl b/Documentation/ABI/testing/sysfs-bus-cxl
index 6b4e8c7a963d..d6080fcf843a 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: Sept, 2025
+KernelVersion: v6.17
+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: Sept, 2025
+KernelVersion: v6.17
+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 55b80d587403..665b603c907b 100644
--- a/drivers/cxl/core/pmem_region.c
+++ b/drivers/cxl/core/pmem_region.c
@@ -45,9 +45,98 @@ 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;
+ 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 && cxlr && cxlr->params.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)
+ cxlr->params.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;
+ 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;
+ cxlr->params.region_label_state = 0;
+ }
+
+ return len;
+}
+static 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
+};
+
+static 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 0d576b359de6..f01f8c942fdf 100644
--- a/drivers/cxl/cxl.h
+++ b/drivers/cxl/cxl.h
@@ -484,6 +484,7 @@ 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