linux-kernel - [RFC PATCH 01/20] nvdimm/label: Introduce NDD_CXL

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Message-Id: <158453976.61750165203630.JavaMail.epsvc@epcpadp1new>
Date: Tue, 17 Jun 2025 18:09:25 +0530
From: Neeraj Kumar <s.neeraj@...sung.com>
To: dan.j.williams@...el.com, dave@...olabs.net,
	jonathan.cameron@...wei.com, dave.jiang@...el.com,
	alison.schofield@...el.com, vishal.l.verma@...el.com, ira.weiny@...el.com
Cc: a.manzanares@...sung.com, nifan.cxl@...il.com, anisa.su@...sung.com,
	vishak.g@...sung.com, krish.reddy@...sung.com, arun.george@...sung.com,
	alok.rathore@...sung.com, s.neeraj@...sung.com, neeraj.kernel@...il.com,
	linux-kernel@...r.kernel.org, linux-cxl@...r.kernel.org,
	nvdimm@...ts.linux.dev, gost.dev@...sung.com, cpgs@...sung.com
Subject: [RFC PATCH 01/20] nvdimm/label: Introduce NDD_CXL_LABEL flag to set
 cxl label format

NDD_CXL_LABEL is introduced to set cxl LSA 2.1 label format
Accordingly updated label index version

Signed-off-by: Neeraj Kumar <s.neeraj@...sung.com>
---
 drivers/nvdimm/dimm.c      |  1 +
 drivers/nvdimm/dimm_devs.c | 10 ++++++++++
 drivers/nvdimm/label.c     | 16 ++++++++++++----
 drivers/nvdimm/nd.h        |  1 +
 include/linux/libnvdimm.h  |  3 +++
 5 files changed, 27 insertions(+), 4 deletions(-)

diff --git a/drivers/nvdimm/dimm.c b/drivers/nvdimm/dimm.c
index 91d9163ee303..8753b5cd91cc 100644
--- a/drivers/nvdimm/dimm.c
+++ b/drivers/nvdimm/dimm.c
@@ -62,6 +62,7 @@ static int nvdimm_probe(struct device *dev)
 	if (rc < 0)
 		dev_dbg(dev, "failed to unlock dimm: %d\n", rc);
 
+	ndd->cxl = nvdimm_check_cxl_label_format(ndd->dev);
 
 	/*
 	 * EACCES failures reading the namespace label-area-properties
diff --git a/drivers/nvdimm/dimm_devs.c b/drivers/nvdimm/dimm_devs.c
index 21498d461fde..e8f545f889fd 100644
--- a/drivers/nvdimm/dimm_devs.c
+++ b/drivers/nvdimm/dimm_devs.c
@@ -18,6 +18,16 @@
 
 static DEFINE_IDA(dimm_ida);
 
+bool nvdimm_check_cxl_label_format(struct device *dev)
+{
+	struct nvdimm *nvdimm = to_nvdimm(dev);
+
+	if (test_bit(NDD_CXL_LABEL, &nvdimm->flags))
+		return true;
+
+	return false;
+}
+
 /*
  * Retrieve bus and dimm handle and return if this bus supports
  * get_config_data commands
diff --git a/drivers/nvdimm/label.c b/drivers/nvdimm/label.c
index 082253a3a956..48b5ba90216d 100644
--- a/drivers/nvdimm/label.c
+++ b/drivers/nvdimm/label.c
@@ -687,11 +687,19 @@ static int nd_label_write_index(struct nvdimm_drvdata *ndd, int index, u32 seq,
 		- (unsigned long) to_namespace_index(ndd, 0);
 	nsindex->labeloff = __cpu_to_le64(offset);
 	nsindex->nslot = __cpu_to_le32(nslot);
-	nsindex->major = __cpu_to_le16(1);
-	if (sizeof_namespace_label(ndd) < 256)
+
+	/* Support CXL LSA 2.1 label format */
+	if (ndd->cxl) {
+		nsindex->major = __cpu_to_le16(2);
 		nsindex->minor = __cpu_to_le16(1);
-	else
-		nsindex->minor = __cpu_to_le16(2);
+	} else {
+		nsindex->major = __cpu_to_le16(1);
+		if (sizeof_namespace_label(ndd) < 256)
+			nsindex->minor = __cpu_to_le16(1);
+		else
+			nsindex->minor = __cpu_to_le16(2);
+	}
+
 	nsindex->checksum = __cpu_to_le64(0);
 	if (flags & ND_NSINDEX_INIT) {
 		unsigned long *free = (unsigned long *) nsindex->free;
diff --git a/drivers/nvdimm/nd.h b/drivers/nvdimm/nd.h
index 5ca06e9a2d29..304f0e9904f1 100644
--- a/drivers/nvdimm/nd.h
+++ b/drivers/nvdimm/nd.h
@@ -522,6 +522,7 @@ void nvdimm_set_labeling(struct device *dev);
 void nvdimm_set_locked(struct device *dev);
 void nvdimm_clear_locked(struct device *dev);
 int nvdimm_security_setup_events(struct device *dev);
+bool nvdimm_check_cxl_label_format(struct device *dev);
 #if IS_ENABLED(CONFIG_NVDIMM_KEYS)
 int nvdimm_security_unlock(struct device *dev);
 #else
diff --git a/include/linux/libnvdimm.h b/include/linux/libnvdimm.h
index e772aae71843..0a55900842c8 100644
--- a/include/linux/libnvdimm.h
+++ b/include/linux/libnvdimm.h
@@ -44,6 +44,9 @@ enum {
 	/* dimm provider wants synchronous registration by __nvdimm_create() */
 	NDD_REGISTER_SYNC = 8,
 
+	/* dimm supports region labels (LSA Format 2.1) */
+	NDD_CXL_LABEL = 9,
+
 	/* need to set a limit somewhere, but yes, this is likely overkill */
 	ND_IOCTL_MAX_BUFLEN = SZ_4M,
 	ND_CMD_MAX_ELEM = 5,
-- 
2.34.1