[PATCH V5 10/17] cxl/mem: Refactor cxl pmem region auto-assembling

Neeraj Kumar
2026-01-09T12:45:27Z

In 84ec985944ef3, devm_cxl_add_nvdimm() sequence was changed and called
before devm_cxl_add_endpoint(). It's because cxl pmem region auto-assembly
used to get called at last in cxl_endpoint_port_probe(), which requires
cxl_nvd presence.

For cxl region persistency, region creation happens during nvdimm_probe
which need the completion of endpoint probe.

In order to accommodate both cxl pmem region auto-assembly and cxl region
persistency, refactored following

1. Re-Sequence devm_cxl_add_nvdimm() after devm_cxl_add_endpoint(). This
will be called only after successful completion of endpoint probe.

2. Create cxl_region_discovery() which performs pmem region
auto-assembly and remove cxl pmem region auto-assembly from
cxl_endpoint_port_probe()

3. Register cxl_region_discovery() with devm_cxl_add_memdev() which gets
called during cxl_pci_probe() in context of cxl_mem_probe()

4. As cxlmd->ops->probe() calls registered cxl_region_discovery(), so
move devm_cxl_add_nvdimm() before cxlmd->ops->probe(). It guarantees
both the completion of endpoint probe and cxl_nvd presence before
calling cxlmd->ops->probe().

Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Signed-off-by: Neeraj Kumar <s.neeraj@samsung.com>
---
drivers/cxl/core/region.c | 37 +++++++++++++++++++++++++++++++++++++
drivers/cxl/cxl.h | 5 +++++
drivers/cxl/mem.c | 18 +++++++++---------
drivers/cxl/pci.c | 4 +++-
drivers/cxl/port.c | 39 +--------------------------------------
5 files changed, 55 insertions(+), 48 deletions(-)

diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c
index ae899f68551f..26238fb5e8cf 100644
--- a/drivers/cxl/core/region.c
+++ b/drivers/cxl/core/region.c
@@ -3727,6 +3727,43 @@ int cxl_add_to_region(struct cxl_endpoint_decoder *cxled)
}
EXPORT_SYMBOL_NS_GPL(cxl_add_to_region, "CXL");

+static int discover_region(struct device *dev, void *unused)
+{
+ struct cxl_endpoint_decoder *cxled;
+ int rc;
+
+ if (!is_endpoint_decoder(dev))
+ return 0;
+
+ cxled = to_cxl_endpoint_decoder(dev);
+ if ((cxled->cxld.flags & CXL_DECODER_F_ENABLE) == 0)
+ return 0;
+
+ if (cxled->state != CXL_DECODER_STATE_AUTO)
+ return 0;
+
+ /*
+ * Region enumeration is opportunistic, if this add-event fails,
+ * continue to the next endpoint decoder.
+ */
+ rc = cxl_add_to_region(cxled);
+ if (rc)
+ dev_dbg(dev, "failed to add to region: %#llx-%#llx\n",
+ cxled->cxld.hpa_range.start, cxled->cxld.hpa_range.end);
+
+ return 0;
+}
+
+int cxl_region_discovery(struct cxl_memdev *cxlmd)
+{
+ struct cxl_port *port = cxlmd->endpoint;
+
+ device_for_each_child(&port->dev, NULL, discover_region);
+
+ return 0;
+}
+EXPORT_SYMBOL_NS_GPL(cxl_region_discovery, "CXL");
+
u64 cxl_port_get_spa_cache_alias(struct cxl_port *endpoint, u64 spa)
{
struct cxl_region_ref *iter;
diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h
index ba17fa86d249..684a0d1b441a 100644
--- a/drivers/cxl/cxl.h
+++ b/drivers/cxl/cxl.h
@@ -904,6 +904,7 @@ struct cxl_pmem_region *to_cxl_pmem_region(struct device *dev);
int cxl_add_to_region(struct cxl_endpoint_decoder *cxled);
struct cxl_dax_region *to_cxl_dax_region(struct device *dev);
u64 cxl_port_get_spa_cache_alias(struct cxl_port *endpoint, u64 spa);
+int cxl_region_discovery(struct cxl_memdev *cxlmd);
#else
static inline bool is_cxl_pmem_region(struct device *dev)
{
@@ -926,6 +927,10 @@ static inline u64 cxl_port_get_spa_cache_alias(struct cxl_port *endpoint,
{
return 0;
}
+static inline int cxl_region_discovery(struct cxl_memdev *cxlmd)
+{
+ return 0;
+}
#endif

void cxl_endpoint_parse_cdat(struct cxl_port *port);
diff --git a/drivers/cxl/mem.c b/drivers/cxl/mem.c
index 13d9e089ecaf..f5e3e2fca86c 100644
--- a/drivers/cxl/mem.c
+++ b/drivers/cxl/mem.c
@@ -115,15 +115,6 @@ static int cxl_mem_probe(struct device *dev)
return -ENXIO;
}

- if (cxl_pmem_size(cxlds) && 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
@@ -143,6 +134,15 @@ static int cxl_mem_probe(struct device *dev)
return rc;
}

+ if (cxl_pmem_size(cxlds) && 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 (cxlmd->ops) {
rc = cxlmd->ops->probe(cxlmd);
if (rc)
diff --git a/drivers/cxl/pci.c b/drivers/cxl/pci.c
index e21051d79b25..d56fdfe4b43b 100644
--- a/drivers/cxl/pci.c
+++ b/drivers/cxl/pci.c
@@ -907,6 +907,7 @@ static int cxl_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
struct cxl_memdev_state *mds;
struct cxl_dev_state *cxlds;
struct cxl_register_map map;
+ struct cxl_memdev_ops ops;
struct cxl_memdev *cxlmd;
int rc, pmu_count;
unsigned int i;
@@ -1006,7 +1007,8 @@ static int cxl_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
if (rc)
dev_dbg(&pdev->dev, "No CXL Features discovered\n");

- cxlmd = devm_cxl_add_memdev(&pdev->dev, cxlds, NULL);
+ ops.probe = cxl_region_discovery;
+ cxlmd = devm_cxl_add_memdev(&pdev->dev, cxlds, &ops);
if (IS_ERR(cxlmd))
return PTR_ERR(cxlmd);

diff --git a/drivers/cxl/port.c b/drivers/cxl/port.c
index d5fd0c5ae49b..ad98b2881fed 100644
--- a/drivers/cxl/port.c
+++ b/drivers/cxl/port.c
@@ -31,33 +31,6 @@ static void schedule_detach(void *cxlmd)
schedule_cxl_memdev_detach(cxlmd);
}

-static int discover_region(struct device *dev, void *unused)
-{
- struct cxl_endpoint_decoder *cxled;
- int rc;
-
- if (!is_endpoint_decoder(dev))
- return 0;
-
- cxled = to_cxl_endpoint_decoder(dev);
- if ((cxled->cxld.flags & CXL_DECODER_F_ENABLE) == 0)
- return 0;
-
- if (cxled->state != CXL_DECODER_STATE_AUTO)
- return 0;
-
- /*
- * Region enumeration is opportunistic, if this add-event fails,
- * continue to the next endpoint decoder.
- */
- rc = cxl_add_to_region(cxled);
- if (rc)
- dev_dbg(dev, "failed to add to region: %#llx-%#llx\n",
- cxled->cxld.hpa_range.start, cxled->cxld.hpa_range.end);
-
- return 0;
-}
-
static int cxl_switch_port_probe(struct cxl_port *port)
{
/* Reset nr_dports for rebind of driver */
@@ -83,17 +56,7 @@ static int cxl_endpoint_port_probe(struct cxl_port *port)
if (rc)
return rc;

- rc = devm_cxl_endpoint_decoders_setup(port);
- if (rc)
- return rc;
-
- /*
- * Now that all endpoint decoders are successfully enumerated, try to
- * assemble regions from committed decoders
- */
- device_for_each_child(&port->dev, NULL, discover_region);
-
- return 0;
+ return devm_cxl_endpoint_decoders_setup(port);
}

static int cxl_port_probe(struct device *dev)
--
2.34.1