[PATCH V6 12/18] cxl/region: Add devm_cxl_pmem_add_region() for pmem region creation

Neeraj Kumar
2026-01-23T11:31:45Z

devm_cxl_pmem_add_region() is used to create cxl region based on region
information scanned from LSA.

devm_cxl_add_region() is used to just allocate cxlr and its fields are
filled later by userspace tool using device attributes (*_store()).

Inspiration for devm_cxl_pmem_add_region() is taken from these device
attributes (_store*) calls. It allocates cxlr and fills information
parsed from LSA and calls device_add(&cxlr->dev) to initiate further
region creation porbes

Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Signed-off-by: Neeraj Kumar <s.neeraj@samsung.com>
---
drivers/cxl/core/region.c | 118 ++++++++++++++++++++++++++++++++++++++
1 file changed, 118 insertions(+)

diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c
index 2e60e5e72551..e384eacc46ae 100644
--- a/drivers/cxl/core/region.c
+++ b/drivers/cxl/core/region.c
@@ -2621,6 +2621,121 @@ static struct cxl_region *devm_cxl_add_region(struct cxl_root_decoder *cxlrd,
return ERR_PTR(rc);
}

+static ssize_t alloc_region_hpa(struct cxl_region *cxlr, u64 size)
+{
+ int rc;
+
+ if (!size)
+ return -EINVAL;
+
+ ACQUIRE(rwsem_write_kill, rwsem)(&cxl_rwsem.region);
+ if ((rc = ACQUIRE_ERR(rwsem_write_kill, &rwsem)))
+ return rc;
+
+ return alloc_hpa(cxlr, size);
+}
+
+static ssize_t alloc_region_dpa(struct cxl_endpoint_decoder *cxled, u64 size)
+{
+ if (!size)
+ return -EINVAL;
+
+ if (!IS_ALIGNED(size, SZ_256M))
+ return -EINVAL;
+
+ return cxl_dpa_alloc(cxled, size);
+}
+
+static struct cxl_region *
+cxl_pmem_region_prep(struct cxl_root_decoder *cxlrd, int id,
+ struct cxl_pmem_region_params *params,
+ struct cxl_endpoint_decoder *cxled,
+ enum cxl_decoder_type type)
+{
+ struct cxl_region_params *p;
+ struct device *dev;
+ int rc;
+
+ struct cxl_region *cxlr __free(put_cxl_region) =
+ cxl_region_alloc(cxlrd, id);
+ if (IS_ERR(cxlr))
+ return cxlr;
+
+ dev = &cxlr->dev;
+ rc = dev_set_name(dev, "region%d", id);
+ if (rc)
+ return ERR_PTR(rc);
+
+ cxlr->mode = CXL_PARTMODE_PMEM;
+ cxlr->type = type;
+
+ p = &cxlr->params;
+ p->uuid = params->uuid;
+ p->interleave_ways = params->nlabel;
+ p->interleave_granularity = params->ig;
+
+ rc = alloc_region_hpa(cxlr, params->rawsize);
+ if (rc)
+ return ERR_PTR(rc);
+
+ rc = cxl_dpa_set_part(cxled, CXL_PARTMODE_PMEM);
+ if (rc)
+ return ERR_PTR(rc);
+
+ rc = alloc_region_dpa(cxled, params->rawsize);
+ if (rc)
+ return ERR_PTR(rc);
+
+ /*
+ * TODO: Currently we have support of interleave_way == 1, where
+ * we can only have one region per mem device. It means mem device
+ * position (params->position) will always be 0. It is therefore
+ * attaching only one target at params->position
+ */
+ if (params->position)
+ return ERR_PTR(-EOPNOTSUPP);
+
+ rc = attach_target(cxlr, cxled, params->position, TASK_INTERRUPTIBLE);
+ if (rc)
+ return ERR_PTR(rc);
+
+ rc = __commit(cxlr);
+ if (rc)
+ return ERR_PTR(rc);
+
+ rc = device_add(dev);
+ if (rc)
+ return ERR_PTR(rc);
+
+ return no_free_ptr(cxlr);
+}
+
+static struct cxl_region *
+devm_cxl_pmem_add_region(struct cxl_root_decoder *cxlrd, int id,
+ struct cxl_pmem_region_params *params,
+ struct cxl_endpoint_decoder *cxled,
+ enum cxl_decoder_type type)
+{
+ struct cxl_port *root_port;
+ struct cxl_region *cxlr;
+ int rc;
+
+ cxlr = cxl_pmem_region_prep(cxlrd, id, params, cxled, type);
+ if (IS_ERR(cxlr))
+ return cxlr;
+
+ root_port = to_cxl_port(cxlrd->cxlsd.cxld.dev.parent);
+ rc = devm_add_action_or_reset(root_port->uport_dev,
+ unregister_region, cxlr);
+ if (rc)
+ return ERR_PTR(rc);
+
+ dev_dbg(root_port->uport_dev, "%s: created %s\n",
+ dev_name(&cxlrd->cxlsd.cxld.dev), dev_name(&cxlr->dev));
+
+ return cxlr;
+}
+
static ssize_t __create_region_show(struct cxl_root_decoder *cxlrd, char *buf)
{
return sysfs_emit(buf, "region%u\n", atomic_read(&cxlrd->region_id));
@@ -2663,6 +2778,9 @@ struct cxl_region *cxl_create_region(struct cxl_root_decoder *cxlrd,
return ERR_PTR(-EBUSY);
}

+ if (pmem_params)
+ return devm_cxl_pmem_add_region(cxlrd, id, pmem_params, cxled,
+ CXL_DECODER_HOSTONLYMEM);
return devm_cxl_add_region(cxlrd, id, mode, CXL_DECODER_HOSTONLYMEM);
}

--
2.34.1