[PATCH V5 11/17] cxl/region: Add devm_cxl_pmem_add_region() for pmem region creation

Neeraj Kumar
2026-01-09T12:45:28Z

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

Rename __create_region() to cxl_create_region(), which will be used
in later patch to create cxl region after fetching region information
from LSA.

Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Signed-off-by: Neeraj Kumar <s.neeraj@samsung.com>
---
drivers/cxl/core/core.h | 12 ++++
drivers/cxl/core/region.c | 137 ++++++++++++++++++++++++++++++++++++--
2 files changed, 144 insertions(+), 5 deletions(-)

diff --git a/drivers/cxl/core/core.h b/drivers/cxl/core/core.h
index 1fb66132b777..268f6d19ab9d 100644
--- a/drivers/cxl/core/core.h
+++ b/drivers/cxl/core/core.h
@@ -42,6 +42,10 @@ int cxl_get_poison_by_endpoint(struct cxl_port *port);
struct cxl_region *cxl_dpa_to_region(const struct cxl_memdev *cxlmd, u64 dpa);
u64 cxl_dpa_to_hpa(struct cxl_region *cxlr, const struct cxl_memdev *cxlmd,
u64 dpa);
+struct cxl_region *cxl_create_region(struct cxl_root_decoder *cxlrd,
+ enum cxl_partition_mode mode, int id,
+ struct cxl_pmem_region_params *pmem_params,
+ struct cxl_endpoint_decoder *cxled);

#else
static inline u64 cxl_dpa_to_hpa(struct cxl_region *cxlr,
@@ -71,6 +75,14 @@ static inline int cxl_region_init(void)
static inline void cxl_region_exit(void)
{
}
+static inline struct cxl_region *
+cxl_create_region(struct cxl_root_decoder *cxlrd,
+ enum cxl_partition_mode mode, int id,
+ struct cxl_pmem_region_params *params,
+ struct cxl_endpoint_decoder *cxled)
+{
+ return ERR_PTR(-EOPNOTSUPP);
+}
#define CXL_REGION_ATTR(x) NULL
#define CXL_REGION_TYPE(x) NULL
#define SET_CXL_REGION_ATTR(x)
diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c
index 26238fb5e8cf..13779aeacd8e 100644
--- a/drivers/cxl/core/region.c
+++ b/drivers/cxl/core/region.c
@@ -2621,6 +2621,127 @@ 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)
+{
+ int rc;
+
+ if (!size)
+ return -EINVAL;
+
+ if (!IS_ALIGNED(size, SZ_256M))
+ return -EINVAL;
+
+ rc = cxl_dpa_free(cxled);
+ if (rc)
+ return rc;
+
+ 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));
@@ -2638,8 +2759,10 @@ static ssize_t create_ram_region_show(struct device *dev,
return __create_region_show(to_cxl_root_decoder(dev), buf);
}

-static struct cxl_region *__create_region(struct cxl_root_decoder *cxlrd,
- enum cxl_partition_mode mode, int id)
+struct cxl_region *cxl_create_region(struct cxl_root_decoder *cxlrd,
+ enum cxl_partition_mode mode, int id,
+ struct cxl_pmem_region_params *pmem_params,
+ struct cxl_endpoint_decoder *cxled)
{
int rc;

@@ -2661,6 +2784,9 @@ static struct cxl_region *__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);
}

@@ -2675,7 +2801,7 @@ static ssize_t create_region_store(struct device *dev, const char *buf,
if (rc != 1)
return -EINVAL;

- cxlr = __create_region(cxlrd, mode, id);
+ cxlr = cxl_create_region(cxlrd, mode, id, NULL, NULL);
if (IS_ERR(cxlr))
return PTR_ERR(cxlr);

@@ -3644,8 +3770,9 @@ static struct cxl_region *construct_region(struct cxl_root_decoder *cxlrd,
struct cxl_region *cxlr;

do {
- cxlr = __create_region(cxlrd, cxlds->part[part].mode,
- atomic_read(&cxlrd->region_id));
+ cxlr = cxl_create_region(cxlrd, cxlds->part[part].mode,
+ atomic_read(&cxlrd->region_id),
+ NULL, NULL);
} while (IS_ERR(cxlr) && PTR_ERR(cxlr) == -EBUSY);

if (IS_ERR(cxlr)) {
--
2.34.1