diff --git a/Documentation/cxl/lib/libcxl.txt b/Documentation/cxl/lib/libcxl.txt
index 7a38ce4..50b0c9c 100644
--- a/Documentation/cxl/lib/libcxl.txt
+++ b/Documentation/cxl/lib/libcxl.txt
@@ -508,6 +508,75 @@ device to represent the root of a PCI device hierarchy. The
 cxl_target_get_physical_node() helper returns the device name of that
 companion object in the PCI hierarchy.
 
+==== REGIONS
+A CXL region is composed of one or more slices of CXL memdevs, with configurable
+interleave settings - both the number of interleave ways, and the interleave
+granularity. In terms of hierarchy, it is the child of a CXL root decoder. A root
+decoder (recall that this corresponds to an ACPI CEDT.CFMWS 'window'), may have
+multiple child regions, but a region is strictly tied to one root decoder.
+
+The slices that compose a region are called mappings. A mapping is a
+tuple of 'memdev', 'endpoint decoder', and the 'position'.
+
+===== REGION: Enumeration
+----
+struct cxl_region *cxl_region_get_first(struct cxl_decoder *decoder);
+struct cxl_region *cxl_region_get_next(struct cxl_region *region);
+
+#define cxl_region_foreach(decoder, region)                                    \
+	for (region = cxl_region_get_first(decoder); region != NULL;           \
+	     region = cxl_region_get_next(region))
+
+#define cxl_region_foreach_safe(decoder, region, _region)                      \
+	for (region = cxl_region_get_first(decoder),                           \
+	     _region = region ? cxl_region_get_next(region) : NULL;            \
+	     region != NULL;                                                   \
+	     region = _region,                                                 \
+	     _region = _region ? cxl_region_get_next(_region) : NULL)
+----
+
+===== REGION: Attributes
+----
+int cxl_region_get_id(struct cxl_region *region);
+const char *cxl_region_get_devname(struct cxl_region *region);
+void cxl_region_get_uuid(struct cxl_region *region, uuid_t uu);
+unsigned long long cxl_region_get_size(struct cxl_region *region);
+unsigned long long cxl_region_get_resource(struct cxl_region *region);
+unsigned int cxl_region_get_interleave_ways(struct cxl_region *region);
+unsigned int cxl_region_get_interleave_granularity(struct cxl_region *region);
+struct cxl_decoder *cxl_region_get_target_decoder(struct cxl_region *region,
+						  int position);
+int cxl_region_set_size(struct cxl_region *region, unsigned long long size);
+int cxl_region_set_uuid(struct cxl_region *region, uuid_t uu);
+int cxl_region_set_interleave_ways(struct cxl_region *region,
+				   unsigned int ways);
+int cxl_region_set_interleave_granularity(struct cxl_region *region,
+					  unsigned int granularity);
+int cxl_region_set_target(struct cxl_region *region, int position,
+			  struct cxl_decoder *decoder);
+int cxl_region_clear_target(struct cxl_region *region, int position);
+int cxl_region_clear_all_targets(struct cxl_region *region);
+int cxl_region_decode_commit(struct cxl_region *region);
+int cxl_region_decode_reset(struct cxl_region *region);
+----
+
+A region's resource attribute is the Host Physical Address at which the region's
+address space starts. The region's address space is a subset of the parent root
+decoder's address space.
+
+The interleave ways is the number of component memdevs participating in the
+region.
+
+The interleave granularity depends on the root decoder's granularity, and must
+follow the interleave math rules defined in the CXL spec.
+
+Regions have a list of targets 0..N, which are programmed with the name of an
+endpoint decoder under each participating memdev.
+
+The 'decode_commit' and 'decode_reset' attributes reserve and free DPA space
+on a given memdev by allocating an endpoint decoder, and programming it based
+on the region's interleave geometry.
+
 include::../../copyright.txt[]
 
 SEE ALSO
diff --git a/cxl/lib/private.h b/cxl/lib/private.h
index 5e2fdd5..8bc9620 100644
--- a/cxl/lib/private.h
+++ b/cxl/lib/private.h
@@ -110,6 +110,8 @@ struct cxl_decoder {
 	int nr_targets;
 	int id;
 	enum cxl_decoder_mode mode;
+	unsigned int interleave_ways;
+	unsigned int interleave_granularity;
 	bool pmem_capable;
 	bool volatile_capable;
 	bool mem_capable;
diff --git a/cxl/lib/libcxl.c b/cxl/lib/libcxl.c
index 1879c15..2b1cf7e 100644
--- a/cxl/lib/libcxl.c
+++ b/cxl/lib/libcxl.c
@@ -17,6 +17,7 @@
 #include <ccan/minmax/minmax.h>
 #include <ccan/array_size/array_size.h>
 #include <ccan/short_types/short_types.h>
+#include <ccan/container_of/container_of.h>
 
 #include <util/log.h>
 #include <util/list.h>
@@ -420,6 +421,40 @@ CXL_EXPORT int cxl_region_enable(struct cxl_region *region)
 	return 0;
 }
 
+static int cxl_region_delete_name(struct cxl_decoder *decoder,
+				  const char *devname)
+{
+	struct cxl_ctx *ctx = cxl_decoder_get_ctx(decoder);
+	char *path = decoder->dev_buf;
+	int rc;
+
+	sprintf(path, "%s/delete_region", decoder->dev_path);
+	rc = sysfs_write_attr(ctx, path, devname);
+	if (rc != 0) {
+		err(ctx, "error deleting region: %s\n", strerror(-rc));
+		return rc;
+	}
+	return 0;
+}
+
+CXL_EXPORT int cxl_region_delete(struct cxl_region *region)
+{
+	struct cxl_decoder *decoder = cxl_region_get_decoder(region);
+	const char *devname = cxl_region_get_devname(region);
+	int rc;
+
+	if (cxl_region_is_enabled(region))
+		return -EBUSY;
+
+	rc = cxl_region_delete_name(decoder, devname);
+	if (rc != 0)
+		return rc;
+
+	decoder->regions_init = 0;
+	free_region(region, &decoder->regions);
+	return 0;
+}
+
 static void *add_cxl_region(void *parent, int id, const char *cxlregion_base)
 {
 	const char *devname = devpath_to_devname(cxlregion_base);
@@ -599,6 +634,258 @@ cxl_region_get_interleave_granularity(struct cxl_region *region)
 	return region->interleave_granularity;
 }
 
+CXL_EXPORT struct cxl_decoder *
+cxl_region_get_target_decoder(struct cxl_region *region, int position)
+{
+	const char *devname = cxl_region_get_devname(region);
+	struct cxl_ctx *ctx = cxl_region_get_ctx(region);
+	int len = region->buf_len, rc;
+	char *path = region->dev_buf;
+	struct cxl_decoder *decoder;
+	char buf[SYSFS_ATTR_SIZE];
+
+	if (snprintf(path, len, "%s/target%d", region->dev_path, position) >=
+	    len) {
+		err(ctx, "%s: buffer too small!\n", devname);
+		return NULL;
+	}
+
+	rc = sysfs_read_attr(ctx, path, buf);
+	if (rc < 0) {
+		err(ctx, "%s: error reading target%d: %s\n", devname,
+		    position, strerror(-rc));
+		return NULL;
+	}
+
+	decoder = cxl_decoder_get_by_name(ctx, buf);
+	if (!decoder) {
+		err(ctx, "%s: error locating decoder for target%d\n", devname,
+		    position);
+		return NULL;
+	}
+	return decoder;
+}
+
+CXL_EXPORT int cxl_region_set_size(struct cxl_region *region,
+				   unsigned long long size)
+{
+	const char *devname = cxl_region_get_devname(region);
+	struct cxl_ctx *ctx = cxl_region_get_ctx(region);
+	int len = region->buf_len, rc;
+	char *path = region->dev_buf;
+	char buf[SYSFS_ATTR_SIZE];
+
+	if (size == 0) {
+		dbg(ctx, "%s: cannot use %s to delete a region\n", __func__,
+		    devname);
+		return -EINVAL;
+	}
+
+	if (snprintf(path, len, "%s/size", region->dev_path) >= len) {
+		err(ctx, "%s: buffer too small!\n", devname);
+		return -ENXIO;
+	}
+
+	sprintf(buf, "%#llx\n", size);
+	rc = sysfs_write_attr(ctx, path, buf);
+	if (rc < 0)
+		return rc;
+
+	region->size = size;
+
+	return 0;
+}
+
+CXL_EXPORT int cxl_region_set_uuid(struct cxl_region *region, uuid_t uu)
+{
+	const char *devname = cxl_region_get_devname(region);
+	struct cxl_ctx *ctx = cxl_region_get_ctx(region);
+	int len = region->buf_len, rc;
+	char *path = region->dev_buf;
+	char uuid[SYSFS_ATTR_SIZE];
+
+	if (snprintf(path, len, "%s/uuid", region->dev_path) >= len) {
+		err(ctx, "%s: buffer too small!\n", devname);
+		return -ENXIO;
+	}
+
+	uuid_unparse(uu, uuid);
+	rc = sysfs_write_attr(ctx, path, uuid);
+	if (rc != 0)
+		return rc;
+	memcpy(region->uuid, uu, sizeof(uuid_t));
+	return 0;
+}
+
+CXL_EXPORT int cxl_region_set_interleave_ways(struct cxl_region *region,
+					      unsigned int ways)
+{
+	const char *devname = cxl_region_get_devname(region);
+	struct cxl_ctx *ctx = cxl_region_get_ctx(region);
+	int len = region->buf_len, rc;
+	char *path = region->dev_buf;
+	char buf[SYSFS_ATTR_SIZE];
+
+	if (snprintf(path, len, "%s/interleave_ways",
+		     region->dev_path) >= len) {
+		err(ctx, "%s: buffer too small!\n", devname);
+		return -ENXIO;
+	}
+
+	sprintf(buf, "%u\n", ways);
+	rc = sysfs_write_attr(ctx, path, buf);
+	if (rc < 0)
+		return rc;
+
+	region->interleave_ways = ways;
+
+	return 0;
+}
+
+CXL_EXPORT int cxl_region_set_interleave_granularity(struct cxl_region *region,
+						     unsigned int granularity)
+{
+	const char *devname = cxl_region_get_devname(region);
+	struct cxl_ctx *ctx = cxl_region_get_ctx(region);
+	int len = region->buf_len, rc;
+	char *path = region->dev_buf;
+	char buf[SYSFS_ATTR_SIZE];
+
+	if (snprintf(path, len, "%s/interleave_granularity",
+		     region->dev_path) >= len) {
+		err(ctx, "%s: buffer too small!\n", devname);
+		return -ENXIO;
+	}
+
+	sprintf(buf, "%u\n", granularity);
+	rc = sysfs_write_attr(ctx, path, buf);
+	if (rc < 0)
+		return rc;
+
+	region->interleave_granularity = granularity;
+
+	return 0;
+}
+
+static int region_write_target(struct cxl_region *region, int position,
+			       struct cxl_decoder *decoder)
+{
+	const char *devname = cxl_region_get_devname(region);
+	struct cxl_ctx *ctx = cxl_region_get_ctx(region);
+	int len = region->buf_len, rc;
+	char *path = region->dev_buf;
+	const char *dec_name = "";
+
+	if (decoder)
+		dec_name = cxl_decoder_get_devname(decoder);
+
+	if (snprintf(path, len, "%s/target%d", region->dev_path, position) >=
+	    len) {
+		err(ctx, "%s: buffer too small!\n", devname);
+		return -ENXIO;
+	}
+
+	rc = sysfs_write_attr(ctx, path, dec_name);
+	if (rc < 0)
+		return rc;
+
+	return 0;
+}
+
+CXL_EXPORT int cxl_region_set_target(struct cxl_region *region, int position,
+				     struct cxl_decoder *decoder)
+{
+	if (!decoder)
+		return -ENXIO;
+
+	return region_write_target(region, position, decoder);
+}
+
+CXL_EXPORT int cxl_region_clear_target(struct cxl_region *region, int position)
+{
+	const char *devname = cxl_region_get_devname(region);
+	struct cxl_ctx *ctx = cxl_region_get_ctx(region);
+	int rc;
+
+	if (cxl_region_is_enabled(region)) {
+		err(ctx, "%s: can't clear targets on an active region\n",
+		    devname);
+		return -EBUSY;
+	}
+
+	rc = region_write_target(region, position, NULL);
+	if (rc) {
+		err(ctx, "%s: error clearing target%d: %s\n",
+		    devname, position, strerror(-rc));
+		return rc;
+	}
+
+	return 0;
+}
+
+CXL_EXPORT int cxl_region_clear_all_targets(struct cxl_region *region)
+{
+	const char *devname = cxl_region_get_devname(region);
+	struct cxl_ctx *ctx = cxl_region_get_ctx(region);
+	unsigned int ways, i;
+	int rc;
+
+	if (cxl_region_is_enabled(region)) {
+		err(ctx, "%s: can't clear targets on an active region\n",
+		    devname);
+		return -EBUSY;
+	}
+
+	ways = cxl_region_get_interleave_ways(region);
+	if (ways == 0 || ways == UINT_MAX)
+		return -ENXIO;
+
+	for (i = 0; i < ways; i++) {
+		rc = region_write_target(region, i, NULL);
+		if (rc) {
+			err(ctx, "%s: error clearing target%d: %s\n",
+			    devname, i, strerror(-rc));
+			return rc;
+		}
+	}
+
+	return 0;
+}
+
+static int set_region_decode(struct cxl_region *region,
+			     enum cxl_decode_state decode_state)
+{
+	const char *devname = cxl_region_get_devname(region);
+	struct cxl_ctx *ctx = cxl_region_get_ctx(region);
+	int len = region->buf_len, rc;
+	char *path = region->dev_buf;
+	char buf[SYSFS_ATTR_SIZE];
+
+	if (snprintf(path, len, "%s/commit", region->dev_path) >= len) {
+		err(ctx, "%s: buffer too small!\n", devname);
+		return -ENXIO;
+	}
+
+	sprintf(buf, "%d\n", decode_state);
+	rc = sysfs_write_attr(ctx, path, buf);
+	if (rc < 0)
+		return rc;
+
+	region->decode_state = decode_state;
+
+	return 0;
+}
+
+CXL_EXPORT int cxl_region_decode_commit(struct cxl_region *region)
+{
+	return set_region_decode(region, CXL_DECODE_COMMIT);
+}
+
+CXL_EXPORT int cxl_region_decode_reset(struct cxl_region *region)
+{
+	return set_region_decode(region, CXL_DECODE_RESET);
+}
+
 static struct cxl_decoder *__cxl_port_match_decoder(struct cxl_port *port,
 						    const char *ident)
 {
@@ -633,8 +920,8 @@ static struct cxl_decoder *cxl_port_find_decoder(struct cxl_port *port,
 	return NULL;
 }
 
-static struct cxl_decoder *cxl_decoder_get_by_name(struct cxl_ctx *ctx,
-						   const char *ident)
+CXL_EXPORT struct cxl_decoder *cxl_decoder_get_by_name(struct cxl_ctx *ctx,
+						       const char *ident)
 {
 	struct cxl_bus *bus;
 
@@ -1398,6 +1685,18 @@ static void *add_cxl_decoder(void *parent, int id, const char *cxldecoder_base)
 	} else
 		decoder->mode = CXL_DECODER_MODE_NONE;
 
+	sprintf(path, "%s/interleave_granularity", cxldecoder_base);
+	if (sysfs_read_attr(ctx, path, buf) < 0)
+		decoder->interleave_granularity = UINT_MAX;
+	else
+		decoder->interleave_granularity = strtoul(buf, NULL, 0);
+
+	sprintf(path, "%s/interleave_ways", cxldecoder_base);
+	if (sysfs_read_attr(ctx, path, buf) < 0)
+		decoder->interleave_ways = UINT_MAX;
+	else
+		decoder->interleave_ways = strtoul(buf, NULL, 0);
+
 	switch (port->type) {
 	case CXL_PORT_ENDPOINT:
 		sprintf(path, "%s/dpa_resource", cxldecoder_base);
@@ -1730,6 +2029,66 @@ CXL_EXPORT bool cxl_decoder_is_locked(struct cxl_decoder *decoder)
 	return decoder->locked;
 }
 
+CXL_EXPORT unsigned int
+cxl_decoder_get_interleave_granularity(struct cxl_decoder *decoder)
+{
+	return decoder->interleave_granularity;
+}
+
+CXL_EXPORT unsigned int
+cxl_decoder_get_interleave_ways(struct cxl_decoder *decoder)
+{
+	return decoder->interleave_ways;
+}
+
+CXL_EXPORT struct cxl_region *
+cxl_decoder_create_pmem_region(struct cxl_decoder *decoder)
+{
+	struct cxl_ctx *ctx = cxl_decoder_get_ctx(decoder);
+	char *path = decoder->dev_buf;
+	char buf[SYSFS_ATTR_SIZE];
+	struct cxl_region *region;
+	int rc;
+
+	sprintf(path, "%s/create_pmem_region", decoder->dev_path);
+	rc = sysfs_read_attr(ctx, path, buf);
+	if (rc < 0) {
+		err(ctx, "failed to read new region name: %s\n",
+		    strerror(-rc));
+		return NULL;
+	}
+
+	rc = sysfs_write_attr(ctx, path, buf);
+	if (rc < 0) {
+		err(ctx, "failed to write new region name: %s\n",
+		    strerror(-rc));
+		return NULL;
+	}
+
+	/* Force a re-init of regions so that the new one can be discovered */
+	decoder->regions_init = 0;
+
+	/* create_region was successful, walk to the new region */
+	cxl_region_foreach(decoder, region) {
+		const char *devname = cxl_region_get_devname(region);
+
+		if (strcmp(devname, buf) == 0)
+			goto found;
+	}
+
+	/*
+	 * If walking to the region we just created failed, something has gone
+	 * very wrong. Attempt to delete it to avoid leaving a dangling region
+	 * id behind.
+	 */
+	err(ctx, "failed to add new region to libcxl\n");
+	cxl_region_delete_name(decoder, buf);
+	return NULL;
+
+ found:
+	return region;
+}
+
 CXL_EXPORT int cxl_decoder_get_nr_targets(struct cxl_decoder *decoder)
 {
 	return decoder->nr_targets;
@@ -1740,6 +2099,24 @@ CXL_EXPORT const char *cxl_decoder_get_devname(struct cxl_decoder *decoder)
 	return devpath_to_devname(decoder->dev_path);
 }
 
+CXL_EXPORT struct cxl_memdev *
+cxl_decoder_get_memdev(struct cxl_decoder *decoder)
+{
+	struct cxl_port *port = cxl_decoder_get_port(decoder);
+	struct cxl_endpoint *ep;
+
+	if (!port)
+		return NULL;
+	if (!cxl_port_is_endpoint(port))
+		return NULL;
+
+	ep = container_of(port, struct cxl_endpoint, port);
+	if (!ep)
+		return NULL;
+
+	return cxl_endpoint_get_memdev(ep);
+}
+
 CXL_EXPORT struct cxl_target *cxl_target_get_first(struct cxl_decoder *decoder)
 {
 	return list_top(&decoder->targets, struct cxl_target, list);
diff --git a/cxl/libcxl.h b/cxl/libcxl.h
index 19d94e4..69d9c09 100644
--- a/cxl/libcxl.h
+++ b/cxl/libcxl.h
@@ -195,7 +195,13 @@ bool cxl_decoder_is_volatile_capable(struct cxl_decoder *decoder);
 bool cxl_decoder_is_mem_capable(struct cxl_decoder *decoder);
 bool cxl_decoder_is_accelmem_capable(struct cxl_decoder *decoder);
 bool cxl_decoder_is_locked(struct cxl_decoder *decoder);
-
+unsigned int
+cxl_decoder_get_interleave_granularity(struct cxl_decoder *decoder);
+unsigned int cxl_decoder_get_interleave_ways(struct cxl_decoder *decoder);
+struct cxl_region *cxl_decoder_create_pmem_region(struct cxl_decoder *decoder);
+struct cxl_decoder *cxl_decoder_get_by_name(struct cxl_ctx *ctx,
+					    const char *ident);
+struct cxl_memdev *cxl_decoder_get_memdev(struct cxl_decoder *decoder);
 #define cxl_decoder_foreach(port, decoder)                                     \
 	for (decoder = cxl_decoder_get_first(port); decoder != NULL;           \
 	     decoder = cxl_decoder_get_next(decoder))
@@ -244,6 +250,7 @@ int cxl_region_decode_is_committed(struct cxl_region *region);
 int cxl_region_is_enabled(struct cxl_region *region);
 int cxl_region_disable(struct cxl_region *region);
 int cxl_region_enable(struct cxl_region *region);
+int cxl_region_delete(struct cxl_region *region);
 struct cxl_ctx *cxl_region_get_ctx(struct cxl_region *region);
 struct cxl_decoder *cxl_region_get_decoder(struct cxl_region *region);
 int cxl_region_get_id(struct cxl_region *region);
@@ -253,6 +260,20 @@ unsigned long long cxl_region_get_size(struct cxl_region *region);
 unsigned long long cxl_region_get_resource(struct cxl_region *region);
 unsigned int cxl_region_get_interleave_ways(struct cxl_region *region);
 unsigned int cxl_region_get_interleave_granularity(struct cxl_region *region);
+struct cxl_decoder *cxl_region_get_target_decoder(struct cxl_region *region,
+						  int position);
+int cxl_region_set_size(struct cxl_region *region, unsigned long long size);
+int cxl_region_set_uuid(struct cxl_region *region, uuid_t uu);
+int cxl_region_set_interleave_ways(struct cxl_region *region,
+				   unsigned int ways);
+int cxl_region_set_interleave_granularity(struct cxl_region *region,
+					  unsigned int granularity);
+int cxl_region_set_target(struct cxl_region *region, int position,
+			  struct cxl_decoder *decoder);
+int cxl_region_clear_target(struct cxl_region *region, int position);
+int cxl_region_clear_all_targets(struct cxl_region *region);
+int cxl_region_decode_commit(struct cxl_region *region);
+int cxl_region_decode_reset(struct cxl_region *region);
 
 #define cxl_region_foreach(decoder, region)                                    \
 	for (region = cxl_region_get_first(decoder); region != NULL;           \
diff --git a/cxl/lib/libcxl.sym b/cxl/lib/libcxl.sym
index e410298..cb23a0b 100644
--- a/cxl/lib/libcxl.sym
+++ b/cxl/lib/libcxl.sym
@@ -140,6 +140,7 @@ global:
 	cxl_decoder_is_mem_capable;
 	cxl_decoder_is_accelmem_capable;
 	cxl_decoder_is_locked;
+	cxl_decoder_create_pmem_region;
 	cxl_target_get_first;
 	cxl_target_get_next;
 	cxl_target_get_decoder;
@@ -183,6 +184,7 @@ global:
 	cxl_region_is_enabled;
 	cxl_region_disable;
 	cxl_region_enable;
+	cxl_region_delete;
 	cxl_region_get_ctx;
 	cxl_region_get_decoder;
 	cxl_region_get_id;
@@ -192,9 +194,23 @@ global:
 	cxl_region_get_resource;
 	cxl_region_get_interleave_ways;
 	cxl_region_get_interleave_granularity;
+	cxl_region_get_target_decoder;
+	cxl_region_set_size;
+	cxl_region_set_uuid;
+	cxl_region_set_interleave_ways;
+	cxl_region_set_interleave_granularity;
+	cxl_region_set_target;
+	cxl_region_clear_target;
+	cxl_region_clear_all_targets;
+	cxl_region_decode_commit;
+	cxl_region_decode_reset;
 	cxl_mapping_get_first;
 	cxl_mapping_get_next;
 	cxl_mapping_get_decoder;
 	cxl_mapping_get_region;
 	cxl_mapping_get_position;
+	cxl_decoder_get_by_name;
+	cxl_decoder_get_memdev;
+	cxl_decoder_get_interleave_granularity;
+	cxl_decoder_get_interleave_ways;
 } LIBCXL_2;
