cxl/region: Store HPA range in struct cxl_region

Each region has a known host physical address (HPA) range it is
assigned to. Endpoint decoders assigned to a region share the same HPA
range. The region's address range is the system's physical address
(SPA) range.

Endpoint decoders in systems that need address translation use HPAs
which are not SPAs. To make the SPA range accessible to the endpoint
decoders, store and track the region's SPA range in struct cxl_region.
Introduce the @hpa_range member to the struct. Now, the SPA range of
an endpoint decoder can be determined based on its assigned region.

Patch is a prerequisite to implement address translation which uses
struct cxl_region to store all relevant region and interleaving
parameters.

Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>
Reviewed-by: Gregory Price <gourry@gourry.net>
Reviewed-by: Alison Schofield <alison.schofield@intel.com>
Signed-off-by: Robert Richter <rrichter@amd.com>
Link: https://patch.msgid.link/20260114164837.1076338-4-rrichter@amd.com
Signed-off-by: Dave Jiang <dave.jiang@intel.com>

Author: Robert Richter

drivers/cxl/core/region.c

@@ -664,6 +664,8 @@ static int alloc_hpa(struct cxl_region *cxlr, resource_size_t size)
 		return PTR_ERR(res);
 	}
 
+	cxlr->hpa_range = DEFINE_RANGE(res->start, res->end);
+
 	p->res = res;
 	p->state = CXL_CONFIG_INTERLEAVE_ACTIVE;
 
@@ -700,6 +702,8 @@ static int free_hpa(struct cxl_region *cxlr)
 	if (p->state >= CXL_CONFIG_ACTIVE)
 		return -EBUSY;
 
+	cxlr->hpa_range = DEFINE_RANGE(0, -1);
+
 	cxl_region_iomem_release(cxlr);
 	p->state = CXL_CONFIG_IDLE;
 	return 0;
@@ -2453,6 +2457,8 @@ static void unregister_region(void *_cxlr)
 	for (i = 0; i < p->interleave_ways; i++)
 		detach_target(cxlr, i);
 
+	cxlr->hpa_range = DEFINE_RANGE(0, -1);
+
 	cxl_region_iomem_release(cxlr);
 	put_device(&cxlr->dev);
 }
@@ -3579,6 +3585,7 @@ static int __construct_region(struct cxl_region *cxlr,
 	}
 
 	set_bit(CXL_REGION_F_AUTO, &cxlr->flags);
+	cxlr->hpa_range = *hpa_range;
 
 	res = kmalloc(sizeof(*res), GFP_KERNEL);
 	if (!res)

drivers/cxl/cxl.h

@@ -530,6 +530,7 @@ enum cxl_partition_mode {
  * @dev: This region's device
  * @id: This region's id. Id is globally unique across all regions
  * @cxlrd: Region's root decoder
+ * @hpa_range: Address range occupied by the region
  * @mode: Operational mode of the mapped capacity
  * @type: Endpoint decoder target type
  * @cxl_nvb: nvdimm bridge for coordinating @cxlr_pmem setup / shutdown
@@ -544,6 +545,7 @@ struct cxl_region {
 	struct device dev;
 	int id;
 	struct cxl_root_decoder *cxlrd;
+	struct range hpa_range;
 	enum cxl_partition_mode mode;
 	enum cxl_decoder_type type;
 	struct cxl_nvdimm_bridge *cxl_nvb;