cxl/mem: Fix memory device capacity probing

The CXL Identify Memory Device output payload emits capacity in 256MB
units. The driver is treating the capacity field as bytes. This was
missed because QEMU reports bytes when it should report bytes / 256MB.

Fixes: 8adaf74 ("cxl/mem: Find device capabilities")
Reviewed-by: Vishal Verma <vishal.l.verma@intel.com>
Cc: Ben Widawsky <ben.widawsky@intel.com>
Link: https://lore.kernel.org/r/161862021044.3259705.7008520073059739760.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

drivers/cxl/mem.c

@@ -4,6 +4,7 @@
 #include <linux/security.h>
 #include <linux/debugfs.h>
 #include <linux/module.h>
+#include <linux/sizes.h>
 #include <linux/mutex.h>
 #include <linux/cdev.h>
 #include <linux/idr.h>
@@ -1419,6 +1420,7 @@ static int cxl_mem_enumerate_cmds(struct cxl_mem *cxlm)
  */
 static int cxl_mem_identify(struct cxl_mem *cxlm)
 {
+	/* See CXL 2.0 Table 175 Identify Memory Device Output Payload */
 	struct cxl_mbox_identify {
 		char fw_revision[0x10];
 		__le64 total_capacity;
@@ -1447,10 +1449,11 @@ static int cxl_mem_identify(struct cxl_mem *cxlm)
 	 * For now, only the capacity is exported in sysfs
 	 */
 	cxlm->ram_range.start = 0;
-	cxlm->ram_range.end = le64_to_cpu(id.volatile_capacity) - 1;
+	cxlm->ram_range.end = le64_to_cpu(id.volatile_capacity) * SZ_256M - 1;
 
 	cxlm->pmem_range.start = 0;
-	cxlm->pmem_range.end = le64_to_cpu(id.persistent_capacity) - 1;
+	cxlm->pmem_range.end =
+		le64_to_cpu(id.persistent_capacity) * SZ_256M - 1;
 
 	memcpy(cxlm->firmware_version, id.fw_revision, sizeof(id.fw_revision));