drm/xe: Annotate xe_mem_region::mapping with __iomem

The pointer points to IO memory, but the __iomem annotation was
incorrectly placed. Annotate it correctly, update its usage accordingly
and fix the corresponding sparse error.

Fixes: 0887a2e7 ("drm/xe: Make xe_mem_region struct")
Cc: Oak Zeng <oak.zeng@intel.com>
Cc: Michael J. Ruhl <michael.j.ruhl@intel.com>
Cc: Matthew Brost <matthew.brost@intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Reviewed-by: Lucas De Marchi <lucas.demarchi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240109112405.108136-3-thomas.hellstrom@linux.intel.com

drivers/gpu/drm/xe/xe_bo.c

@@ -442,7 +442,7 @@ static int xe_ttm_io_mem_reserve(struct ttm_device *bdev,
 
 		if (vram->mapping &&
 		    mem->placement & TTM_PL_FLAG_CONTIGUOUS)
-			mem->bus.addr = (u8 *)vram->mapping +
+			mem->bus.addr = (u8 __force *)vram->mapping +
 				mem->bus.offset;
 
 		mem->bus.offset += vram->io_start;
@@ -748,7 +748,7 @@ static int xe_bo_move(struct ttm_buffer_object *ttm_bo, bool evict,
 			/* Create a new VMAP once kernel BO back in VRAM */
 			if (!ret && resource_is_vram(new_mem)) {
 				struct xe_mem_region *vram = res_to_mem_region(new_mem);
-				void *new_addr = vram->mapping +
+				void __iomem *new_addr = vram->mapping +
 					(new_mem->start << PAGE_SHIFT);
 
 				if (XE_WARN_ON(new_mem->start == XE_BO_INVALID_OFFSET)) {

drivers/gpu/drm/xe/xe_device_types.h

@@ -98,7 +98,7 @@ struct xe_mem_region {
 	 */
 	resource_size_t actual_physical_size;
 	/** @mapping: pointer to VRAM mappable space */
-	void *__iomem mapping;
+	void __iomem *mapping;
 };
 
 /**