cxl/pci: Ignore unknown register block types

In an effort to explicit avoid supporting vendor specific register
blocks (which can happily be mapped from userspace), entirely skip
probing unknown types. The secondary benefit of this will be revealed
in the future with code simplification.
Signed-off-by: Ben Widawsky <ben.widawsky@intel.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Link: https://lore.kernel.org/r/20210716231548.174778-2-ben.widawsky@intel.comSigned-off-by: Dan Williams <dan.j.williams@intel.com>

drivers/cxl/pci.c

@@ -1118,14 +1118,6 @@ static int cxl_mem_setup_regs(struct cxl_mem *cxlm)
 		u64 offset;
 		u8 bar;
 
-		map = kzalloc(sizeof(*map), GFP_KERNEL);
-		if (!map) {
-			ret = -ENOMEM;
-			goto free_maps;
-		}
-
-		list_add(&map->list, &register_maps);
-
 		pci_read_config_dword(pdev, regloc, &reg_lo);
 		pci_read_config_dword(pdev, regloc + 4, &reg_hi);
 
@@ -1135,6 +1127,18 @@ static int cxl_mem_setup_regs(struct cxl_mem *cxlm)
 		dev_dbg(dev, "Found register block in bar %u @ 0x%llx of type %u\n",
 			bar, offset, reg_type);
 
+		/* Ignore unknown register block types */
+		if (reg_type > CXL_REGLOC_RBI_MEMDEV)
+			continue;
+
+		map = kzalloc(sizeof(*map), GFP_KERNEL);
+		if (!map) {
+			ret = -ENOMEM;
+			goto free_maps;
+		}
+
+		list_add(&map->list, &register_maps);
+
 		base = cxl_mem_map_regblock(cxlm, bar, offset);
 		if (!base) {
 			ret = -ENOMEM;