cxl/region: Validate region mode vs decoder mode

In preparation for a new region mode, do not, for example, allow
'ram' decoders to be assigned to 'pmem' regions and vice versa.

Reviewed-by: Vishal Verma <[email protected]>
Reviewed-by: Gregory Price <[email protected]>
Reviewed-by: Dave Jiang <[email protected]>
Reviewed-by: Ira Weiny <[email protected]>
Reviewed-by: Jonathan Cameron <[email protected]>
Tested-by: Fan Ni <[email protected]>
Link: https://lore.kernel.org/r/167601995111.1924368.7459128614177994602.stgit@dwillia2-xfh.jf.intel.com
Signed-off-by: Dan Williams <[email protected]>

Author: djbw

drivers/cxl/core/region.c

@@ -1221,6 +1221,12 @@ static int cxl_region_attach(struct cxl_region *cxlr,
 	struct cxl_dport *dport;
 	int i, rc = -ENXIO;
 
+	if (cxled->mode != cxlr->mode) {
+		dev_dbg(&cxlr->dev, "%s region mode: %d mismatch: %d\n",
+			dev_name(&cxled->cxld.dev), cxlr->mode, cxled->mode);
+		return -EINVAL;
+	}
+
 	if (cxled->mode == CXL_DECODER_DEAD) {
 		dev_dbg(&cxlr->dev, "%s dead\n", dev_name(&cxled->cxld.dev));
 		return -ENODEV;