diff --git a/drivers/pci/setup-res.c b/drivers/pci/setup-res.c
index 85774b7a316a..7818cfeea53a 100644
--- a/drivers/pci/setup-res.c
+++ b/drivers/pci/setup-res.c
@@ -214,6 +214,17 @@ static int pci_revert_fw_address(struct resource *res, struct pci_dev *dev,
 
 	root = pci_find_parent_resource(dev, res);
 	if (!root) {
+		/*
+		 * If dev is behind a bridge, accesses will only reach it
+		 * if res is inside the relevant bridge window.
+		 */
+		if (pci_upstream_bridge(dev))
+			return -ENXIO;
+
+		/*
+		 * On the root bus, assume the host bridge will forward
+		 * everything.
+		 */
 		if (res->flags & IORESOURCE_IO)
 			root = &ioport_resource;
 		else