[PATCH 5.10 463/563] PCI: pci-bridge-emul: Make expansion ROM Base Address register read-only

[Greg Kroah-Hartman]

From: Pali Rohár <pali@xxxxxxxxxx>

commit 1c1a3b4d3e86b997a313ffb297c1129540882859 upstream.

If expansion ROM is unsupported (which is the case of pci-bridge-emul.c
driver) then ROM Base Address register must be implemented as read-only
register that return 0 when read, same as for unused Base Address
registers.

Link: https://lore.kernel.org/r/20211124155944.1290-2-pali@xxxxxxxxxx
Fixes: 23a5fba4d941 ("PCI: Introduce PCI bridge emulated config space common logic")
Signed-off-by: Pali Rohár <pali@xxxxxxxxxx>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@xxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 drivers/pci/pci-bridge-emul.c |    7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

--- a/drivers/pci/pci-bridge-emul.c
+++ b/drivers/pci/pci-bridge-emul.c
@@ -139,8 +139,13 @@ struct pci_bridge_reg_behavior pci_regs_
 		.ro = GENMASK(7, 0),
 	},
 
+	/*
+	 * If expansion ROM is unsupported then ROM Base Address register must
+	 * be implemented as read-only register that return 0 when read, same
+	 * as for unused Base Address registers.
+	 */
 	[PCI_ROM_ADDRESS1 / 4] = {
-		.rw = GENMASK(31, 11) | BIT(0),
+		.ro = ~0,
 	},
 
 	/*