[PATCH 2/6] PCI: pci-bridge-emul: Properly mark reserved PCIe bits in PCI config space

[Pali Rohár]

Some bits in PCI config space are reserved when device is PCIe. Properly
define behavior of PCI registers for PCIe emulated bridge and ensure that
it would not be possible change these reserved bits.

Signed-off-by: Pali Rohár <pali@xxxxxxxxxx>
Fixes: 23a5fba4d941 ("PCI: Introduce PCI bridge emulated config space common logic")
Cc: stable@xxxxxxxxxxxxxxx
---
 drivers/pci/pci-bridge-emul.c | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/drivers/pci/pci-bridge-emul.c b/drivers/pci/pci-bridge-emul.c
index 5de8b8dde209..0cbb4e3ca827 100644
--- a/drivers/pci/pci-bridge-emul.c
+++ b/drivers/pci/pci-bridge-emul.c
@@ -295,6 +295,27 @@ int pci_bridge_emul_init(struct pci_bridge_emul *bridge,
 			kfree(bridge->pci_regs_behavior);
 			return -ENOMEM;
 		}
+		/* These bits are applicable only for PCI and reserved on PCIe */
+		bridge->pci_regs_behavior[PCI_CACHE_LINE_SIZE / 4].ro &=
+			~GENMASK(15, 8);
+		bridge->pci_regs_behavior[PCI_COMMAND / 4].ro &=
+			~((PCI_COMMAND_SPECIAL | PCI_COMMAND_INVALIDATE |
+			   PCI_COMMAND_VGA_PALETTE | PCI_COMMAND_WAIT |
+			   PCI_COMMAND_FAST_BACK) |
+			  (PCI_STATUS_66MHZ | PCI_STATUS_FAST_BACK |
+			   PCI_STATUS_DEVSEL_MASK) << 16);
+		bridge->pci_regs_behavior[PCI_PRIMARY_BUS / 4].ro &=
+			~GENMASK(31, 24);
+		bridge->pci_regs_behavior[PCI_IO_BASE / 4].ro &=
+			~((PCI_STATUS_66MHZ | PCI_STATUS_FAST_BACK |
+			   PCI_STATUS_DEVSEL_MASK) << 16);
+		bridge->pci_regs_behavior[PCI_INTERRUPT_LINE / 4].rw &=
+			~((PCI_BRIDGE_CTL_MASTER_ABORT |
+			   BIT(8) | BIT(9) | BIT(11)) << 16);
+		bridge->pci_regs_behavior[PCI_INTERRUPT_LINE / 4].ro &=
+			~((PCI_BRIDGE_CTL_FAST_BACK) << 16);
+		bridge->pci_regs_behavior[PCI_INTERRUPT_LINE / 4].w1c &=
+			~(BIT(10) << 16);
 	}
 
 	if (flags & PCI_BRIDGE_EMUL_NO_PREFETCHABLE_BAR) {
-- 
2.20.1