1 files changed, 38 insertions, 1 deletions

diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 490031fd2108..b47c2dd5b9e1 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -984,6 +984,43 @@ void set_pcie_hotplug_bridge(struct pci_dev *pdev)
 
 
 /**
+ * pci_ext_cfg_is_aliased - is ext config space just an alias of std config?
+ * @dev: PCI device
+ *
+ * PCI Express to PCI/PCI-X Bridge Specification, rev 1.0, 4.1.4 says that
+ * when forwarding a type1 configuration request the bridge must check that
+ * the extended register address field is zero.  The bridge is not permitted
+ * to forward the transactions and must handle it as an Unsupported Request.
+ * Some bridges do not follow this rule and simply drop the extended register
+ * bits, resulting in the standard config space being aliased, every 256
+ * bytes across the entire configuration space.  Test for this condition by
+ * comparing the first dword of each potential alias to the vendor/device ID.
+ * Known offenders:
+ *   ASM1083/1085 PCIe-to-PCI Reversible Bridge (1b21:1080, rev 01 & 03)
+ *   AMD/ATI SBx00 PCI to PCI Bridge (1002:4384, rev 40)
+ */
+static bool pci_ext_cfg_is_aliased(struct pci_dev *dev)
+{
+#ifdef CONFIG_PCI_QUIRKS
+        int pos;
+        u32 header, tmp;
+
+        pci_read_config_dword(dev, PCI_VENDOR_ID, &header);
+
+        for (pos = PCI_CFG_SPACE_SIZE;
+             pos < PCI_CFG_SPACE_EXP_SIZE; pos += PCI_CFG_SPACE_SIZE) {
+                if (pci_read_config_dword(dev, pos, &tmp) != PCIBIOS_SUCCESSFUL
+                    || header != tmp)
+                        return false;
+        }
+
+        return true;
+#else
+        return false;
+#endif
+}
+
+/**
  * pci_cfg_space_size - get the configuration space size of the PCI device.
  * @dev: PCI device
  *
@@ -1001,7 +1038,7 @@ static int pci_cfg_space_size_ext(struct pci_dev *dev)
 
         if (pci_read_config_dword(dev, pos, &status) != PCIBIOS_SUCCESSFUL)
                 goto fail;
-        if (status == 0xffffffff)
+        if (status == 0xffffffff || pci_ext_cfg_is_aliased(dev))
                 goto fail;
 
         return PCI_CFG_SPACE_EXP_SIZE;