1 files changed, 22 insertions, 2 deletions

diff --git a/arch/x86/pci/acpi.c b/arch/x86/pci/acpi.c
index e4695985f9de..d93963340c3c 100644
--- a/arch/x86/pci/acpi.c
+++ b/arch/x86/pci/acpi.c
@@ -325,6 +325,26 @@ static void release_pci_root_info(struct pci_host_bridge *bridge)
         kfree(info);
 }
 
+/*
+ * An IO port or MMIO resource assigned to a PCI host bridge may be
+ * consumed by the host bridge itself or available to its child
+ * bus/devices. The ACPI specification defines a bit (Producer/Consumer)
+ * to tell whether the resource is consumed by the host bridge itself,
+ * but firmware hasn't used that bit consistently, so we can't rely on it.
+ *
+ * On x86 and IA64 platforms, all IO port and MMIO resources are assumed
+ * to be available to child bus/devices except one special case:
+ *     IO port [0xCF8-0xCFF] is consumed by the host bridge itself
+ *     to access PCI configuration space.
+ *
+ * So explicitly filter out PCI CFG IO ports[0xCF8-0xCFF].
+ */
+static bool resource_is_pcicfg_ioport(struct resource *res)
+{
+        return (res->flags & IORESOURCE_IO) &&
+                res->start == 0xCF8 && res->end == 0xCFF;
+}
+
 static void probe_pci_root_info(struct pci_root_info *info,
                                 struct acpi_device *device,
                                 int busnum, int domain,
@@ -346,8 +366,8 @@ static void probe_pci_root_info(struct pci_root_info *info,
                         "no IO and memory resources present in _CRS\n");
         else
                 resource_list_for_each_entry_safe(entry, tmp, list) {
-                        if ((entry->res->flags & IORESOURCE_WINDOW) == 0 ||
-                            (entry->res->flags & IORESOURCE_DISABLED))
+                        if ((entry->res->flags & IORESOURCE_DISABLED) ||
+                            resource_is_pcicfg_ioport(entry->res))
                                 resource_list_destroy_entry(entry);
                         else
                                 entry->res->name = info->name;