diff --git a/arch/i386/pci/mmconfig-shared.c b/arch/i386/pci/mmconfig-shared.c
index 4ea0852..473db62 100644
--- a/arch/i386/pci/mmconfig-shared.c
+++ b/arch/i386/pci/mmconfig-shared.c
@@ -43,12 +43,14 @@
 			if (val1 == 0xffffffff)
 				continue;
 
-			raw_pci_ops->read(0, bus, devfn, 0, 4, &val2);
-			if (val1 != val2) {
-				set_bit(i + 32 * bus, pci_mmcfg_fallback_slots);
-				printk(KERN_NOTICE "PCI: No mmconfig possible"
-				       " on device %02x:%02x\n", bus, i);
+			if (pci_mmcfg_arch_reachable(0, bus, devfn)) {
+				raw_pci_ops->read(0, bus, devfn, 0, 4, &val2);
+				if (val1 == val2)
+					continue;
 			}
+			set_bit(i + 32 * bus, pci_mmcfg_fallback_slots);
+			printk(KERN_NOTICE "PCI: No mmconfig possible on device"
+			       " %02x:%02x\n", bus, i);
 		}
 	}
 }
diff --git a/arch/i386/pci/mmconfig.c b/arch/i386/pci/mmconfig.c
index 11be089..bb1afd9 100644
--- a/arch/i386/pci/mmconfig.c
+++ b/arch/i386/pci/mmconfig.c
@@ -136,6 +136,12 @@
 	.write =	pci_mmcfg_write,
 };
 
+int __init pci_mmcfg_arch_reachable(unsigned int seg, unsigned int bus,
+				    unsigned int devfn)
+{
+	return get_base_addr(seg, bus, devfn) != 0;
+}
+
 int __init pci_mmcfg_arch_init(void)
 {
 	printk(KERN_INFO "PCI: Using MMCONFIG\n");
diff --git a/arch/i386/pci/pci.h b/arch/i386/pci/pci.h
index 2ce3d44..e58bae2 100644
--- a/arch/i386/pci/pci.h
+++ b/arch/i386/pci/pci.h
@@ -101,4 +101,6 @@
 #define PCI_MMCFG_MAX_CHECK_BUS 16
 extern DECLARE_BITMAP(pci_mmcfg_fallback_slots, 32*PCI_MMCFG_MAX_CHECK_BUS);
 
+extern int __init pci_mmcfg_arch_reachable(unsigned int seg, unsigned int bus,
+					   unsigned int devfn);
 extern int __init pci_mmcfg_arch_init(void);
diff --git a/arch/x86_64/pci/mmconfig.c b/arch/x86_64/pci/mmconfig.c
index 918fc5b..65d8273 100644
--- a/arch/x86_64/pci/mmconfig.c
+++ b/arch/x86_64/pci/mmconfig.c
@@ -126,6 +126,12 @@
 	return addr;
 }
 
+int __init pci_mmcfg_arch_reachable(unsigned int seg, unsigned int bus,
+				    unsigned int devfn)
+{
+	return pci_dev_base(seg, bus, devfn) != NULL;
+}
+
 int __init pci_mmcfg_arch_init(void)
 {
 	int i;