Merge tag 'pci-v3.12-fixes-1' of git://git.kernel.org/pub/scm/linux/kernel/git/helgaas/pci

Pull PCI fix from Bjorn Helgaas:
 "We merged what was intended to be an MMCONFIG cleanup, but in fact,
  for systems without _CBA (which is almost everything), it broke
  extended config space for domain 0 and it broke all config space for
  other domains.

  This reverts the change"

* tag 'pci-v3.12-fixes-1' of git://git.kernel.org/pub/scm/linux/kernel/git/helgaas/pci:
  Revert "x86/PCI: MMCONFIG: Check earlier for MMCONFIG region at address zero"

arch/x86/pci/mmconfig-shared.c

@@ -700,7 +700,7 @@ int pci_mmconfig_insert(struct device *dev, u16 seg, u8 start, u8 end,
 	if (!(pci_probe & PCI_PROBE_MMCONF) || pci_mmcfg_arch_init_failed)
 		return -ENODEV;
 
-	if (start > end || !addr)
+	if (start > end)
 		return -EINVAL;
 
 	mutex_lock(&pci_mmcfg_lock);
@@ -716,6 +716,11 @@ int pci_mmconfig_insert(struct device *dev, u16 seg, u8 start, u8 end,
 		return -EEXIST;
 	}
 
+	if (!addr) {
+		mutex_unlock(&pci_mmcfg_lock);
+		return -EINVAL;
+	}
+
 	rc = -EBUSY;
 	cfg = pci_mmconfig_alloc(seg, start, end, addr);
 	if (cfg == NULL) {