diff --git a/drivers/pci/xen-pcifront.c b/drivers/pci/xen-pcifront.c
index 030ce37..5c7b6ad 100644
--- a/drivers/pci/xen-pcifront.c
+++ b/drivers/pci/xen-pcifront.c
@@ -277,18 +277,24 @@
 	if (likely(!err)) {
 		if (likely(!op.value)) {
 			/* we get the result */
-			for (i = 0; i < nvec; i++)
+			for (i = 0; i < nvec; i++) {
+				if (op.msix_entries[i].vector <= 0) {
+					dev_warn(&dev->dev, "MSI-X entry %d is invalid: %d!\n",
+						i, op.msix_entries[i].vector);
+					err = -EINVAL;
+					*(*vector+i) = -1;
+					continue;
+				}
 				*(*vector+i) = op.msix_entries[i].vector;
-			return 0;
+			}
 		} else {
 			printk(KERN_DEBUG "enable msix get value %x\n",
 				op.value);
-			return op.value;
 		}
 	} else {
 		dev_err(&dev->dev, "enable msix get err %x\n", err);
-		return err;
 	}
+	return err;
 }
 
 static void pci_frontend_disable_msix(struct pci_dev *dev)
@@ -325,6 +331,12 @@
 	err = do_pci_op(pdev, &op);
 	if (likely(!err)) {
 		*(*vector) = op.value;
+		if (op.value <= 0) {
+			dev_warn(&dev->dev, "MSI entry is invalid: %d!\n",
+				op.value);
+			err = -EINVAL;
+			*(*vector) = -1;	
+		}
 	} else {
 		dev_err(&dev->dev, "pci frontend enable msi failed for dev "
 				    "%x:%x\n", op.bus, op.devfn);