--- a/arch/arm/xen/p2m.c
+++ b/arch/arm/xen/p2m.c
@@ -11,6 +11,7 @@
 
 #include <xen/xen.h>
 #include <xen/interface/memory.h>
+#include <xen/grant_table.h>
 #include <xen/page.h>
 #include <xen/swiotlb-xen.h>
 
@@ -109,7 +110,7 @@ int set_foreign_p2m_mapping(struct gntta
 		map_ops[i].status = GNTST_general_error;
 		unmap.host_addr = map_ops[i].host_addr,
 		unmap.handle = map_ops[i].handle;
-		map_ops[i].handle = ~0;
+		map_ops[i].handle = INVALID_GRANT_HANDLE;
 		if (map_ops[i].flags & GNTMAP_device_map)
 			unmap.dev_bus_addr = map_ops[i].dev_bus_addr;
 		else
--- a/arch/x86/xen/p2m.c
+++ b/arch/x86/xen/p2m.c
@@ -741,7 +741,7 @@ int set_foreign_p2m_mapping(struct gntta
 		map_ops[i].status = GNTST_general_error;
 		unmap[0].host_addr = map_ops[i].host_addr,
 		unmap[0].handle = map_ops[i].handle;
-		map_ops[i].handle = ~0;
+		map_ops[i].handle = INVALID_GRANT_HANDLE;
 		if (map_ops[i].flags & GNTMAP_device_map)
 			unmap[0].dev_bus_addr = map_ops[i].dev_bus_addr;
 		else
@@ -751,7 +751,7 @@ int set_foreign_p2m_mapping(struct gntta
 			kmap_ops[i].status = GNTST_general_error;
 			unmap[1].host_addr = kmap_ops[i].host_addr,
 			unmap[1].handle = kmap_ops[i].handle;
-			kmap_ops[i].handle = ~0;
+			kmap_ops[i].handle = INVALID_GRANT_HANDLE;
 			if (kmap_ops[i].flags & GNTMAP_device_map)
 				unmap[1].dev_bus_addr = kmap_ops[i].dev_bus_addr;
 			else
--- a/drivers/pci/xen-pcifront.c
+++ b/drivers/pci/xen-pcifront.c
@@ -26,7 +26,7 @@
 #include <xen/platform_pci.h>
 
 #include <asm/xen/swiotlb-xen.h>
-#define INVALID_GRANT_REF (0)
+
 #define INVALID_EVTCHN    (-1)
 
 struct pci_bus_entry {
@@ -42,7 +42,7 @@ struct pcifront_device {
 	struct list_head root_buses;
 
 	int evtchn;
-	int gnt_ref;
+	grant_ref_t gnt_ref;
 
 	int irq;
 
--- a/drivers/xen/gntdev.c
+++ b/drivers/xen/gntdev.c
@@ -186,11 +186,11 @@ struct gntdev_grant_map *gntdev_alloc_ma
 		goto err;
 
 	for (i = 0; i < count; i++) {
-		add->map_ops[i].handle = -1;
-		add->unmap_ops[i].handle = -1;
+		add->map_ops[i].handle = INVALID_GRANT_HANDLE;
+		add->unmap_ops[i].handle = INVALID_GRANT_HANDLE;
 		if (use_ptemod) {
-			add->kmap_ops[i].handle = -1;
-			add->kunmap_ops[i].handle = -1;
+			add->kmap_ops[i].handle = INVALID_GRANT_HANDLE;
+			add->kunmap_ops[i].handle = INVALID_GRANT_HANDLE;
 		}
 	}
 
@@ -279,7 +279,7 @@ static int find_grant_ptes(pte_t *pte, u
 			  map->grants[pgnr].ref,
 			  map->grants[pgnr].domid);
 	gnttab_set_unmap_op(&map->unmap_ops[pgnr], pte_maddr, flags,
-			    -1 /* handle */);
+			    INVALID_GRANT_HANDLE);
 	return 0;
 }
 
@@ -297,7 +297,7 @@ int gntdev_map_grant_pages(struct gntdev
 
 	if (!use_ptemod) {
 		/* Note: it could already be mapped */
-		if (map->map_ops[0].handle != -1)
+		if (map->map_ops[0].handle != INVALID_GRANT_HANDLE)
 			return 0;
 		for (i = 0; i < map->count; i++) {
 			unsigned long addr = (unsigned long)
@@ -306,7 +306,7 @@ int gntdev_map_grant_pages(struct gntdev
 				map->grants[i].ref,
 				map->grants[i].domid);
 			gnttab_set_unmap_op(&map->unmap_ops[i], addr,
-				map->flags, -1 /* handle */);
+				map->flags, INVALID_GRANT_HANDLE);
 		}
 	} else {
 		/*
@@ -332,7 +332,7 @@ int gntdev_map_grant_pages(struct gntdev
 				map->grants[i].ref,
 				map->grants[i].domid);
 			gnttab_set_unmap_op(&map->kunmap_ops[i], address,
-				flags, -1);
+				flags, INVALID_GRANT_HANDLE);
 		}
 	}
 
@@ -390,7 +390,7 @@ static int __unmap_grant_pages(struct gn
 		pr_debug("unmap handle=%d st=%d\n",
 			map->unmap_ops[offset+i].handle,
 			map->unmap_ops[offset+i].status);
-		map->unmap_ops[offset+i].handle = -1;
+		map->unmap_ops[offset+i].handle = INVALID_GRANT_HANDLE;
 	}
 	return err;
 }
@@ -406,13 +406,15 @@ static int unmap_grant_pages(struct gntd
 	 * already unmapped some of the grants. Only unmap valid ranges.
 	 */
 	while (pages && !err) {
-		while (pages && map->unmap_ops[offset].handle == -1) {
+		while (pages &&
+		       map->unmap_ops[offset].handle == INVALID_GRANT_HANDLE) {
 			offset++;
 			pages--;
 		}
 		range = 0;
 		while (range < pages) {
-			if (map->unmap_ops[offset+range].handle == -1)
+			if (map->unmap_ops[offset + range].handle ==
+			    INVALID_GRANT_HANDLE)
 				break;
 			range++;
 		}
--- a/include/xen/grant_table.h
+++ b/include/xen/grant_table.h
@@ -50,6 +50,13 @@
 #include <linux/page-flags.h>
 #include <linux/kernel.h>
 
+/*
+ * Technically there's no reliably invalid grant reference or grant handle,
+ * so pick the value that is the most unlikely one to be observed valid.
+ */
+#define INVALID_GRANT_REF          ((grant_ref_t)-1)
+#define INVALID_GRANT_HANDLE       ((grant_handle_t)-1)
+
 #define GNTTAB_RESERVED_XENSTORE 1
 
 /* NR_GRANT_FRAMES must be less than or equal to that configured in Xen */
--- a/include/xen/xenbus.h
+++ b/include/xen/xenbus.h
@@ -51,7 +51,6 @@
 
 #define XENBUS_MAX_RING_GRANT_ORDER 4
 #define XENBUS_MAX_RING_GRANTS      (1U << XENBUS_MAX_RING_GRANT_ORDER)
-#define INVALID_GRANT_HANDLE       (~0U)
 
 /* Register callback to watch this node. */
 struct xenbus_watch
