diff --git a/drivers/xen/privcmd.c b/drivers/xen/privcmd.c
index f00ad5f5f1d4..da88173bac43 100644
--- a/drivers/xen/privcmd.c
+++ b/drivers/xen/privcmd.c
@@ -935,7 +935,7 @@ static int privcmd_irqfd_assign(struct privcmd_irqfd *irqfd)
 		return -ENOMEM;
 	dm_op = kirqfd + 1;
 
-	if (copy_from_user(dm_op, irqfd->dm_op, irqfd->size)) {
+	if (copy_from_user(dm_op, u64_to_user_ptr(irqfd->dm_op), irqfd->size)) {
 		ret = -EFAULT;
 		goto error_kfree;
 	}
diff --git a/include/uapi/xen/privcmd.h b/include/uapi/xen/privcmd.h
index 375718ba4ab6..b143fafce84d 100644
--- a/include/uapi/xen/privcmd.h
+++ b/include/uapi/xen/privcmd.h
@@ -102,7 +102,7 @@ struct privcmd_mmap_resource {
 #define PRIVCMD_IRQFD_FLAG_DEASSIGN (1 << 0)
 
 struct privcmd_irqfd {
-	void __user *dm_op;
+	__u64 dm_op;
 	__u32 size; /* Size of structure pointed by dm_op */
 	__u32 fd;
 	__u32 flags;