vdpa: accept VHOST_BACKEND_F_ENABLE_AFTER_DRIVER_OK backend feature

Accepting VHOST_BACKEND_F_ENABLE_AFTER_DRIVER_OK backend feature if
userland sets it.

Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
Acked-by: Shannon Nelson <shannon.nelson@amd.com>
Message-Id: <20230609092127.170673-3-eperezma@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

Author: eugpermar

drivers/vhost/vdpa.c

@@ -680,7 +680,8 @@ static long vhost_vdpa_unlocked_ioctl(struct file *filep,
 			return -EFAULT;
 		if (features & ~(VHOST_VDPA_BACKEND_FEATURES |
 				 BIT_ULL(VHOST_BACKEND_F_SUSPEND) |
-				 BIT_ULL(VHOST_BACKEND_F_RESUME)))
+				 BIT_ULL(VHOST_BACKEND_F_RESUME) |
+				 BIT_ULL(VHOST_BACKEND_F_ENABLE_AFTER_DRIVER_OK)))
 			return -EOPNOTSUPP;
 		if ((features & BIT_ULL(VHOST_BACKEND_F_SUSPEND)) &&
 		     !vhost_vdpa_can_suspend(v))