--- zzzz-none-000/linux-3.10.107/include/uapi/linux/virtio_balloon.h	2017-06-27 09:49:32.000000000 +0000
+++ scorpion-7490-727/linux-3.10.107/include/uapi/linux/virtio_balloon.h	2021-02-04 17:41:59.000000000 +0000
@@ -25,22 +25,24 @@
  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE. */
+#include <linux/types.h>
+#include <linux/virtio_types.h>
 #include <linux/virtio_ids.h>
 #include <linux/virtio_config.h>
 
 /* The feature bitmap for virtio balloon */
 #define VIRTIO_BALLOON_F_MUST_TELL_HOST	0 /* Tell before reclaiming pages */
 #define VIRTIO_BALLOON_F_STATS_VQ	1 /* Memory Stats virtqueue */
+#define VIRTIO_BALLOON_F_DEFLATE_ON_OOM	2 /* Deflate balloon on OOM */
 
 /* Size of a PFN in the balloon interface. */
 #define VIRTIO_BALLOON_PFN_SHIFT 12
 
-struct virtio_balloon_config
-{
+struct virtio_balloon_config {
 	/* Number of pages host wants Guest to give up. */
-	__le32 num_pages;
+	__u32 num_pages;
 	/* Number of pages we've actually got in balloon. */
-	__le32 actual;
+	__u32 actual;
 };
 
 #define VIRTIO_BALLOON_S_SWAP_IN  0   /* Amount of memory swapped in */
@@ -51,9 +53,32 @@
 #define VIRTIO_BALLOON_S_MEMTOT   5   /* Total amount of memory */
 #define VIRTIO_BALLOON_S_NR       6
 
+/*
+ * Memory statistics structure.
+ * Driver fills an array of these structures and passes to device.
+ *
+ * NOTE: fields are laid out in a way that would make compiler add padding
+ * between and after fields, so we have to use compiler-specific attributes to
+ * pack it, to disable this padding. This also often causes compiler to
+ * generate suboptimal code.
+ *
+ * We maintain this statistics structure format for backwards compatibility,
+ * but don't follow this example.
+ *
+ * If implementing a similar structure, do something like the below instead:
+ *     struct virtio_balloon_stat {
+ *         __virtio16 tag;
+ *         __u8 reserved[6];
+ *         __virtio64 val;
+ *     };
+ *
+ * In other words, add explicit reserved fields to align field and
+ * structure boundaries at field size, avoiding compiler padding
+ * without the packed attribute.
+ */
 struct virtio_balloon_stat {
-	__u16 tag;
-	__u64 val;
+	__virtio16 tag;
+	__virtio64 val;
 } __attribute__((packed));
 
 #endif /* _LINUX_VIRTIO_BALLOON_H */