1. 根目录:
2. include
3. linux
4. virtio_balloon.h

#ifndef _LINUX_VIRTIO_BALLOON_H
#define _LINUX_VIRTIO_BALLOON_H
/* This header is BSD licensed so anyone can use the definitions to implement
 * compatible drivers/servers. */
#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 */

/* Size of a PFN in the balloon interface. */
#define VIRTIO_BALLOON_PFN_SHIFT 12

struct virtio_balloon_config
{
	/* Number of pages host wants Guest to give up. */
	__le32 num_pages;
	/* Number of pages we've actually got in balloon. */
	__le32 actual;
};

#define VIRTIO_BALLOON_S_SWAP_IN  0   /* Amount of memory swapped in */
#define VIRTIO_BALLOON_S_SWAP_OUT 1   /* Amount of memory swapped out */
#define VIRTIO_BALLOON_S_MAJFLT   2   /* Number of major faults */
#define VIRTIO_BALLOON_S_MINFLT   3   /* Number of minor faults */
#define VIRTIO_BALLOON_S_MEMFREE  4   /* Total amount of free memory */
#define VIRTIO_BALLOON_S_MEMTOT   5   /* Total amount of memory */
#define VIRTIO_BALLOON_S_NR       6

struct virtio_balloon_stat {
	u16 tag;
	u64 val;
} __attribute__((packed));

#endif /* _LINUX_VIRTIO_BALLOON_H */