1 #ifndef _LINUX_VIRTIO_BALLOON_H
2 #define _LINUX_VIRTIO_BALLOON_H
3 /* This header is BSD licensed so anyone can use the definitions to implement
4  * compatible drivers/servers.
5  *
6  * Redistribution and use in source and binary forms, with or without
7  * modification, are permitted provided that the following conditions
8  * are met:
9  * 1. Redistributions of source code must retain the above copyright
10  *    notice, this list of conditions and the following disclaimer.
11  * 2. Redistributions in binary form must reproduce the above copyright
12  *    notice, this list of conditions and the following disclaimer in the
13  *    documentation and/or other materials provided with the distribution.
14  * 3. Neither the name of IBM nor the names of its contributors
15  *    may be used to endorse or promote products derived from this software
16  *    without specific prior written permission.
17  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS ``AS IS'' AND
18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20  * ARE DISCLAIMED.  IN NO EVENT SHALL IBM OR CONTRIBUTORS BE LIABLE
21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27  * SUCH DAMAGE. */
28 #include "standard-headers/linux/types.h"
29 #include "standard-headers/linux/virtio_types.h"
30 #include "standard-headers/linux/virtio_ids.h"
31 #include "standard-headers/linux/virtio_config.h"
32 
33 /* The feature bitmap for virtio balloon */
34 #define VIRTIO_BALLOON_F_MUST_TELL_HOST	0 /* Tell before reclaiming pages */
35 #define VIRTIO_BALLOON_F_STATS_VQ	1 /* Memory Stats virtqueue */
36 #define VIRTIO_BALLOON_F_DEFLATE_ON_OOM	2 /* Deflate balloon on OOM */
37 
38 /* Size of a PFN in the balloon interface. */
39 #define VIRTIO_BALLOON_PFN_SHIFT 12
40 
41 struct virtio_balloon_config {
42 	/* Number of pages host wants Guest to give up. */
43 	uint32_t num_pages;
44 	/* Number of pages we've actually got in balloon. */
45 	uint32_t actual;
46 };
47 
48 #define VIRTIO_BALLOON_S_SWAP_IN  0   /* Amount of memory swapped in */
49 #define VIRTIO_BALLOON_S_SWAP_OUT 1   /* Amount of memory swapped out */
50 #define VIRTIO_BALLOON_S_MAJFLT   2   /* Number of major faults */
51 #define VIRTIO_BALLOON_S_MINFLT   3   /* Number of minor faults */
52 #define VIRTIO_BALLOON_S_MEMFREE  4   /* Total amount of free memory */
53 #define VIRTIO_BALLOON_S_MEMTOT   5   /* Total amount of memory */
54 #define VIRTIO_BALLOON_S_AVAIL    6   /* Amount of available memory in guest */
55 #define VIRTIO_BALLOON_S_NR       7
56 
57 /*
58  * Memory statistics structure.
59  * Driver fills an array of these structures and passes to device.
60  *
61  * NOTE: fields are laid out in a way that would make compiler add padding
62  * between and after fields, so we have to use compiler-specific attributes to
63  * pack it, to disable this padding. This also often causes compiler to
64  * generate suboptimal code.
65  *
66  * We maintain this statistics structure format for backwards compatibility,
67  * but don't follow this example.
68  *
69  * If implementing a similar structure, do something like the below instead:
70  *     struct virtio_balloon_stat {
71  *         __virtio16 tag;
72  *         uint8_t reserved[6];
73  *         __virtio64 val;
74  *     };
75  *
76  * In other words, add explicit reserved fields to align field and
77  * structure boundaries at field size, avoiding compiler padding
78  * without the packed attribute.
79  */
80 struct virtio_balloon_stat {
81 	__virtio16 tag;
82 	__virtio64 val;
83 } QEMU_PACKED;
84 
85 #endif /* _LINUX_VIRTIO_BALLOON_H */
86