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 <linux/types.h>
29 #include <linux/virtio_types.h>
30 #include <linux/virtio_ids.h>
31 #include <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 #define VIRTIO_BALLOON_F_FREE_PAGE_HINT	3 /* VQ to report free pages */
38 #define VIRTIO_BALLOON_F_PAGE_POISON	4 /* Guest is using page poisoning */
39 #define VIRTIO_BALLOON_F_REPORTING	5 /* Page reporting virtqueue */
40 
41 /* Size of a PFN in the balloon interface. */
42 #define VIRTIO_BALLOON_PFN_SHIFT 12
43 
44 #define VIRTIO_BALLOON_CMD_ID_STOP	0
45 #define VIRTIO_BALLOON_CMD_ID_DONE	1
46 struct virtio_balloon_config {
47 	/* Number of pages host wants Guest to give up. */
48 	__le32 num_pages;
49 	/* Number of pages we've actually got in balloon. */
50 	__le32 actual;
51 	/*
52 	 * Free page hint command id, readonly by guest.
53 	 * Was previously named free_page_report_cmd_id so we
54 	 * need to carry that name for legacy support.
55 	 */
56 	union {
57 		__le32 free_page_hint_cmd_id;
58 		__le32 free_page_report_cmd_id;	/* deprecated */
59 	};
60 	/* Stores PAGE_POISON if page poisoning is in use */
61 	__le32 poison_val;
62 };
63 
64 #define VIRTIO_BALLOON_S_SWAP_IN  0   /* Amount of memory swapped in */
65 #define VIRTIO_BALLOON_S_SWAP_OUT 1   /* Amount of memory swapped out */
66 #define VIRTIO_BALLOON_S_MAJFLT   2   /* Number of major faults */
67 #define VIRTIO_BALLOON_S_MINFLT   3   /* Number of minor faults */
68 #define VIRTIO_BALLOON_S_MEMFREE  4   /* Total amount of free memory */
69 #define VIRTIO_BALLOON_S_MEMTOT   5   /* Total amount of memory */
70 #define VIRTIO_BALLOON_S_AVAIL    6   /* Available memory as in /proc */
71 #define VIRTIO_BALLOON_S_CACHES   7   /* Disk caches */
72 #define VIRTIO_BALLOON_S_HTLB_PGALLOC  8  /* Hugetlb page allocations */
73 #define VIRTIO_BALLOON_S_HTLB_PGFAIL   9  /* Hugetlb page allocation failures */
74 #define VIRTIO_BALLOON_S_NR       10
75 
76 #define VIRTIO_BALLOON_S_NAMES_WITH_PREFIX(VIRTIO_BALLOON_S_NAMES_prefix) { \
77 	VIRTIO_BALLOON_S_NAMES_prefix "swap-in", \
78 	VIRTIO_BALLOON_S_NAMES_prefix "swap-out", \
79 	VIRTIO_BALLOON_S_NAMES_prefix "major-faults", \
80 	VIRTIO_BALLOON_S_NAMES_prefix "minor-faults", \
81 	VIRTIO_BALLOON_S_NAMES_prefix "free-memory", \
82 	VIRTIO_BALLOON_S_NAMES_prefix "total-memory", \
83 	VIRTIO_BALLOON_S_NAMES_prefix "available-memory", \
84 	VIRTIO_BALLOON_S_NAMES_prefix "disk-caches", \
85 	VIRTIO_BALLOON_S_NAMES_prefix "hugetlb-allocations", \
86 	VIRTIO_BALLOON_S_NAMES_prefix "hugetlb-failures" \
87 }
88 
89 #define VIRTIO_BALLOON_S_NAMES VIRTIO_BALLOON_S_NAMES_WITH_PREFIX("")
90 
91 /*
92  * Memory statistics structure.
93  * Driver fills an array of these structures and passes to device.
94  *
95  * NOTE: fields are laid out in a way that would make compiler add padding
96  * between and after fields, so we have to use compiler-specific attributes to
97  * pack it, to disable this padding. This also often causes compiler to
98  * generate suboptimal code.
99  *
100  * We maintain this statistics structure format for backwards compatibility,
101  * but don't follow this example.
102  *
103  * If implementing a similar structure, do something like the below instead:
104  *     struct virtio_balloon_stat {
105  *         __virtio16 tag;
106  *         __u8 reserved[6];
107  *         __virtio64 val;
108  *     };
109  *
110  * In other words, add explicit reserved fields to align field and
111  * structure boundaries at field size, avoiding compiler padding
112  * without the packed attribute.
113  */
114 struct virtio_balloon_stat {
115 	__virtio16 tag;
116 	__virtio64 val;
117 } __attribute__((packed));
118 
119 #endif /* _LINUX_VIRTIO_BALLOON_H */
120