1 /*- 2 * SPDX-License-Identifier: BSD-3-Clause 3 * 4 * This header is BSD licensed so anyone can use the definitions to implement 5 * compatible drivers/servers. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 3. Neither the name of IBM nor the names of its contributors 16 * may be used to endorse or promote products derived from this software 17 * without specific prior written permission. 18 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 19 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 20 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 21 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL IBM OR CONTRIBUTORS BE LIABLE 22 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 23 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 24 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 25 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 26 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 27 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 28 * SUCH DAMAGE. 29 */ 30 31 #ifndef _VIRTIO_BALLOON_H 32 #define _VIRTIO_BALLOON_H 33 34 /* Feature bits. */ 35 #define VIRTIO_BALLOON_F_MUST_TELL_HOST 0x1 /* Tell before reclaiming pages */ 36 #define VIRTIO_BALLOON_F_STATS_VQ 0x2 /* Memory stats virtqueue */ 37 #define VIRTIO_BALLOON_F_DEFLATE_ON_OOM 0x4 /* Deflate balloon on OOM */ 38 39 /* Size of a PFN in the balloon interface. */ 40 #define VIRTIO_BALLOON_PFN_SHIFT 12 41 42 struct virtio_balloon_config { 43 /* Number of pages host wants Guest to give up. */ 44 uint32_t num_pages; 45 46 /* Number of pages we've actually got in balloon. */ 47 uint32_t actual; 48 }; 49 50 #define VIRTIO_BALLOON_S_SWAP_IN 0 /* Amount of memory swapped in */ 51 #define VIRTIO_BALLOON_S_SWAP_OUT 1 /* Amount of memory swapped out */ 52 #define VIRTIO_BALLOON_S_MAJFLT 2 /* Number of major faults */ 53 #define VIRTIO_BALLOON_S_MINFLT 3 /* Number of minor faults */ 54 #define VIRTIO_BALLOON_S_MEMFREE 4 /* Total amount of free memory */ 55 #define VIRTIO_BALLOON_S_MEMTOT 5 /* Total amount of memory */ 56 #define VIRTIO_BALLOON_S_AVAIL 6 /* Available memory as in /proc */ 57 #define VIRTIO_BALLOON_S_CACHES 7 /* Disk caches */ 58 #define VIRTIO_BALLOON_S_NR 8 59 60 /* 61 * Memory statistics structure. 62 * Driver fills an array of these structures and passes to device. 63 * 64 * NOTE: fields are laid out in a way that would make compiler add padding 65 * between and after fields, so we have to use compiler-specific attributes to 66 * pack it, to disable this padding. This also often causes compiler to 67 * generate suboptimal code. 68 * 69 * We maintain this statistics structure format for backwards compatibility, 70 * but don't follow this example. 71 * 72 * If implementing a similar structure, do something like the below instead: 73 * struct virtio_balloon_stat { 74 * __virtio16 tag; 75 * __u8 reserved[6]; 76 * __virtio64 val; 77 * }; 78 * 79 * In other words, add explicit reserved fields to align field and 80 * structure boundaries at field size, avoiding compiler padding 81 * without the packed attribute. 82 */ 83 struct virtio_balloon_stat { 84 uint16_t tag; 85 uint64_t val; 86 } __packed; 87 88 #endif /* _VIRTIO_BALLOON_H */ 89