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 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 __u32 num_pages; 44 /* Number of pages we've actually got in balloon. */ 45 __u32 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 /* Available memory as in /proc */ 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 * __u8 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 } __attribute__((packed)); 84 85 #endif /* _LINUX_VIRTIO_BALLOON_H */ 86
