include/uapi/linux/virtio_balloon.h

   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 */