kvm/user/balloon_ctl.c

   1 /*
   2  * This binary provides access to the guest's balloon driver
   3  * module.
   4  *
   5  * Copyright (C) 2007 Qumranet
   6  *
   7  * Author:
   8  *
   9  *  Dor Laor <dor.laor@qumranet.com>
  10  *
  11  * This work is licensed under the GNU LGPL license, version 2.
  12  */
  13
  14 #include <unistd.h>
  15 #include <fcntl.h>
  16 #include <stdio.h>
  17 #include <stdlib.h>
  18 #include <sys/mman.h>
  19 #include <string.h>
  20 #include <errno.h>
  21 #include <sys/ioctl.h>
  22
  23 #define __user
  24 #include <linux/kvm.h>
  25
  26 #define PAGE_SIZE 4096ul
  27
  28
  29 static int balloon_op(int *fd, int bytes)
  30 {
  31         struct kvm_balloon_op bop;
  32         int r;
  33
  34         bop.npages = bytes/PAGE_SIZE;
  35         r = ioctl(*fd, KVM_BALLOON_OP, &bop);
  36         if (r == -1)
  37                 return -errno;
  38         printf("Ballon handled %d pages successfully\n", bop.npages);
  39
  40         return 0;
  41 }
  42
  43 static int balloon_init(int *fd)
  44 {
  45         *fd = open("/dev/kvm_balloon", O_RDWR);
  46         if (*fd == -1) {
  47                 perror("open /dev/kvm_balloon");
  48                 return -1;
  49         }
  50
  51         return 0;
  52 }
  53
  54 int main(int argc, char *argv[])
  55 {
  56         int fd;
  57         int r;
  58         int bytes;
  59
  60         if (argc != 3) {
  61                 perror("Please provide op=[i|d], bytes\n");
  62                 return 1;
  63         }
  64         bytes = atoi(argv[2]);
  65
  66         switch (*argv[1]) {
  67         case 'i':
  68                 break;
  69         case 'd':
  70                 bytes = -bytes;
  71                 break;
  72         default:
  73                 perror("Wrong op param\n");
  74                 return 1;
  75         }
  76
  77         if (balloon_init(&fd)) {
  78                 perror("balloon_init failed\n");
  79                 return 1;
  80         }
  81
  82         if ((r = balloon_op(&fd, bytes))) {
  83                 perror("balloon_op failed\n");
  84                 goto out;
  85         }
  86
  87 out:
  88         close(fd);
  89
  90         return r;
  91 }
  92