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balloon.c 3.5KB

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  1. /*
  2. * Generic Balloon handlers and management
  3. *
  4. * Copyright (c) 2003-2008 Fabrice Bellard
  5. * Copyright (C) 2011 Red Hat, Inc.
  6. * Copyright (C) 2011 Amit Shah <amit.shah@redhat.com>
  7. *
  8. * Permission is hereby granted, free of charge, to any person obtaining a copy
  9. * of this software and associated documentation files (the "Software"), to deal
  10. * in the Software without restriction, including without limitation the rights
  11. * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  12. * copies of the Software, and to permit persons to whom the Software is
  13. * furnished to do so, subject to the following conditions:
  14. *
  15. * The above copyright notice and this permission notice shall be included in
  16. * all copies or substantial portions of the Software.
  17. *
  18. * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  19. * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  20. * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
  21. * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  22. * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  23. * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  24. * THE SOFTWARE.
  25. */
  26. #include "qemu/osdep.h"
  27. #include "qemu/atomic.h"
  28. #include "exec/cpu-common.h"
  29. #include "sysemu/kvm.h"
  30. #include "sysemu/balloon.h"
  31. #include "trace-root.h"
  32. #include "qapi/error.h"
  33. #include "qapi/qapi-commands-misc.h"
  34. #include "qapi/qmp/qerror.h"
  35. static QEMUBalloonEvent *balloon_event_fn;
  36. static QEMUBalloonStatus *balloon_stat_fn;
  37. static void *balloon_opaque;
  38. static int balloon_inhibit_count;
  39. bool qemu_balloon_is_inhibited(void)
  40. {
  41. return atomic_read(&balloon_inhibit_count) > 0;
  42. }
  43. void qemu_balloon_inhibit(bool state)
  44. {
  45. if (state) {
  46. atomic_inc(&balloon_inhibit_count);
  47. } else {
  48. atomic_dec(&balloon_inhibit_count);
  49. }
  50. assert(atomic_read(&balloon_inhibit_count) >= 0);
  51. }
  52. static bool have_balloon(Error **errp)
  53. {
  54. if (kvm_enabled() && !kvm_has_sync_mmu()) {
  55. error_set(errp, ERROR_CLASS_KVM_MISSING_CAP,
  56. "Using KVM without synchronous MMU, balloon unavailable");
  57. return false;
  58. }
  59. if (!balloon_event_fn) {
  60. error_set(errp, ERROR_CLASS_DEVICE_NOT_ACTIVE,
  61. "No balloon device has been activated");
  62. return false;
  63. }
  64. return true;
  65. }
  66. int qemu_add_balloon_handler(QEMUBalloonEvent *event_func,
  67. QEMUBalloonStatus *stat_func, void *opaque)
  68. {
  69. if (balloon_event_fn || balloon_stat_fn || balloon_opaque) {
  70. /* We're already registered one balloon handler. How many can
  71. * a guest really have?
  72. */
  73. return -1;
  74. }
  75. balloon_event_fn = event_func;
  76. balloon_stat_fn = stat_func;
  77. balloon_opaque = opaque;
  78. return 0;
  79. }
  80. void qemu_remove_balloon_handler(void *opaque)
  81. {
  82. if (balloon_opaque != opaque) {
  83. return;
  84. }
  85. balloon_event_fn = NULL;
  86. balloon_stat_fn = NULL;
  87. balloon_opaque = NULL;
  88. }
  89. BalloonInfo *qmp_query_balloon(Error **errp)
  90. {
  91. BalloonInfo *info;
  92. if (!have_balloon(errp)) {
  93. return NULL;
  94. }
  95. info = g_malloc0(sizeof(*info));
  96. balloon_stat_fn(balloon_opaque, info);
  97. return info;
  98. }
  99. void qmp_balloon(int64_t target, Error **errp)
  100. {
  101. if (!have_balloon(errp)) {
  102. return;
  103. }
  104. if (target <= 0) {
  105. error_setg(errp, QERR_INVALID_PARAMETER_VALUE, "target", "a size");
  106. return;
  107. }
  108. trace_balloon_event(balloon_opaque, target);
  109. balloon_event_fn(balloon_opaque, target);
  110. }