Add ballooning infrastructure.

Balloon devices allow you to ask the guest to allocate memory.  This allows you
to release that memory.  It's mostly useful for freeing up large chunks of
memory from cooperative guests.

Ballooning is supported by both Xen and VirtIO.

Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@5873 c046a42c-6fe2-441c-8c8c-71466251a162

diff --git a/monitor.c b/monitor.c
index 22360fce3034cfc66783f00c2c840ea9b0038fb4..a928c3eb0de255e6332a072976ba3245d4d9c383 100644 (file)
--- a/monitor.c
+++ b/monitor.c
@@ -34,6 +34,7 @@
 #include "block.h"
 #include "audio/audio.h"
 #include "disas.h"
+#include "balloon.h"
 #include <dirent.h>
 #include "qemu-timer.h"
 #include "migration.h"
@@ -1390,6 +1391,23 @@ static void do_inject_nmi(int cpu_index)
 }
 #endif
 
+static void do_balloon(int value)
+{
+    ram_addr_t target = value;
+    qemu_balloon(target << 20);
+}
+
+static void do_info_balloon(void)
+{
+    ram_addr_t actual;
+
+    actual = qemu_balloon_status();
+    if (actual == 0)
+        term_printf("Ballooning not activated in VM\n");
+    else
+        term_printf("balloon: actual=%d\n", (int)(actual >> 20));
+}
+
 static const term_cmd_t term_cmds[] = {
     { "help|?", "s?", do_help,
       "[cmd]", "show the help" },
@@ -1475,6 +1493,8 @@ static const term_cmd_t term_cmds[] = {
       "", "cancel the current VM migration" },
     { "migrate_set_speed", "s", do_migrate_set_speed,
       "value", "set maximum speed (in bytes) for migrations" },
+    { "balloon", "i", do_balloon,
+      "target", "request VM to change it's memory allocation (in MB)" },
     { NULL, NULL, },
 };
 
@@ -1542,6 +1562,8 @@ static const term_cmd_t info_cmds[] = {
       "", "show SLIRP statistics", },
 #endif
     { "migrate", "", do_info_migrate, "", "show migration status" },
+    { "balloon", "", do_info_balloon,
+      "", "show balloon information" },
     { NULL, NULL, },
 };
 

diff --git a/vl.c b/vl.c
index 2b5366e7ec684de303c9485249e2e171f619cc99..1cee2a793f4ea909d2db04ec4062115d51dabe79 100644 (file)
--- a/vl.c
+++ b/vl.c
@@ -40,6 +40,7 @@
 #include "audio/audio.h"
 #include "migration.h"
 #include "kvm.h"
+#include "balloon.h"
 
 #include <unistd.h>
 #include <fcntl.h>
@@ -514,6 +515,31 @@ void hw_error(const char *fmt, ...)
     va_end(ap);
     abort();
 }
+ 
+/***************/
+/* ballooning */
+
+static QEMUBalloonEvent *qemu_balloon_event;
+void *qemu_balloon_event_opaque;
+
+void qemu_add_balloon_handler(QEMUBalloonEvent *func, void *opaque)
+{
+    qemu_balloon_event = func;
+    qemu_balloon_event_opaque = opaque;
+}
+
+void qemu_balloon(ram_addr_t target)
+{
+    if (qemu_balloon_event)
+        qemu_balloon_event(qemu_balloon_event_opaque, target);
+}
+
+ram_addr_t qemu_balloon_status(void)
+{
+    if (qemu_balloon_event)
+        return qemu_balloon_event(qemu_balloon_event_opaque, 0);
+    return 0;
+}
 
 /***********************************************************/
 /* keyboard/mouse */