From 6306ee6249024322bda2ab0f6f53bec7e24ea897 Mon Sep 17 00:00:00 2001
From: Peter Krempa <pkrempa@redhat.com>
Date: Wed, 6 Apr 2016 15:57:57 +0200
Subject: [PATCH] qemu: hotplug: Properly recalculate/reload balloon size after
 hot(un)plug

Rather than trying some magic calculations on our side query the monitor
for the current size of the memory balloon both on hotplug and
hotunplug.

Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1220702
---
 src/qemu/qemu_hotplug.c | 15 ++++++---------
 src/qemu/qemu_process.c |  2 +-
 src/qemu/qemu_process.h |  4 ++++
 3 files changed, 11 insertions(+), 10 deletions(-)

diff --git a/src/qemu/qemu_hotplug.c b/src/qemu/qemu_hotplug.c
index b72b08018a..ef8696be46 100644
--- a/src/qemu/qemu_hotplug.c
+++ b/src/qemu/qemu_hotplug.c
@@ -33,6 +33,7 @@
 #include "qemu_command.h"
 #include "qemu_hostdev.h"
 #include "qemu_interface.h"
+#include "qemu_process.h"
 #include "domain_audit.h"
 #include "netdev_bandwidth_conf.h"
 #include "domain_nwfilter.h"
@@ -1742,7 +1743,6 @@ qemuDomainAttachMemory(virQEMUDriverPtr driver,
     const char *backendType;
     virJSONValuePtr props = NULL;
     virObjectEventPtr event;
-    bool fix_balloon = false;
     int id;
     int ret = -1;
 
@@ -1757,9 +1757,6 @@ qemuDomainAttachMemory(virQEMUDriverPtr driver,
     if (virAsprintf(&objalias, "mem%s", mem->info.alias) < 0)
         goto cleanup;
 
-    if (vm->def->mem.cur_balloon == virDomainDefGetMemoryActual(vm->def))
-        fix_balloon = true;
-
     if (!(devstr = qemuBuildMemoryDeviceStr(mem)))
         goto cleanup;
 
@@ -1800,9 +1797,8 @@ qemuDomainAttachMemory(virQEMUDriverPtr driver,
     event = virDomainEventDeviceAddedNewFromObj(vm, objalias);
     qemuDomainEventQueue(driver, event);
 
-    /* fix the balloon size if it was set to maximum */
-    if (fix_balloon)
-        vm->def->mem.cur_balloon += mem->size;
+    /* fix the balloon size */
+    ignore_value(qemuProcessRefreshBalloonState(driver, vm, QEMU_ASYNC_JOB_NONE));
 
     /* mem is consumed by vm->def */
     mem = NULL;
@@ -2938,13 +2934,14 @@ qemuDomainRemoveMemoryDevice(virQEMUDriverPtr driver,
     if (rc < 0)
         return -1;
 
-    vm->def->mem.cur_balloon -= mem->size;
-
     if ((idx = virDomainMemoryFindByDef(vm->def, mem)) >= 0)
         virDomainMemoryRemove(vm->def, idx);
 
     virDomainMemoryDefFree(mem);
 
+    /* fix the balloon size */
+    ignore_value(qemuProcessRefreshBalloonState(driver, vm, QEMU_ASYNC_JOB_NONE));
+
     /* decrease the mlock limit after memory unplug if necessary */
     ignore_value(qemuDomainAdjustMaxMemLock(vm));
 
diff --git a/src/qemu/qemu_process.c b/src/qemu/qemu_process.c
index de5c52f753..3da23ce3d8 100644
--- a/src/qemu/qemu_process.c
+++ b/src/qemu/qemu_process.c
@@ -1993,7 +1993,7 @@ qemuRefreshVirtioChannelState(virQEMUDriverPtr driver,
 }
 
 
-static int
+int
 qemuProcessRefreshBalloonState(virQEMUDriverPtr driver,
                                virDomainObjPtr vm,
                                int asyncJob)
diff --git a/src/qemu/qemu_process.h b/src/qemu/qemu_process.h
index d5f50f2a67..98cc9a849f 100644
--- a/src/qemu/qemu_process.h
+++ b/src/qemu/qemu_process.h
@@ -193,4 +193,8 @@ int qemuProcessSetupIOThread(virDomainObjPtr vm,
 
 int qemuRefreshVirtioChannelState(virQEMUDriverPtr driver,
                                   virDomainObjPtr vm);
+
+int qemuProcessRefreshBalloonState(virQEMUDriverPtr driver,
+                                   virDomainObjPtr vm,
+                                   int asyncJob);
 #endif /* __QEMU_PROCESS_H__ */
-- 
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