qemu: Emit correct audit message for memory hot unplug

https://bugzilla.redhat.com/show_bug.cgi?id=1226234#c3

If the qemu monitor fails to remove the memory from the guest for
any reason, the auditlog message will incorrectly use the current
actual memory (via virDomainDefGetMemoryActual) instead of the
value we were attempting to reduce to. The result is the 'new-mem'
and 'old-mem' values for the auditlog message would be identical.

This patch creates a local 'newmem' which accounts for the current
memory size minus the memory which is being removed. NB, for the
success case this results in the same value that would be returned
by virDomainDefGetMemoryActual without the need to do the math. This
follows the existing code which would subtract the size for cur_balloon.

Signed-off-by: Luyao Huang <lhuang@redhat.com>

diff --git a/src/qemu/qemu_hotplug.c b/src/qemu/qemu_hotplug.c
index 29f526ff379b15214f69099d4b18bc47b948dd71..e71a204bfd5c902e8c03e912d7fe2d456a383af3 100644 (file)
--- a/src/qemu/qemu_hotplug.c
+++ b/src/qemu/qemu_hotplug.c
@@ -2912,11 +2912,11 @@ qemuDomainRemoveMemoryDevice(virQEMUDriverPtr driver,
 {
     qemuDomainObjPrivatePtr priv = vm->privateData;
     unsigned long long oldmem = virDomainDefGetMemoryActual(vm->def);
+    unsigned long long newmem = oldmem - mem->size;
     virObjectEventPtr event;
     char *backendAlias = NULL;
     int rc;
     int idx;
-    int ret = -1;
 
     VIR_DEBUG("Removing memory device %s from domain %p %s",
               mem->info.alias, vm, vm->def->name);
@@ -2925,12 +2925,18 @@ qemuDomainRemoveMemoryDevice(virQEMUDriverPtr driver,
         qemuDomainEventQueue(driver, event);
 
     if (virAsprintf(&backendAlias, "mem%s", mem->info.alias) < 0)
-        goto cleanup;
+        return -1;
 
     qemuDomainObjEnterMonitor(driver, vm);
     rc = qemuMonitorDelObject(priv->mon, backendAlias);
-    if (qemuDomainObjExitMonitor(driver, vm) < 0 || rc < 0)
-        goto cleanup;
+    if (qemuDomainObjExitMonitor(driver, vm) < 0)
+        rc = -1;
+
+    VIR_FREE(backendAlias);
+
+    virDomainAuditMemory(vm, oldmem, newmem, "update", rc == 0);
+    if (rc < 0)
+        return -1;
 
     vm->def->mem.cur_balloon -= mem->size;
 
@@ -2938,14 +2944,7 @@ qemuDomainRemoveMemoryDevice(virQEMUDriverPtr driver,
         virDomainMemoryRemove(vm->def, idx);
 
     virDomainMemoryDefFree(mem);
-    ret = 0;
-
- cleanup:
-    virDomainAuditMemory(vm, oldmem, virDomainDefGetMemoryActual(vm->def),
-                         "update", ret == 0);
-
-    VIR_FREE(backendAlias);
-    return ret;
+    return 0;
 }