conf: Don't always recalculate initial memory size from NUMA size totals

When implementing memory hotplug I've opted to recalculate the initial
memory size (contents of the <memory> element) as a sum of the sizes of
NUMA nodes when NUMA was enabled. This was based on an assumption that
qemu did not allow starting when the NUMA node size total didn't equal
to the initial memory size. Unfortunately the check was introduced to
qemu just lately.

This patch uses the new XML parser flag to decide whether it's safe to
update the memory size total from the NUMA cell sizes or not.

As an additional improvement we now report an error in case when the
size of hotplug memory would exceed the total memory size.

The rest of the changes assures that the function is called with correct
flags.

src/conf/domain_conf.c

@@ -3726,15 +3726,34 @@ virDomainDefRemoveDuplicateMetadata(virDomainDefPtr def)
 
 
 static int
-virDomainDefPostParseMemory(virDomainDefPtr def)
+virDomainDefPostParseMemory(virDomainDefPtr def,
+                            unsigned int parseFlags)
 {
     size_t i;
+    unsigned long long numaMemory = 0;
+    unsigned long long hotplugMemory = 0;
 
-    if ((def->mem.initial_memory = virDomainNumaGetMemorySize(def->numa)) == 0) {
-        def->mem.initial_memory = def->mem.total_memory;
+    /* Attempt to infer the initial memory size from the sum NUMA memory sizes
+     * in case ABI updates are allowed or the <memory> element wasn't specified */
+    if (def->mem.total_memory == 0 ||
+        parseFlags & VIR_DOMAIN_DEF_PARSE_ABI_UPDATE)
+        numaMemory = virDomainNumaGetMemorySize(def->numa);
 
+    if (numaMemory) {
+        virDomainDefSetMemoryInitial(def, numaMemory);
+    } else {
+        /* calculate the sizes of hotplug memory */
         for (i = 0; i < def->nmems; i++)
-            def->mem.initial_memory -= def->mems[i]->size;
+            hotplugMemory += def->mems[i]->size;
+
+        if (hotplugMemory > def->mem.total_memory) {
+            virReportError(VIR_ERR_XML_ERROR, "%s",
+                           _("Total size of memory devices exceeds the total "
+                             "memory size"));
+            return -1;
+        }
+
+        virDomainDefSetMemoryInitial(def, def->mem.total_memory - hotplugMemory);
     }
 
     if (virDomainDefGetMemoryInitial(def) == 0) {
@@ -3770,7 +3789,8 @@ virDomainDefPostParseMemory(virDomainDefPtr def)
 
 static int
 virDomainDefPostParseInternal(virDomainDefPtr def,
-                              virCapsPtr caps ATTRIBUTE_UNUSED)
+                              virCapsPtr caps ATTRIBUTE_UNUSED,
+                              unsigned int parseFlags)
 {
     size_t i;
 
@@ -3781,7 +3801,7 @@ virDomainDefPostParseInternal(virDomainDefPtr def,
         return -1;
     }
 
-    if (virDomainDefPostParseMemory(def) < 0)
+    if (virDomainDefPostParseMemory(def, parseFlags) < 0)
         return -1;
 
     /*
@@ -4274,6 +4294,7 @@ virDomainDefPostParseDeviceIterator(virDomainDefPtr def ATTRIBUTE_UNUSED,
 int
 virDomainDefPostParse(virDomainDefPtr def,
                       virCapsPtr caps,
+                      unsigned int parseFlags,
                       virDomainXMLOptionPtr xmlopt)
 {
     int ret;
@@ -4299,7 +4320,7 @@ virDomainDefPostParse(virDomainDefPtr def,
         return ret;
 
 
-    if ((ret = virDomainDefPostParseInternal(def, caps)) < 0)
+    if ((ret = virDomainDefPostParseInternal(def, caps, parseFlags)) < 0)
         return ret;
 
     return 0;
@@ -16426,7 +16447,7 @@ virDomainDefParseXML(xmlDocPtr xml,
         goto error;
 
     /* callback to fill driver specific domain aspects */
-    if (virDomainDefPostParse(def, caps, xmlopt) < 0)
+    if (virDomainDefPostParse(def, caps, flags, xmlopt) < 0)
         goto error;
 
     /* Auto-add any implied controllers which aren't present */

src/conf/domain_conf.h

@@ -2459,6 +2459,7 @@ virDomainXMLOptionGetNamespace(virDomainXMLOptionPtr xmlopt)
 int
 virDomainDefPostParse(virDomainDefPtr def,
                       virCapsPtr caps,
+                      unsigned int parseFlags,
                       virDomainXMLOptionPtr xmlopt);
 
 static inline bool

src/qemu/qemu_command.c

@@ -13958,7 +13958,8 @@ qemuParseCommandLine(virCapsPtr qemuCaps,
     if (virDomainDefAddImplicitControllers(def) < 0)
         goto error;
 
-    if (virDomainDefPostParse(def, qemuCaps, xmlopt) < 0)
+    if (virDomainDefPostParse(def, qemuCaps, VIR_DOMAIN_DEF_PARSE_ABI_UPDATE,
+                              xmlopt) < 0)
         goto error;
 
     if (cmd->num_args || cmd->num_env) {