esx: esxNodeGetFreeMemory return info from host.

Before this patch, when connected via vCenter, the free memory returned
was from the resorcePool (usually a cluster). This is in conflict with
e.g esxNodeGetInfo which always pulls info from the ESX host.
Since libvirt ESX driver works primarily with ESX hosts, this patch
changes esxNodeGetFreeMemory to pull that information from ESX host so
it's consistent with behavior of esxNodeGetInfo.

src/esx/esx_driver.c

@@ -3990,52 +3990,37 @@ static unsigned long long
 esxNodeGetFreeMemory(virConnectPtr conn)
 {
     unsigned long long result = 0;
+    unsigned long long usageBytes = 0;
     esxPrivate *priv = conn->privateData;
     esxVI_String *propertyNameList = NULL;
-    esxVI_ObjectContent *resourcePool = NULL;
-    esxVI_DynamicProperty *dynamicProperty = NULL;
-    esxVI_ResourcePoolResourceUsage *resourcePoolResourceUsage = NULL;
+    esxVI_ObjectContent *hostSystem = NULL;
+    esxVI_Int *memoryUsage = NULL;
+    esxVI_Long *memorySize = NULL;
 
     if (esxVI_EnsureSession(priv->primary) < 0)
         return 0;
 
-    /* Get memory usage of resource pool */
-    if (esxVI_String_AppendValueToList(&propertyNameList,
-                                       "runtime.memory") < 0 ||
-        esxVI_LookupObjectContentByType(priv->primary,
-                                        priv->primary->computeResource->resourcePool,
-                                        "ResourcePool", propertyNameList,
-                                        &resourcePool,
+    /* Get memory usage of host system */
+    if (esxVI_String_AppendValueListToList(&propertyNameList,
+                                           "summary.quickStats.overallMemoryUsage\0"
+                                           "hardware.memorySize\0") < 0 ||
+        esxVI_LookupHostSystemProperties(priv->primary, propertyNameList,
+                                         &hostSystem) < 0 ||
+        esxVI_GetInt(hostSystem, "summary.quickStats.overallMemoryUsage",
+                      &memoryUsage, esxVI_Occurrence_RequiredItem) < 0 ||
+        esxVI_GetLong(hostSystem, "hardware.memorySize", &memorySize,
                       esxVI_Occurrence_RequiredItem) < 0) {
         goto cleanup;
     }
 
-    for (dynamicProperty = resourcePool->propSet; dynamicProperty;
-         dynamicProperty = dynamicProperty->_next) {
-        if (STREQ(dynamicProperty->name, "runtime.memory")) {
-            if (esxVI_ResourcePoolResourceUsage_CastFromAnyType
-                  (dynamicProperty->val, &resourcePoolResourceUsage) < 0) {
-                goto cleanup;
-            }
-
-            break;
-        } else {
-            VIR_WARN("Unexpected '%s' property", dynamicProperty->name);
-        }
-    }
-
-    if (!resourcePoolResourceUsage) {
-        virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
-                       _("Could not retrieve memory usage of resource pool"));
-        goto cleanup;
-    }
-
-    result = resourcePoolResourceUsage->unreservedForVm->value;
+    usageBytes = (unsigned long long) (memoryUsage->value) * 1048576;
+    result = memorySize->value - usageBytes;
 
  cleanup:
     esxVI_String_Free(&propertyNameList);
-    esxVI_ObjectContent_Free(&resourcePool);
-    esxVI_ResourcePoolResourceUsage_Free(&resourcePoolResourceUsage);
+    esxVI_ObjectContent_Free(&hostSystem);
+    esxVI_Int_Free(&memoryUsage);
+    esxVI_Long_Free(&memorySize);
 
     return result;
 }