conf: Add support for parsing and formatting max memory and slot count

Add a XML element that will allow to specify maximum supportable memory
and the count of memory slots to use with memory hotplug.

To avoid possible confusion and misuse of the new element this patch
also explicitly forbids the use of the maxMemory setting in individual
drivers's post parse callbacks. This limitation will be lifted when the
support is implemented.

docs/formatdomain.html.in

@@ -675,6 +675,7 @@
 <pre>
 &lt;domain&gt;
   ...
+  &lt;maxMemory slots='16' unit='KiB'&gt;1524288&lt;/maxMemory&gt;
   &lt;memory unit='KiB'&gt;524288&lt;/memory&gt;
   &lt;currentMemory unit='KiB'&gt;524288&lt;/currentMemory&gt;
   ...
@@ -708,6 +709,25 @@
         <span class='since'><code>unit</code> since 0.9.11</span>,
         <span class='since'><code>dumpCore</code> since 0.10.2
         (QEMU only)</span></dd>
+      <dt><code>maxMemory</code></dt>
+      <dd>The run time maximum memory allocation of the guest. The initial
+        memory specified by either the <code>&lt;memory&gt;</code> element or
+        the NUMA cell size configuration can be increased by hot-plugging of
+        memory to the limit specified by this element.
+
+        The <code>unit</code> attribute behaves the same as for
+        <code>&lt;memory&gt;</code>.
+
+        The <code>slots</code> attribute specifies the number of slots
+        available for adding memory to the guest. The bounds are hypervisor
+        specific.
+
+        Note that due to alignment of the memory chunks added via memory
+        hotplug the full size allocation specified by this element may be
+        impossible to achieve.
+        <span class='since'>Since 1.2.14</span>
+      </dd>
+
       <dt><code>currentMemory</code></dt>
       <dd>The actual allocation of memory for the guest. This value can
         be less than the maximum allocation, to allow for ballooning

docs/schemas/domaincommon.rng

@@ -592,6 +592,14 @@
           </optional>
         </element>
       </optional>
+      <optional>
+        <element name="maxMemory">
+          <ref name="scaledInteger"/>
+          <attribute name="slots">
+            <ref name="unsignedInt"/>
+          </attribute>
+        </element>
+      </optional>
       <optional>
         <element name="currentMemory">
           <ref name='scaledInteger'/>

src/bhyve/bhyve_domain.c

@@ -67,6 +67,10 @@ bhyveDomainDefPostParse(virDomainDefPtr def,
                                        VIR_DOMAIN_CONTROLLER_MODEL_PCI_ROOT) < 0)
         return -1;
 
+    /* memory hotplug tunables are not supported by this driver */
+    if (virDomainDefCheckUnsupportedMemoryHotplug(def) < 0)
+        return -1;
+
     return 0;
 }
 

src/conf/domain_conf.c

@@ -981,6 +981,27 @@ virDomainBlkioDeviceParseXML(xmlNodePtr root,
 }
 
 
+/**
+ * virDomainDefCheckUnsupportedMemoryHotplug:
+ * @def: domain definition
+ *
+ * Returns -1 if the domain definition would enable memory hotplug via the
+ * <maxMemory> tunable and reports an error. Otherwise returns 0.
+ */
+int
+virDomainDefCheckUnsupportedMemoryHotplug(virDomainDefPtr def)
+{
+    /* memory hotplug tunables are not supported by this driver */
+    if (def->mem.max_memory > 0 || def->mem.memory_slots > 0) {
+        virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
+                       _("memory hotplug tunables <maxMemory> are not "
+                         "supported by this hypervisor driver"));
+        return -1;
+    }
+
+    return 0;
+}
+
 
 static void
 virDomainObjListDataFree(void *payload, const void *name ATTRIBUTE_UNUSED)
@@ -3238,6 +3259,22 @@ virDomainDefPostParseInternal(virDomainDefPtr def,
         def->mem.cur_balloon = virDomainDefGetMemoryActual(def);
     }
 
+    if ((def->mem.max_memory || def->mem.memory_slots) &&
+        !(def->mem.max_memory && def->mem.memory_slots)) {
+        virReportError(VIR_ERR_XML_ERROR, "%s",
+                       _("both maximum memory size and "
+                         "memory slot count must be specified"));
+        return -1;
+    }
+
+    if (def->mem.max_memory &&
+        def->mem.max_memory < virDomainDefGetMemoryActual(def)) {
+        virReportError(VIR_ERR_XML_ERROR, "%s",
+                       _("maximum memory size must be equal or greater than "
+                         "the actual memory size"));
+        return -1;
+    }
+
     /*
      * Some really crazy backcompat stuff for consoles
      *
@@ -13264,6 +13301,16 @@ virDomainDefParseXML(xmlDocPtr xml,
                              &def->mem.cur_balloon, false, true) < 0)
         goto error;
 
+    if (virDomainParseMemory("./maxMemory[1]", NULL, ctxt,
+                             &def->mem.max_memory, false, false) < 0)
+        goto error;
+
+    if (virXPathUInt("string(./maxMemory[1]/@slots)", ctxt, &def->mem.memory_slots) == -2) {
+        virReportError(VIR_ERR_XML_ERROR, "%s",
+                       _("Failed to parse memory slot count"));
+        goto error;
+    }
+
     /* and info about it */
     if ((tmp = virXPathString("string(./memory[1]/@dumpCore)", ctxt)) &&
         (def->mem.dump_core = virTristateSwitchTypeFromString(tmp)) <= 0) {
@@ -16190,6 +16237,19 @@ virDomainDefCheckABIStability(virDomainDefPtr src,
     if (!virDomainNumaCheckABIStability(src->numa, dst->numa))
         goto error;
 
+    if (src->mem.memory_slots != dst->mem.memory_slots) {
+        virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
+                       _("Target domain memory slots count '%u' doesn't match source '%u"),
+                       dst->mem.memory_slots, src->mem.memory_slots);
+        goto error;
+    }
+    if (src->mem.max_memory != dst->mem.max_memory) {
+        virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
+                       _("Target maximum memory size '%llu' doesn't match source '%llu'"),
+                       dst->mem.max_memory, src->mem.max_memory);
+        goto error;
+    }
+
     if (src->vcpus != dst->vcpus) {
         virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
                        _("Target domain vCPU count %d does not match source %d"),
@@ -19879,6 +19939,12 @@ virDomainDefFormatInternal(virDomainDefPtr def,
         xmlIndentTreeOutput = oldIndentTreeOutput;
     }
 
+    if (def->mem.max_memory) {
+        virBufferAsprintf(buf,
+                          "<maxMemory slots='%u' unit='KiB'>%llu</maxMemory>\n",
+                          def->mem.memory_slots, def->mem.max_memory);
+    }
+
     virBufferAddLit(buf, "<memory");
     if (def->mem.dump_core)
         virBufferAsprintf(buf, " dumpCore='%s'",

src/conf/domain_conf.h

@@ -2041,6 +2041,10 @@ struct _virDomainMemtune {
     virDomainHugePagePtr hugepages;
     size_t nhugepages;
 
+    /* maximum supported memory for a guest, for hotplugging */
+    unsigned long long max_memory; /* in kibibytes */
+    unsigned int memory_slots; /* maximum count of RAM memory slots */
+
     bool nosharepages;
     bool locked;
     int dump_core; /* enum virTristateSwitch */
@@ -2336,6 +2340,9 @@ virDomainObjPtr virDomainObjListFindByName(virDomainObjListPtr doms,
 bool virDomainObjTaint(virDomainObjPtr obj,
                        virDomainTaintFlags taint);
 
+
+int virDomainDefCheckUnsupportedMemoryHotplug(virDomainDefPtr def);
+
 void virDomainPanicDefFree(virDomainPanicDefPtr panic);
 void virDomainResourceDefFree(virDomainResourceDefPtr resource);
 void virDomainGraphicsDefFree(virDomainGraphicsDefPtr def);

src/libvirt_private.syms

@@ -187,6 +187,7 @@ virDomainCpuPlacementModeTypeFromString;
 virDomainCpuPlacementModeTypeToString;
 virDomainDefAddImplicitControllers;
 virDomainDefCheckABIStability;
+virDomainDefCheckUnsupportedMemoryHotplug;
 virDomainDefClearCCWAddresses;
 virDomainDefClearDeviceAliases;
 virDomainDefClearPCIAddresses;

src/libxl/libxl_domain.c

@@ -567,6 +567,11 @@ libxlDomainDefPostParse(virDomainDefPtr def,
         def->nconsoles = 1;
         def->consoles[0] = chrdef;
     }
+
+    /* memory hotplug tunables are not supported by this driver */
+    if (virDomainDefCheckUnsupportedMemoryHotplug(def) < 0)
+        return -1;
+
     return 0;
 }
 

src/lxc/lxc_domain.c

@@ -94,6 +94,10 @@ virLXCDomainDefPostParse(virDomainDefPtr def,
         !(def->emulator = virDomainDefGetDefaultEmulator(def, caps)))
         return -1;
 
+    /* memory hotplug tunables are not supported by this driver */
+    if (virDomainDefCheckUnsupportedMemoryHotplug(def) < 0)
+        return -1;
+
     return 0;
 }
 

src/openvz/openvz_driver.c

@@ -96,8 +96,15 @@ openvzDomainDefPostParse(virDomainDefPtr def,
                          void *opaque ATTRIBUTE_UNUSED)
 {
     /* fill the init path */
-    if (STREQ(def->os.type, "exe") && !def->os.init)
+    if (STREQ(def->os.type, "exe") && !def->os.init) {
-        return VIR_STRDUP(def->os.init, "/sbin/init") < 0 ? -1 : 0;
+        if (VIR_STRDUP(def->os.init, "/sbin/init") < 0)
+            return -1;
+    }
+
+    /* memory hotplug tunables are not supported by this driver */
+    if (virDomainDefCheckUnsupportedMemoryHotplug(def) < 0)
+        return -1;
+
     return 0;
 }
 

src/parallels/parallels_driver.c

@@ -161,10 +161,14 @@ parallelsConnectGetCapabilities(virConnectPtr conn)
 }
 
 static int
-parallelsDomainDefPostParse(virDomainDefPtr def ATTRIBUTE_UNUSED,
+parallelsDomainDefPostParse(virDomainDefPtr def,
                             virCapsPtr caps ATTRIBUTE_UNUSED,
                             void *opaque ATTRIBUTE_UNUSED)
 {
+    /* memory hotplug tunables are not supported by this driver */
+    if (virDomainDefCheckUnsupportedMemoryHotplug(def) < 0)
+        return -1;
+
     return 0;
 }
 

src/phyp/phyp_driver.c

@@ -1094,10 +1094,14 @@ openSSHSession(virConnectPtr conn, virConnectAuthPtr auth,
 
 
 static int
-phypDomainDefPostParse(virDomainDefPtr def ATTRIBUTE_UNUSED,
+phypDomainDefPostParse(virDomainDefPtr def,
                        virCapsPtr caps ATTRIBUTE_UNUSED,
                        void *opaque ATTRIBUTE_UNUSED)
 {
+    /* memory hotplug tunables are not supported by this driver */
+    if (virDomainDefCheckUnsupportedMemoryHotplug(def) < 0)
+        return -1;
+
     return 0;
 }
 

src/qemu/qemu_domain.c

@@ -1052,6 +1052,10 @@ qemuDomainDefPostParse(virDomainDefPtr def,
                                   VIR_DOMAIN_INPUT_BUS_USB) < 0)
         return -1;
 
+    /* memory hotplug tunables are not supported by this driver */
+    if (virDomainDefCheckUnsupportedMemoryHotplug(def) < 0)
+        return -1;
+
     return 0;
 }
 

src/uml/uml_driver.c

@@ -444,10 +444,14 @@ umlDomainDeviceDefPostParse(virDomainDeviceDefPtr dev,
 
 
 static int
-umlDomainDefPostParse(virDomainDefPtr def ATTRIBUTE_UNUSED,
+umlDomainDefPostParse(virDomainDefPtr def,
                       virCapsPtr caps ATTRIBUTE_UNUSED,
                       void *opaque ATTRIBUTE_UNUSED)
 {
+    /* memory hotplug tunables are not supported by this driver */
+    if (virDomainDefCheckUnsupportedMemoryHotplug(def) < 0)
+        return -1;
+
     return 0;
 }
 

src/vbox/vbox_common.c

@@ -249,10 +249,14 @@ static char *vboxGenerateMediumName(PRUint32  storageBus,
 }
 
 static int
-vboxDomainDefPostParse(virDomainDefPtr def ATTRIBUTE_UNUSED,
+vboxDomainDefPostParse(virDomainDefPtr def,
                        virCapsPtr caps ATTRIBUTE_UNUSED,
                        void *opaque ATTRIBUTE_UNUSED)
 {
+    /* memory hotplug tunables are not supported by this driver */
+    if (virDomainDefCheckUnsupportedMemoryHotplug(def) < 0)
+        return -1;
+
     return 0;
 }
 

src/vmware/vmware_driver.c

@@ -83,10 +83,14 @@ vmwareDataFreeFunc(void *data)
 }
 
 static int
-vmwareDomainDefPostParse(virDomainDefPtr def ATTRIBUTE_UNUSED,
+vmwareDomainDefPostParse(virDomainDefPtr def,
                          virCapsPtr caps ATTRIBUTE_UNUSED,
                          void *opaque ATTRIBUTE_UNUSED)
 {
+    /* memory hotplug tunables are not supported by this driver */
+    if (virDomainDefCheckUnsupportedMemoryHotplug(def) < 0)
+        return -1;
+
     return 0;
 }
 

src/vmx/vmx.c

@@ -524,10 +524,14 @@ VIR_ENUM_IMPL(virVMXControllerModelSCSI, VIR_DOMAIN_CONTROLLER_MODEL_SCSI_LAST,
  * Helpers
  */
 static int
-vmxDomainDefPostParse(virDomainDefPtr def ATTRIBUTE_UNUSED,
+vmxDomainDefPostParse(virDomainDefPtr def,
                       virCapsPtr caps ATTRIBUTE_UNUSED,
                       void *opaque ATTRIBUTE_UNUSED)
 {
+    /* memory hotplug tunables are not supported by this driver */
+    if (virDomainDefCheckUnsupportedMemoryHotplug(def) < 0)
+        return -1;
+
     return 0;
 }
 

src/xen/xen_driver.c

@@ -388,6 +388,10 @@ xenDomainDefPostParse(virDomainDefPtr def,
         def->memballoon = memballoon;
     }
 
+    /* memory hotplug tunables are not supported by this driver */
+    if (virDomainDefCheckUnsupportedMemoryHotplug(def) < 0)
+        return -1;
+
     return 0;
 }
 

src/xenapi/xenapi_driver.c

@@ -70,10 +70,14 @@ xenapiDomainDeviceDefPostParse(virDomainDeviceDefPtr dev,
 
 
 static int
-xenapiDomainDefPostParse(virDomainDefPtr def ATTRIBUTE_UNUSED,
+xenapiDomainDefPostParse(virDomainDefPtr def,
                          virCapsPtr caps ATTRIBUTE_UNUSED,
                          void *opaque ATTRIBUTE_UNUSED)
 {
+    /* memory hotplug tunables are not supported by this driver */
+    if (virDomainDefCheckUnsupportedMemoryHotplug(def) < 0)
+        return -1;
+
     return 0;
 }
 

tests/domainschemadata/maxMemory.xml

@@ -0,0 +1,19 @@
+<domain type='qemu'>
+  <name>QEMUGuest1</name>
+  <uuid>c7a5fdbd-edaf-9455-926a-d65c16db1809</uuid>
+  <maxMemory slots='9' unit='KiB'>1233456789</maxMemory>
+  <memory unit='KiB'>219136</memory>
+  <currentMemory unit='KiB'>219136</currentMemory>
+  <vcpu placement='static'>1</vcpu>
+  <os>
+    <type arch='i686' machine='pc'>hvm</type>
+    <boot dev='hd'/>
+  </os>
+  <clock offset='utc'/>
+  <on_poweroff>destroy</on_poweroff>
+  <on_reboot>restart</on_reboot>
+  <on_crash>destroy</on_crash>
+  <devices>
+    <emulator>/usr/bin/qemu</emulator>
+  </devices>
+</domain>