[Kimchi-devel] [PATCH][Kimchi 1/2] Issue #838: Extend memory hotplug feature test

[Rodrigo Trujillo]

If QEMU version is < 2.1, qemu is not going to start guest which have
maxmemory tag configured in the XML. Kimchi adds this tag by default in
order to allow memory hotplug.
In other words, in order to allow memory hotplug, versions must be
libvirt >= 1.2.14 and qemu >= 2.1. Libvirt was already being tested by
the feature test, but qemu did not. Distros as Red Hat 7 and CentOS
still are in qemu 1.5.
This patch extend the feature test and do not create maxmemory tag in
order to avoid problems in those distros.

Signed-off-by: Rodrigo Trujillo <rodrigo.trujillo at linux.vnet.ibm.com>
---
 i18n.py               |  2 +-
 model/featuretests.py | 20 +++++++++++++-------
 model/vms.py          |  8 ++++++++
 vmtemplate.py         |  7 ++++++-
 4 files changed, 28 insertions(+), 9 deletions(-)

diff --git a/i18n.py b/i18n.py
index beefeb5..6214687 100644
--- a/i18n.py
+++ b/i18n.py
@@ -99,7 +99,7 @@ messages = {
     "KCHVM0043E": _("Only increase memory is allowed in active VMs"),
     "KCHVM0044E": _("For live memory update, new memory value must be equal old memory value plus multiples of 1024 Mib"),
     "KCHVM0045E": _("There are not enough free slots of 1024 Mib in the guest."),
-    "KCHVM0046E": _("Host's libvirt version does not support memory devices. Libvirt must be >= 1.2.14"),
+    "KCHVM0046E": _("Host's libvirt or qemu version does not support memory devices and memory hotplug. Libvirt must be >= 1.2.14 and QEMU must be >= 2.1."),
     "KCHVM0047E": _("Error attaching memory device. Details: %(error)s"),
     "KCHVM0048E": _("Cannot start %(name)s. Virtual machine is already running."),
     "KCHVM0049E": _("Cannot power off %(name)s. Virtual machine is shut off."),
diff --git a/model/featuretests.py b/model/featuretests.py
index 378335a..ba728e1 100644
--- a/model/featuretests.py
+++ b/model/featuretests.py
@@ -72,6 +72,14 @@ MAXMEM_VM_XML = """
     <type arch='%(arch)s'>hvm</type>
     <boot dev='hd'/>
   </os>
+  <cpu>
+    <numa>
+      <cell id='0' cpus='0' memory='10240' unit='KiB'/>
+    </numa>
+  </cpu>
+  <features>
+    <acpi/>
+  </features>
 </domain>"""
 
 DEV_MEM_XML = """
@@ -209,13 +217,9 @@ class FeatureTests(object):
         A memory device can be hot-plugged or hot-unplugged since libvirt
         version 1.2.14.
         '''
-        # Libvirt < 1.2.14 does not support memory devices, so firstly, check
-        # its version, then try to attach a device. These steps avoid errors
-        # with Libvirt 'test' driver for KVM
-        version = 1000000*1 + 1000*2 + 14
-        if libvirt.getVersion() < version:
-            return False
-
+        # Libvirt < 1.2.14 does not support memory devices, so try to attach a
+        # device. Then check if QEMU (>= 2.1) supports memory hotplug, starting
+        # the guest These steps avoid errors with Libvirt 'test' driver for KVM
         with RollbackContext() as rollback:
             FeatureTests.disable_libvirt_error_logging()
             rollback.prependDefer(FeatureTests.enable_libvirt_error_logging)
@@ -230,6 +234,8 @@ class FeatureTests(object):
             try:
                 dom.attachDeviceFlags(DEV_MEM_XML,
                                       libvirt.VIR_DOMAIN_MEM_CONFIG)
+                dom.create()
+                rollback.prependDefer(dom.destroy)
                 return True
             except libvirt.libvirtError:
                 return False
diff --git a/model/vms.py b/model/vms.py
index 03ffdae..557d37a 100644
--- a/model/vms.py
+++ b/model/vms.py
@@ -809,6 +809,14 @@ class VMModel(object):
         return (nonascii_name if nonascii_name is not None else vm_name, dom)
 
     def _update_memory_config(self, xml, params):
+        # Cannot pass max memory if there is not support to memory hotplug
+        # Then set max memory as memory, just to continue with the update
+        if not self.caps.mem_hotplug_support:
+            if 'maxmemory' in params['memory']:
+                raise InvalidOperation("KCHVM0046E")
+            else:
+                params['memory']['maxmemory'] = params['memory']['current']
+
         root = ET.fromstring(xml)
         # MiB to KiB
         hasMem = 'current' in params['memory']
diff --git a/vmtemplate.py b/vmtemplate.py
index 4bcf324..535efd7 100644
--- a/vmtemplate.py
+++ b/vmtemplate.py
@@ -32,6 +32,7 @@ from wok.exception import MissingParameter, OperationFailed
 from wok.plugins.kimchi import imageinfo
 from wok.plugins.kimchi import osinfo
 from wok.plugins.kimchi.isoinfo import IsoImage
+from wok.plugins.kimchi.model.config import CapabilitiesModel
 from wok.plugins.kimchi.utils import check_url_path, pool_name_from_uri
 from wok.plugins.kimchi.xmlutils.cpu import get_cpu_xml
 from wok.plugins.kimchi.xmlutils.disk import get_disk_xml
@@ -118,6 +119,8 @@ class VMTemplate(object):
             disk_info['index'] = disk_info.get('index', index)
             self.info['disks'][index] = disk_info
 
+        self.caps = CapabilitiesModel()
+
     def _get_os_info(self, args, scan):
         distro = version = 'unknown'
 
@@ -376,7 +379,9 @@ class VMTemplate(object):
         # Rearrange memory parameters
         params['memory'] = self.info['memory'].get('current')
         params['max_memory'] = ""
-        if memory != maxmemory:
+        # if there is not support to memory hotplug in Libvirt or qemu, we
+        # cannot add the tag maxMemory
+        if memory != maxmemory and self.caps.mem_hotplug_support:
             maxmem_xml = "<maxMemory slots='%s' unit='MiB'>%s</maxMemory>"
             params['max_memory'] = maxmem_xml % (slots, maxmemory)
 
-- 
2.1.0