[Kimchi-devel] [PATCH 1/4 v4] [Memory HotPlug] Feature test to check support to memory devices

[Rodrigo Trujillo]

This patch adds a new feature test to check if the host libvirt
version supports memory devices attachment. This support is provided
since libvirt 1.2.14 and is the base to make memory hotplug work.
When libvirt does not support memory devices, it is going to fail when
we try to attach it, raising the libvirt.libvirtError:
"unsupported configuration: unknown device type 'memory'"

Signed-off-by: Rodrigo Trujillo <rodrigo.trujillo at linux.vnet.ibm.com>
---
 src/kimchi/model/config.py       |  3 +++
 src/kimchi/model/featuretests.py | 50 ++++++++++++++++++++++++++++++++++++++++
 2 files changed, 53 insertions(+)

diff --git a/src/kimchi/model/config.py b/src/kimchi/model/config.py
index 687531b..8735beb 100644
--- a/src/kimchi/model/config.py
+++ b/src/kimchi/model/config.py
@@ -55,6 +55,7 @@ class CapabilitiesModel(object):
         self.fc_host_support = False
         self.metadata_support = False
         self.kernel_vfio = False
+        self.mem_hotplug_support = False
 
         # Subscribe function to set host capabilities to be run when cherrypy
         # server is up
@@ -91,6 +92,7 @@ class CapabilitiesModel(object):
         self.fc_host_support = FeatureTests.libvirt_support_fc_host(conn)
         self.metadata_support = FeatureTests.has_metadata_support(conn)
         self.kernel_vfio = FeatureTests.kernel_support_vfio()
+        self.mem_hotplug_support = FeatureTests.has_mem_hotplug_support(conn)
 
         self.libvirt_stream_protocols = []
         for p in ['http', 'https', 'ftp', 'ftps', 'tftp']:
@@ -139,6 +141,7 @@ class CapabilitiesModel(object):
                 'auth': kconfig.get("authentication", "method"),
                 'kernel_vfio': self.kernel_vfio,
                 'nm_running': FeatureTests.is_nm_running(),
+                'mem_hotplug_support': self.mem_hotplug_support
                 }
 
 
diff --git a/src/kimchi/model/featuretests.py b/src/kimchi/model/featuretests.py
index 9400151..047108f 100644
--- a/src/kimchi/model/featuretests.py
+++ b/src/kimchi/model/featuretests.py
@@ -63,6 +63,25 @@ SIMPLE_VM_XML = """
   </os>
 </domain>"""
 
+MAXMEM_VM_XML = """
+<domain type='%(domain)s'>
+  <name>%(name)s</name>
+  <maxMemory slots='1' unit='KiB'>20480</maxMemory>
+  <memory unit='KiB'>10240</memory>
+  <os>
+    <type arch='%(arch)s'>hvm</type>
+    <boot dev='hd'/>
+  </os>
+</domain>"""
+
+DEV_MEM_XML = """
+<memory model='dimm'>
+  <target>
+    <size unit='KiB'>10240</size>
+    <node>0</node>
+  </target>
+</memory>"""
+
 SCSI_FC_XML = """
 <pool type='scsi'>
   <name>%(name)s</name>
@@ -207,3 +226,34 @@ class FeatureTests(object):
             return False
 
         return True
+
+    @staticmethod
+    def has_mem_hotplug_support(conn):
+        '''
+        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
+
+        with RollbackContext() as rollback:
+            FeatureTests.disable_libvirt_error_logging()
+            rollback.prependDefer(FeatureTests.enable_libvirt_error_logging)
+            conn_type = conn.getType().lower()
+            domain_type = 'test' if conn_type == 'test' else 'kvm'
+            arch = 'i686' if conn_type == 'test' else platform.machine()
+            arch = 'ppc64' if arch == 'ppc64le' else arch
+            dom = conn.defineXML(MAXMEM_VM_XML % {'name': FEATURETEST_VM_NAME,
+                                                  'domain': domain_type,
+                                                  'arch': arch})
+            rollback.prependDefer(dom.undefine)
+            try:
+                dom.attachDeviceFlags(DEV_MEM_XML,
+                                      libvirt.VIR_DOMAIN_MEM_CONFIG)
+                return True
+            except libvirt.libvirtError:
+                return False
-- 
2.1.0