nova修改libvirt.xml及自定义xml文件修改nova代码支持vhost

<interface type='bridge'>

      <mac address='00:1a:4a:4d:63:a0'/>

      <source bridge='sdcos-vmnet'/>

      <model type='virtio'/>

      <filterref filter='vdsm-no-mac-spoofing'/>

      <link state='up'/>

      <bandwidth>

      </bandwidth>

      <address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/>

      <driver name='qemu'/>

    </interface>

    <interface type="bridge">

      <mac address="fa:16:3e:ea:69:50"/>

      <model type="virtio"/>

      <source bridge="qbr3bcc4870-b3"/>

      <target dev="tap3bcc4870-b3"/>

      <driver name='qemu'/> #加上此配置文件，则启动的虚拟机参数中就会有vhost=off

    </interface>

修改nova代码支持：

    def get_config(self, instance, vif, image_meta, inst_type):

        conf = vconfig.LibvirtConfigGuestInterface()

        # Default to letting libvirt / the hypervisor choose the model

        model = None

        driver = None

        # If the user has specified a 'vif_model' against the

        # image then honour that model

        if image_meta:

            vif_model = image_meta.get('properties',

                                       {}).get('hw_vif_model')

            if vif_model is not None:

                model = vif_model

        # Else if the virt type is KVM/QEMU, use virtio according

        # to the global config parameter

        if (model is None and

            CONF.libvirt.virt_type in ('kvm', 'qemu') and

                    CONF.libvirt.use_virtio_for_bridges):

            model = "virtio"

        # Workaround libvirt bug, where it mistakenly

        # enables vhost mode, even for non-KVM guests

        if model == "virtio" and CONF.libvirt.virt_type == "qemu":

            driver = "qemu"

修改为：

if model == "virtio" and CONF.libvirt.virt_type == "qemu":

            driver = "qemu"

driver = "qemu"//增加此句，代表永远为qemu