CODEWITHSUNDEEP
qemukvmlibvirtovirt
meustrus
meustrus

Reputation: 7315

Error creating libvirt KVM domain: invalid argument: could not get preferred machine for /usr/libexec/qemu-kvm type=kvm

I'm trying to create the following domain on a host running oVirt Node in nested virtualization (it won't be nested forever, just for now):

<domain type="kvm">
    <name>clara</name>
    <memory unit="MiB">4096</memory>
    <vcpu>2</vcpu>
    <os>
        <type>hvm</type>
        <boot dev="hd"></boot>
    </os>
    <features>
        <pae></pae>
        <acpi></acpi>
        <apic></apic>
    </features>
    <cpu></cpu>
    <devices>
        <disk type="volume" device="disk">
            <driver name="qemu" type="qcow2"></driver>
            <source pool="default" volume="clara-rootfs"></source>
            <target dev="vda" bus="scsi"></target>
            <wwn>05abcd62857fe8f1</wwn>
        </disk>
        <disk type="file" device="cdrom">
            <driver name="qemu" type="raw"></driver>
            <source file="/var/lib/libvirt/images/cloudinit.clara.iso"></source>
            <target dev="hdd" bus="ide"></target>
        </disk>
        <controller type="scsi" model="virtio-scsi"></controller>
        <interface type="bridge">
            <mac address="E2:F5:2A:A9:4A:42"></mac>
            <source bridge="bridge0"></source>
            <model type="virtio"></model>
        </interface>
        <channel type="unix">
            <target type="virtio" name="org.qemu.guest_agent.0"></target>
        </channel>
        <graphics type="spice" autoport="yes"></graphics>
        <rng model="virtio">
            <backend model="random">/dev/urandom</backend>
        </rng>
    </devices>
</domain>

When I do, I get this error:

# virsh define clara.xml 
error: Failed to define domain from clara.xml
error: invalid argument: could not get preferred machine for /usr/libexec/qemu-kvm type=kvm

What does this error mean, and how do I fix it?

Upvotes: 1

Views: 5494

Answers (1)

meustrus
meustrus

Reputation: 7315

Figured it out. This error happened because of a combination of two problems:

  1. The machine type was not specified in <type>hvm</type>, and an error happened when trying to discover the "preferred" default value. Setting the arch and machine fields revealed the real problem:
  2. kvm is not available in my setup because the host is running in nested virtualization. Changing <domain type="kvm"> to <domain type="qemu"> made it work.

If you are doing this in Terraform, you can modify the generated XML file by adding this configuration:

resource "libvirt_domain" "vm" {
  # ...

  xml {
    xslt = <<-EOT
      <?xml version="1.0" ?>
      <xsl:stylesheet version="1.0"
                      xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
        <xsl:output omit-xml-declaration="yes" indent="yes"/>

        <!-- Copy everything from the generated XML -->
        <xsl:template match="node()|@*">
          <xsl:copy>
            <xsl:apply-templates select="node()|@*"/>
          </xsl:copy>
        </xsl:template>

        <!-- Set domain#type to 'qemu' for nested virtualization -->
        <xsl:template match="/domain/@type">
          <xsl:attribute name="type">
              <xsl:value-of select="'qemu'"/>
          </xsl:attribute>
        </xsl:template>

      </xsl:stylesheet>
    EOT
  }
}

Upvotes: 4

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