A few examples of using `xpath` to query the guest XML from the
command-line.

(1) CPU "mode": whether customer is using `host-model`,
    `host-passthrough` or `custom`.  You can find that as the value of
    the "mode" attribute for the 'cpu' element.  Or this `xpath`
    one-liner on a libvirt guest XML will show it:
      
      $> xpath -q -e '//cpu/@mode' el8-vm1.xml
      mode="host-model"

    Run the above on all your XML files (and output that into a file):

      $> xpath -q -e '//cpu/@mode'  *.xml |& tee Customer-CPU-mode.txt
      [...]

(2) Entire guest CPU configuration.  This will dump the entire guest CPU
    config.  So it would be the entire content between the 'cpu'
    element: <cpu mode=...> ... </cpu>.  Or run this `xpath` one-liner
    on an XML file (and then on rest of them all):

      $> xpath -q -e '//cpu/' el8-vm1.xml
      [...]

(3) The 'disk' element: how many are using 'qcow2' vs 'raw'.

      $> xpath -q -e '//disk/' el8-vm1.xml
      <disk type='file' device='disk'>
        <driver name='qemu' type='qcow2'/>
        <source file='/export/disk-images/rhel-7.qcow2'/>
        [...]
      </disk>

    But to get the format ('qcow2' or 'raw') of file:

      $> xpath -q -e '//driver/@type' el8-vm1.xml
      type="qcow2"

(4) The "machine type" in use:

      <os>
        <type arch='x86_64' machine='pc-q35-2.11'>hvm</type>
        <boot dev='hd'/>
      </os>

    Or a convenient `xpath` query to just extract the machine type:

      $> xpath -q -e '//type/@machine' el8-vm1.xml
      machine="pc-q35-2.11"


        - - -

Querying the 'os'-related bits from getdomainCapabilities():

    [...]
    <os supported='yes'>
      <enum name='firmware'>
        <value>efi</value>
      </enum>
      <loader supported='yes'>
        <value>/usr/share/edk2/ovmf/OVMF_CODE.fd</value>
        <enum name='type'>
          <value>rom</value>
          <value>pflash</value>
        </enum>
        <enum name='readonly'>
          <value>yes</value>
          <value>no</value>
        </enum>
        <enum name='secure'>
          <value>no</value>
        </enum>
      </loader>
    </os>
    [..]

And the `xpath` queries:

    $> virsh domcapabilities --machine q35 | \
        xpath -q -e "//os/@supported"
     supported="yes"


    $> virsh domcapabilities --machine q35 | \
        xpath -q -e "//enum[@name='firmware']/value/text()"
    efi 


    $> virsh domcapabilities --machine q35 | \
        xpath -q -e "//loader/@supported"
    supported="yes"


    $> virsh domcapabilities --machine q35 | \
        xpath -q -e "//loader/value/text()"
    /usr/share/edk2/ovmf/OVMF_CODE.fd


    $> virsh domcapabilities --machine q35 | \
        xpath -q -e "//loader/enum[@name='type']/value/text()"
    rom
    pflash