virsh attach-device can't attach a new device to a kvm guest OS

Issue

• virsh attach-device can't attach a new device to a kvm guest OS.

• We ran virsh attach-device while a kvm guest OS is not running.  The command failed with the following error messages.

  # virsh attach-device RHEL60beta1_kvm disk1.xml
  error: Failed to attach device from disk1.xml
  error: Requested operation is not valid: cannot attach device on inactive domain
  

• Additionally, we ran "virsh attach-device" while the kvm guest OS is running.  The command failed with the following error messages.

  # virsh attach-device RHEL60beta1_kvm disk1.xml
  error: Failed to attach device from disk1.xml
  error: internal error unable to execute QEMU command 'drive_add': The command drive_add has not been found
  

• Step to Reproduce:

      0. Define a new device in an XML file.

# cat disk1.xml
<disk type='block' device='disk'>
  <driver name='qemu'/>
  <source dev='/dev/sdc1'/>
  <target dev='vdd' bus='virtio'/>
  <alias name='virtio-disk0'/>
</disk>

      [Case 1: A kvm guest OS is not running.]
      1-1. Run the following command to shut down a kvm guest OS.

# virsh shutdown <kvm-guestOS-name>

      1-2. Run the following command to check that the kvm guest OS is not running.

# virsh list --all
 Id Name                 State
 ----------------------------------
  - RHEL60beta1_kvm      shut off

     1-3. Run the following command to attach the new device to the kvm guest OS.

# virsh attach-device RHEL60beta1_kvm disk1.xml

     [Case 2: A kvm guest OS is running.]
     2-1. Run the following command to start a kvm guest OS.

# virsh start <kvm-guestOS-name>

      2-2. Run the following command to check that the kvm guest OS is running.

# virsh list --all
 Id Name                 State
 ----------------------------------
 30 RHEL60beta1_kvm      running

      2-3. Run the following command to attach the new device to the kvm guest OS.

# virsh attach-device RHEL60beta1_kvm disk1.xml

We know this problem is related to BZ573946 and BZ581963.
BZ573946: QMP: broken drive hotplug due to missing 'blockdev_add' /
           'drive_add' commands in QEMU
           (https://bugzilla.redhat.com/show_bug.cgi?id=573946)
BZ581963: QMP: missing drive_add command in JSON mode
           (https://bugzilla.redhat.com/show_bug.cgi?id=581963)