You can just use a flattened mapping of any 'blockdev-add' command for
the command-line '-drive'.  Use dots for nesting.  [Thanks, Kevin Wolf,
on #qemu, OFTC]:

For example, given this QMP input of 'blockdev-add':

-----------------------------------------------------------------------
{
    "execute":"blockdev-add",
    "arguments":{
        "options":{
            "driver":"qcow2",
            "id":"drive-ide2-0-0",
            "file":{
                "driver":"file",
                "filename":"/export/disk2.qcow2"
            }
        }
    }
}
-----------------------------------------------------------------------

The'-drive' command-line equivalent of the above:

	-drive driver=qcow2,id=drive-ide2-0-0,file.driver=file,file.filename=/export/disk2.qcow2

Similarly, if it's a 'virtio' device:

   -drive driver=qcow2,id=drive-virtio-disk1,file.driver=file,file.filename=disk1.qcow2