Description of problem:
there is a lack of 'drive_add /drive_del' command in QMP, while existing in HMP monitor.

Version-Release number of selected component (if applicable):
host info:
3.10.0-50.el7.x86_64
qemu-kvm-rhev-1.5.3-19.el7.x86_64
seabios-1.7.2.2-4.el7.x86_64
guest info:
2.6.32-425.el6.x86_64

How reproducible:
100%

Steps to Reproduce:
1.boot QEMU with qmp server.
# /usr/libexec/qemu-kvm... -qmp tcp:0:4444,server,nowait 
2.connect to QMP and check the commands.
# telnet localhost 4444
{"execute":"qmp_capabilities"}
{"return": {}}
{"execute":"query-commands"}

Actual results:
after step 2, there is a lack of 'drive_add /drive_del' command in QMP.

Expected results:
it should have drive_add /drive_del or the same to rhel6.5 to support hotpluging.

Additional info:
{"execute":"qmp_capabilities"}
{"return": {}}
{"execute":"query-commands"}
{"return": [{"name": "query-rx-filter"}, {"name": "blockdev-add"}, {"name": "chardev-remove"}, {"name": "chardev-add"}, {"name": "query-tpm-types"}, {"name": "query-tpm-models"}, {"name": "query-tpm"}, {"name": "query-target"}, {"name": "query-cpu-definitions"}, {"name": "query-machines"}, {"name": "device-list-properties"}, {"name": "qom-list-types"}, {"name": "change-vnc-password"}, {"name": "nbd-server-stop"}, {"name": "nbd-server-add"}, {"name": "nbd-server-start"}, {"name": "qom-get"}, {"name": "qom-set"}, {"name": "qom-list"}, {"name": "query-block-jobs"}, {"name": "query-balloon"}, {"name": "query-migrate-capabilities"}, {"name": "migrate-set-capabilities"}, {"name": "query-migrate"}, {"name": "query-command-line-options"}, {"name": "query-uuid"}, {"name": "query-name"}, {"name": "query-spice"}, {"name": "query-vnc"}, {"name": "query-mice"}, {"name": "query-status"}, {"name": "query-kvm"}, {"name": "query-pci"}, {"name": "query-cpus"}, {"name": "query-blockstats"}, {"name": "query-block"}, {"name": "query-chardev"}, {"name": "query-events"}, {"name": "query-commands"}, {"name": "query-version"}, {"name": "human-monitor-command"}, {"name": "qmp_capabilities"}, {"name": "add_client"}, {"name": "expire_password"}, {"name": "set_password"}, {"name": "block_set_io_throttle"}, {"name": "block_passwd"}, {"name": "query-fdsets"}, {"name": "remove-fd"}, {"name": "add-fd"}, {"name": "closefd"}, {"name": "getfd"}, {"name": "set_link"}, {"name": "balloon"}, {"name": "block-job-complete"}, {"name": "block-job-resume"}, {"name": "block-job-pause"}, {"name": "block-job-cancel"}, {"name": "block-job-set-speed"}, {"name": "block_resize"}, {"name": "netdev_del"}, {"name": "netdev_add"}, {"name": "dump-guest-memory"}, {"name": "client_migrate_info"}, {"name": "migrate_set_downtime"}, {"name": "migrate_set_speed"}, {"name": "query-migrate-cache-size"}, {"name": "migrate-set-cache-size"}, {"name": "migrate_cancel"}, {"name": "migrate"}, {"name": "xen-set-global-dirty-log"}, {"name": "xen-save-devices-state"}, {"name": "ringbuf-read"}, {"name": "ringbuf-write"}, {"name": "inject-nmi"}, {"name": "pmemsave"}, {"name": "memsave"}, {"name": "cpu-add"}, {"name": "cpu"}, {"name": "send-key"}, {"name": "device_del"}, {"name": "device_add"}, {"name": "system_powerdown"}, {"name": "system_reset"}, {"name": "system_wakeup"}, {"name": "cont"}, {"name": "stop"}, {"name": "__com.redhat_qxl_screendump"}, {"name": "screendump"}, {"name": "change"}, {"name": "eject"}, {"name": "quit"}]}