Description of problem:
this issue has been fixed under pc-xx machine type(bug 771610), but still hit it under Q35.
Btw, if with a cdrom media attaching, the tray_open value can be changed correctly, refer to bug 984406.

Version-Release number of selected component (if applicable):
host info:
3.10.0-0.rc7.64.el7.x86_64
qemu-kvm-1.5.1-2.el7.x86_64
guest info:
3.10.0-0.rc7.64.el7.x86_64

How reproducible:
100%

Steps to Reproduce:
1.boot guest *without* any media cdrom under Q35.
# /usr/libexec/qemu-kvm -S -M q35...
2.check the block info via HMP and QMP monitor.
(qemu) info block
drive-system-disk: removable=0 io-status=ok file=/home/RHEL-7.0-20130628.0-Server-x86_64.qcow3 ro=0 drv=qcow2 encrypted=0 bps=0 bps_rd=0 bps_wr=0 iops=0 iops_rd=0 iops_wr=0
drive-data-disk1: removable=0 io-status=ok file=/home/my-data-disk1.qcow3 ro=0 drv=qcow2 encrypted=0 bps=0 bps_rd=0 bps_wr=0 iops=0 iops_rd=0 iops_wr=0
ide1-cd0: removable=1 locked=0 tray-open=0 [not inserted]
floppy0: removable=1 locked=0 tray-open=0 [not inserted]
sd0: removable=1 locked=0 tray-open=0 [not inserted]
3.force to eject the media device.
(qemu) eject -f ide1-cd0
4.check the tray-open value via HMP or QMP monitor.
(qemu) info block
{"execute": "query-block"}

Actual results:
(qemu) info block
ide1-cd0: removable=1 locked=0 tray-open=0 [not inserted]
...
{"execute": "query-block"}
{"device": "ide1-cd0", "locked": false, "removable": true, "tray_open": false, "type": "unknown"}, {"device": "floppy0", "locked": false, "removable": true, "tray_open": false, "type": "unknown"}

Expected results:
the tray_open value should be: tray-open=1 & tray_open": true.

Additional info: