Description of problem:
ctrl-alt-delete key does not work when guest enter into grub stage

Version-Release number of selected component (if applicable):
kvm-83-207.el5

How reproducible:
100%

Steps to Reproduce:
1.Launch previous installed rhel6 guest
/usr/libexec/qemu-kvm -M rhel5.4.0 -m 8G -smp 4 -name test-img -uuid 39a565d2-2032-848d-bda0-de7adb149048 -boot cd -drive file=/root/RHEL6.0-64.qcow2,if=virtio,bus=0,unit=0,boot=on,format=qcow2 -serial pty -parallel none -usb -usbdevice tablet  -balloon virtio -monitor stdio -spice host=0,ic=on,port=5937,disable-ticketing -qxl 1  -net none
2.Press "ctrl-alt-del" key when guest enter into grub as attached screenshot

  
Actual results:
guest does not reboot

Expected results:
guest should reboot

Additional info:
1. guest can not reboot when send key via monitor when enter into grub
(qemu) sendkey ctrl-alt-delete
2. this issue does happen when using "send ctrl-alt-del " via vncviewer.