Description of problem:
As subject, disabled S4 inside guest with "#powercfg -h off" and then send {"execute": "guest-suspend-disk"} command to guest agent, meet some problems:
(1) For win7-32, guest gets black screen and does not return back after long time (I wait 10 mins).
(2) For win2012-64, qemu-ga service will be stop.

Version-Release number of selected component (if applicable):
Host:
kernel-2.6.32-348.el6.x86_64
qemu-kvm-0.12.1.2-2.346.el6.x86_64

Guest:
Win7-32 and win2012, installed the executable from qemu-guest-agent-win32-0.12.1.2-2.346.el6.x86_64


How reproducible:
Always

Steps to Reproduce:
1.Boot a guest:
 /usr/libexec/qemu-kvm -M rhel6.4.0 -enable-kvm -m 2048 -smp 2,sockets=2,cores=1,threads=1 -enable-kvm -name t2-rhel6.4-32 -uuid 61b6c504-5a8b-4fe1-8347-6c929b750dde -k en-us -rtc base=localtime,clock=host,driftfix=slew -no-kvm-pit-reinjection -device piix3-usb-uhci,id=usb,bus=pci.0,addr=0x1.0x2 -device usb-tablet,id=input0 -drive file=/home/win7-32.qcow2,if=none,id=disk0,format=qcow2,werror=stop,rerror=stop,aio=native -device ide-drive,bus=ide.0,unit=1,drive=disk0,id=disk0  -drive file=/home/en_windows_7_ultimate_with_sp1_x86_dvd_619077.iso,if=none,media=cdrom,id=drive-ide0-1-0,readonly=on,format=raw -device ide-drive,drive=drive-ide0-1-0,bus=ide.1,unit=0,id=cdrom -netdev tap,id=hostnet0 -device rtl8139,netdev=hostnet0,id=net0,mac=44:37:E6:5E:91:85,bus=pci.0,addr=0x5 -monitor stdio -qmp tcp:0:6666,server,nowait -chardev socket,path=/tmp/isa-serial,server,nowait,id=isa1 -device isa-serial,chardev=isa1,id=isa-serial1 -device virtio-serial-pci,id=virtio-serial0,bus=pci.0,addr=0x8 -chardev socket,id=charchannel0,path=/tmp/serial-socket,server,nowait -device virtserialport,bus=virtio-serial0.0,nr=1,chardev=charchannel0,id=channel0,name=com.redhat.rhevm.vdsm -chardev socket,path=/tmp/foo,server,nowait,id=foo -device virtconsole,chardev=foo,id=console0 -chardev spicevmc,id=charchannel1,name=vdagent -device virtserialport,bus=virtio-serial0.0,nr=2,chardev=charchannel1,id=channel1,name=com.redhat.spice.0 -device virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x9 -spice port=5930,disable-ticketing -vga qxl -global qxl-vga.vram_size=67108864 -k en-us -boot c -chardev socket,path=/tmp/qga.sock,server,nowait,id=qga0 -device virtserialport,bus=virtio-serial0.0,chardev=qga0,name=org.qemu.guest_agent.0  -global  PIIX4_PM.disable_s3=0 -global PIIX4_PM.disable_s4=0

2. Install the qemu-guest-agent-win32-0.12.1.2-2.346.el6.x86_64 on a rhel host and get the executable.

3. Install the qemu-ga.exe inside windows guest.
#c:\qemu-ga>qemu-ga.exe --service install

4. In guest:
In guest, open "services.msc" and check if qemu-ga service is started. If not, start the qemu-ga service.

5. Send some commands to guest agent to make sure it works:
# nc -U /tmp/qga.sock 
{ "execute": "guest-ping"}
{"return": {}}
{ "execute": "guest-sync-delimited", "arguments": { "id": 123456 } }
�{"return": 123456}

6. Turn off 'Hibernate' inside guest.
#powercfg -h off

7. Inside guest, check if S4 is really disabled.
#powercfg -a

8. Send {"execute": "guest-suspend-disk"} command to guest agent.

  
Actual results:
(1) For win7-32, guest gets black screen and does not return back after long time (I wait 10 mins).
(2) For win2012-64, qemu-ga service will be stop.

Expected results:
Should give some friendly prompt like doing S3 when S3 is disabled. The following prompt is acceptable.

{ "execute": "guest-suspend-ram"}
{"error": {"class": "QgaCommandFailed", "desc": "Guest agent command failed, error was 'suspend-to-ram not supported by OS'", "data": {"message": "suspend-to-ram not supported by OS"}}}


Additional info: