Created attachment 602475 [details]
gdb log

Created attachment 602476 [details]
libvirtd log

What's the qemu-guest-agent version in the guest? and seabios version on the host?

It's very strange for me, I can't reproduce it on my RHEL6.2(2.6.32-220.el6.x86_64) with libvirt-0.10.0-0rc0.el6.x86_64, qemu-kvm-rhev-0.12.1.2-2.295.el6.x86_64 and seabios-0.6.1.2-19.el6.x86_64, and I installed qemu-guest-agent-0.12.1.2-2.295.el6.x86_64 in RHEL6 guest.

# virsh dumpxml myRHEL6

  xxxx

  <os>
    <type arch='x86_64' machine='rhel6.3.0'>hvm</type>
    <loader>/usr/share/seabios/bios-pm.bin</loader>
    <boot dev='hd'/>
  </os>

  xxxx

    <channel type='unix'>
      <source mode='bind' path='/var/lib/libvirt/qemu/myRHEL6.agent'/>
      <target type='virtio' name='org.qemu.guest_agent.0'/>
      <address type='virtio-serial' controller='0' bus='0' port='2'/>
    </channel>

  xxxx

However, I also can reproduce the issue on Wenlong test machine even though I don't need to start qemu-ga in the guest.

(In reply to comment #4)
> What's the qemu-guest-agent version in the guest? and seabios version on the
> host?
> 
I just check Wenlong machine:

On the guest:

qemu-guest-agent-0.12.1.2-2.298.el6.x86_64

On the host:

seabios-0.6.1.2-19.el6.x86_64

I checked it further, it's relationship with qemu-guest-agent version, and I can reproduce it on qemu-guest-agent-0.12.1.2-2.298.el6.x86_64 and qemu-guest-agent-0.12.1.2-2.302.el6.x86_64.rpm, it may be qemu-guest-agent changes some places, however, libvirt hasn't follow it.

Path for upstream and wait for developers review:
https://www.redhat.com/archives/libvir-list/2012-August/msg00417.html

Daniel's commit b57ee09 potentially fix the issue via using virObjectUnref() instead of qemuAgentUnref(), the old qemuAgentUnref(priv->agent) hasn't judge whether its parameter is NULL then will deref a NULL pointer, however, if the parameter 'priv->agent' is NULL then the virObjectUnref(priv->agent) will directly return false without executing subsequent codes.

commit b57ee0921ec7c5c2cfc51ce34fcc296aaad52dd5
Author: Daniel P. Berrange <berrange@redhat.com>
Date:   Wed Jul 11 14:35:47 2012 +0100

    Turn qemuAgentPtr and qemuMonitorPtr into virObjectPtr instances
    
    Make qemuAgentPtr and qemuMonitorPtr types use the virObject APIs
    for reference counting
    
    Signed-off-by: Daniel P. Berrange <berrange@redhat.com>

Verify this bug with :
libvirt-0.10.2-2.el6.x86_64
qemu-kvm-0.12.1.2-2.316.el6.x86_64
seabios-0.6.1.2-22.el6.x86_64

add these pattern in the xml 

...
 <os>
    <type arch='x86_64' machine='rhel6.4.0'>hvm</type>
    <loader>/usr/share/seabios/bios-pm.bin</loader>
    <boot dev='hd'/>
  </os>
 <pm>
    <suspend-to-mem enabled='no'/>
    <suspend-to-disk enabled='yes'/>
  </pm>

  <devices>
...
   <channel type='unix'>
      <source mode='bind' path='/var/lib/libvirt/qemu/rhel6-dvs.agent'/>
      <target type='virtio' name='org.qemu.guest_agent.0'/>
      <alias name='channel1'/>
      <address type='virtio-serial' controller='0' bus='0' port='2'/>
    </channel>
...
  </devices>

...


#virsh dompmsuspend rhel6-dvs disk
Domain rhel6-dvs successfully suspended

#virsh start rhel6-dvs 

guest is fine

Now, in pkg qemu-guest-agent-win32-0.12.1.2-2.346.el6.x86_64.rpm  we can do the s3/s4 in windows guest based the windows guest agent supported commands list
supported commands:
"guest-info"
"guest-ping"
"guest-sync-delimited"
"guest-sync"
"guest-shutdown" (include shutdown,reboot,halt)
"guest-suspend-disk"
"guest-suspend-ram"
Since there was a bug 888716 over there ,so the command "guest-susend-disk " did not work well so far

Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

http://rhn.redhat.com/errata/RHSA-2013-0276.html