Description of problem:
dd a file and save the file md5sum value to a file, then quit guest with qemu cmd "q", the md5sum value is lost after re-start guest.

Version-Release number of selected component (if applicable):
qemu-kvm-0.12.1.2-2.150.el6.x86_64

How reproducible:
100%

Steps to Reproduce:
1. cmd

/usr/libexec/qemu-kvm -drive file=/usr/Auto/autotest/client/tests/kvm/images/RHEL-Server-6.0-64-virtio.qcow2,index=0,if=none,id=drive-virtio-disk1,media=disk,cache=none,format=qcow2,aio=native -device virtio-blk-pci,bus=pci.0,addr=0x4,drive=drive-virtio-disk1,id=virtio-disk1 -device virtio-net-pci,netdev=idLOEwv7,mac=9a:51:74:0d:82:53,id=ndev00idLOEwv7,bus=pci.0,addr=0x3 -netdev tap,id=idLOEwv7,vhost=on,script=/usr/Auto/autotest/client/tests/kvm/scripts/qemu-ifup-switch,downscript='no' -m 1024 -smp 2,cores=1,threads=1,sockets=2 -cpu cpu64-rhel6 -vnc :1 -rtc base=utc,clock=host,driftfix=none  -boot order=cdn,once=c,menu=off   -usbdevice tablet -no-kvm-pit-reinjection -enable-kvm -monitor stdio
2. save file md5sum value to a file
#md5sum file_name > data

3. quit guest
(qemu)q

4. Boot guest again
  
Actual results:


Expected results:
The md5sum value saved is lost

Additional info:

1. host:

kernel: 2.6.32-118.el6.x86_64

cpu: 
processor	: 3
vendor_id	: AuthenticAMD
cpu family	: 16
model		: 2
model name	: AMD Phenom(tm) 9600B Quad-Core Processor
stepping	: 3
cpu MHz		: 1150.000
cache size	: 512 KB
physical id	: 0
siblings	: 4
core id		: 3
cpu cores	: 4
apicid		: 3
initial apicid	: 3
fpu		: yes
fpu_exception	: yes
cpuid level	: 5
wp		: yes
flags		: fpu vme de pse tsc msr pae mce cx8 apic mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall nx mmxext fxsr_opt pdpe1gb rdtscp lm 3dnowext 3dnow constant_tsc rep_good nonstop_tsc extd_apicid pni monitor cx16 popcnt lahf_lm cmp_legacy svm extapic cr8_legacy abm sse4a misalignsse 3dnowprefetch osvw ibs npt lbrv svm_lock
bogomips	: 4587.44
TLB size	: 1024 4K pages
clflush size	: 64
cache_alignment	: 64
address sizes	: 48 bits physical, 48 bits virtual
power management: ts ttp tm stc 100mhzsteps hwpstate