Although it's a fairly simple change to make this work, I think
deferring it to RHEL >= 7.2 is the correct decision because:

 - old virt-v2v had the same missing feature

 - the listen address is more restrictive than before conversion, so
   it doesn't open any security holes

 - users can work around easily by adjusting the libvirt XML

 - it's risky to add new features just before RHEL 7.1 is released

Fixed upstream with
https://github.com/libguestfs/libguestfs/commit/9360675dc244a8762e07a8a4289e7a30ca3e1eef
which is in libguestfs >= 1.29.34.

1.Prepare a guest with vnc graphics type,which listens to '0.0.0.0'
# virsh -c xen+ssh://10.66.106.64 dumpxml rhel7
    <graphics type='vnc' port='-1' autoport='yes' listen='0.0.0.0' keymap='en-us'/>

2.Use virt-v2v to convert the guest.
# virt-v2v -ic xen+ssh://10.66.106.64 -os default -b br1 rhel7 -of raw -on rhel7-vncaddress-test
[   0.0] Opening the source -i libvirt -ic xen+ssh://10.66.106.64 rhel7
[   0.0] Creating an overlay to protect the source from being modified
[   1.0] Opening the overlay
[   7.0] Initializing the target -o libvirt -os default
[   7.0] Inspecting the overlay
[  16.0] Checking for sufficient free disk space in the guest
[  16.0] Estimating space required on target for each disk
[  16.0] Converting Red Hat Enterprise Linux Server release 7.0 Beta (Maipo) to run on KVM
virt-v2v: This guest has virtio drivers installed.
[  86.0] Mapping filesystem data to avoid copying unused and blank areas
[  87.0] Closing the overlay
[  87.0] Copying disk 1/1 to /var/lib/libvirt/images/rhel7-vncaddress-test-sda (raw)
    (100.00/100%)
[ 160.0] Creating output metadata
Pool default refreshed

Domain rhel7-vncaddress-test defined from /tmp/v2vlibvirt13d108.xml

3.After conversion,check the xml of guest.
# virsh dumpxml rhel7-vncaddress-test
   <graphics type='vnc' port='5901' autoport='yes' listen='127.0.0.1' keymap='en-us'>
      <listen type='address' address='127.0.0.1'/>
    </graphics>

Refer to comment 3,the listen address has been changed to '127.0.0.1'.

So the bug is not fixed yet,would you pls help to check it?thanks.

(In reply to tingting zheng from comment #4)
> 1.Prepare a guest with vnc graphics type,which listens to '0.0.0.0'
> # virsh -c xen+ssh://10.66.106.64 dumpxml rhel7
>     <graphics type='vnc' port='-1' autoport='yes' listen='0.0.0.0'
> keymap='en-us'/>

The libvirt documentation [1] seems to recommend a separate <listen> child node rather than an address="" attribute in <graphics> though, as it is more detailed, and v2v supports that so far. I will add support for the old format as well in case <listen> is missing, but you should better use the new one.

[1] http://libvirt.org/formatdomain.html#elementsGraphics

(In reply to Pino Toscano from comment #5)
> (In reply to tingting zheng from comment #4)
> > 1.Prepare a guest with vnc graphics type,which listens to '0.0.0.0'
> > # virsh -c xen+ssh://10.66.106.64 dumpxml rhel7
> >     <graphics type='vnc' port='-1' autoport='yes' listen='0.0.0.0'
> > keymap='en-us'/>
> 
> The libvirt documentation [1] seems to recommend a separate <listen> child
> node rather than an address="" attribute in <graphics> though, as it is more
> detailed, and v2v supports that so far. I will add support for the old
> format as well in case <listen> is missing, but you should better use the
> new one.
> 
> [1] http://libvirt.org/formatdomain.html#elementsGraphics

The guest exist on xen server which is rhel5 system,and this is the default configuration.

Also tried the new way on xen server,it just ignores address line,so I think the new way on xen server is not supported as it's too old.

Refer to comment 4,5,6,move this bug back to ASSIGNED.

Extra upstream fix:
https://github.com/libguestfs/libguestfs/commit/8c26ef91f95a9de68cea4c2341e00c938586f950

Tested with:
libvirt-1.2.16-1.el7.x86_64
virt-v2v-1.28.1-1.42.el7.x86_64
qemu-kvm-1.5.3-92.el7.x86_64

1.Prepare a guest with vnc graphics type,which listens to '0.0.0.0'
# virsh -c xen+ssh://10.66.106.64 dumpxml rhel7
    <graphics type='vnc' port='-1' autoport='yes' listen='0.0.0.0' keymap='en-us'/>

2.Use virt-v2v to convert the guest.
# virt-v2v -ic xen+ssh://10.66.106.64 -os default -b virbr0 rhel7 -of raw -on rhel7-vncaddress-test
[   0.0] Opening the source -i libvirt -ic xen+ssh://10.66.106.64 rhel7
[   1.0] Creating an overlay to protect the source from being modified
[   1.0] Opening the overlay
[  11.0] Initializing the target -o libvirt -os default
[  11.0] Inspecting the overlay
[  23.0] Checking for sufficient free disk space in the guest
[  23.0] Estimating space required on target for each disk
[  23.0] Converting Red Hat Enterprise Linux Server release 7.0 Beta (Maipo) to run on KVM
virt-v2v: This guest has virtio drivers installed.
[  90.0] Mapping filesystem data to avoid copying unused and blank areas
[  91.0] Closing the overlay
[  91.0] Copying disk 1/1 to /var/lib/libvirt/images/rhel7-vncaddress-test-sda (raw)
    (100.00/100%)
[ 329.0] Creating output metadata
Pool default refreshed

Domain rhel7-vncaddress-test defined from /tmp/v2vlibvirt23ff44.xml

[ 330.0] Finishing off

3.After conversion,check the listen address for guest,it is the same as before.
# virsh dumpxml rhel7-vncaddress-test
    <graphics type='vnc' port='-1' autoport='yes' listen='0.0.0.0'>
      <listen type='address' address='0.0.0.0'/>
    </graphics>

Refer to the above comments,move the bug to VERIFIED.

Miss this comment:
For the new format of graphics,it is not supported on xen server,as v2v supports conversion kvm guests running on rhel7 to RHEV,guests graphics defaults to spice on rhev,so I didn't test the new format of graphics.

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.

https://rhn.redhat.com/errata/RHBA-2015-2183.html