Bug 1186142

Bug 1064831 backported upstream commit 7d5bf484747979ce842fea9ae3ae673ab09bf935 to RHEL6. This was the patch that cause Bug 1177194 in RHEL7. I haven't tested it, but based on the above information, RHEL6 will have the same bug, beginning with RHEL6.6.

+++ This bug was initially created as a clone of Bug #1177194 +++

description of problem:
Fail to Migrate with Bridged network, eth + macvtap ,with different interface name on two hosts 

Version-Release number of selected component (if applicable):
libvirt-1.2.8-11.el7.x86_64

How reproducible:
100%

Steps to Reproduce:
prepare two host .On both source and target host create a new network .
NOTE , source and target host has different interface name .

1.on source host .

1.1 define and start a new network
#cat vepa-network.xml

<network>
  <name>vepa-net</name>
  <forward dev='eno1' mode='vepa'>
    <interface dev='eno1'/>
  </forward>
</network>

# virsh net-define vepa-network.xml
# virsh net-start vepa-net
# virsh net-list --all
 Name                 State      Autostart     Persistent
----------------------------------------------------------
 default              active     no            yes
 vepa-net             active     no            yes


1.2 start a guest with the following interface using vepa-net:
......
<interface type='network'>
  <mac address='52:54:00:1b:6f:e5'/>
  <source network='vepa-net'/>
  <target dev='vnet0'/>
  <model type='virtio'/>
  <alias name='net0'/>
  <address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/>
</interface>
....

2. on the target host .

2.1 define and start a new network ,using the same network name as source host
#cat vepa-network.xml

<network>
  <name>vepa-net</name>  <==== note  same network name
  <forward dev='enp2s0' mode='vepa'>
    <interface dev='enp2s0'/>
  </forward>
</network>

# virsh net-define vepa-network.xml
# virsh net-start vepa-net
# virsh net-list --all
 Name                 State      Autostart     Persistent
----------------------------------------------------------
 default              active     no            yes
 vepa-net             active     no            yes


3. migrate

# virsh migrate --live r7 qemu+ssh://$ip/system
error: Unable to get index for interface eno1: No such device

Actual results:

Fail to migrate .
error: Unable to get index for interface eno1: No such device
      
Expected results:
Guest can migrate successfully .

additional info:
after start guest , dumpxml :
# virsh dumpxml r7 | grep interface -A 9
    <interface type='direct'>   <==== it change to direct
      <mac address='52:54:00:15:f5:12'/>
      <source network='vepa-net' dev='eno1' mode='vepa'/> <==and set the dev
      <target dev='macvtap0'/>
      <model type='virtio'/>
      <alias name='net0'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/>
    </interface>

this issue alao can produce when using private mode .

--- Additional comment from Pei Zhang on 2014-12-25 02:41:02 EST ---

additional info :
On RHEL7.0 . It can migrate successfully and the domain XML won't change between active and inactive status. 

version :
libvirt-1.1.1-29.el7_0.4.x86_64
qemu-kvm-rhev-1.5.3-60.el7_0.11.x86_64
kernel-3.10.0-123.el7.x86_64

domain XML :

active domain xml:

# virsh dumpxml r7 | grep interface -A 8
    <interface type='network'>   <=== It will not be changed to direct 
      <mac address='52:54:00:d9:99:2c'/>
      <source network='vepa-net'/>  <===  no extra dev info  
      <target dev='macvtap0'/>
      <model type='virtio'/>
      <alias name='net0'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/>
    </interface>

inactive domain xml :

# virsh dumpxml r7  --inactive | grep interface -A 8
    <interface type='network'>
      <mac address='52:54:00:d9:99:2c'/>
      <source network='vepa-net'/>
      <model type='virtio'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/>
    </interface>

--- Additional comment from Jiri Denemark on 2015-01-05 05:04:19 EST ---

Patch sent upstream for review: https://www.redhat.com/archives/libvir-list/2014-December/msg01013.html

--- Additional comment from Jiri Denemark on 2015-01-07 07:17:12 EST ---

Fixed upstream by v1.2.11-109-gdb19a4a:

commit db19a4a3c6f72e464bc3ad00e904d8df13887382
Author: Luyao Huang <lhuang>
Date:   Thu Dec 25 11:38:00 2014 +0800

    conf: Don't format actual network definition in migratable XML
    
    https://bugzilla.redhat.com/show_bug.cgi?id=1177194
    
    When migrate a vm, we will generate a xml via qemuDomainDefFormatLive and
    pass this xml to target libvirtd. Libvirt will use the current network
    state in def->data.network.actual to generate the xml, this will make
    migrate failed when we set a network type guest interface use a macvtap
    network as a source in a vm then migrate vm to another host(which has the
    different macvtap network settings: different interface name, bridge name...)
    
    Add a flag check in virDomainNetDefFormat, if we set a VIR_DOMAIN_XML_MIGRATABLE
    flag when call virDomainNetDefFormat, we won't get the current vm interface
    state.
    
    Signed-off-by: Luyao Huang <lhuang>
    Signed-off-by: Jiri Denemark <jdenemar>

--- Additional comment from hongming on 2015-01-08 03:47:20 EST ---

Verify it as follows.The result is expected .Move its status to VERIFIED.

# rpm -q libvirt
libvirt-1.2.8-12.el7.x86_64

On source host
# virsh net-dumpxml vepa-net
<network connections='1'>
  <name>vepa-net</name>
  <uuid>78a038e7-dab9-4ce6-b63e-054031a22408</uuid>
  <forward dev='enp2s0' mode='vepa'>
    <interface dev='enp2s0' connections='1'/>
  </forward>
</network>

# virsh dumpxml r7a|grep interface -A6
    <interface type='direct'>
      <mac address='52:54:00:0a:e5:15'/>
      <source network='vepa-net' dev='enp2s0' mode='vepa'/>
      <target dev='macvtap0'/>
      <model type='rtl8139'/>
      <alias name='net0'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/>
    </interface>



# virsh migrate --live r7a qemu+ssh://$targetip/system --persistent
root.4.135's password: 


On target host
# virsh list |grep r7a
 48    r7a                            running


# virsh net-dumpxml vepa-net
<network connections='1'>
  <name>vepa-net</name>
  <uuid>db38469f-bb10-44e5-8ffe-384ddfec61bb</uuid>
  <forward dev='eno1' mode='vepa'>
    <interface dev='eno1' connections='1'/>
  </forward>
</network>


# virsh dumpxml r7a|grep interface -A6
    <interface type='direct'>
      <mac address='52:54:00:0a:e5:15'/>
      <source network='vepa-net' dev='eno1' mode='vepa'/>
      <target dev='macvtap1'/>
      <model type='rtl8139'/>
      <alias name='net0'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/>
    </interface>

# virsh dumpxml r7a --migratable|grep interface -A6
    <interface type='network'>
      <mac address='52:54:00:0a:e5:15'/>
      <source network='vepa-net'/>
      <target dev='macvtap1'/>
      <model type='rtl8139'/>
      <alias name='net0'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/>
    </interface>


The guest also can successfully migrated in the opposite direction.