Some discution have been started upstream: https://www.redhat.com/archives/libvir-list/2016-November/msg00915.html

I've just pushed patches upstream:

commit e0d893e86df2daa51b88fdb5f0195fec279da99f
Author:     Mehdi Abaakouk <sileht>
AuthorDate: Fri Nov 18 23:51:15 2016 +0100
Commit:     Michal Privoznik <mprivozn>
CommitDate: Fri Dec 9 10:28:07 2016 +0100

    Move virstat.c code to virnetdevtap.c
    
    This is just a code move of virstat.c to virnetdevtap.c

commit 9b6de7c506c1bfc76fdcb9a42f990b699fe18d2e
Author:     Mehdi Abaakouk <sileht>
AuthorDate: Fri Nov 18 23:51:14 2016 +0100
Commit:     Michal Privoznik <mprivozn>
CommitDate: Fri Dec 9 10:27:56 2016 +0100

    virstat: fix signature of virstat helper
    
    In preparation to the code move to virnetdevtap.c, this change:
    
    * renames virNetInterfaceStats to virNetDevTapInterfaceStats
    * changes 'path' to 'ifname', to use the same vocable as other
      method in virnetdevtap.c.
    * Add the attributes checker

commit 013df874db7e3e4b4f8a8fa25e068da776e0e2c7
Author:     Mehdi Abaakouk <sileht>
AuthorDate: Fri Nov 18 23:51:13 2016 +0100
Commit:     Michal Privoznik <mprivozn>
CommitDate: Fri Dec 9 10:23:09 2016 +0100

    Gathering vhostuser interface stats with ovs
    
    When vhostuser interfaces are used, the interface statistics
    are not available in /proc/net/dev.
    
    This change looks at the openvswitch interfaces statistics
    tables to provide this information for vhostuser interface.
    
    Note that in openvswitch world drop/error doesn't always make sense
    for some interface type. When these informations are not available we
    set them to 0 on the virDomainInterfaceStats.
    
    Signed-off-by: Michal Privoznik <mprivozn>

v2.5.0-57-ge0d893e86

Hi,  Michal

I tried to verify this bug, however, when I use 'virsh domifstat <domain_name>',
I can't get the interface name.

# virsh domiflist r7-4t1
Interface  Type       Source     Model       MAC
-------------------------------------------------------
-          vhostuser  -          virtio      52:54:01:93:55:db

And then, I can't get the statistics of this interface by `virsh domifstat <domain_name> <interface>`

Will you please help to have a look at this problem? Thank you!
You can find more details in below:


Try to verify the bug on packages:
libvirt-3.2.0-5.el7.x86_64
qemu-kvm-rhev-2.9.0-4.el7.x86_64
kernel-3.10.0-660.el7.x86_64

Test steps:
1. Prepare 2 guests like this:
guest1:
  <memoryBacking>
    <hugepages>
      <page size='2048' unit='KiB'/>
    </hugepages>
  </memoryBacking>
  ......
  <cpu mode='custom' match='exact' check='full'>
    <model fallback='forbid'>Broadwell</model>
    ......
    <feature policy='require' name='abm'/>
    <numa>
      <cell id='0' cpus='0-1' memory='1048576' unit='KiB' memAccess='shared'/>
    </numa>
  </cpu>
  ......
    <interface type='vhostuser'>
      <mac address='52:54:01:93:55:db'/>
      <source type='unix' path='/var/run/openvswitch/vhost-user1' mode='client'/>
      <model type='virtio'/>
      <alias name='net0'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x08' function='0x0'/>
    </interface>

guest2: with path='/var/run/openvswitch/vhost-user2'

2. Start the guests
# virsh start r7-4t1
Domain r7-4t1 started

# virsh start r7-4t2
Domain r7-4t2 started

# virsh list --all
 Id    Name                           State
----------------------------------------------------
 6     r7-4t1                         running
 7     r7-4t2                         running

3. Configure the IP for vNIC
In guest1:
ifconfig eth0 192.168.100.1

In guest2:
# ifconfig eth0 192.168.100.2

4. On one guest ping the other one.
In guest1: ping 192.168.100.2
In guest2: ping 192.168.100.1

5. Check the network statistics
# ovs-vsctl list interface
_uuid               : 8725f0de-e8ae-4ac2-abba-0a9ae716c4a2
admin_state         : down
......
mac                 : []
mac_in_use          : "00:00:00:00:00:00"
mtu                 : 1500
name                : "vhost-user1"
......
statistics          : {rx_bytes=301030, rx_errors=0, rx_packets=1859, tx_bytes=290924, tx_dropped=1, tx_packets=1830}
status              : {}
type                : dpdkvhostuser

_uuid               : a73ae67e-0d16-415a-8c6a-5132e4766d94
admin_state         : down
......
mac                 : []
mac_in_use          : "00:00:00:00:00:00"
mtu                 : 1500
name                : "vhost-user2"
......
statistics          : {rx_bytes=291266, rx_errors=0, rx_packets=1831, tx_bytes=292630, tx_dropped=50, tx_packets=1809}
status              : {}
type                : dpdkvhostuser

#ovs-ofctl dump-flows ovsbr0
NXST_FLOW reply (xid=0x4):
 cookie=0x0, duration=90456.579s, table=0, n_packets=1843, n_bytes=297950, idle_age=2, hard_age=65534, in_port=1 actions=output:2
 cookie=0x0, duration=90449.118s, table=0, n_packets=1807, n_bytes=287698, idle_age=0, hard_age=65534, in_port=2 actions=output:1

6. Check the virsh domiflist: no Interface is listed
#virsh domiflist r7-4t1
Interface  Type       Source     Model       MAC
-------------------------------------------------------
-          vhostuser  -          virtio      52:54:01:93:55:db

#virsh domiflist r7-4t2
Interface  Type       Source     Model       MAC
-------------------------------------------------------
-          vhostuser  -          virtio      52:59:21:13:11:db

7. Can't run virsh domifstat as don't know the interface name.

# virsh domifstat r7-4t1
error: command 'domifstat' requires <interface> option

# virsh domifstat r7-4t1 eth0
error: Failed to get interface stats r7-4t1 eth0
error: invalid argument: invalid path, 'eth0' is not a known interface

(In reply to chhu from comment #6)
> Hi,  Michal
> 
> I tried to verify this bug, however, when I use 'virsh domifstat
> <domain_name>',
> I can't get the interface name.
> 
> # virsh domiflist r7-4t1
> Interface  Type       Source     Model       MAC
> -------------------------------------------------------
> -          vhostuser  -          virtio      52:54:01:93:55:db
> 
> And then, I can't get the statistics of this interface by `virsh domifstat
> <domain_name> <interface>`

virsh domifstat r7-4t1 vhost-user1   should do the trick.

Michal

(In reply to Michal Privoznik from comment #7)
> (In reply to chhu from comment #6)
> > Hi,  Michal
> > 
> > I tried to verify this bug, however, when I use 'virsh domifstat
> > <domain_name>',
> > I can't get the interface name.
> > 
> > # virsh domiflist r7-4t1
> > Interface  Type       Source     Model       MAC
> > -------------------------------------------------------
> > -          vhostuser  -          virtio      52:54:01:93:55:db
> > 
> > And then, I can't get the statistics of this interface by `virsh domifstat
> > <domain_name> <interface>`
> 
> virsh domifstat r7-4t1 vhost-user1   should do the trick.
> 
> Michal


Hi, Michal

I tried `virsh domifstat r7-4t1 vhost-user1 or vhost-user or eth0`. 
They are not work.

How about file a new bug about:
"virsh domiflist return NULL for the vhostuser interface name and source". 

And then set this one blocked by that bug? Waiting for your reply, thank you!


More detail as below:
# virsh domifstat r7-4t1 vhostuser1
error: Failed to get interface stats r7-4t1 vhostuser1
error: invalid argument: invalid path, 'vhostuser1' is not a known interface


# virsh domifstat r7-4t1 vhostuser
error: Failed to get interface stats r7-4t1 vhostuser
error: invalid argument: invalid path, 'vhostuser' is not a known interface

# virsh domifstat r7-4t1 eth0
error: Failed to get interface stats r7-4t1 eth0
error: invalid argument: invalid path, 'eth0' is not a known interface


Regards,
chhu

(In reply to chhu from comment #8)
> (In reply to Michal Privoznik from comment #7)
> > (In reply to chhu from comment #6)
> > > Hi,  Michal
> > > 
> > > I tried to verify this bug, however, when I use 'virsh domifstat
> > > <domain_name>',
> > > I can't get the interface name.
> > > 
> > > # virsh domiflist r7-4t1
> > > Interface  Type       Source     Model       MAC
> > > -------------------------------------------------------
> > > -          vhostuser  -          virtio      52:54:01:93:55:db
> > > 
> > > And then, I can't get the statistics of this interface by `virsh domifstat
> > > <domain_name> <interface>`
> > 
> > virsh domifstat r7-4t1 vhost-user1   should do the trick.
> > 
> > Michal
> 
> 
> Hi, Michal
> 
> I tried `virsh domifstat r7-4t1 vhost-user1 or vhost-user or eth0`. 
> They are not work.
> 
> How about file a new bug about:
> "virsh domiflist return NULL for the vhostuser interface name and source". 
> 
> And then set this one blocked by that bug? Waiting for your reply, thank you!
> 
> 
> More detail as below:
> # virsh domifstat r7-4t1 vhostuser1
> error: Failed to get interface stats r7-4t1 vhostuser1
> error: invalid argument: invalid path, 'vhostuser1' is not a known interface
> 
> 
> # virsh domifstat r7-4t1 vhostuser
> error: Failed to get interface stats r7-4t1 vhostuser
> error: invalid argument: invalid path, 'vhostuser' is not a known interface
> 
> # virsh domifstat r7-4t1 eth0
> error: Failed to get interface stats r7-4t1 eth0
> error: invalid argument: invalid path, 'eth0' is not a known interface
> 
> 
> Regards,
> chhu

Thanks Michal's confirm, file bug1459091 for this issue.

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://access.redhat.com/errata/RHEA-2017:1846

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://access.redhat.com/errata/RHEA-2017:1846