libvirt users - Dec 2022 - Need help

Hi,

We have an openstack platform and we are trying to get the network details
of the guest vm on the hypervisors using the python libvirt library
(domain.interfaceStats) . But in cases of SR-IOV vms, the interface is not
being reported by the above tool.  The interface in this case is
"hostdev"
in the guest xml definition. Can anyone let me know how to find out the
sr-iov network interface details of the guest vm ?

Thanks
Kumar
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On 12/2/22 7:43 AM, Gk Gk wrote:
> Hi,
> 
> We have an openstack platform and we are trying to get the network 
> details of the guest vm on the hypervisors using the python libvirt 
> library (domain.interfaceStats) . But in cases of SR-IOV vms, the 
> interface is not being reported by the above tool.? The interface in 
> this case is "hostdev" in the guest xml definition. Can anyone
let me
> know how to find out the sr-iov network interface details of the guest vm ?
Support for reporting stats of SRIOV VF-backed "hostdev" interfaces
was
added with commit b295f06d, which first appeared in libvirt-6.9.0. 
Because there is no named "netdev" type interface on the host side,
you
need to use the MAC address of the interface when calling 
virDomainInterfaceStats().

Unfortunately, the method used to get the stats for these interfaces 
(see the commit log for details) isn't supported by all SRIOV netdev 
drivers. The Intel 82559 I have uses the igb driver, which doesn't 
support it, so all the stats show up as "0". Even the ixgbe driver 
doesn't support it. According to the commit log if you have a 
sufficiently new (but not *too* new!) Mellanox card, then you may be in 
luck.