[libvirt] nodedev-dumpxml doesn't refresh supported offload NIC capabilities

[Moshe Levi]

Hi Laine,
I verified your fix and it working.
Do I need to fill bug for this?

From: sendmail [mailto:justsendmailnothingelse at gmail.com] On Behalf Of Laine Stump
Sent: Tuesday, June 16, 2015 6:50 PM
To: libvir-list at redhat.com
Cc: Moshe Levi
Subject: Re: [libvirt] nodedev-dumpxml doesn't refresh supported offload NIC capabilities

On 06/16/2015 10:12 AM, Moshe Levi wrote:
Hi,

I was playing with the nodedev-dumpxml to see the supported offload NIC capabilities, and
It seem that if I disable one of offloading capabilities using ethtool command nodedev-dumpxml it still return
the feature as enabled. To get the correct offloading capabilities I have to restart libvirtd.
I was wandering if that is an expected behavior in lbivirt .

the nodedevice driver caches all the information it gets from udev, and tries to rely on udev generating events when something changes. In general this is a bad idea, and has led to at least 2 bug reports I can think of. The function update_caps() in the nodedev driver is intended to be filled in with code to update those attributes of a device that don't get properly updated via udev event responses. It looks like all that would be required in your situation would be to add a call to virNetDevGetFeatures() to the VIR_NODE_DEV_CAP_NET case of the switch in that function. It's complicated a bit by the fact that virNetDevGetFeatures() leaks any existing bitmap of features when it's called. I'm sending a short patch that should fix your problem, which should show up on the list in a few minutes.



Please see example below with the rx capabilities disabled.

virsh # nodedev-dumpxml net_enp4s0_f4_52_14_11_73_81
<device>
  <name>net_enp4s0_f4_52_14_11_73_81</name>
  <path>/sys/devices/pci0000:00/0000:00:02.0/0000:04:00.0/net/enp4s0</path>
  <parent>pci_0000_04_00_0</parent>
  <capability type='net'>
    <interface>enp4s0</interface>
    <address>f4:52:14:11:73:81</address>
    <link speed='40000' state='up'/>
    <feature name='rx'/>
    <feature name='tx'/>
    <feature name='sg'/>
    <feature name='tso'/>
    <feature name='gso'/>
    <feature name='gro'/>
    <feature name='rxvlan'/>
    <feature name='txvlan'/>
    <feature name='rxhash'/>
    <capability type='80203'/>
  </capability>
</device>
ethtool -K enp4s0 rx off
virsh # nodedev-dumpxml net_enp4s0_f4_52_14_11_73_81
<device>
  <name>net_enp4s0_f4_52_14_11_73_81</name>
  <path>/sys/devices/pci0000:00/0000:00:02.0/0000:04:00.0/net/enp4s0</path>
  <parent>pci_0000_04_00_0</parent>
  <capability type='net'>
    <interface>enp4s0</interface>
    <address>f4:52:14:11:73:81</address>
    <link speed='40000' state='up'/>
    <feature name='rx'/>
    <feature name='tx'/>
    <feature name='sg'/>
    <feature name='tso'/>
    <feature name='gso'/>
    <feature name='gro'/>
    <feature name='rxvlan'/>
    <feature name='txvlan'/>
    <feature name='rxhash'/>
    <capability type='80203'/>
  </capability>
</device>


virsh #
[root at r-ae-host05 bin]# ps -ef | grep libvirt
root     16743 23086  0 16:43 pts/2    00:00:00 ../sbin/libvirtd
root     17440 23086  0 16:47 pts/2    00:00:00 grep --color=auto libvirt
[root at r-ae-host05 bin]# kill 16743
[root at r-ae-host05 bin]# ../sbin/libvirtd &
[2] 17489
[1]   Done                    ../sbin/libvirtd
[root at r-ae-host05 bin]#
[root at r-ae-host05 bin]#
[root at r-ae-host05 bin]# ./virsh

virsh # nodedev-dumpxml net_enp4s0_f4_52_14_11_73_81
<device>
  <name>net_enp4s0_f4_52_14_11_73_81</name>
  <path>/sys/devices/pci0000:00/0000:00:02.0/0000:04:00.0/net/enp4s0</path>
  <parent>pci_0000_04_00_0</parent>
  <capability type='net'>
    <interface>enp4s0</interface>
    <address>f4:52:14:11:73:81</address>
    <link speed='40000' state='up'/>
    <feature name='tx'/>
    <feature name='sg'/>
    <feature name='tso'/>
    <feature name='gso'/>
    <feature name='gro'/>
    <feature name='rxvlan'/>
    <feature name='txvlan'/>
    <feature name='rxhash'/>
    <feature name='rdma'/>
    <capability type='80203'/>
  </capability>
</device>


Thanks,
                Moshe Levi.





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