From: sendmail [mailto:justsendmailnothingelse@gmail.com] On Behalf Of Laine Stump
Sent: Tuesday, June 16, 2015 6:50 PM
To: libvir-list@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@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@r-ae-host05 bin]# kill 16743

[root@r-ae-host05 bin]# ../sbin/libvirtd &

[2] 17489

[1]   Done                    ../sbin/libvirtd

[root@r-ae-host05 bin]#

[root@r-ae-host05 bin]#

[root@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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