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Bug 1232880

Summary:	network device feature flags are not updated in nodedev-dumpxml output, out of date cached values are returned instead
Product:	Red Hat Enterprise Linux 7	Reporter:	Laine Stump <laine>
Component:	libvirt	Assignee:	Laine Stump <laine>
Status:	CLOSED ERRATA	QA Contact:	Virtualization Bugs <virt-bugs>
Severity:	unspecified	Docs Contact:
Priority:	unspecified
Version:	7.2	CC:	dyuan, honzhang, moshele, mzhan, rbalakri
Target Milestone:	rc	Keywords:	Upstream
Target Release:	---
Hardware:	Unspecified
OS:	Unspecified
Whiteboard:
Fixed In Version:	libvirt-1.2.17-1.el7	Doc Type:	Bug Fix
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2015-11-19 06:41:36 UTC	Type:	Bug
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:

Description Laine Stump 2015-06-17 17:49:53 UTC

Reported by Moshe Levi <moshele> on libvir-list:

https://www.redhat.com/archives/libvir-list/2015-June/msg00786.html

  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.

My description of the cause:

https://www.redhat.com/archives/libvir-list/2015-June/msg00798.html

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.

This is the same class of problem as Bug 979290 and Bug 981546

Comment 1 Laine Stump 2015-06-17 17:53:29 UTC

A fix has been pushed upstream:

commit 307081796ee07d5f47e1fef66766de82d5fce642
Author: Laine Stump <laine>
Date:   Tue Jun 16 11:57:11 2015 -0400

    nodedev: update netdev feature bits before each dumpxml

Comment 2 Laine Stump 2015-06-17 17:59:44 UTC

Note - if you backport the above patch to a libvirt release earlier than 1.2.16, you will also need to backport all of the patches listed in Bug 981546.

Comment 4 hongming 2015-07-16 07:40:11 UTC

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

# rpm -q libvirt
libvirt-1.2.17-1.el7.x86_64

# virsh nodedev-dumpxml net_eno1_44_37_e6_67_11_a2
<device>
  <name>net_eno1_44_37_e6_67_11_a2</name>
  <path>/sys/devices/pci0000:00/0000:00:19.0/net/eno1</path>
  <parent>pci_0000_00_19_0</parent>
  <capability type='net'>
    <interface>eno1</interface>
    <address>44:37:e6:67:11:a2</address>
    <link speed='1000' 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>


[root@localhost images]# ethtool -K eno1 rx off
[root@localhost images]# ethtool -K eno1 tx off
[root@localhost images]# ethtool -K eno1 sg off
Actual changes:
scatter-gather: off
	tx-scatter-gather: off
tcp-segmentation-offload: off
	tx-tcp-segmentation: off [requested on]
	tx-tcp6-segmentation: off [requested on]
generic-segmentation-offload: off [requested on]

[root@localhost images]# virsh nodedev-dumpxml net_eno1_44_37_e6_67_11_a2
<device>
  <name>net_eno1_44_37_e6_67_11_a2</name>
  <path>/sys/devices/pci0000:00/0000:00:19.0/net/eno1</path>
  <parent>pci_0000_00_19_0</parent>
  <capability type='net'>
    <interface>eno1</interface>
    <address>44:37:e6:67:11:a2</address>
    <link speed='1000' state='up'/>
    <feature name='gro'/>
    <feature name='rxvlan'/>
    <feature name='txvlan'/>
    <feature name='rxhash'/>
    <capability type='80203'/>
  </capability>
</device>


[root@localhost images]# ethtool -K eno1 rx on
[root@localhost images]# ethtool -K eno1 tx on
[root@localhost images]# ethtool -K eno1 sg on 
Actual changes:
scatter-gather: on
	tx-scatter-gather: on
tcp-segmentation-offload: on
	tx-tcp-segmentation: on
	tx-tcp6-segmentation: on
generic-segmentation-offload: on


[root@localhost images]# virsh nodedev-dumpxml net_eno1_44_37_e6_67_11_a2
<device>
  <name>net_eno1_44_37_e6_67_11_a2</name>
  <path>/sys/devices/pci0000:00/0000:00:19.0/net/eno1</path>
  <parent>pci_0000_00_19_0</parent>
  <capability type='net'>
    <interface>eno1</interface>
    <address>44:37:e6:67:11:a2</address>
    <link speed='1000' 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>

Comment 6 errata-xmlrpc 2015-11-19 06:41:36 UTC

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://rhn.redhat.com/errata/RHBA-2015-2202.html