Public bug reported:

Line speed is incorrectly reported on z/VM instances in /sys when
compared to what is claimed to be supported and advertised.

for example, ethtool shows supported and advertised speeds of 1000Mb/s
but /sys is only indicating 10Mb/s.

ubuntu@hwe0008:~$ ethtool enc600
Settings for enc600:
        Supported ports: [ TP ]
        Supported link modes:   10baseT/Half 10baseT/Full 
                                100baseT/Half 100baseT/Full 
                                1000baseT/Half 1000baseT/Full 
        Supported pause frame use: No
        Supports auto-negotiation: Yes
        Advertised link modes:  10baseT/Half 10baseT/Full 
                                100baseT/Half 100baseT/Full 
                                1000baseT/Half 1000baseT/Full 
        Advertised pause frame use: No
        Advertised auto-negotiation: Yes
        Speed: 10Mb/s
        Duplex: Full
        Port: Twisted Pair
        PHYAD: 0
        Transceiver: internal
        Auto-negotiation: on
        MDI-X: Unknown
Cannot get wake-on-lan settings: Operation not permitted
        Link detected: yes
ubuntu@hwe0008:~$ cat /sys/class/net/enc600/speed 
10

I'm presuming this issue lies somewhere in the qeth driver:
P: /devices/qeth/0.0.0600/net/enc600
E: DEVPATH=/devices/qeth/0.0.0600/net/enc600
E: ID_NET_DRIVER=qeth_l2
E: ID_NET_LINK_FILE=/lib/systemd/network/99-default.link
E: ID_NET_NAME=enc600
E: ID_NET_NAME_MAC=enx02280b000004
E: ID_NET_NAME_PATH=enc600
E: ID_PATH=ccwgroup-0.0.0600
E: ID_PATH_TAG=ccwgroup-0_0_0600
E: IFINDEX=2
E: INTERFACE=enc600
E: SUBSYSTEM=net
E: SYSTEMD_ALIAS=/sys/subsystem/net/devices/enc600 
/sys/subsystem/net/devices/enc600
E: TAGS=:systemd:
E: USEC_INITIALIZED=3784115

This is not an issue on my LPAR that uses the same drivers (but also
adds ctcm and zfcp, so maybe therein lies the difference in speed
reporting?)

In any case, if the speeds cannot be correctly reported, they shouldn't be 
reported at all.  virtio handles this by setting speed to -1:
ubuntu@s1lp9g003:~$ cat /sys/class/net/eth0/speed 
-1
ubuntu@s1lp9g003:~$ ethtool eth0
Settings for eth0:
        Supported ports: [ ]
        Supported link modes:   Not reported
        Supported pause frame use: No
        Supports auto-negotiation: No
        Advertised link modes:  Not reported
        Advertised pause frame use: No
        Advertised auto-negotiation: No
        Speed: Unknown!
        Duplex: Unknown! (255)
        Port: Other
        PHYAD: 0
        Transceiver: internal
        Auto-negotiation: off
Cannot get wake-on-lan settings: Operation not permitted
        Link detected: yes

That last example is a 1Gb/s interface on a z/KVM instance.

ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: linux-image-4.8.0-36-generic 4.8.0-36.36~16.04.1
ProcVersionSignature: Ubuntu 4.8.0-36.36~16.04.1-generic 4.8.11
Uname: Linux 4.8.0-36-generic s390x
ApportVersion: 2.20.1-0ubuntu2.5
Architecture: s390x
Date: Fri Feb 24 17:08:59 2017
ProcEnviron:
 TERM=screen
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=C
 SHELL=/bin/bash
SourcePackage: linux-hwe
UpgradeStatus: No upgrade log present (probably fresh install)

** Affects: linux-hwe (Ubuntu)
     Importance: Undecided
         Status: New


** Tags: apport-bug s390x xenial

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https://bugs.launchpad.net/bugs/1667828

Title:
  Network device on z/VM instance incorrectly reports line speed

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