New Xen have new kernel.
But still very very old kernel packages:
EthTool is stuck at version 3.15 (2014-07-20)
Name : ethtool
Arch : x86_64
Epoch : 2
Version : 3.15
Release : 2.el7
Size : 306 k
Repo : installed
From repo : install
Summary : Settings tool for Ethernet NICs
URL : http://ftp.kernel.org/pub/software/network/ethtool/
License : GPLv2
Description : This utility allows querying and changing settings such as speed,
: port, auto-negotiation, PCI locations and checksum offload on many
: network devices, especially of Ethernet devices.
This package is very old and is misbehaving causing.
(command "ethtool -m" will fail).
In the 2014 weren't born many technology which new version of ethtool can handle.