Virtualbox extension packインストール

# yum list *release-el7*
# yum install oracle-softwarecollection-release-el7
# yum update
# yum -y upgrade
# yum -y install bzip2 gcc make perl kernel-devel kernel-headers elfutils-libelf-devel
# yum -y localinstall kernel-devel kernel-headers

2.3.3 Oracle Linux Yum Serverリポジトリ・ファイルのダウンロード
https://docs.oracle.com/cd/E39368_01/adminsg/ol-downloading-yum-repo.html