参考官方文档：
https://www.virtualbox.org/wiki/Linux_Downloads
配置yum源：
vim /etc/yum.repos.d/virtualbox.repo
[virtualbox] name=Oracle Linux / RHEL / CentOS-$releasever / $basearch - VirtualBox baseurl=http://download.virtualbox.org/virtualbox/rpm/el/$releasever/$basearch enabled=1 gpgcheck=1 repo_gpgcheck=1 gpgkey=https://www.virtualbox.org/download/oracle_vbox.asc
然后用yum直接安装即可：
yum install VirtualBox-5.1