我是用Vmvare 装的centos7， 在centos7 上装的 virtualbox 2.12 以及vagrant5.2 ，最后卡在 ssh 上面了：
==> homestead-7: Booting VM...
==> homestead-7: Waiting for machine to boot. This may take a few minutes...
homestead-7: SSH address: 127.0.0.1:2222
homestead-7: SSH username: vagrant
homestead-7: SSH auth method: private key
Timed out while waiting for the machine to boot. This means that
Vagrant was unable to communicate with the guest machine within
the configured ("config.vm.boot_timeout" value) time period.
If you look above, you should be able to see the error(s) that
Vagrant had when attempting to connect to the machine. These errors
are usually good hints as to what may be wrong.
If you're using a custom box, make sure that networking is properly
working and you're able to connect to the machine. It is a common
problem that networking isn't setup properly in these boxes.
Verify that authentication configurations are also setup properly,
If the box appears to be booting properly, you may want to increase
the timeout ("config.vm.boot_timeout") value.
感觉像是步骤4 出了问题，因为在虚拟机系统上装 VB 和vagrant 无法再开启虚拟化支持了，所以感觉这样是不可行。