vagrant创建虚拟机共享文件夹出错

报错内容如下

Vagrant was unable to mount VirtualBox shared folders. This is usually
because the filesystem "vboxsf" is not available. This filesystem is
made available via the VirtualBox Guest Additions and kernel module.
Please verify that these guest additions are properly installed in the
guest. This is not a bug in Vagrant and is usually caused by a faulty
Vagrant box. For context, the command attempted was:

mount -t vboxsf -o uid=1000,gid=1000 var_www_ /var/www

The error output from the command was:

mount: unknown filesystem type 'vboxsf'

解决方法：

vagrant plugin install vagrant-vbguest
vagrant destroy && vagrant up