CentOS 7上使用virt-manager创建新虚拟机时出现下面错误：
Error connecting to graphical console: Error initializing USB support: Other errors[-99]
造成上面问题的原因是虚拟机的显示协议不匹配，设置一下现实协议为VNC即可。
也可以通过以下方法解决：
I added a usb controller to the virtual machine in vmware that I was using KVM and the console connected.
参考链接：
/questions/641285/error-installing-ubuntu-14-04-in-kvm
/questions/226884/error-initializing-usb-support-other-error-99