Some recently released Linux distributions are not mounting USBFS to /proc/bus/usb. The virtual machine's USB back end uses this to detect USB Devices that are attached to the host.
Solution
To work around this issue, mount USBFS to /proc/bus/usb.
To do this while the host is running, execute the following command as root:
# mount -t usbfs none /proc/bus/usb
You need to power cycle the virtual machines after the mount command to have access to available USB devices.
To configure the host to mount USBFS automatically on bootup, add the following line in the /etc/fstab file:
usbfs /proc/bus/usb usbfs auto 0 0
If this line is already present in /etc/fstab, it likely has the noauto option set in the options column (4th column). Change this to auto.
Some of the Linux distributions that are known not to mount USBFS by default include:
Note: This issue affects these operating systems only when they are used as a host for VMware virtual machines. These operating systems, when used as guests, do not exhibit this problem.