What kind of passthrough do you expect? Linux doesn't use any hardware dongles to generate entropy in /dev/random (there are dongles available though that are capable to generate high secure one time pads). Therefore this hasn't to do anything with VMWare but with the entropy pool your virtual machine may collect.
This pool is filled by timing events, interrupt events, input events and disk I/O. Verify this here
in the Linux source code. If you now live in VMWare or not, just make sure one of this collectors is able to gather some events in order to receive more entropy.