I posted this question here: How are virtual machine integration packages implemented internally?, but it was closed as too broad. Originally, it asked about how are integration features implemented in several popular emulators, but now I narrowed it down to just one. Is it still too broad? If it isn't, can it be reopened and answered?
I reopened it.
I didn't feel like the question was actually too broad. Of course, the actual implementation details are too broad of a topic to discuss here, but I don't think that's what's being asked here.
A general overview of the concept of how a virtualization solution communicates with a guest operating system though these integration features is very much within the scope of our site and can be answered reasonably.