[vbox-dev] Question regarding channel callbacks between guest and host

[Jaeyong Yoo]

Hello VirtualBox!

While I'm reading the source, I found the following sequence of function call:

[In xpdm directory] VBoxMPHGSMIDpc () -->
                             VBoxHGSMIProcessHostQueue ()  -->
                             hgsmiHostCommandQueryProcess() -->
                             hgsmiHostCmdProcess () -->
                             HGSMIBufferProcess () -->
                             hgsmiBufferProcess () -->
                             HGSMIChannelHandlerCall ()  -->
                             pfnHandler()   ==
[Host side]             vbvaChannelHandler

It looks like a guest-side function (in VGA driver) VBoxMPHGSMIDpc  calls the host-side function (in VGA emulator) vbvaChannelHandler.
How is this possible since host and guest are in different address space (if we are using nested paging table)?
Or, I'm feeling like I miss something.

Thanks,
Jaeyong