EBX: Contains a Windows VM Handle.
EBP: Points to the Windows VM's Client Registers.
Save anything that you use. You must not fail this call. If it is hooked, it must be implemented.
If you implement SAVE_LATCHES, you must also implement RESTORE_LATCHES. Many chipsets have a method by which the VGA processor latches can be directly saved and/or restored. If your hardware can do this, it increases the performance of your 4 plane VGA virtualization greatly if you implement SAVE_LATCHES and RESTORE_LATCHES.