Getting Volume of a negative cavity

I have to find the Volume of a cavity that I created using a lofted cut.  Is there any easy way to do this?  I know I can re-create the loft in a new part and get the volue using mass properties on it.  But is there any way to do it from the orginal model?

Here is my model

And here is the viod that I created as solid using a loft

SolidworksParts And Features