$$\vec v^\star \cdot \vec v $$ you mean?
You can figure it out for yourself...
So let ##\vec v = (v_1,v_2,v_3,\cdots)^t## And ##\vec u = (u_1,u_2,u_3,\cdots)^t## where ##v_i,u_i\in\mathbb{C}##
What would ##\vec u \cdot \vec v## be, in terms of the components?
Now let ##\vec u = \vec v^\star##