How to express the constraint 15e in cvx

[Mark_L_Stone]

How to express " log(1+1/xy)" in cvx?

We can prove that the Hessian matrix of function f(x,y)=log2(1+1/xy) is positive semidefinite when x>0 and y>0. So f(x,y) is a convex function. Can this function be expressed in cvx? Thanks all.