I don’t think so. Your objective function may be concave over the constraint region you have provided, but it is not concave everywhere. For example, it is convex at x(1)=x(2) = -1. This is usually problematic for CVX.
With just the first term, you could use rel_entr, as in Writing a constraint in DCP complient format , but this can not be done with your 2 terms… Also see $\log(\frac{1+x\ (a+1)}{1+x \ a})$ and its perspective $y\log(\frac{1+x/y\ (a+1)}{1+x/y \ a})$ in CVX