I am interested in the solutions of a very large quadratic programming (QP) problem
\begin{align} \min_{x \in \mathbb{R}^n} & x^T Q x\\ \mathrm{subject\ to} & A x = b\\ & x \in \{0,1\}^n \end{align}
where $n=10^7$, $Q$ is a dense, positive-semidefinite matrix whose entries are natural numbers that can be computed rapidly, and $A \in \mathbb{N}^{n \times 20}$.
What is a suitable algorithm for such a large problem, and what is a good implementation?