Reuters reports that the free upgrade for users on Windows 7 and 8 includes all versions -- genuine or otherwise.
Terry Myerson, Microsoft's Executive Vice President of Operating Systems, told the news agency that "We are upgrading all qualified PCs, genuine and non-genuine, to Windows 10."
The report only mentions China, a huge market where piracy of Windows is rife.
Ballmer once stated the firm makes more revenue from the Netherlands, than China. It seems the idea is to get more official users, and then up-sell them later on Microsoft's extended suite of software and services.
Whether the same treatment will be given to those with bootleg copies elsewhere remains unclear.