Don't Copy That Floppy
Reset and Close
To re-use a command list start with running ID3D12GraphicsCommandList::Reset() on it. This can be done after the ExecuteCommandList() has been called. To submit command lists for execution they need to be closed. To close a command list use ID3D12GraphicsCommandList::Close().
Copy a Resource
To copy a resource use ID3D12GraphicsCommandList::CopyResource(). The resources must be of the same type, have identical dimensions and by of compatible DXGI formats. None of the resources can be mapped. The copy operation is performed on the GPU.
Copy a part of a resource