can i go to shanghai from hongkong? Do i need to get visa for Hongkong?

I am filipina,i have a chinese visa. I will be back to shanghai china this september,but before going back shanghai i plan to visit hongkong for 3 days. What requirements do i need so i can go to hongkong from cebu? Can i stay 3 days in Hongkong before going back Shanghai? From hongkong can i go directly to Shanghai or i have to return to philippines?