This article covers the User Guides to reference when Migrating and Upgrading IP.

For general information on migrating IP from 2014.4 to 2015.1, refer to (UG973) the Vivado Design Suite User Guide: Release Notes, Installation, and Licensing
 
http://www.xilinx.com/support/documentation/sw_manuals/xilinx2015_1/ug973-vivado-release-notes-install-license.pdf
 

For general information on upgrading all IP, see the "Upgrading IP" section in (UG896) Vivado Design Suite User Guide: Designing with IP.
 
http://www.xilinx.com/support/documentation/sw_manuals/xilinx2015_1/ug896-vivado-ip.pdf
 

For general information on the Vivado I/O Planner, and migrating MIG IP into Vivado 2015.1 see the "I/O Pin Planning" sections in (UG899) Vivado Design Suite User Guide: I/O and Clock Planning.
 

http://www.xilinx.com/support/documentation/sw_manuals/xilinx2015_1/ug899-vivado-io-clock-planning.pdf

Note: If the I/O locations of "sys_clk_p/n" were modified in the top-level XDC constraint file prior to upgrading to 2015.1 then you will need to manually upgrade these constraints into the 2015.1 design.

For a proper upgrade of the MIG design into 2015.1, it is recommended to do the following:
 

04/30/2015 - Initial Release