The TX and RX polarity inversion is available and controlled with a parameter within the source RTL.
After generating the PHY with the Megawizard, locate the file "sv_xcvr_10gbaser_native.sv" and search of the lines below.
localparam RX_POLARITY_INV = "invert_disable";
localparam TX_POLARITY_INV = "invert_disable";
The valid parameters are "invert_enable" or "invert_disable" The default value is "invert_disable". To invert the polarity,
simply change the parameter to "invert_enable".