You are building kernel with non-retpoline compiler

 [root@ test]# make -C /lib/modules/4.18.0-408.el8.x86_64/build/ M=linux-4.18.0-408.el8/drivers/pci/pcie/

make: Entering directory '/usr/src/kernels/4.18.0-408.el8.x86_64'

arch/x86/Makefile:248: *** You are building kernel with non-retpoline compiler, please update your compiler..  Stop.

make: Leaving directory '/usr/src/kernels/4.18.0-408.el8.x86_64'

# cp /boot/config-4.18.0-408.el8.x86_64 .config

# make oldconfig

# make prepare

# make modules_prepare

# make M=/home/work/test/linux-4.18.0-408.el8/drivers/pci/pcie/