The function efi_set_virtual_address_map() is left after hitting the first EFI_RUNTIME_SERVICES_CODE to relocate. But if EFI runtime drivers have been loaded into U-Boot there will be multiple such blocks.

SetVirtualAddressMap() as described in the UEFI spec is rather complex to implement. It involves runtime drivers updating the pointers they hold upon an event they receive and the firmware reapplying the relocation information provided when loading the images of the runtime drivers.

Best regards

Heinrich