CPU idle is a generic framework for supporting software-controlled idle processor power management. It includes modular cross-platform governors that can be swapped during runtime. If you're using an ACPI-enabled platform, you should say Y here.
This governor implements a simplified idle state selection method focused on timer events and does not do any interactivity boosting. Some workloads benefit from using it and it generally should be safe to use. Say Y here if you are not happy with the alternatives.
This governor implements haltpoll idle state selection, to be used in conjunction with the haltpoll cpuidle driver, allowing for polling for a certain amount of time before entering idle state. Some virtualized workloads benefit from using it.
This option enables halt poll cpuidle driver, which allows to poll before halting in the guest (more efficient than polling in the host via halt_poll_ns for some scenarios).