[PATCHv7 16/16] x86/acpi: Add support for CPU offlining for ACPI MADT wakeup method

[Thomas Gleixner]

On Mon, Feb 12 2024 at 12:44, Kirill A. Shutemov wrote:
> MADT Multiprocessor Wakeup structure version 1 brings support of CPU
> offlining: BIOS provides a reset vector where the CPU has to jump to
> for offlining itself. The new TEST mailbox command can be used to test
> whether the CPU offlined itself which means the BIOS has control over
> the CPU and can online it again via the ACPI MADT wakeup method.
>
> Add CPU offling support for the ACPI MADT wakeup method by implementing
> custom cpu_die(), play_dead() and stop_this_cpu() SMP operations.
>
> CPU offlining makes is possible to hand over secondary CPUs over kexec,
> not limiting the second kernel to a single CPU.
>
> The change conforms to the approved ACPI spec change proposal. See the
> Link.
>
> Signed-off-by: Kirill A. Shutemov <kirill.shutemov at linux.intel.com>
> Link: https://lore.kernel.org/all/13356251.uLZWGnKmhe@kreacher
> Acked-by: Kai Huang <kai.huang at intel.com>
> Reviewed-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy at linux.intel.com>

Reviewed-by: Thomas Gleixner <tglx at linutronix.de>