Implement CPU microcode loading

[kallisti5]

Haiku currently lacks CPU patching via microcode updates.

Linux (as exampled here) and other operating systems support CPU microcode updates via signed binary blobs provided by the CPU vendor.

These microcode updates can improve performance, or protect users from hardware vulnerabilities such as Spectre.

Here is a quick run-down on how Linux patches microcode:

• Microcode is placed in /lib/firmware/amd-ucode or /lib/firmware/intel-ucode by microcode package updates.
• The "microcode" kernel module hot-applies supported microcode updates to the running host.

References:

• ​https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/arch/x86/kernel/cpu/microcode
• ​http://pkgs.fedoraproject.org/repo/pkgs/microcode_ctl/
• ​http://www.linux-mag.com/id/723/

[nzimmermann]

Ticket #14802 has a WIP patch for microcode updating, currently limited to AMD only, to get started.

[pulkomandy]

Please submit patches on review.haiku-os.org, not as ticket attachments. They will get lost otherwise.

[nephele]

Intel microcode loading is implemented, it now only needs AMD one.

references:
​http://cvsweb.netbsd.org/bsdweb.cgi/src/sys/arch/x86/x86/cpu_ucode_amd.c

haiku:
src/system/boot/arch/x86/cpu.cpp : void ucode_load(BootVolume& volume)
src/system/kernel/arch/x86/arch_cpu.cpp
headers/private/kernel/arch/x86/arch_cpu.h

​https://git.haiku-os.org/haiku/commit/?id=11f8b65a797d8bb721a0223542f5f6ce42fc3474
​https://git.haiku-os.org/haiku/commit/?id=56bb1bd5c992ca2dd09bb501c44707396273f438

[pulkomandy]

Intel microcode loading is implemented but the microcode is not shipped with haiku by default and need to be installed separately. This patch should be finished: ​https://review.haiku-os.org/c/haiku/+/2266