Change in coreboot[master]: *x86: Support x2apic mode

[Wonkyu Kim (Code Review)]

Attention is currently required from: Nico Huber, Furquan Shaikh, Jamie Ryu, Paul Menzel, Angel Pons, Subrata Banik, Kyösti Mälkki, Raj Astekar, Aaron Durbin, Patrick Rudolph.
Wonkyu Kim has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/51723 )

Change subject: *x86: Support x2apic mode
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Patch Set 6:

(7 comments)

Commit Message:

https://review.coreboot.org/c/coreboot/+/51723/comment/eb102ea9_360d426a 
PS6, Line 10: LAPIC_BASE_MSR(LAPIC_BASE_MSR_X2APIC_MODE)
> Please add a space before the (.

Done

https://review.coreboot.org/c/coreboot/+/51723/comment/45393bb9_41f8e1a5 
PS6, Line 11: implment
> implement

Done

https://review.coreboot.org/c/coreboot/+/51723/comment/3b35836a_9b5f8981 
PS6, Line 21: cat /proc/cpuinfo | grep "apicid"
> I don't like the grep-only approach, especially when I want to change what I'm grepping for. […]

Done

File src/cpu/x86/lapic/lapic_cpu_init.c:

https://review.coreboot.org/c/coreboot/+/51723/comment/36b1cbd5_94bce1af 
PS6, Line 355: 			LAPIC_DM_INIT | LAPIC_INT_LEVELTRIG, id);
> No need to break the line here.

Done

File src/cpu/x86/mp_init.c:

https://review.coreboot.org/c/coreboot/+/51723/comment/401400a8_8d9f0d09 
PS6, Line 458: 	} else {
> Or even better, add more functions. e.g. start_aps_lapic(), start_aps_lx2apic(). […]

Done

https://review.coreboot.org/c/coreboot/+/51723/comment/58e6ed7b_22bfe339 
PS6, Line 678: 	} else {
> Simpler: […]

Done

File src/include/cpu/x86/lapic_def.h:

https://review.coreboot.org/c/coreboot/+/51723/comment/509113ea_b23a1ae1 
PS6, Line 99: #define		X2APIC_LAPIC_ID		(X2APIC_MSR_BASE_ADDRESS | (LAPIC_ID >> 4))
> These definitions are misplaced (they're not fields in LAPIC_TDCR, not even LAPIC registers)

Done