x86/smpboot: Serialize topology updates for secondary bringup

x86/smpboot: Serialize topology updates for secondary bringup

The toplogy update is performed by the AP via smp_callin() after the BSP
has called do_wait_cpu_initialized(), setting the AP's bit in
cpu_callout_mask to allow it to proceed.

In preparation to enable further parallelism of AP bringup, add locking to
serialize the update even if multiple APs are (in future) permitted to
proceed through the next stages of bringup in parallel.

Without such ordering (and with that future extra parallelism), confusion
ensues:

[    1.360149] x86: Booting SMP configuration:
[    1.360221] .... node  #0, CPUs:        #1  #2  #3  #4  #5  #6  #7  #8  #9 #10 #11 #12 #13 #14 #15 #16 #17 #18 #19 #20 #21 #22 #23
[    1.366225] .... node  #1, CPUs:   #24 #25 #26 #27 #28 #29 #30 #31 #32 #33 #34 #35 #36 #37 #38 #39 #40 #41 #42 #43 #44 #45 #46 #47
[    1.370219] .... node  #0, CPUs:   #48 #49 #50 #51 #52 #53 #54 #55 #56 #57 #58 #59 #60 #61 #62 #63 #64 #65 #66 #67 #68 #69 #70 #71
[    1.378226] .... node  #1, CPUs:   #72 #73 #74 #75 #76 #77 #78 #79 #80 #81 #82 #83 #84 #85 #86 #87 #88 #89 #90 #91 #92 #93 #94 #95
[    1.382037] Brought 96 CPUs to x86/cpu:kick in 72232606 cycles
[    0.104104] smpboot: CPU 26 Converting physical 0 to logical die 1
[    0.104104] smpboot: CPU 27 Converting physical 1 to logical package 2
[    0.104104] smpboot: CPU 24 Converting physical 1 to logical package 3
[    0.104104] smpboot: CPU 27 Converting physical 0 to logical die 2
[    0.104104] smpboot: CPU 25 Converting physical 1 to logical package 4
[    1.385609] Brought 96 CPUs to x86/cpu:wait-init in 9269218 cycles
[    1.395285] Brought CPUs online in 28930764 cycles
[    1.395469] smp: Brought up 2 nodes, 96 CPUs
[    1.395689] smpboot: Max logical packages: 2
[    1.396222] smpboot: Total of 96 processors activated (576000.00 BogoMIPS)

Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: Usama Arif <usama.arif@bytedance.com>
Tested-by: Paul E. McKenney <paulmck@kernel.org>
Tested-by: Kim Phillips <kim.phillips@amd.com>
Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name>
Tested-by: Guilherme G. Piccoli <gpiccoli@igalia.com>