Early boot regression from f0551af0213 ("x86/topology: Ignore non-present APIC IDs in a present package")

[Lyude Paul]

Hi! I just wanted to let you know that one of the desktops I use for
testing no longer seems to boot after this commit (just finished
bisecting and confirming). The machine hangs before it gets to fbcon,
and the error I'm seeing in the early boot console is as such:

   Kernel panic - not syncing: timer doesn't work through Interrupt-remapped IO-APIC
   CPU: 0 PID: 0 Comm: swapper/0 Not tainted 6.8.0-rc5Lyude-Test+ #20
   Hardware name: MSI MS-7A39/A320M GAMING PRO (MS-7A39), BIOS 1.10 01/22/2019
   Call trace:
     <TASK>
     dump_stack_lvl+0x47/0x60
     panic+0x340/0x370
     ? timer_irq_works+0x67/0x130
     panic_if_irq_remap+0x1d/0x20
     setup_IO_APIC+0x82d/0x950
     ? _raw_spin_unlock_irqrestore+0x1d/0x40
     ? clear_IO_APIC_pin+0x16c/0x260
     apic_intr_mode_init+0x5d/0xf0
     x86_late_time_init+0x24/0x40
     start_kernel+0x673/0xa90
     x86_64_start_reservations+0x18/0x30
     x86_64_start_kernel+0x96/0xa0
     secondary_startup_64_no_verify+0x180/0x18b
     </TASK>
   --- [ end Kernel panic - not syncing: timer doesn't work through Interrupt-remapped IO-APIC ]---

Assuming I copied this over by hand to my computer correctly, the
decoded backtrace should be:

   Kernel panic - not syncing: timer doesn't work through Interrupt-remapped IO-APIC
   Hardware name: MSI MS-7A39/A320M GAMING PRO (MS-7A39), BIOS 1.10 01/22/2019
   Call trace:
      <TASK>
      dump_stack_lvl (/home/lyudess/Projects/linux/worktrees/nouveau-aux-fixes/lib/dump_stack.c:107) 
      panic (/home/lyudess/Projects/linux/worktrees/nouveau-aux-fixes/kernel/panic.c:344) 
      ? timer_irq_works (/home/lyudess/Projects/linux/worktrees/nouveau-aux-fixes/./arch/x86/include/asm/msr.h:186 /home/lyudess/Projects/linux/worktrees/nouveau-aux-fixes/arch/x86/kernel/apic/io_apic.c:1595 /home/lyudess/Projects/linux/worktrees/nouveau-aux-fixes/arch/x86/kernel/apic/io_apic.c:1634) 
      panic_if_irq_remap (??:?) 
      setup_IO_APIC (/home/lyudess/Projects/linux/worktrees/nouveau-aux-fixes/arch/x86/kernel/apic/io_apic.c:2241 /home/lyudess/Projects/linux/worktrees/nouveau-aux-fixes/arch/x86/kernel/apic/io_apic.c:2413) 
      ? _raw_spin_unlock_irqrestore (/home/lyudess/Projects/linux/worktrees/nouveau-aux-fixes/./arch/x86/include/asm/preempt.h:94 (discriminator 1) /home/lyudess/Projects/linux/worktrees/nouveau-aux-fixes/./include/linux/spinlock_api_smp.h:152 (discriminator 1) /home/lyudess/Projects/linux/worktrees/nouveau-aux-fixes/kernel/locking/spinlock.c:194 (discriminator 1)) 
      ? clear_IO_APIC_pin (/home/lyudess/Projects/linux/worktrees/nouveau-aux-fixes/arch/x86/kernel/apic/io_apic.c:563) 
      apic_intr_mode_init (/home/lyudess/Projects/linux/worktrees/nouveau-aux-fixes/arch/x86/kernel/apic/apic.c:2330 /home/lyudess/Projects/linux/worktrees/nouveau-aux-fixes/arch/x86/kernel/apic/apic.c:1374) 
      x86_late_time_init (/home/lyudess/Projects/linux/worktrees/nouveau-aux-fixes/arch/x86/kernel/time.c:101) 
      start_kernel (/home/lyudess/Projects/linux/worktrees/nouveau-aux-fixes/init/main.c:1035) 
      x86_64_start_reservations (/home/lyudess/Projects/linux/worktrees/nouveau-aux-fixes/arch/x86/kernel/head64.c:543) 
      x86_64_start_kernel (/home/lyudess/Projects/linux/worktrees/nouveau-aux-fixes/arch/x86/kernel/head64.c:485 (discriminator 5)) 
      secondary_startup_64_no_verify (/home/lyudess/Projects/linux/worktrees/nouveau-aux-fixes/arch/x86/kernel/head_64.S:459) 
      </TASK>
   --- [ end Kernel panic - not syncing: timer doesn't work through Interrupt-remapped IO-APIC ]---

Happy to provide any more information from this machine if you need it
:). And hopefully i'm not just late to the party and reporting a
regression someone else found already lol

-- 
Cheers,
 Lyude Paul (she/her)
 Software Engineer at Red Hat