Re: [PATCH] Revert "x86/acpi/boot: Do not register processors that cannot be onlined for x2APIC"

[Lyude Paul]

On Fri, 2023-03-31 at 19:53 -0400, Lyude Paul wrote:
> This reverts commit e2869bd7af608c343988429ceb1c2fe99644a01f. This commit
> unfortunately seems to have resulted in one of my machines no longer
> booting. Specifically, this machine is a custom build with a MS-7A39/A320M
> GAMING PRO motherboard with firmware version v1.10. I'm not entirely sure
> of the cause yet, but starting it up with "earlycon=efifb keep_bootcon" has
> informed me that the kernel panics like so:
> 
> Call Trace:
>   <TASK>
>   dump_stack_lvl+0x33/0x46
>   panic+0x105/0x2b1
>   ? timer_irq_works+0x53/0xef
>   panic_if_irq_remap.cold+0x5/0x5
>   setup_IO_APIC+0x3c4/0x831
>   ? __pfx_native_io_apic_read+0x10/0x10
>   ? __ioapic_read_entry+0x34/0x50
>   ? _raw_spin_unlock_irqrestore+0x1b/0x40
>   ? clear_IO_APIC_pin+0x16b/0x240
>   apic_intr_mode_init+0x101/0x106
>   x86_late_time_init+0x20/0x34
>   start_kernel+0x8b4/0x95f
>   secondary_startup_64_no_verify+0x5e/0xeb
>   </TASK>
> ---[ end Kernel panic - not syncing: timer doesn't work through
>  interrupt-mapped IO-APIC ]---

Agh, I totally forgot to actually decode the stacktrace on this before sending
it out. I can do that if anyone would think it would help, but I have a
feeling the stacktrace here isn't particularly useful in the first place
considering the culprit commit here.

As well, hopefully it goes without saying but: I'm happy to try any kind of
fixes or provide any more information from this machine. Just let me know ♥

> 
> My assumption is there's probably something funky with the firmware on the
> machine seeing as it's a random gaming motherboard, but that also probably
> means there are other boards out there like this that are cold, afraid, and
> unable to boot. We could warm their hearts by reverting this, or maybe by
> figuring out a proper fix.
> 
> Signed-off-by: Lyude Paul <lyude@xxxxxxxxxx>
> Fixes: e2869bd7af60 ("x86/acpi/boot: Do not register processors that cannot be onlined for x2APIC")
> Cc: Leo Duran <leo.duran@xxxxxxx>
> Cc: Kishon Vijay Abraham I <kvijayab@xxxxxxx>
> Cc: Borislav Petkov (AMD) <bp@xxxxxxxxx>
> Cc: Zhang Rui <rui.zhang@xxxxxxxxx>
> Cc: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
> Cc: "Rafael J. Wysocki" <rafael@xxxxxxxxxx>
> Cc: Len Brown <lenb@xxxxxxxxxx>
> Cc: linux-acpi@xxxxxxxxxxxxxxx
> ---
>  arch/x86/kernel/acpi/boot.c | 19 +++----------------
>  1 file changed, 3 insertions(+), 16 deletions(-)
> 
> diff --git a/arch/x86/kernel/acpi/boot.c b/arch/x86/kernel/acpi/boot.c
> index 1c38174b5f019..4177577c173bf 100644
> --- a/arch/x86/kernel/acpi/boot.c
> +++ b/arch/x86/kernel/acpi/boot.c
> @@ -188,17 +188,6 @@ static int acpi_register_lapic(int id, u32 acpiid, u8 enabled)
>  	return cpu;
>  }
>  
> -static bool __init acpi_is_processor_usable(u32 lapic_flags)
> -{
> -	if (lapic_flags & ACPI_MADT_ENABLED)
> -		return true;
> -
> -	if (acpi_support_online_capable && (lapic_flags & ACPI_MADT_ONLINE_CAPABLE))
> -		return true;
> -
> -	return false;
> -}
> -
>  static int __init
>  acpi_parse_x2apic(union acpi_subtable_headers *header, const unsigned long end)
>  {
> @@ -223,10 +212,6 @@ acpi_parse_x2apic(union acpi_subtable_headers *header, const unsigned long end)
>  	if (apic_id == 0xffffffff)
>  		return 0;
>  
> -	/* don't register processors that cannot be onlined */
> -	if (!acpi_is_processor_usable(processor->lapic_flags))
> -		return 0;
> -
>  	/*
>  	 * We need to register disabled CPU as well to permit
>  	 * counting disabled CPUs. This allows us to size
> @@ -265,7 +250,9 @@ acpi_parse_lapic(union acpi_subtable_headers * header, const unsigned long end)
>  		return 0;
>  
>  	/* don't register processors that can not be onlined */
> -	if (!acpi_is_processor_usable(processor->lapic_flags))
> +	if (acpi_support_online_capable &&
> +	    !(processor->lapic_flags & ACPI_MADT_ENABLED) &&
> +	    !(processor->lapic_flags & ACPI_MADT_ONLINE_CAPABLE))
>  		return 0;
>  
>  	/*

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