On Thu, Dec 22, 2022 at 7:26 PM James Puthukattukaran
<james.puthukattukaran@xxxxxxxxxx> wrote:
>
> Extending commit aa06e20f1be6 ("x86/ACPI: Don't add CPUs that are not
> online capable") to include acpi_parse_x2apic as well. There is a check
> for invalid apicid; however, there are BIOS FW with madt version >= 5
It would be good to give at least one example of a platform where this happens.
> support that do not bother setting apic id to an invalid value since they
> assume the OS will check the enabled and online capable flags.
>
> Signed-off-by: James Puthukattukaran<james.puthukattukaran@xxxxxxxxxx>
> Reported-by: Benjamin Fuller<ben.fuller@xxxxxxxxxx>
>
> v2 : use 'enabled' local variable. Also fix checkpatch.pl catches
> v3 : updates as per Rafael's comments
> ---
> arch/x86/kernel/acpi/boot.c | 10 +++++++++-
> 1 file changed, 9 insertions(+), 1 deletion(-)
>
> diff --git a/arch/x86/kernel/acpi/boot.c b/arch/x86/kernel/acpi/boot.c
> index 907cc98b1938..cf2509f9de31 100644
> --- a/arch/x86/kernel/acpi/boot.c
> +++ b/arch/x86/kernel/acpi/boot.c
> @@ -208,7 +208,15 @@ acpi_parse_x2apic(union acpi_subtable_headers *header, const unsigned long end)
> apic_id = processor->local_apic_id;
> enabled = processor->lapic_flags & ACPI_MADT_ENABLED;
>
> - /* Ignore invalid ID */
> + /* don't register processors that can not be onlined */
> + if (!enabled && acpi_support_online_capable &&
> + !(processor->lapic_flags & ACPI_MADT_ONLINE_CAPABLE))
I would add a MADT version check to this, because
ACPI_MADT_ONLINE_CAPABLE may be set by mistake in an older BIOS too.
> + return 0;
> +
> + /*
> + * for systems older than madt version 5 (does not have
Also please spell MADT in capitals.
> + * ACPI_MADT_ONLINE_CAPABLE defined); ignore invalid ID
> + */
> if (apic_id == 0xffffffff)
> return 0;
>
> --
