Messages in this thread Patch in this message | | | From | "Zhang, Rui" <> | Subject | Re: [PATCH v2] x86/acpi/boot: Do not register processors that cannot be onlined for x2apic | Date | Fri, 6 Jan 2023 00:57:09 +0000 |
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On Thu, 2023-01-05 at 18:09 +0100, Rafael J. Wysocki wrote: > On Thu, Jan 5, 2023 at 5:11 AM Kishon Vijay Abraham I < > kvijayab@amd.com> wrote: > > Section 5.2.12.12 Processor Local x2APIC Structure in the ACPI v6.5 > > spec mandates that both "enabled" and "online capable" Local APIC > > Flags > > should be used to determine if the processor is usable or not. > > > > However, Linux doesn't use the "online capable" flag for x2APIC to > > determine if the processor is usable. As a result, > > cpu_possible_mask has > > incorrect value and results in more memory getting allocated for > > per_cpu > > variables than it is going to be used. > > > > Make sure Linux parses both "enabled" and "online capable" flags > > for > > x2APIC to correctly determine if the processor is usable. > > > > Fixes: aa06e20f1be6 ("x86/ACPI: Don't add CPUs that are not online > > capable") > > Reviewed-by: Borislav Petkov (AMD) <bp@alien8.de> > > Reported-by: Leo Duran <leo.duran@amd.com> > > Signed-off-by: Kishon Vijay Abraham I <kvijayab@amd.com> > > Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> >
Reviewed-by: Zhang Rui <rui.zhang@intel.com>
thanks, rui > > --- > > Changes from v1: > > 1) Changed the ACPI spec version to 6.5 in the commit log > > 2) Changed the Fixes tag to point to commit aa06e20f1be6 > > 3) Added "Reported-by: Leo Duran <leo.duran@amd.com>" > > arch/x86/kernel/acpi/boot.c | 19 ++++++++++++++++--- > > 1 file changed, 16 insertions(+), 3 deletions(-) > > > > diff --git a/arch/x86/kernel/acpi/boot.c > > b/arch/x86/kernel/acpi/boot.c > > index 907cc98b1938..518bda50068c 100644 > > --- a/arch/x86/kernel/acpi/boot.c > > +++ b/arch/x86/kernel/acpi/boot.c > > @@ -188,6 +188,17 @@ 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) > > { > > @@ -212,6 +223,10 @@ 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 > > @@ -250,9 +265,7 @@ 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_support_online_capable && > > - !(processor->lapic_flags & ACPI_MADT_ENABLED) && > > - !(processor->lapic_flags & ACPI_MADT_ONLINE_CAPABLE)) > > + if (!acpi_is_processor_usable(processor->lapic_flags)) > > return 0; > > > > /* > > -- > > 2.34.1 > >
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