From: Kishon Vijay Abraham I kvijayab@amd.com
[ Upstream commit e2869bd7af608c343988429ceb1c2fe99644a01f ]
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") Reported-by: Leo Duran leo.duran@amd.com Signed-off-by: Kishon Vijay Abraham I kvijayab@amd.com Signed-off-by: Borislav Petkov (AMD) bp@alien8.de Reviewed-by: Borislav Petkov (AMD) bp@alien8.de Reviewed-by: Zhang Rui rui.zhang@intel.com Acked-by: Rafael J. Wysocki rafael.j.wysocki@intel.com Link: https://lore.kernel.org/r/20230105041059.39366-1-kvijayab@amd.com Signed-off-by: Sasha Levin sashal@kernel.org --- 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 907cc98b19380..518bda50068cb 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;
/*