From aa06e20f1be628186f0c2dcec09ea0009eb69778 Mon Sep 17 00:00:00 2001 From: Mario Limonciello Date: Wed, 8 Sep 2021 16:41:46 -0500 Subject: [PATCH] x86/ACPI: Don't add CPUs that are not online capable A number of systems are showing "hotplug capable" CPUs when they are not really hotpluggable. This is because the MADT has extra CPU entries to support different CPUs that may be inserted into the socket with different numbers of cores. Starting with ACPI 6.3 the spec has an Online Capable bit in the MADT used to determine whether or not a CPU is hotplug capable when the enabled bit is not set. Link: https://uefi.org/htmlspecs/ACPI_Spec_6_4_html/05_ACPI_Software_Programming_Model/ACPI_Software_Programming_Model.html?#local-apic-flags Signed-off-by: Mario Limonciello Signed-off-by: Rafael J. Wysocki --- arch/x86/kernel/acpi/boot.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/arch/x86/kernel/acpi/boot.c b/arch/x86/kernel/acpi/boot.c index 14bcd59..5b6d1a9 100644 --- a/arch/x86/kernel/acpi/boot.c +++ b/arch/x86/kernel/acpi/boot.c @@ -62,6 +62,7 @@ int acpi_fix_pin2_polarity __initdata; #ifdef CONFIG_X86_LOCAL_APIC static u64 acpi_lapic_addr __initdata = APIC_DEFAULT_PHYS_BASE; +static bool acpi_support_online_capable; #endif #ifdef CONFIG_X86_IO_APIC @@ -138,6 +139,8 @@ static int __init acpi_parse_madt(struct acpi_table_header *table) pr_debug("Local APIC address 0x%08x\n", madt->address); } + if (madt->header.revision >= 5) + acpi_support_online_capable = true; default_acpi_madt_oem_check(madt->header.oem_id, madt->header.oem_table_id); @@ -239,6 +242,12 @@ acpi_parse_lapic(union acpi_subtable_headers * header, const unsigned long end) if (processor->id == 0xff) 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)) + return 0; + /* * We need to register disabled CPU as well to permit * counting disabled CPUs. This allows us to size -- 2.7.4