From: Mario Limonciello <mario.limonciello@amd.com>
Date: Wed, 8 Sep 2021 16:41:46 -0500
Subject: x86/ACPI: Don't add CPUs that are not online capable
Patch-mainline: v5.16-rc1
Git-commit: aa06e20f1be628186f0c2dcec09ea0009eb69778
References: jsc#PED-1408
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 <mario.limonciello@amd.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Lee, Chun-Yi <jlee@suse.com>
---
arch/x86/kernel/acpi/boot.c | 9 +++++++++
1 file changed, 9 insertions(+)
--- 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
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_hea
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