summaryrefslogtreecommitdiffstats
path: root/arch/x86
diff options
context:
space:
mode:
authorMario Limonciello <mario.limonciello@amd.com>2021-09-08 23:41:46 +0200
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>2021-09-13 19:19:02 +0200
commitaa06e20f1be628186f0c2dcec09ea0009eb69778 (patch)
treee9e9e350d654320829cf9281bf9445347f0c190f /arch/x86
parentACPICA: Add support for MADT online enabled bit (diff)
downloadlinux-aa06e20f1be628186f0c2dcec09ea0009eb69778.tar.xz
linux-aa06e20f1be628186f0c2dcec09ea0009eb69778.zip
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 <mario.limonciello@amd.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Diffstat (limited to 'arch/x86')
-rw-r--r--arch/x86/kernel/acpi/boot.c9
1 files changed, 9 insertions, 0 deletions
diff --git a/arch/x86/kernel/acpi/boot.c b/arch/x86/kernel/acpi/boot.c
index 14bcd59bcdee..5b6d1a95776f 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