ACPI 6.3 introduced a flag allowing to tell MADT entries describing hotpluggable processors from ones which are simply placeholders (often used by firmware writers to simplify handling there).
Inspired by a Linux patch by Mario Limonciello <[email protected]>. Requested-by: Andrew Cooper <[email protected]> Signed-off-by: Jan Beulich <[email protected]> --- a/xen/arch/x86/acpi/boot.c +++ b/xen/arch/x86/acpi/boot.c @@ -53,6 +53,8 @@ bool __initdata acpi_ioapic; static bool __initdata acpi_skip_timer_override; boolean_param("acpi_skip_timer_override", acpi_skip_timer_override); +static uint8_t __initdata madt_revision; + static u64 acpi_lapic_addr __initdata = APIC_DEFAULT_PHYS_BASE; /* -------------------------------------------------------------------------- @@ -64,6 +66,8 @@ static int __init acpi_parse_madt(struct struct acpi_table_madt *madt = container_of(table, struct acpi_table_madt, header); + madt_revision = madt->header.revision; + if (madt->address) { acpi_lapic_addr = (u64) madt->address; @@ -86,6 +90,12 @@ acpi_parse_x2apic(struct acpi_subtable_h if (BAD_MADT_ENTRY(processor, end)) return -EINVAL; + /* Don't register processors that cannot be onlined. */ + if (madt_revision >= 5 && + !(processor->lapic_flags & ACPI_MADT_ENABLED) && + !(processor->lapic_flags & ACPI_MADT_ONLINE_CAPABLE)) + return 0; + if ((processor->lapic_flags & ACPI_MADT_ENABLED) || processor->local_apic_id != 0xffffffff || opt_cpu_info) { acpi_table_print_madt_entry(header); @@ -136,6 +146,12 @@ acpi_parse_lapic(struct acpi_subtable_he if (BAD_MADT_ENTRY(processor, end)) return -EINVAL; + /* Don't register processors that cannot be onlined. */ + if (madt_revision >= 5 && + !(processor->lapic_flags & ACPI_MADT_ENABLED) && + !(processor->lapic_flags & ACPI_MADT_ONLINE_CAPABLE)) + return 0; + if ((processor->lapic_flags & ACPI_MADT_ENABLED) || processor->id != 0xff || opt_cpu_info) acpi_table_print_madt_entry(header); --- a/xen/include/acpi/actbl1.h +++ b/xen/include/acpi/actbl1.h @@ -858,7 +858,8 @@ struct acpi_madt_generic_translator { /* MADT Local APIC flags */ -#define ACPI_MADT_ENABLED (1) /* 00: Processor is usable if set */ +#define ACPI_MADT_ENABLED (1 << 0) /* 00: Processor is usable if set */ +#define ACPI_MADT_ONLINE_CAPABLE (1 << 1) /* 01: Processor can be onlined */ /* MADT MPS INTI flags (inti_flags) */
