6.12-stable review patch. If anyone has any objections, please let me know.
------------------
From: Zhang Rui rui.zhang@intel.com
commit 0141978ae75bd48bac13fca6de131a5071c32011 upstream.
On some systems, the same CPU (with the same APIC ID) is assigned a different logical CPU id after commit ec9aedb2aa1a ("x86/acpi: Ignore invalid x2APIC entries").
This means that Linux enumerates the CPUs in a different order, which violates ACPI specification[1] that states:
"OSPM should initialize processors in the order that they appear in the MADT"
The problematic commit parses all LAPIC entries before any x2APIC entries, aiming to ignore x2APIC entries with APIC ID < 255 when valid LAPIC entries exist. However, it disrupts the CPU enumeration order on systems where x2APIC entries precede LAPIC entries in the MADT.
Fix this problem by:
1) Parsing LAPIC entries first without registering them in the topology to evaluate whether valid LAPIC entries exist.
2) Restoring the MADT in order parser which invokes either the LAPIC or the X2APIC parser function depending on the entry type.
The X2APIC parser still ignores entries < 0xff in case that #1 found valid LAPIC entries independent of their position in the MADT table.
Link: https://uefi.org/specs/ACPI/6.5/05_ACPI_Software_Programming_Model.html#madt... Cc: All applicable stable@vger.kernel.org Reported-by: Jim Mattson jmattson@google.com Closes: https://lore.kernel.org/all/20241010213136.668672-1-jmattson@google.com/ Fixes: ec9aedb2aa1a ("x86/acpi: Ignore invalid x2APIC entries") Signed-off-by: Zhang Rui rui.zhang@intel.com Reviewed-by: Jim Mattson jmattson@google.com Tested-by: Jim Mattson jmattson@google.com Reviewed-by: Thomas Gleixner tglx@linutronix.de Link: https://patch.msgid.link/20250117081420.4046737-1-rui.zhang@intel.com Signed-off-by: Rafael J. Wysocki rafael.j.wysocki@intel.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/x86/kernel/acpi/boot.c | 50 +++++++++++++++++++++++++++++++++++++++----- 1 file changed, 45 insertions(+), 5 deletions(-)
--- a/arch/x86/kernel/acpi/boot.c +++ b/arch/x86/kernel/acpi/boot.c @@ -227,6 +227,28 @@ acpi_parse_x2apic(union acpi_subtable_he }
static int __init +acpi_check_lapic(union acpi_subtable_headers *header, const unsigned long end) +{ + struct acpi_madt_local_apic *processor = NULL; + + processor = (struct acpi_madt_local_apic *)header; + + if (BAD_MADT_ENTRY(processor, end)) + return -EINVAL; + + /* Ignore invalid ID */ + if (processor->id == 0xff) + return 0; + + /* Ignore processors that can not be onlined */ + if (!acpi_is_processor_usable(processor->lapic_flags)) + return 0; + + has_lapic_cpus = true; + return 0; +} + +static int __init acpi_parse_lapic(union acpi_subtable_headers * header, const unsigned long end) { struct acpi_madt_local_apic *processor = NULL; @@ -257,7 +279,6 @@ acpi_parse_lapic(union acpi_subtable_hea processor->processor_id, /* ACPI ID */ processor->lapic_flags & ACPI_MADT_ENABLED);
- has_lapic_cpus = true; return 0; }
@@ -1029,6 +1050,8 @@ static int __init early_acpi_parse_madt_ static int __init acpi_parse_madt_lapic_entries(void) { int count, x2count = 0; + struct acpi_subtable_proc madt_proc[2]; + int ret;
if (!boot_cpu_has(X86_FEATURE_APIC)) return -ENODEV; @@ -1037,10 +1060,27 @@ static int __init acpi_parse_madt_lapic_ acpi_parse_sapic, MAX_LOCAL_APIC);
if (!count) { - count = acpi_table_parse_madt(ACPI_MADT_TYPE_LOCAL_APIC, - acpi_parse_lapic, MAX_LOCAL_APIC); - x2count = acpi_table_parse_madt(ACPI_MADT_TYPE_LOCAL_X2APIC, - acpi_parse_x2apic, MAX_LOCAL_APIC); + /* Check if there are valid LAPIC entries */ + acpi_table_parse_madt(ACPI_MADT_TYPE_LOCAL_APIC, acpi_check_lapic, MAX_LOCAL_APIC); + + /* + * Enumerate the APIC IDs in the order that they appear in the + * MADT, no matter LAPIC entry or x2APIC entry is used. + */ + memset(madt_proc, 0, sizeof(madt_proc)); + madt_proc[0].id = ACPI_MADT_TYPE_LOCAL_APIC; + madt_proc[0].handler = acpi_parse_lapic; + madt_proc[1].id = ACPI_MADT_TYPE_LOCAL_X2APIC; + madt_proc[1].handler = acpi_parse_x2apic; + ret = acpi_table_parse_entries_array(ACPI_SIG_MADT, + sizeof(struct acpi_table_madt), + madt_proc, ARRAY_SIZE(madt_proc), MAX_LOCAL_APIC); + if (ret < 0) { + pr_err("Error parsing LAPIC/X2APIC entries\n"); + return ret; + } + count = madt_proc[0].count; + x2count = madt_proc[1].count; } if (!count && !x2count) { pr_err("No LAPIC entries present\n");