@@ -266,6 +266,7 @@ static int __init
acpi_parse_lapic(union acpi_subtable_headers * header, const unsigned long end)
{
struct acpi_madt_local_apic *processor = NULL;
+ int cpu;
processor = (struct acpi_madt_local_apic *)header;
@@ -289,9 +290,13 @@ acpi_parse_lapic(union acpi_subtable_headers * header, const unsigned long end)
* to not preallocating memory for all NR_CPUS
* when we use CPU hotplug.
*/
- acpi_register_lapic(processor->id, /* APIC ID */
- processor->processor_id, /* ACPI ID */
- processor->lapic_flags & ACPI_MADT_ENABLED);
+ cpu = acpi_register_lapic(processor->id, /* APIC ID */
+ processor->processor_id, /* ACPI ID */
+ processor->lapic_flags & ACPI_MADT_ENABLED);
+
+ /* Do strict X2APIC ID check only when LAPIC contains enabled CPUs */
+ if (cpu >= 0)
+ has_lapic_cpus = true;
return 0;
}
@@ -1134,7 +1139,6 @@ static int __init acpi_parse_madt_lapic_entries(void)
if (!count) {
count = acpi_table_parse_madt(ACPI_MADT_TYPE_LOCAL_APIC,
acpi_parse_lapic, MAX_LOCAL_APIC);
- has_lapic_cpus = count > 0;
x2count = acpi_table_parse_madt(ACPI_MADT_TYPE_LOCAL_X2APIC,
acpi_parse_x2apic, MAX_LOCAL_APIC);
}
Commit 8e9c42d776d6 ("x86/acpi: Ignore invalid x2APIC entries") does strict X2APIC ID check when LAPIC contains valid CPUs. The code assumes LAPIC contains valid CPUs when acpi_table_parse_madt(LAPIC) returns a postive value. This is wrong because acpi_table_parse_madt() return value only represents the number of legal entries parsed. For example, LAPIC entry with LAPIC ID 0xff is counted as a legal entry, but it doesn't describe a valid CPU. And when all LAPIC entries have LAPIC ID 0xff, the return value is positive but LAPIC does not contain any valid CPU. In this case, kernel erroneously does strict X2APIC ID check and loses the CPUs described in X2APIC entries. Fix the problem by doing strict X2APIC ID check less aggressively, say only when LAPIC contains enabled CPUs. Fixes: 8e9c42d776d6 ("x86/acpi: Ignore invalid x2APIC entries") Reported-by: John Sperbeck <jsperbeck@google.com> Closes: https://lore.kernel.org/all/20231122221947.781812-1-jsperbeck@google.com/ Tested-by: John Sperbeck <jsperbeck@google.com> Reported-by: Andres Freund <andres@anarazel.de> Closes: https://lore.kernel.org/all/20231206065850.hs7k554v6wym7gw5@awork3.anarazel.de/ Tested-by: Andres Freund <andres@anarazel.de> Signed-off-by: Zhang Rui <rui.zhang@intel.com> --- arch/x86/kernel/acpi/boot.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-)