@@ -694,6 +694,25 @@ void __init acpi_processor_init(void)
acpi_scan_add_handler(&processor_container_handler);
}
+static int acpi_processor_register_missing_cpus(void)
+{
+ int cpu;
+
+ if (acpi_disabled)
+ return 0;
+
+ for_each_online_cpu(cpu) {
+ if (!get_cpu_device(cpu)) {
+ pr_err_once(FW_BUG "CPU %u has no ACPI namespace description!\n", cpu);
+ add_taint(TAINT_FIRMWARE_WORKAROUND, LOCKDEP_STILL_OK);
+ arch_register_cpu(cpu);
+ }
+ }
+
+ return 0;
+}
+subsys_initcall_sync(acpi_processor_register_missing_cpus);
+
#ifdef CONFIG_ACPI_PROCESSOR_CSTATE
/**
* acpi_processor_claim_cst_control - Request _CST control from the platform.
ACPI has two descriptions of CPUs, on in the MADT/APIC table, the other in the DSDT. Both are required. (ACPI 6.5's 8.4 "Declaring Processors" says "Each processor in the system must be declared in the ACPI namespace"). Having two descriptions allows firmware authors to get this wrong. If CPUs are described in the MADT/APIC, they will be brought online early during boot. Once the register_cpu() calls are moved to ACPI, they will be based on the ACPI description of the CPUs. When CPUs are missing from the ACPI description, they will end up online, but not registered. Add a helper that runs after acpi_init() has completed to register CPUs that are online, but weren't found in the DSDT. Any CPU that is registered by this code triggers a firmware-bug warning and kernel taint. Qemu TCG only describes the first CPU in the DSDT, unless cpu-hotplug is configured. Signed-off-by: James Morse <james.morse@arm.com> --- drivers/acpi/acpi_processor.c | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+)