Commit b6e0a37a authored by James Morse's avatar James Morse Committed by liwei
Browse files

ACPI: processor: Register CPUs that are online, but not described in the DSDT 

maillist inclusion
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I8XMTL


CVE: NA

---------------------------------

ACPI has two descriptions of CPUs, one 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 DSDT description of the CPUs. When CPUs are
missing from the DSDT 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: default avatarJames Morse <james.morse@arm.com>
Reviewed-by: default avatarJonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: default avatarGavin Shan <gshan@redhat.com>
Tested-by: default avatarMiguel Luis <miguel.luis@oracle.com>
Tested-by: default avatarVishnu Pajjuri <vishnu@os.amperecomputing.com>
Tested-by: default avatarJianyong Wu <jianyong.wu@arm.com>
Signed-off-by: default avatarRussell King (Oracle) <rmk+kernel@armlinux.org.uk>
Signed-off-by: default avatarliwei <liwei728@huawei.com>
parent 2f257a8e

drivers/acpi/acpi_processor.c

+19 −0
Original line number Diff line number Diff line
@@ -791,6 +791,25 @@ void __init acpi_processor_init(void) 
	acpi_pcc_cpufreq_init();

}



static int __init 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.