From: James Morse <james.morse@xxxxxxx> ACPI has two ways of describing processors in the DSDT. From ACPI v6.5, 5.2.12: "Starting with ACPI Specification 6.3, the use of the Processor() object was deprecated. Only legacy systems should continue with this usage. On the Itanium architecture only, a _UID is provided for the Processor() that is a string object. This usage of _UID is also deprecated since it can preclude an OSPM from being able to match a processor to a non-enumerable device, such as those defined in the MADT. From ACPI Specification 6.3 onward, all processor objects for all architectures except Itanium must now use Device() objects with an _HID of ACPI0007, and use only integer _UID values." Also see https://uefi.org/specs/ACPI/6.5/08_Processor_Configuration_and_Control.html#declaring-processors Duplicate descriptions are not allowed, the ACPI processor driver already parses the UID from both devices and containers. acpi_processor_get_info() returns an error if the UID exists twice in the DSDT. The missing probe for CPUs described as packages creates a problem for moving the cpu_register() calls into the acpi_processor driver, as CPUs described like this don't get registered, leading to errors from other subsystems when they try to add new sysfs entries to the CPU node. (e.g. topology_sysfs_init()'s use of topology_add_dev() via cpuhp) To fix this, parse the processor container and call acpi_processor_add() for each processor that is discovered like this. The processor container handler is added with acpi_scan_add_handler(), so no detach call will arrive. Qemu TCG describes CPUs using processor devices in a processor container. For more information, see build_cpus_aml() in Qemu hw/acpi/cpu.c and https://uefi.org/specs/ACPI/6.5/08_Processor_Configuration_and_Control.html#processor-container-device Signed-off-by: James Morse <james.morse@xxxxxxx> Tested-by: Miguel Luis <miguel.luis@xxxxxxxxxx> Tested-by: Vishnu Pajjuri <vishnu@xxxxxxxxxxxxxxxxxxxxxx> Tested-by: Jianyong Wu <jianyong.wu@xxxxxxx> --- Outstanding comments: https://lore.kernel.org/r/20230914145353.000072e2@xxxxxxxxxx https://lore.kernel.org/r/50571c2f-aa3c-baeb-3add-cd59e0eddc02@xxxxxxxxxx --- drivers/acpi/acpi_processor.c | 22 ++++++++++++++++++++++ 1 file changed, 22 insertions(+) diff --git a/drivers/acpi/acpi_processor.c b/drivers/acpi/acpi_processor.c index 4fe2ef54088c..6a542e0ce396 100644 --- a/drivers/acpi/acpi_processor.c +++ b/drivers/acpi/acpi_processor.c @@ -626,9 +626,31 @@ static struct acpi_scan_handler processor_handler = { }, }; +static acpi_status acpi_processor_container_walk(acpi_handle handle, + u32 lvl, + void *context, + void **rv) +{ + struct acpi_device *adev; + acpi_status status; + + adev = acpi_get_acpi_dev(handle); + if (!adev) + return AE_ERROR; + + status = acpi_processor_add(adev, &processor_device_ids[0]); + acpi_put_acpi_dev(adev); + + return status; +} + static int acpi_processor_container_attach(struct acpi_device *dev, const struct acpi_device_id *id) { + acpi_walk_namespace(ACPI_TYPE_PROCESSOR, dev->handle, + ACPI_UINT32_MAX, acpi_processor_container_walk, + NULL, NULL, NULL); + return 1; } -- 2.30.2
