On Wed, Dec 13, 2023 at 1:49 PM Russell King <rmk+kernel@xxxxxxxxxxxxxxx> wrote: > > 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. I'm not really sure how the above is related to the actual patch. > The missing probe for CPUs described as packages It is unclear what exactly is meant by "CPUs described as packages". >From the patch, it looks like those would be Processor() objects defined under a processor container device. > 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. Discovered like what? > The processor container > handler is added with acpi_scan_add_handler(), so no detach call will > arrive. The above requires clarification too. > 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; Why is the reference counting needed here? Wouldn't acpi_fetch_acpi_dev() suffice? Also, should the walk really be terminated on the first 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); This covers processor objects only, so why is this not needed for processor devices defined under a processor container object? It is not obvious, so it would be nice to add a comment explaining the difference. > + > return 1; > } > > --
