kernel/linux.git/drivers/acpi/processor_driver.c, branch v7.0-rc7

ACPI: processor: Do not expose global variable acpi_idle_driver

2026-01-09T21:38:22+00:00

Move the cpuidle driver check from __acpi_processor_start() to acpi_processor_power_init() which allows variable acpi_idle_driver to become static. No intentional functional impact. Signed-off-by: Huisong Li Tested-by: Borislav Petkov (AMD) Link: https://patch.msgid.link/20251223100914.2407069-7-lihuisong@huawei.com Signed-off-by: Rafael J. Wysocki

ACPI: processor: Update cpuidle driver check in __acpi_processor_start()

2026-01-09T21:38:22+00:00

Commit 7a8c994cbb2d ("ACPI: processor: idle: Optimize ACPI idle driver registration") moved the ACPI idle driver registration to acpi_processor_driver_init() and acpi_processor_power_init() does not register an idle driver any more. Accordingly, the cpuidle driver check in __acpi_processor_start() needs to be updated to avoid calling acpi_processor_power_init() without a cpuidle driver, in which case the registration of the cpuidle device in that function would lead to a NULL pointer dereference in __cpuidle_register_device(). Fixes: 7a8c994cbb2d ("ACPI: processor: idle: Optimize ACPI idle driver registration") Signed-off-by: Rafael J. Wysocki Reviewed-by: Mario Limonciello (AMD) Tested-by: Borislav Petkov (AMD) Link: https://patch.msgid.link/20251223100914.2407069-4-lihuisong@huawei.com Signed-off-by: Rafael J. Wysocki

ACPI: processor: idle: Optimize ACPI idle driver registration

2026-01-09T21:38:21+00:00

Currently, the ACPI idle driver is registered from within a CPU hotplug callback. Although this didn't cause any functional issues, this is questionable and confusing. And it is better to register the cpuidle driver when all of the CPUs have been brought up. So add a new function to initialize acpi_idle_driver based on the power management information of an available CPU and register cpuidle driver in acpi_processor_driver_init(). This commit has four changes under the commit 7a8c994cbb2d (ACPI: processor: idle: Optimize ACPI idle driver registration): 1) move acpi_processor_register_idle_driver() ahead of the driver_register(). 2) add acpi_processor_cstate_first_run_checks() before calling acpi_processor_get_power_info(). 3) squash the commit 9d68320b2bca (ACPI: processor: idle: Fix function defined but not used warning) into this change. 4) use for_each_possible_cpu(cpu) to scan all possible cpus. Signed-off-by: Huisong Li Tested-by: Borislav Petkov (AMD) [ rjw: New comment edits, changelog tweak ] Link: https://patch.msgid.link/20251223100914.2407069-2-lihuisong@huawei.com Signed-off-by: Rafael J. Wysocki

Revert "ACPI: processor: Update cpuidle driver check in __acpi_processor_start()"

2025-11-27T19:52:55+00:00

Revert commit 8a1b5d412cb4 ("ACPI: processor: Update cpuidle driver check in __acpi_processor_start()") which depends on commit 7a8c994cbb2d ("ACPI: processor: idle: Optimize ACPI idle driver registration") that got reverted. Signed-off-by: Rafael J. Wysocki

Revert "ACPI: processor: idle: Optimize ACPI idle driver registration"

2025-11-25T15:08:06+00:00

Revert commit 7a8c994cbb2d ("ACPI: processor: idle: Optimize ACPI idle driver registration") because it is reported to introduce a cpuidle regression leading to a kernel crash on a platform using the ACPI idle driver. Signed-off-by: Rafael J. Wysocki Reported-by: Borislav Petkov Tested-by: Borislav Petkov (AMD) Closes: https://lore.kernel.org/lkml/20251124200019.GIaSS5U9HhsWBotrQZ@fat_crate.local/

Revert "ACPI: processor: Do not expose global variable acpi_idle_driver"

2025-11-25T13:50:25+00:00

Revert commit 559f2eacc8a2 ACPI: processor: Do not expose global variable acpi_idle_driver" because it depends on a problematic one. Signed-off-by: Rafael J. Wysocki

ACPI: processor: Do not expose global variable acpi_idle_driver

2025-09-23T13:33:19+00:00

Move the cpuidle driver check from __acpi_processor_start() to acpi_processor_power_init() which allows variable acpi_idle_driver to become static. No intentional functional impact. Signed-off-by: Huisong Li Link: https://patch.msgid.link/20250923032428.2656329-2-lihuisong@huawei.com [ rjw: Subject tweak, new changelog, adjustment of a new comment ] Signed-off-by: Rafael J. Wysocki

ACPI: processor: Update cpuidle driver check in __acpi_processor_start()

2025-09-19T20:49:49+00:00

Commit 7a8c994cbb2d ("ACPI: processor: idle: Optimize ACPI idle driver registration") moved the ACPI idle driver registration to acpi_processor_driver_init() and acpi_processor_power_init() does not register an idle driver any more. Accordingly, the cpuidle driver check in __acpi_processor_start() needs to be updated to avoid calling acpi_processor_power_init() without a cpuidle driver, in which case the registration of the cpuidle device in that function would lead to a NULL pointer dereference in __cpuidle_register_device(). Fixes: 7a8c994cbb2d ("ACPI: processor: idle: Optimize ACPI idle driver registration") Signed-off-by: Rafael J. Wysocki Reviewed-by: Mario Limonciello (AMD) Link: https://patch.msgid.link/5044465.31r3eYUQgx@rafael.j.wysocki [ rjw: Changelog update ] Signed-off-by: Rafael J. Wysocki

ACPI: processor: idle: Optimize ACPI idle driver registration

2025-09-02T14:08:25+00:00

ACPI: processor: Rescan "dead" SMT siblings during initialization

2025-06-07T12:23:22+00:00

Make acpi_processor_driver_init() call arch_cpu_rescan_dead_smt_siblings(), via a new wrapper function called acpi_idle_rescan_dead_smt_siblings(), after successfully initializing the driver, to allow the "dead" SMT siblings to go into deep idle states, which is necessary for the processor to be able to reach deep package C-states (like PC10) going forward, so that power can be reduced sufficiently in suspend-to-idle, among other things. However, do it only if the ACPI idle driver is the current cpuidle driver (otherwise it is assumed that another cpuidle driver will take care of this) and avoid doing it on architectures other than x86. Signed-off-by: Rafael J. Wysocki Tested-by: Artem Bityutskiy Link: https://patch.msgid.link/2005721.PYKUYFuaPT@rjwysocki.net