linux-stable.git/drivers/acpi/processor_idle.c, branch v6.15

ACPI: processor: idle: Return an error if both P_LVL{2,3} idle states are invalid

2025-03-31T11:59:04+00:00

Prior to commit 496121c02127 ("ACPI: processor: idle: Allow probing on
platforms with one ACPI C-state"), the acpi_idle driver wouldn't load on
systems without a valid C-State at least as deep as C2.

The behavior was desirable for guests on hypervisors such as VMWare
ESXi, which by default don't have the _CST ACPI method, and set the C2
and C3 latencies to 101 and 1001 microseconds respectively via the FADT,
to signify they're unsupported.

Since the above change though, these virtualized deployments end up
loading acpi_idle, and thus entering the default C1 C-State set by
acpi_processor_get_power_info_default(); this is undesirable for a
system that's communicating to the OS it doesn't want C-States (missing
_CST, and invalid C2/C3 in FADT).

Make acpi_processor_get_power_info_fadt() return -ENODEV in that case,
so that acpi_processor_get_cstate_info() exits early and doesn't set
pr->flags.power = 1.

Fixes: 496121c02127 ("ACPI: processor: idle: Allow probing on platforms with one ACPI C-state")
Signed-off-by: Giovanni Gherdovich 
Reviewed-by: Zhang Rui 
Link: https://patch.msgid.link/20250328143040.9348-1-ggherdovich@suse.cz
[ rjw: Changelog edits ]
Signed-off-by: Rafael J. Wysocki

ACPI/processor_idle: Add FFH state handling

2025-02-05T18:44:52+00:00

Recent Intel platforms will depend on the idle driver to pass the
correct hint for playing dead via mwait_play_dead_with_hint(). Expand
the existing enter_dead interface with handling for FFH states and pass
the MWAIT hint to the mwait_play_dead code.

Suggested-by: Gautham R. Shenoy 
Signed-off-by: Patryk Wlazlyn 
Signed-off-by: Artem Bityutskiy 
Signed-off-by: Dave Hansen 
Acked-by: Rafael J. Wysocki 
Link: https://lore.kernel.org/all/20250205155211.329780-3-artem.bityutskiy%40linux.intel.com

Merge tag 'acpi-6.13-rc1-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm

2024-11-27T22:50:31+00:00

Pull more ACPI updates from Rafael Wysocki:
 "These add a common init function for arch-specific ACPI
  initialization, clean up idle states initialization in the ACPI
  processor_idle driver and update quirks:

   - Introduce acpi_arch_init() for architecture-specific ACPI subsystem
     initialization (Miao Wang)

   - Clean up Asus quirks in acpi_quirk_skip_dmi_ids[] and add a quirk
     to skip I2C clients on Acer Iconia One 8 A1-840 (Hans de Goede)

   - Make the ACPI processor_idle driver use acpi_idle_play_dead() for
     all idle states regardless of their types (Rafael Wysocki)"

* tag 'acpi-6.13-rc1-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
  ACPI: introduce acpi_arch_init()
  ACPI: x86: Clean up Asus entries in acpi_quirk_skip_dmi_ids[]
  ACPI: x86: Add skip i2c clients quirk for Acer Iconia One 8 A1-840
  ACPI: processor_idle: Use acpi_idle_play_dead() for all C-states

cpuidle: Change :enter_dead() driver callback return type to void

2024-11-19T20:46:51+00:00

After a previous change, cpuidle_play_dead(), which is the only caller
of idle state :enter_dead() callbacks, ignores their return values, so
they may as well be void.

Suggested-by: Peter Zijlstra 
Signed-off-by: Rafael J. Wysocki 
Reviewed-by: Gautham R. Shenoy 
Reviewed-by: Mario Limonciello 
Link: https://patch.msgid.link/2285569.iZASKD2KPV@rjwysocki.net

ACPI: processor_idle: Use acpi_idle_play_dead() for all C-states

2024-11-19T20:43:51+00:00

Notice that acpi_processor_setup_cstates() can set state->enter_dead to acpi_idle_play_dead() for all C-states unconditionally and remove the
confusing C-state type check done before setting it.

No intentional functional impact.

Suggested-by: Peter Zijlstra 
Signed-off-by: Rafael J. Wysocki 
Reviewed-by: Mario Limonciello 
Tested-by: Mario Limonciello  # 6.12-rc7
Acked-by: Peter Zijlstra (Intel) 
Link: https://patch.msgid.link/2373563.ElGaqSPkdT@rjwysocki.net

ACPI: processor_idle: Fix invalid comparison with insertion sort for latency

2024-07-02T18:35:29+00:00

The acpi_cst_latency_cmp() comparison function currently used for
sorting C-state latencies does not satisfy transitivity, causing
incorrect sorting results.

Specifically, if there are two valid acpi_processor_cx elements A and B
and one invalid element C, it may occur that A < B, A = C, and B = C.
Sorting algorithms assume that if A < B and A = C, then C < B, leading
to incorrect ordering.

Given the small size of the array (<=8), we replace the library sort
function with a simple insertion sort that properly ignores invalid
elements and sorts valid ones based on latency. This change ensures
correct ordering of the C-state latencies.

Fixes: 65ea8f2c6e23 ("ACPI: processor idle: Fix up C-state latency if not ordered")
Reported-by: Julian Sikorski 
Closes: https://lore.kernel.org/lkml/70674dc7-5586-4183-8953-8095567e73df@gmail.com
Signed-off-by: Kuan-Wei Chiu 
Tested-by: Julian Sikorski 
Cc: All applicable 
Link: https://patch.msgid.link/20240701205639.117194-1-visitorckw@gmail.com
Signed-off-by: Rafael J. Wysocki

ACPI: processor_idle: Fix memory leak in acpi_processor_power_exit()

2024-02-15T19:26:40+00:00

After unregistering the CPU idle device, the memory associated with
it is not freed, leading to a memory leak:

unreferenced object 0xffff896282f6c000 (size 1024):
  comm "swapper/0", pid 1, jiffies 4294893170
  hex dump (first 32 bytes):
    00 00 00 00 0b 00 00 00 00 00 00 00 00 00 00 00  ................
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
  backtrace (crc 8836a742):
    [] kmalloc_trace+0x29d/0x340
    [] acpi_processor_power_init+0xf3/0x1c0
    [] __acpi_processor_start+0xd3/0xf0
    [] acpi_processor_start+0x2c/0x50
    [] really_probe+0xe2/0x480
    [] __driver_probe_device+0x78/0x160
    [] driver_probe_device+0x1f/0x90
    [] __driver_attach+0xce/0x1c0
    [] bus_for_each_dev+0x70/0xc0
    [] bus_add_driver+0x112/0x210
    [] driver_register+0x55/0x100
    [] acpi_processor_driver_init+0x3b/0xc0
    [] do_one_initcall+0x41/0x300
    [] kernel_init_freeable+0x320/0x470
    [] kernel_init+0x16/0x1b0
    [] ret_from_fork+0x2d/0x50

Fix this by freeing the CPU idle device after unregistering it.

Fixes: 3d339dcbb56d ("cpuidle / ACPI : move cpuidle_device field out of the acpi_processor_power structure")
Signed-off-by: Armin Wolf 
Signed-off-by: Rafael J. Wysocki

ACPI: processor_idle: use raw_safe_halt() in acpi_idle_play_dead()

2023-11-20T16:26:20+00:00

Xen HVM guests were observed taking triple-faults when attempting to
online a previously offlined vCPU.

Investigation showed that the fault was coming from a failing call
to lockdep_assert_irqs_disabled(), in load_current_idt() which was
too early in the CPU bringup to actually catch the exception and
report the failure cleanly.

This was a false positive, caused by acpi_idle_play_dead() setting
the per-cpu hardirqs_enabled flag by calling safe_halt(). Switch it
to use raw_safe_halt() instead, which doesn't do so.

Signed-off-by: David Woodhouse 
Acked-by: Peter Zijlstra (Intel) 
Cc: 6.6+  # 6.6+
Signed-off-by: Rafael J. Wysocki

cpuidle, ACPI: Evaluate LPI arch_flags for broadcast timer

2023-10-04T15:31:27+00:00

Arm® Functional Fixed Hardware Specification defines LPI states,
which provide an architectural context loss flags field that can
be used to describe the context that might be lost when an LPI
state is entered.

- Core context Lost
        - General purpose registers.
        - Floating point and SIMD registers.
        - System registers, include the System register based
        - generic timer for the core.
        - Debug register in the core power domain.
        - PMU registers in the core power domain.
        - Trace register in the core power domain.
- Trace context loss
- GICR
- GICD

Qualcomm's custom CPUs preserves the architectural state,
including keeping the power domain for local timers active.
when core is power gated, the local timers are sufficient to
wake the core up without needing broadcast timer.

The patch fixes the evaluation of cpuidle arch_flags, and moves only to
broadcast timer if core context lost is defined in ACPI LPI.

Fixes: a36a7fecfe60 ("ACPI / processor_idle: Add support for Low Power Idle(LPI) states")
Reviewed-by: Sudeep Holla 
Acked-by: Rafael J. Wysocki 
Signed-off-by: Oza Pawandeep 
Link: https://lore.kernel.org/r/20231003173333.2865323-1-quic_poza@quicinc.com
Signed-off-by: Will Deacon

x86/smpboot: Remove the CPU0 hotplug kludge

2023-05-15T11:44:49+00:00

This was introduced with commit e1c467e69040 ("x86, hotplug: Wake up CPU0
via NMI instead of INIT, SIPI, SIPI") to eventually support physical
hotplug of CPU0:

 "We'll change this code in the future to wake up hard offlined CPU0 if
  real platform and request are available."

11 years later this has not happened and physical hotplug is not officially
supported. Remove the cruft.

Signed-off-by: Thomas Gleixner 
Signed-off-by: Peter Zijlstra (Intel) 
Tested-by: Michael Kelley 
Tested-by: Oleksandr Natalenko 
Tested-by: Helge Deller  # parisc
Tested-by: Guilherme G. Piccoli  # Steam Deck
Link: https://lore.kernel.org/r/20230512205255.768845190@linutronix.de