kernel/linux.git/drivers/cpuidle, branch v6.6.39

cpuidle: Avoid potential overflow in integer multiplication

2024-04-13T11:07:29+00:00

[ Upstream commit 88390dd788db485912ee7f9a8d3d56fc5265d52f ] In detail: In C language, when you perform a multiplication operation, if both operands are of int type, the multiplication operation is performed on the int type, and then the result is converted to the target type. This means that if the product of int type multiplication exceeds the range that int type can represent, an overflow will occur even if you store the result in a variable of int64_t type. For a multiplication of two int values, it is better to use mul_u32_u32() rather than s->exit_latency_ns = s->exit_latency * NSEC_PER_USEC to avoid potential overflow happenning. Signed-off-by: C Cheng Signed-off-by: Bo Ye Reviewed-by: AngeloGioacchino Del Regno [ rjw: New subject ] Signed-off-by: Rafael J. Wysocki Signed-off-by: Sasha Levin

cpuidle: haltpoll: Do not enable interrupts when entering idle

2024-01-25T23:35:15+00:00

[ Upstream commit c8f5caec3df84a02b937d6d9cda1f7ffa8dc443f ] The cpuidle drivers' ->enter() methods are supposed to be IRQ invariant: 5e26aa933911 ("cpuidle/poll: Ensure IRQs stay disabled after cpuidle_state::enter() calls") bb7b11258561 ("cpuidle: Move IRQ state validation") Do that in the haltpoll driver too. Fixes: 5e26aa933911 ("cpuidle/poll: Ensure IRQs stay disabled after cpuidle_state::enter() calls") Closes: https://bugzilla.kernel.org/show_bug.cgi?id=218245 Reported-by: Tested-by: Signed-off-by: Borislav Petkov (AMD) [ rjw: Changelog edits ] Signed-off-by: Rafael J. Wysocki Signed-off-by: Sasha Levin

Merge tag 'powerpc-6.6-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux

2023-08-31T19:43:10+00:00

Pull powerpc updates from Michael Ellerman: - Add HOTPLUG_SMT support (/sys/devices/system/cpu/smt) and honour the configured SMT state when hotplugging CPUs into the system - Combine final TLB flush and lazy TLB mm shootdown IPIs when using the Radix MMU to avoid a broadcast TLBIE flush on exit - Drop the exclusion between ptrace/perf watchpoints, and drop the now unused associated arch hooks - Add support for the "nohlt" command line option to disable CPU idle - Add support for -fpatchable-function-entry for ftrace, with GCC >= 13.1 - Rework memory block size determination, and support 256MB size on systems with GPUs that have hotpluggable memory - Various other small features and fixes Thanks to Andrew Donnellan, Aneesh Kumar K.V, Arnd Bergmann, Athira Rajeev, Benjamin Gray, Christophe Leroy, Frederic Barrat, Gautam Menghani, Geoff Levand, Hari Bathini, Immad Mir, Jialin Zhang, Joel Stanley, Jordan Niethe, Justin Stitt, Kajol Jain, Kees Cook, Krzysztof Kozlowski, Laurent Dufour, Liang He, Linus Walleij, Mahesh Salgaonkar, Masahiro Yamada, Michal Suchanek, Nageswara R Sastry, Nathan Chancellor, Nathan Lynch, Naveen N Rao, Nicholas Piggin, Nick Desaulniers, Omar Sandoval, Randy Dunlap, Reza Arbab, Rob Herring, Russell Currey, Sourabh Jain, Thomas Gleixner, Trevor Woerner, Uwe Kleine-König, Vaibhav Jain, Xiongfeng Wang, Yuan Tan, Zhang Rui, and Zheng Zengkai. * tag 'powerpc-6.6-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux: (135 commits) macintosh/ams: linux/platform_device.h is needed powerpc/xmon: Reapply "Relax frame size for clang" powerpc/mm/book3s64: Use 256M as the upper limit with coherent device memory attached powerpc/mm/book3s64: Fix build error with SPARSEMEM disabled powerpc/iommu: Fix notifiers being shared by PCI and VIO buses powerpc/mpc5xxx: Add missing fwnode_handle_put() powerpc/config: Disable SLAB_DEBUG_ON in skiroot powerpc/pseries: Remove unused hcall tracing instruction powerpc/pseries: Fix hcall tracepoints with JUMP_LABEL=n powerpc: dts: add missing space before { powerpc/eeh: Use pci_dev_id() to simplify the code powerpc/64s: Move CPU -mtune options into Kconfig powerpc/powermac: Fix unused function warning powerpc/pseries: Rework lppaca_shared_proc() to avoid DEBUG_PREEMPT powerpc: Don't include lppaca.h in paca.h powerpc/pseries: Move hcall_vphn() prototype into vphn.h powerpc/pseries: Move VPHN constants into vphn.h cxl: Drop unused detach_spa() powerpc: Drop zalloc_maybe_bootmem() powerpc/powernv: Use struct opal_prd_msg in more places ...

Merge branches 'pm-cpuidle' and 'pm-cpufreq'

2023-08-25T19:15:56+00:00

Merge CPU power management updates for 6.6-rc1: - Rework the menu and teo cpuidle governors to avoid calling tick_nohz_get_sleep_length(), which is likely to become quite expensive going forward, too often and improve making decisions regarding whether or not to stop the scheduler tick in the teo governor (Rafael Wysocki). - Improve the performance of cpufreq_stats_create_table() in some cases (Liao Chang). - Fix two issues in the amd-pstate-ut cpufreq driver (Swapnil Sapkal). - Use clamp() helper macro to improve the code readability in cpufreq_verify_within_limits() (Liao Chang). - Set stale CPU frequency to minimum in intel_pstate (Doug Smythies). * pm-cpuidle: cpuidle: teo: Avoid unnecessary variable assignments cpuidle: menu: Skip tick_nohz_get_sleep_length() call in some cases cpuidle: teo: Gather statistics regarding whether or not to stop the tick cpuidle: teo: Skip tick_nohz_get_sleep_length() call in some cases cpuidle: teo: Do not call tick_nohz_get_sleep_length() upfront cpuidle: teo: Drop utilized from struct teo_cpu cpuidle: teo: Avoid stopping the tick unnecessarily when bailing out cpuidle: teo: Update idle duration estimate when choosing shallower state * pm-cpufreq: cpufreq: amd-pstate-ut: Fix kernel panic when loading the driver cpufreq: amd-pstate-ut: Remove module parameter access cpufreq: Use clamp() helper macro to improve the code readability cpufreq: intel_pstate: set stale CPU frequency to minimum cpufreq: stats: Improve the performance of cpufreq_stats_create_table()

powerpc/pseries: Rework lppaca_shared_proc() to avoid DEBUG_PREEMPT

2023-08-24T12:33:17+00:00

lppaca_shared_proc() takes a pointer to the lppaca which is typically accessed through get_lppaca(). With DEBUG_PREEMPT enabled, this leads to checking if preemption is enabled, for example: BUG: using smp_processor_id() in preemptible [00000000] code: grep/10693 caller is lparcfg_data+0x408/0x19a0 CPU: 4 PID: 10693 Comm: grep Not tainted 6.5.0-rc3 #2 Call Trace: dump_stack_lvl+0x154/0x200 (unreliable) check_preemption_disabled+0x214/0x220 lparcfg_data+0x408/0x19a0 ... This isn't actually a problem however, as it does not matter which lppaca is accessed, the shared proc state will be the same. vcpudispatch_stats_procfs_init() already works around this by disabling preemption, but the lparcfg code does not, erroring any time /proc/powerpc/lparcfg is accessed with DEBUG_PREEMPT enabled. Instead of disabling preemption on the caller side, rework lppaca_shared_proc() to not take a pointer and instead directly access the lppaca, bypassing any potential preemption checks. Fixes: f13c13a00512 ("powerpc: Stop using non-architected shared_proc field in lppaca") Signed-off-by: Russell Currey [mpe: Rework to avoid needing a definition in paca.h and lppaca.h] Signed-off-by: Michael Ellerman Link: https://msgid.link/20230823055317.751786-4-mpe@ellerman.id.au

cpuidle: teo: Avoid unnecessary variable assignments

2023-08-23T16:25:04+00:00

Notice that it is not necessary to assign tick_intercept_sum in every iteration of the first loop over idle states in teo_select(), because the intercept_sum value does not change after the assignment in a given iteration of the loop, so its value after the last iteration of the loop can be used for computing the tick_intercept_sum value directly. Modify the code accordingly. No intentional functional impact. Signed-off-by: Rafael J. Wysocki

cpuidle: menu: Skip tick_nohz_get_sleep_length() call in some cases

2023-08-17T09:28:38+00:00

Because the cost of calling tick_nohz_get_sleep_length() may increase in the future, reorder the code in menu_select() so it first uses the statistics to determine the expected idle duration. If that value is higher than RESIDENCY_THRESHOLD_NS, tick_nohz_get_sleep_length() will be called to obtain the time till the closest timer and refine the idle duration prediction if necessary. This causes the governor to always take the full overhead of get_typical_interval() with the assumption that the cost will be amortized by skipping the tick_nohz_get_sleep_length() call in the cases when the predicted idle duration is relatively very small. Signed-off-by: Rafael J. Wysocki Tested-by: Doug Smythies

cpuidle: teo: Gather statistics regarding whether or not to stop the tick

2023-08-09T17:58:53+00:00

Currently, if the target residency of the deepest idle state is less than the tick period length, which is quite likely for HZ=100, and the deepest idle state is about to be selected by the TEO idle governor, the decision on whether or not to stop the scheduler tick is based entirely on the time till the closest timer. This is often insufficient, because timers may not be in heavy use and there may be a plenty of other CPU wakeup events between the deepest idle state's target residency and the closest tick. Allow the governor to count those events by making the deepest idle state's bin effectively end at TICK_NSEC and introducing an additional "bin" for collecting "hit" events (ie. the ones in which the measured idle duration falls into the same bin as the time till the closest timer) with idle duration values past TICK_NSEC. This way the "intercepts" metric for the deepest idle state's bin becomes nonzero in general, and so it can influence the decision on whether or not to stop the tick possibly increasing the governor's accuracy in that respect. Signed-off-by: Rafael J. Wysocki Tested-by: Kajetan Puchalski Tested-by: Anna-Maria Behnsen

cpuidle: teo: Skip tick_nohz_get_sleep_length() call in some cases

2023-08-09T17:58:46+00:00

Make teo_select() avoid calling tick_nohz_get_sleep_length() if the candidate idle state to return is state 0 or if state 0 is a polling one and the target residency of the current candidate one is below a certain threshold, in which cases it may be assumed that the CPU will be woken up immediately by a non-timer wakeup source and the timers are not likely to matter. Signed-off-by: Rafael J. Wysocki Tested-by: Kajetan Puchalski Tested-by: Anna-Maria Behnsen

cpuidle: teo: Do not call tick_nohz_get_sleep_length() upfront

2023-08-09T17:58:05+00:00

Because the cost of calling tick_nohz_get_sleep_length() may increase in the future, reorder the code in teo_select() so it first uses the statistics to pick up a candidate idle state and applies the utilization heuristic to it and only then calls tick_nohz_get_sleep_length() to obtain the sleep length value and refine the selection if necessary. This change by itself does not cause tick_nohz_get_sleep_length() to be called less often, but it prepares the code for subsequent changes that will do so. Signed-off-by: Rafael J. Wysocki Tested-by: Kajetan Puchalski Tested-by: Anna-Maria Behnsen