summaryrefslogtreecommitdiffstats
path: root/kernel/cpu.c
AgeCommit message (Collapse)AuthorFilesLines
2019-03-28cpu/hotplug: Prevent crash when CPU bringup fails on CONFIG_HOTPLUG_CPU=nThomas Gleixner1-2/+18
Tianyu reported a crash in a CPU hotplug teardown callback when booting a kernel which has CONFIG_HOTPLUG_CPU disabled with the 'nosmt' boot parameter. It turns out that the SMP=y CONFIG_HOTPLUG_CPU=n case has been broken forever in case that a bringup callback fails. Unfortunately this issue was not recognized when the CPU hotplug code was reworked, so the shortcoming just stayed in place. When a bringup callback fails, the CPU hotplug code rolls back the operation and takes the CPU offline. The 'nosmt' command line argument uses a bringup failure to abort the bringup of SMT sibling CPUs. This partial bringup is required due to the MCE misdesign on Intel CPUs. With CONFIG_HOTPLUG_CPU=y the rollback works perfectly fine, but CONFIG_HOTPLUG_CPU=n lacks essential mechanisms to exercise the low level teardown of a CPU including the synchronizations in various facilities like RCU, NOHZ and others. As a consequence the teardown callbacks which must be executed on the outgoing CPU within stop machine with interrupts disabled are executed on the control CPU in interrupt enabled and preemptible context causing the kernel to crash and burn. The pre state machine code has a different failure mode which is more subtle and resulting in a less obvious use after free crash because the control side frees resources which are still in use by the undead CPU. But this is not a x86 only problem. Any architecture which supports the SMP=y HOTPLUG_CPU=n combination suffers from the same issue. It's just less likely to be triggered because in 99.99999% of the cases all bringup callbacks succeed. The easy solution of making HOTPLUG_CPU mandatory for SMP is not working on all architectures as the following architectures have either no hotplug support at all or not all subarchitectures support it: alpha, arc, hexagon, openrisc, riscv, sparc (32bit), mips (partial). Crashing the kernel in such a situation is not an acceptable state either. Implement a minimal rollback variant by limiting the teardown to the point where all regular teardown callbacks have been invoked and leave the CPU in the 'dead' idle state. This has the following consequences: - the CPU is brought down to the point where the stop_machine takedown would happen. - the CPU stays there forever and is idle - The CPU is cleared in the CPU active mask, but not in the CPU online mask which is a legit state. - Interrupts are not forced away from the CPU - All facilities which only look at online mask would still see it, but that is the case during normal hotplug/unplug operations as well. It's just a (way) longer time frame. This will expose issues, which haven't been exposed before or only seldom, because now the normally transient state of being non active but online is a permanent state. In testing this exposed already an issue vs. work queues where the vmstat code schedules work on the almost dead CPU which ends up in an unbound workqueue and triggers 'preemtible context' warnings. This is not a problem of this change, it merily exposes an already existing issue. Still this is better than crashing fully without a chance to debug it. This is mainly thought as workaround for those architectures which do not support HOTPLUG_CPU. All others should enforce HOTPLUG_CPU for SMP. Fixes: 2e1a3483ce74 ("cpu/hotplug: Split out the state walk into functions") Reported-by: Tianyu Lan <Tianyu.Lan@microsoft.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Tested-by: Tianyu Lan <Tianyu.Lan@microsoft.com> Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Konrad Wilk <konrad.wilk@oracle.com> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Mukesh Ojha <mojha@codeaurora.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Jiri Kosina <jkosina@suse.cz> Cc: Rik van Riel <riel@surriel.com> Cc: Andy Lutomirski <luto@kernel.org> Cc: Micheal Kelley <michael.h.kelley@microsoft.com> Cc: "K. Y. Srinivasan" <kys@microsoft.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Borislav Petkov <bp@alien8.de> Cc: K. Y. Srinivasan <kys@microsoft.com> Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/20190326163811.503390616@linutronix.de
2019-02-04Merge tag 'v5.0-rc5' into locking/core to pick up fixesIngo Molnar1-33/+5
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-01-30cpu/hotplug: Fix "SMT disabled by BIOS" detection for KVMJosh Poimboeuf1-29/+4
With the following commit: 73d5e2b47264 ("cpu/hotplug: detect SMT disabled by BIOS") ... the hotplug code attempted to detect when SMT was disabled by BIOS, in which case it reported SMT as permanently disabled. However, that code broke a virt hotplug scenario, where the guest is booted with only primary CPU threads, and a sibling is brought online later. The problem is that there doesn't seem to be a way to reliably distinguish between the HW "SMT disabled by BIOS" case and the virt "sibling not yet brought online" case. So the above-mentioned commit was a bit misguided, as it permanently disabled SMT for both cases, preventing future virt sibling hotplugs. Going back and reviewing the original problems which were attempted to be solved by that commit, when SMT was disabled in BIOS: 1) /sys/devices/system/cpu/smt/control showed "on" instead of "notsupported"; and 2) vmx_vm_init() was incorrectly showing the L1TF_MSG_SMT warning. I'd propose that we instead consider #1 above to not actually be a problem. Because, at least in the virt case, it's possible that SMT wasn't disabled by BIOS and a sibling thread could be brought online later. So it makes sense to just always default the smt control to "on" to allow for that possibility (assuming cpuid indicates that the CPU supports SMT). The real problem is #2, which has a simple fix: change vmx_vm_init() to query the actual current SMT state -- i.e., whether any siblings are currently online -- instead of looking at the SMT "control" sysfs value. So fix it by: a) reverting the original "fix" and its followup fix: 73d5e2b47264 ("cpu/hotplug: detect SMT disabled by BIOS") bc2d8d262cba ("cpu/hotplug: Fix SMT supported evaluation") and b) changing vmx_vm_init() to query the actual current SMT state -- instead of the sysfs control value -- to determine whether the L1TF warning is needed. This also requires the 'sched_smt_present' variable to exported, instead of 'cpu_smt_control'. Fixes: 73d5e2b47264 ("cpu/hotplug: detect SMT disabled by BIOS") Reported-by: Igor Mammedov <imammedo@redhat.com> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Joe Mario <jmario@redhat.com> Cc: Jiri Kosina <jikos@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: kvm@vger.kernel.org Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/e3a85d585da28cc333ecbc1e78ee9216e6da9396.1548794349.git.jpoimboe@redhat.com
2019-01-29x86/speculation: Remove redundant arch_smt_update() invocationZhenzhong Duan1-4/+1
With commit a74cfffb03b7 ("x86/speculation: Rework SMT state change"), arch_smt_update() is invoked from each individual CPU hotplug function. Therefore the extra arch_smt_update() call in the sysfs SMT control is redundant. Fixes: a74cfffb03b7 ("x86/speculation: Rework SMT state change") Signed-off-by: Zhenzhong Duan <zhenzhong.duan@oracle.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: <konrad.wilk@oracle.com> Cc: <dwmw@amazon.co.uk> Cc: <bp@suse.de> Cc: <srinivas.eeda@oracle.com> Cc: <peterz@infradead.org> Cc: <hpa@zytor.com> Link: https://lkml.kernel.org/r/e2e064f2-e8ef-42ca-bf4f-76b612964752@default
2019-01-21cpu/hotplug: Mute hotplug lockdep during initValentin Schneider1-0/+9
Since we've had: commit cb538267ea1e ("jump_label/lockdep: Assert we hold the hotplug lock for _cpuslocked() operations") we've been getting some lockdep warnings during init, such as on HiKey960: [ 0.820495] WARNING: CPU: 4 PID: 0 at kernel/cpu.c:316 lockdep_assert_cpus_held+0x3c/0x48 [ 0.820498] Modules linked in: [ 0.820509] CPU: 4 PID: 0 Comm: swapper/4 Tainted: G S 4.20.0-rc5-00051-g4cae42a #34 [ 0.820511] Hardware name: HiKey960 (DT) [ 0.820516] pstate: 600001c5 (nZCv dAIF -PAN -UAO) [ 0.820520] pc : lockdep_assert_cpus_held+0x3c/0x48 [ 0.820523] lr : lockdep_assert_cpus_held+0x38/0x48 [ 0.820526] sp : ffff00000a9cbe50 [ 0.820528] x29: ffff00000a9cbe50 x28: 0000000000000000 [ 0.820533] x27: 00008000b69e5000 x26: ffff8000bff4cfe0 [ 0.820537] x25: ffff000008ba69e0 x24: 0000000000000001 [ 0.820541] x23: ffff000008fce000 x22: ffff000008ba70c8 [ 0.820545] x21: 0000000000000001 x20: 0000000000000003 [ 0.820548] x19: ffff00000a35d628 x18: ffffffffffffffff [ 0.820552] x17: 0000000000000000 x16: 0000000000000000 [ 0.820556] x15: ffff00000958f848 x14: 455f3052464d4d34 [ 0.820559] x13: 00000000769dde98 x12: ffff8000bf3f65a8 [ 0.820564] x11: 0000000000000000 x10: ffff00000958f848 [ 0.820567] x9 : ffff000009592000 x8 : ffff00000958f848 [ 0.820571] x7 : ffff00000818ffa0 x6 : 0000000000000000 [ 0.820574] x5 : 0000000000000000 x4 : 0000000000000001 [ 0.820578] x3 : 0000000000000000 x2 : 0000000000000001 [ 0.820582] x1 : 00000000ffffffff x0 : 0000000000000000 [ 0.820587] Call trace: [ 0.820591] lockdep_assert_cpus_held+0x3c/0x48 [ 0.820598] static_key_enable_cpuslocked+0x28/0xd0 [ 0.820606] arch_timer_check_ool_workaround+0xe8/0x228 [ 0.820610] arch_timer_starting_cpu+0xe4/0x2d8 [ 0.820615] cpuhp_invoke_callback+0xe8/0xd08 [ 0.820619] notify_cpu_starting+0x80/0xb8 [ 0.820625] secondary_start_kernel+0x118/0x1d0 We've also had a similar warning in sched_init_smp() for every asymmetric system that would enable the sched_asym_cpucapacity static key, although that was singled out in: commit 40fa3780bac2 ("sched/core: Take the hotplug lock in sched_init_smp()") Those warnings are actually harmless, since we cannot have hotplug operations at the time they appear. Instead of starting to sprinkle useless hotplug lock operations in the init codepaths, mute the warnings until they start warning about real problems. Suggested-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Valentin Schneider <valentin.schneider@arm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Will Deacon <will.deacon@arm.com> Cc: cai@gmx.us Cc: daniel.lezcano@linaro.org Cc: dietmar.eggemann@arm.com Cc: linux-arm-kernel@lists.infradead.org Cc: longman@redhat.com Cc: marc.zyngier@arm.com Cc: mark.rutland@arm.com Link: https://lkml.kernel.org/r/1545243796-23224-2-git-send-email-valentin.schneider@arm.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-11-28x86/speculation: Rework SMT state changeThomas Gleixner1-6/+9
arch_smt_update() is only called when the sysfs SMT control knob is changed. This means that when SMT is enabled in the sysfs control knob the system is considered to have SMT active even if all siblings are offline. To allow finegrained control of the speculation mitigations, the actual SMT state is more interesting than the fact that siblings could be enabled. Rework the code, so arch_smt_update() is invoked from each individual CPU hotplug function, and simplify the update function while at it. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Ingo Molnar <mingo@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Andy Lutomirski <luto@kernel.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Jiri Kosina <jkosina@suse.cz> Cc: Tom Lendacky <thomas.lendacky@amd.com> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: David Woodhouse <dwmw@amazon.co.uk> Cc: Tim Chen <tim.c.chen@linux.intel.com> Cc: Andi Kleen <ak@linux.intel.com> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Casey Schaufler <casey.schaufler@intel.com> Cc: Asit Mallick <asit.k.mallick@intel.com> Cc: Arjan van de Ven <arjan@linux.intel.com> Cc: Jon Masters <jcm@redhat.com> Cc: Waiman Long <longman9394@gmail.com> Cc: Greg KH <gregkh@linuxfoundation.org> Cc: Dave Stewart <david.c.stewart@intel.com> Cc: Kees Cook <keescook@chromium.org> Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/20181125185004.521974984@linutronix.de
2018-10-23Merge branch 'x86-pti-for-linus' of ↵Linus Torvalds1-1/+10
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull x86 pti updates from Ingo Molnar: "The main changes: - Make the IBPB barrier more strict and add STIBP support (Jiri Kosina) - Micro-optimize and clean up the entry code (Andy Lutomirski) - ... plus misc other fixes" * 'x86-pti-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86/speculation: Propagate information about RSB filling mitigation to sysfs x86/speculation: Enable cross-hyperthread spectre v2 STIBP mitigation x86/speculation: Apply IBPB more strictly to avoid cross-process data leak x86/speculation: Add RETPOLINE_AMD support to the inline asm CALL_NOSPEC variant x86/CPU: Fix unused variable warning when !CONFIG_IA32_EMULATION x86/pti/64: Remove the SYSCALL64 entry trampoline x86/entry/64: Use the TSS sp2 slot for SYSCALL/SYSRET scratch space x86/entry/64: Document idtentry
2018-10-23Merge branch 'sched-core-for-linus' of ↵Linus Torvalds1-0/+1
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull scheduler updates from Ingo Molnar: "The main changes are: - Migrate CPU-intense 'misfit' tasks on asymmetric capacity systems, to better utilize (much) faster 'big core' CPUs. (Morten Rasmussen, Valentin Schneider) - Topology handling improvements, in particular when CPU capacity changes and related load-balancing fixes/improvements (Morten Rasmussen) - ... plus misc other improvements, fixes and updates" * 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (28 commits) sched/completions/Documentation: Add recommendation for dynamic and ONSTACK completions sched/completions/Documentation: Clean up the document some more sched/completions/Documentation: Fix a couple of punctuation nits cpu/SMT: State SMT is disabled even with nosmt and without "=force" sched/core: Fix comment regarding nr_iowait_cpu() and get_iowait_load() sched/fair: Remove setting task's se->runnable_weight during PELT update sched/fair: Disable LB_BIAS by default sched/pelt: Fix warning and clean up IRQ PELT config sched/topology: Make local variables static sched/debug: Use symbolic names for task state constants sched/numa: Remove unused numa_stats::nr_running field sched/numa: Remove unused code from update_numa_stats() sched/debug: Explicitly cast sched_feat() to bool sched/core: Disable SD_PREFER_SIBLING on asymmetric CPU capacity domains sched/fair: Don't move tasks to lower capacity CPUs unless necessary sched/fair: Set rq->rd->overload when misfit sched/fair: Wrap rq->rd->overload accesses with READ/WRITE_ONCE() sched/core: Change root_domain->overload type to int sched/fair: Change 'prefer_sibling' type to bool sched/fair: Kick nohz balance if rq->misfit_task_load ...
2018-10-05cpu/SMT: State SMT is disabled even with nosmt and without "=force"Borislav Petkov1-0/+1
When booting with "nosmt=force" a message is issued into dmesg to confirm that SMT has been force-disabled but such a message is not issued when only "nosmt" is on the kernel command line. Fix that. Signed-off-by: Borislav Petkov <bp@suse.de> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/20181004172227.10094-1-bp@alien8.de Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-09-26x86/speculation: Enable cross-hyperthread spectre v2 STIBP mitigationJiri Kosina1-1/+10
STIBP is a feature provided by certain Intel ucodes / CPUs. This feature (once enabled) prevents cross-hyperthread control of decisions made by indirect branch predictors. Enable this feature if - the CPU is vulnerable to spectre v2 - the CPU supports SMT and has SMT siblings online - spectre_v2 mitigation autoselection is enabled (default) After some previous discussion, this leaves STIBP on all the time, as wrmsr on crossing kernel boundary is a no-no. This could perhaps later be a bit more optimized (like disabling it in NOHZ, experiment with disabling it in idle, etc) if needed. Note that the synchronization of the mask manipulation via newly added spec_ctrl_mutex is currently not strictly needed, as the only updater is already being serialized by cpu_add_remove_lock, but let's make this a little bit more future-proof. Signed-off-by: Jiri Kosina <jkosina@suse.cz> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: "WoodhouseDavid" <dwmw@amazon.co.uk> Cc: Andi Kleen <ak@linux.intel.com> Cc: Tim Chen <tim.c.chen@linux.intel.com> Cc: "SchauflerCasey" <casey.schaufler@intel.com> Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/nycvar.YFH.7.76.1809251438240.15880@cbobk.fhfr.pm
2018-09-11locking/lockdep, cpu/hotplug: Annotate AP threadPeter Zijlstra1-0/+28
Anybody trying to assert the cpu_hotplug_lock is held (lockdep_assert_cpus_held()) from AP callbacks will fail, because the lock is held by the BP. Stick in an explicit annotation in cpuhp_thread_fun() to make this work. Reported-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-tip-commits@vger.kernel.org Fixes: cb538267ea1e ("jump_label/lockdep: Assert we hold the hotplug lock for _cpuslocked() operations") Link: http://lkml.kernel.org/r/20180911095127.GT24082@hirez.programming.kicks-ass.net Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-09-06cpu/hotplug: Prevent state corruption on error rollbackThomas Gleixner1-2/+3
When a teardown callback fails, the CPU hotplug code brings the CPU back to the previous state. The previous state becomes the new target state. The rollback happens in undo_cpu_down() which increments the state unconditionally even if the state is already the same as the target. As a consequence the next CPU hotplug operation will start at the wrong state. This is easily to observe when __cpu_disable() fails. Prevent the unconditional undo by checking the state vs. target before incrementing state and fix up the consequently wrong conditional in the unplug code which handles the failure of the final CPU take down on the control CPU side. Fixes: 4dddfb5faa61 ("smp/hotplug: Rewrite AP state machine core") Reported-by: Neeraj Upadhyay <neeraju@codeaurora.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Tested-by: Geert Uytterhoeven <geert+renesas@glider.be> Tested-by: Sudeep Holla <sudeep.holla@arm.com> Tested-by: Neeraj Upadhyay <neeraju@codeaurora.org> Cc: josh@joshtriplett.org Cc: peterz@infradead.org Cc: jiangshanlai@gmail.com Cc: dzickus@redhat.com Cc: brendan.jackman@arm.com Cc: malat@debian.org Cc: sramana@codeaurora.org Cc: linux-arm-msm@vger.kernel.org Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/alpine.DEB.2.21.1809051419580.1416@nanos.tec.linutronix.de ----
2018-09-06cpu/hotplug: Adjust misplaced smb() in cpuhp_thread_fun()Neeraj Upadhyay1-3/+3
The smp_mb() in cpuhp_thread_fun() is misplaced. It needs to be after the load of st->should_run to prevent reordering of the later load/stores w.r.t. the load of st->should_run. Fixes: 4dddfb5faa61 ("smp/hotplug: Rewrite AP state machine core") Signed-off-by: Neeraj Upadhyay <neeraju@codeaurora.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Peter Zijlstra (Intel) <peterz@infraded.org> Cc: josh@joshtriplett.org Cc: peterz@infradead.org Cc: jiangshanlai@gmail.com Cc: dzickus@redhat.com Cc: brendan.jackman@arm.com Cc: malat@debian.org Cc: mojha@codeaurora.org Cc: sramana@codeaurora.org Cc: linux-arm-msm@vger.kernel.org Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/1536126727-11629-1-git-send-email-neeraju@codeaurora.org
2018-08-31cpu/hotplug: Remove skip_onerr field from cpuhp_step structureMukesh Ojha1-22/+4
When notifiers were there, `skip_onerr` was used to avoid calling particular step startup/teardown callbacks in the CPU up/down rollback path, which made the hotplug asymmetric. As notifiers are gone now after the full state machine conversion, the `skip_onerr` field is no longer required. Remove it from the structure and its usage. Signed-off-by: Mukesh Ojha <mojha@codeaurora.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/1535439294-31426-1-git-send-email-mojha@codeaurora.org
2018-08-14cpu/hotplug: Non-SMP machines do not make use of booted_onceAbel Vesa1-0/+2
Commit 0cc3cd21657b ("cpu/hotplug: Boot HT siblings at least once") breaks non-SMP builds. [ I suspect the 'bool' fields should just be made to be bitfields and be exposed regardless of configuration, but that's a separate cleanup that I'll leave to the owners of this file for later. - Linus ] Fixes: 0cc3cd21657b ("cpu/hotplug: Boot HT siblings at least once") Cc: Dave Hansen <dave.hansen@intel.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Tony Luck <tony.luck@intel.com> Signed-off-by: Abel Vesa <abelvesa@linux.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-08-14Merge tag 'pm-4.19-rc1' of ↵Linus Torvalds1-0/+6
git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm Pull power management updates from Rafael Wysocki: "These add a new framework for CPU idle time injection, to be used by all of the idle injection code in the kernel in the future, fix some issues and add a number of relatively small extensions in multiple places. Specifics: - Add a new framework for CPU idle time injection (Daniel Lezcano). - Add AVS support to the armada-37xx cpufreq driver (Gregory CLEMENT). - Add support for current CPU frequency reporting to the ACPI CPPC cpufreq driver (George Cherian). - Rework the cooling device registration in the imx6q/thermal driver (Bastian Stender). - Make the pcc-cpufreq driver refuse to work with dynamic scaling governors on systems with many CPUs to avoid scalability issues with it (Rafael Wysocki). - Fix the intel_pstate driver to report different maximum CPU frequencies on systems where they really are different and to ignore the turbo active ratio if hardware-managend P-states (HWP) are in use; make it use the match_string() helper (Xie Yisheng, Srinivas Pandruvada). - Fix a minor deferred probe issue in the qcom-kryo cpufreq driver (Niklas Cassel). - Add a tracepoint for the tracking of frequency limits changes (from Andriod) to the cpufreq core (Ruchi Kandoi). - Fix a circular lock dependency between CPU hotplug and sysfs locking in the cpufreq core reported by lockdep (Waiman Long). - Avoid excessive error reports on driver registration failures in the ARM cpuidle driver (Sudeep Holla). - Add a new device links flag to the driver core to make links go away automatically on supplier driver removal (Vivek Gautam). - Eliminate potential race condition between system-wide power management transitions and system shutdown (Pingfan Liu). - Add a quirk to save NVS memory on system suspend for the ASUS 1025C laptop (Willy Tarreau). - Make more systems use suspend-to-idle (instead of ACPI S3) by default (Tristian Celestin). - Get rid of stack VLA usage in the low-level hibernation code on 64-bit x86 (Kees Cook). - Fix error handling in the hibernation core and mark an expected fall-through switch in it (Chengguang Xu, Gustavo Silva). - Extend the generic power domains (genpd) framework to support attaching a device to a power domain by name (Ulf Hansson). - Fix device reference counting and user limits initialization in the devfreq core (Arvind Yadav, Matthias Kaehlcke). - Fix a few issues in the rk3399_dmc devfreq driver and improve its documentation (Enric Balletbo i Serra, Lin Huang, Nick Milner). - Drop a redundant error message from the exynos-ppmu devfreq driver (Markus Elfring)" * tag 'pm-4.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm: (35 commits) PM / reboot: Eliminate race between reboot and suspend PM / hibernate: Mark expected switch fall-through cpufreq: intel_pstate: Ignore turbo active ratio in HWP cpufreq: Fix a circular lock dependency problem cpu/hotplug: Add a cpus_read_trylock() function x86/power/hibernate_64: Remove VLA usage cpufreq: trace frequency limits change cpufreq: intel_pstate: Show different max frequency with turbo 3 and HWP cpufreq: pcc-cpufreq: Disable dynamic scaling on many-CPU systems cpufreq: qcom-kryo: Silently error out on EPROBE_DEFER cpufreq / CPPC: Add cpuinfo_cur_freq support for CPPC cpufreq: armada-37xx: Add AVS support dt-bindings: marvell: Add documentation for the Armada 3700 AVS binding PM / devfreq: rk3399_dmc: Fix duplicated opp table on reload. PM / devfreq: Init user limits from OPP limits, not viceversa PM / devfreq: rk3399_dmc: fix spelling mistakes. PM / devfreq: rk3399_dmc: do not print error when get supply and clk defer. dt-bindings: devfreq: rk3399_dmc: move interrupts to be optional. PM / devfreq: rk3399_dmc: remove wait for dcf irq event. dt-bindings: clock: add rk3399 DDR3 standard speed bins. ...
2018-08-14Merge branch 'l1tf-final' of ↵Linus Torvalds1-12/+268
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Merge L1 Terminal Fault fixes from Thomas Gleixner: "L1TF, aka L1 Terminal Fault, is yet another speculative hardware engineering trainwreck. It's a hardware vulnerability which allows unprivileged speculative access to data which is available in the Level 1 Data Cache when the page table entry controlling the virtual address, which is used for the access, has the Present bit cleared or other reserved bits set. If an instruction accesses a virtual address for which the relevant page table entry (PTE) has the Present bit cleared or other reserved bits set, then speculative execution ignores the invalid PTE and loads the referenced data if it is present in the Level 1 Data Cache, as if the page referenced by the address bits in the PTE was still present and accessible. While this is a purely speculative mechanism and the instruction will raise a page fault when it is retired eventually, the pure act of loading the data and making it available to other speculative instructions opens up the opportunity for side channel attacks to unprivileged malicious code, similar to the Meltdown attack. While Meltdown breaks the user space to kernel space protection, L1TF allows to attack any physical memory address in the system and the attack works across all protection domains. It allows an attack of SGX and also works from inside virtual machines because the speculation bypasses the extended page table (EPT) protection mechanism. The assoicated CVEs are: CVE-2018-3615, CVE-2018-3620, CVE-2018-3646 The mitigations provided by this pull request include: - Host side protection by inverting the upper address bits of a non present page table entry so the entry points to uncacheable memory. - Hypervisor protection by flushing L1 Data Cache on VMENTER. - SMT (HyperThreading) control knobs, which allow to 'turn off' SMT by offlining the sibling CPU threads. The knobs are available on the kernel command line and at runtime via sysfs - Control knobs for the hypervisor mitigation, related to L1D flush and SMT control. The knobs are available on the kernel command line and at runtime via sysfs - Extensive documentation about L1TF including various degrees of mitigations. Thanks to all people who have contributed to this in various ways - patches, review, testing, backporting - and the fruitful, sometimes heated, but at the end constructive discussions. There is work in progress to provide other forms of mitigations, which might be less horrible performance wise for a particular kind of workloads, but this is not yet ready for consumption due to their complexity and limitations" * 'l1tf-final' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (75 commits) x86/microcode: Allow late microcode loading with SMT disabled tools headers: Synchronise x86 cpufeatures.h for L1TF additions x86/mm/kmmio: Make the tracer robust against L1TF x86/mm/pat: Make set_memory_np() L1TF safe x86/speculation/l1tf: Make pmd/pud_mknotpresent() invert x86/speculation/l1tf: Invert all not present mappings cpu/hotplug: Fix SMT supported evaluation KVM: VMX: Tell the nested hypervisor to skip L1D flush on vmentry x86/speculation: Use ARCH_CAPABILITIES to skip L1D flush on vmentry x86/speculation: Simplify sysfs report of VMX L1TF vulnerability Documentation/l1tf: Remove Yonah processors from not vulnerable list x86/KVM/VMX: Don't set l1tf_flush_l1d from vmx_handle_external_intr() x86/irq: Let interrupt handlers set kvm_cpu_l1tf_flush_l1d x86: Don't include linux/irq.h from asm/hardirq.h x86/KVM/VMX: Introduce per-host-cpu analogue of l1tf_flush_l1d x86/irq: Demote irq_cpustat_t::__softirq_pending to u16 x86/KVM/VMX: Move the l1tf_flush_l1d test to vmx_l1d_flush() x86/KVM/VMX: Replace 'vmx_l1d_flush_always' with 'vmx_l1d_flush_cond' x86/KVM/VMX: Don't set l1tf_flush_l1d to true from vmx_l1d_flush() cpu/hotplug: detect SMT disabled by BIOS ...
2018-08-13Merge branch 'smp-hotplug-for-linus' of ↵Linus Torvalds1-1/+1
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull CPU hotplug update from Thomas Gleixner: "A trivial name fix for the hotplug state machine" * 'smp-hotplug-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: cpu/hotplug: Clarify CPU hotplug step name for timers
2018-08-13Merge branch 'sched-core-for-linus' of ↵Linus Torvalds1-0/+5
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull scheduler updates from Thomas Gleixner: - Cleanup and improvement of NUMA balancing - Refactoring and improvements to the PELT (Per Entity Load Tracking) code - Watchdog simplification and related cleanups - The usual pile of small incremental fixes and improvements * 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (41 commits) watchdog: Reduce message verbosity stop_machine: Reflow cpu_stop_queue_two_works() sched/numa: Move task_numa_placement() closer to numa_migrate_preferred() sched/numa: Use group_weights to identify if migration degrades locality sched/numa: Update the scan period without holding the numa_group lock sched/numa: Remove numa_has_capacity() sched/numa: Modify migrate_swap() to accept additional parameters sched/numa: Remove unused task_capacity from 'struct numa_stats' sched/numa: Skip nodes that are at 'hoplimit' sched/debug: Reverse the order of printing faults sched/numa: Use task faults only if numa_group is not yet set up sched/numa: Set preferred_node based on best_cpu sched/numa: Simplify load_too_imbalanced() sched/numa: Evaluate move once per node sched/numa: Remove redundant field sched/debug: Show the sum wait time of a task group sched/fair: Remove #ifdefs from scale_rt_capacity() sched/core: Remove get_cpu() from sched_fork() sched/cpufreq: Clarify sugov_get_util() sched/sysctl: Remove unused sched_time_avg_ms sysctl ...
2018-08-12init: rename and re-order boot_cpu_state_init()Linus Torvalds1-1/+1
This is purely a preparatory patch for upcoming changes during the 4.19 merge window. We have a function called "boot_cpu_state_init()" that isn't really about the bootup cpu state: that is done much earlier by the similarly named "boot_cpu_init()" (note lack of "state" in name). This function initializes some hotplug CPU state, and needs to run after the percpu data has been properly initialized. It even has a comment to that effect. Except it _doesn't_ actually run after the percpu data has been properly initialized. On x86 it happens to do that, but on at least arm and arm64, the percpu base pointers are initialized by the arch-specific 'smp_prepare_boot_cpu()' hook, which ran _after_ boot_cpu_state_init(). This had some unexpected results, and in particular we have a patch pending for the merge window that did the obvious cleanup of using 'this_cpu_write()' in the cpu hotplug init code: - per_cpu_ptr(&cpuhp_state, smp_processor_id())->state = CPUHP_ONLINE; + this_cpu_write(cpuhp_state.state, CPUHP_ONLINE); which is obviously the right thing to do. Except because of the ordering issue, it actually failed miserably and unexpectedly on arm64. So this just fixes the ordering, and changes the name of the function to be 'boot_cpu_hotplug_init()' to make it obvious that it's about cpu hotplug state, because the core CPU state was supposed to have already been done earlier. Marked for stable, since the (not yet merged) patch that will show this problem is marked for stable. Reported-by: Vlastimil Babka <vbabka@suse.cz> Reported-by: Mian Yousaf Kaukab <yousaf.kaukab@suse.com> Suggested-by: Catalin Marinas <catalin.marinas@arm.com> Acked-by: Thomas Gleixner <tglx@linutronix.de> Cc: Will Deacon <will.deacon@arm.com> Cc: stable@kernel.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-08-07cpu/hotplug: Fix SMT supported evaluationThomas Gleixner1-13/+28
Josh reported that the late SMT evaluation in cpu_smt_state_init() sets cpu_smt_control to CPU_SMT_NOT_SUPPORTED in case that 'nosmt' was supplied on the kernel command line as it cannot differentiate between SMT disabled by BIOS and SMT soft disable via 'nosmt'. That wreckages the state and makes the sysfs interface unusable. Rework this so that during bringup of the non boot CPUs the availability of SMT is determined in cpu_smt_allowed(). If a newly booted CPU is not a 'primary' thread then set the local cpu_smt_available marker and evaluate this explicitely right after the initial SMP bringup has finished. SMT evaulation on x86 is a trainwreck as the firmware has all the information _before_ booting the kernel, but there is no interface to query it. Fixes: 73d5e2b47264 ("cpu/hotplug: detect SMT disabled by BIOS") Reported-by: Josh Poimboeuf <jpoimboe@redhat.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2018-07-30cpu/hotplug: Clarify CPU hotplug step name for timersMukesh Ojha1-1/+1
After commit 249d4a9b3246 ("timers: Reinitialize per cpu bases on hotplug") i.e. the introduction of state CPUHP_TIMERS_PREPARE instead of CPUHP_TIMERS_DEAD the step name "timers:dead" is not longer accurate. Rename it to "timers:prepare". [ tglx: Massaged changelog ] Signed-off-by: Mukesh Ojha <mojha@codeaurora.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: gkohli@codeaurora.org Cc: neeraju@codeaurora.org Cc: Peter Zijlstra <peterz@infradead.org> Cc: Lai Jiangshan <jiangshanlai@gmail.com> Cc: Brendan Jackman <brendan.jackman@arm.com> Cc: Mathieu Malaterre <malat@debian.org> Link: https://lkml.kernel.org/r/1532443668-26810-1-git-send-email-mojha@codeaurora.org
2018-07-26cpu/hotplug: Add a cpus_read_trylock() functionWaiman Long1-0/+6
There are use cases where it can be useful to have a cpus_read_trylock() function to work around circular lock dependency problem involving the cpu_hotplug_lock. Signed-off-by: Waiman Long <longman@redhat.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2018-07-24cpu/hotplug: detect SMT disabled by BIOSJosh Poimboeuf1-0/+9
If SMT is disabled in BIOS, the CPU code doesn't properly detect it. The /sys/devices/system/cpu/smt/control file shows 'on', and the 'l1tf' vulnerabilities file shows SMT as vulnerable. Fix it by forcing 'cpu_smt_control' to CPU_SMT_NOT_SUPPORTED in such a case. Unfortunately the detection can only be done after bringing all the CPUs online, so we have to overwrite any previous writes to the variable. Reported-by: Joe Mario <jmario@redhat.com> Tested-by: Jiri Kosina <jkosina@suse.cz> Fixes: f048c399e0f7 ("x86/topology: Provide topology_smt_supported()") Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Signed-off-by: Peter Zijlstra <peterz@infradead.org>
2018-07-13cpu/hotplug: Set CPU_SMT_NOT_SUPPORTED earlyThomas Gleixner1-3/+10
The CPU_SMT_NOT_SUPPORTED state is set (if the processor does not support SMT) when the sysfs SMT control file is initialized. That was fine so far as this was only required to make the output of the control file correct and to prevent writes in that case. With the upcoming l1tf command line parameter, this needs to be set up before the L1TF mitigation selection and command line parsing happens. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Tested-by: Jiri Kosina <jkosina@suse.cz> Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Reviewed-by: Josh Poimboeuf <jpoimboe@redhat.com> Link: https://lkml.kernel.org/r/20180713142323.121795971@linutronix.de
2018-07-13cpu/hotplug: Expose SMT control init functionJiri Kosina1-3/+13
The L1TF mitigation will gain a commend line parameter which allows to set a combination of hypervisor mitigation and SMT control. Expose cpu_smt_disable() so the command line parser can tweak SMT settings. [ tglx: Split out of larger patch and made it preserve an already existing force off state ] Signed-off-by: Jiri Kosina <jkosina@suse.cz> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Tested-by: Jiri Kosina <jkosina@suse.cz> Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Reviewed-by: Josh Poimboeuf <jpoimboe@redhat.com> Link: https://lkml.kernel.org/r/20180713142323.039715135@linutronix.de
2018-07-09cpu/hotplug: Online siblings when SMT control is turned onThomas Gleixner1-2/+24
Writing 'off' to /sys/devices/system/cpu/smt/control offlines all SMT siblings. Writing 'on' merily enables the abilify to online them, but does not online them automatically. Make 'on' more useful by onlining all offline siblings. Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2018-07-04x86/KVM: Warn user if KVM is loaded SMT and L1TF CPU bug being presentKonrad Rzeszutek Wilk1-0/+1
If the L1TF CPU bug is present we allow the KVM module to be loaded as the major of users that use Linux and KVM have trusted guests and do not want a broken setup. Cloud vendors are the ones that are uncomfortable with CVE 2018-3620 and as such they are the ones that should set nosmt to one. Setting 'nosmt' means that the system administrator also needs to disable SMT (Hyper-threading) in the BIOS, or via the 'nosmt' command line parameter, or via the /sys/devices/system/cpu/smt/control. See commit 05736e4ac13c ("cpu/hotplug: Provide knobs to control SMT"). Other mitigations are to use task affinity, cpu sets, interrupt binding, etc - anything to make sure that _only_ the same guests vCPUs are running on sibling threads. Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2018-07-03watchdog/softlockup: Replace "watchdog/%u" threads with cpu_stop_workPeter Zijlstra1-0/+5
Oleg suggested to replace the "watchdog/%u" threads with cpu_stop_work. That removes one thread per CPU while at the same time fixes softlockup vs SCHED_DEADLINE. But more importantly, it does away with the single smpboot_update_cpumask_percpu_thread() user, which allows cleanups/shrinkage of the smpboot interface. Suggested-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-07-02cpu/hotplug: Boot HT siblings at least onceThomas Gleixner1-24/+48
Due to the way Machine Check Exceptions work on X86 hyperthreads it's required to boot up _all_ logical cores at least once in order to set the CR4.MCE bit. So instead of ignoring the sibling threads right away, let them boot up once so they can configure themselves. After they came out of the initial boot stage check whether its a "secondary" sibling and cancel the operation which puts the CPU back into offline state. Reported-by: Dave Hansen <dave.hansen@intel.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Tested-by: Tony Luck <tony.luck@intel.com>
2018-06-21cpu/hotplug: Provide knobs to control SMTThomas Gleixner1-0/+170
Provide a command line and a sysfs knob to control SMT. The command line options are: 'nosmt': Enumerate secondary threads, but do not online them 'nosmt=force': Ignore secondary threads completely during enumeration via MP table and ACPI/MADT. The sysfs control file has the following states (read/write): 'on': SMT is enabled. Secondary threads can be freely onlined 'off': SMT is disabled. Secondary threads, even if enumerated cannot be onlined 'forceoff': SMT is permanentely disabled. Writes to the control file are rejected. 'notsupported': SMT is not supported by the CPU The command line option 'nosmt' sets the sysfs control to 'off'. This can be changed to 'on' to reenable SMT during runtime. The command line option 'nosmt=force' sets the sysfs control to 'forceoff'. This cannot be changed during runtime. When SMT is 'on' and the control file is changed to 'off' then all online secondary threads are offlined and attempts to online a secondary thread later on are rejected. When SMT is 'off' and the control file is changed to 'on' then secondary threads can be onlined again. The 'off' -> 'on' transition does not automatically online the secondary threads. When the control file is set to 'forceoff', the behaviour is the same as setting it to 'off', but the operation is irreversible and later writes to the control file are rejected. When the control status is 'notsupported' then writes to the control file are rejected. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Acked-by: Ingo Molnar <mingo@kernel.org>
2018-06-21cpu/hotplug: Split do_cpu_down()Thomas Gleixner1-9/+8
Split out the inner workings of do_cpu_down() to allow reuse of that function for the upcoming SMT disabling mechanism. No functional change. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Acked-by: Ingo Molnar <mingo@kernel.org>
2018-06-21cpu/hotplug: Make bringup/teardown of smp threads symmetricThomas Gleixner1-2/+1
The asymmetry caused a warning to trigger if the bootup was stopped in state CPUHP_AP_ONLINE_IDLE. The warning no longer triggers as kthread_park() can now be invoked on already or still parked threads. But there is still no reason to have this be asymmetric. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Acked-by: Ingo Molnar <mingo@kernel.org>
2018-03-15cpu/hotplug: Fix unused function warningArnd Bergmann1-9/+9
The cpuhp_is_ap_state() function is no longer called outside of the CONFIG_SMP #ifdef section, causing a harmless warning: kernel/cpu.c:129:13: error: 'cpuhp_is_ap_state' defined but not used [-Werror=unused-function] This moves the function into the #ifdef to get a clean build again. Fixes: 17a2f1ced028 ("cpu/hotplug: Merge cpuhp_bp_states and cpuhp_ap_states") Signed-off-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Cc: Lai Jiangshan <jiangshanlai@gmail.com> Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> Link: https://lkml.kernel.org/r/20180315153829.3819606-1-arnd@arndb.de
2018-03-14cpu/hotplug: Merge cpuhp_bp_states and cpuhp_ap_statesLai Jiangshan1-27/+15
cpuhp_bp_states and cpuhp_ap_states have different set of steps without any conflicting steps, so that they can be merged. The original `[CPUHP_BRINGUP_CPU] = { },` is removed, because the new cpuhp_hp_states has CPUHP_ONLINE index which is larger than CPUHP_BRINGUP_CPU. Signed-off-by: Lai Jiangshan <jiangshanlai@gmail.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> Link: https://lkml.kernel.org/r/20171201135008.21633-1-jiangshanlai@gmail.com
2017-12-31Merge branch 'timers-urgent-for-linus' of ↵Linus Torvalds1-2/+2
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull timer fixes from Thomas Gleixner: "A pile of fixes for long standing issues with the timer wheel and the NOHZ code: - Prevent timer base confusion accross the nohz switch, which can cause unlocked access and data corruption - Reinitialize the stale base clock on cpu hotplug to prevent subtle side effects including rollovers on 32bit - Prevent an interrupt storm when the timer softirq is already pending caused by tick_nohz_stop_sched_tick() - Move the timer start tracepoint to a place where it actually makes sense - Add documentation to timerqueue functions as they caused confusion several times now" * 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: timerqueue: Document return values of timerqueue_add/del() timers: Invoke timer_start_debug() where it makes sense nohz: Prevent a timer interrupt storm in tick_nohz_stop_sched_tick() timers: Reinitialize per cpu bases on hotplug timers: Use deferrable base independent of base::nohz_active
2017-12-29timers: Reinitialize per cpu bases on hotplugThomas Gleixner1-2/+2
The timer wheel bases are not (re)initialized on CPU hotplug. That leaves them with a potentially stale clk and next_expiry valuem, which can cause trouble then the CPU is plugged. Add a prepare callback which forwards the clock, sets next_expiry to far in the future and reset the control flags to a known state. Set base->must_forward_clk so the first timer which is queued will try to forward the clock to current jiffies. Fixes: 500462a9de65 ("timers: Switch to a non-cascading wheel") Reported-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Sebastian Siewior <bigeasy@linutronix.de> Cc: Anna-Maria Gleixner <anna-maria@linutronix.de> Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/alpine.DEB.2.20.1712272152200.2431@nanos
2017-12-27cpu/hotplug: Move inline keyword at the beginning of declarationMathieu Malaterre1-4/+4
Fix non-fatal warnings such as: kernel/cpu.c:95:1: warning: ‘inline’ is not at beginning of declaration [-Wold-style-declaration] static void inline cpuhp_lock_release(bool bringup) { } ^~~~~~ Signed-off-by: Mathieu Malaterre <malat@debian.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> Link: https://lkml.kernel.org/r/20171226140855.16583-1-malat@debian.org
2017-12-06Merge branch 'smp-urgent-for-linus' of ↵Linus Torvalds1-5/+5
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull CPU hotplug fix from Ingo Molnar: "A single fix moving the smp-call queue flush step to the intended point in the state machine" * 'smp-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: smp/hotplug: Move step CPUHP_AP_SMPCFD_DYING to the correct place
2017-12-06cpu/hotplug: Fix state name in takedown_cpu() commentBrendan Jackman1-2/+2
CPUHP_AP_SCHED_MIGRATE_DYING doesn't exist, it looks like this was supposed to refer to CPUHP_AP_SCHED_STARTING's teardown callback, i.e. sched_cpu_dying(). Signed-off-by: Brendan Jackman <brendan.jackman@arm.com> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: Dietmar Eggemann <dietmar.eggemann@arm.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Quentin Perret <quentin.perret@arm.com> Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/20171206105911.28093-1-brendan.jackman@arm.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-11-28smp/hotplug: Move step CPUHP_AP_SMPCFD_DYING to the correct placeLai Jiangshan1-5/+5
Commit 31487f8328f2 ("smp/cfd: Convert core to hotplug state machine") accidently put this step on the wrong place. The step should be at the cpuhp_ap_states[] rather than the cpuhp_bp_states[]. grep smpcfd /sys/devices/system/cpu/hotplug/states 40: smpcfd:prepare 129: smpcfd:dying "smpcfd:dying" was missing before. So was the invocation of the function smpcfd_dying_cpu(). Fixes: 31487f8328f2 ("smp/cfd: Convert core to hotplug state machine") Signed-off-by: Lai Jiangshan <jiangshanlai@gmail.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Richard Weinberger <richard@nod.at> Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Cc: stable@vger.kernel.org Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> Link: https://lkml.kernel.org/r/20171128131954.81229-1-jiangshanlai@gmail.com
2017-10-21cpu/hotplug: Reset node state after operationThomas Gleixner1-0/+5
The recent rework of the cpu hotplug internals changed the usage of the per cpu state->node field, but missed to clean it up after usage. So subsequent hotplug operations use the stale pointer from a previous operation and hand it into the callback functions. The callbacks then dereference a pointer which either belongs to a different facility or points to freed and potentially reused memory. In either case data corruption and crashes are the obvious consequence. Reset the node and the last pointers in the per cpu state to NULL after the operation which set them has completed. Fixes: 96abb968549c ("smp/hotplug: Allow external multi-instance rollback") Reported-by: Tvrtko Ursulin <tursulin@ursulin.net> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> Link: https://lkml.kernel.org/r/alpine.DEB.2.20.1710211606130.3213@nanos
2017-10-06Merge branch 'core-watchdog-for-linus' of ↵Linus Torvalds1-0/+6
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull watchddog clean-up and fixes from Thomas Gleixner: "The watchdog (hard/softlockup detector) code is pretty much broken in its current state. The patch series addresses this by removing all duct tape and refactoring it into a workable state. The reasons why I ask for inclusion that late in the cycle are: 1) The code causes lockdep splats vs. hotplug locking which get reported over and over. Unfortunately there is no easy fix. 2) The risk of breakage is minimal because it's already broken 3) As 4.14 is a long term stable kernel, I prefer to have working watchdog code in that and the lockdep issues resolved. I wouldn't ask you to pull if 4.14 wouldn't be a LTS kernel or if the solution would be easy to backport. 4) The series was around before the merge window opened, but then got delayed due to the UP failure caused by the for_each_cpu() surprise which we discussed recently. Changes vs. V1: - Addressed your review points - Addressed the warning in the powerpc code which was discovered late - Changed two function names which made sense up to a certain point in the series. Now they match what they do in the end. - Fixed a 'unused variable' warning, which got not detected by the intel robot. I triggered it when trying all possible related config combinations manually. Randconfig testing seems not random enough. The changes have been tested by and reviewed by Don Zickus and tested and acked by Micheal Ellerman for powerpc" * 'core-watchdog-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (36 commits) watchdog/core: Put softlockup_threads_initialized under ifdef guard watchdog/core: Rename some softlockup_* functions powerpc/watchdog: Make use of watchdog_nmi_probe() watchdog/core, powerpc: Lock cpus across reconfiguration watchdog/core, powerpc: Replace watchdog_nmi_reconfigure() watchdog/hardlockup/perf: Fix spelling mistake: "permanetely" -> "permanently" watchdog/hardlockup/perf: Cure UP damage watchdog/hardlockup: Clean up hotplug locking mess watchdog/hardlockup/perf: Simplify deferred event destroy watchdog/hardlockup/perf: Use new perf CPU enable mechanism watchdog/hardlockup/perf: Implement CPU enable replacement watchdog/hardlockup/perf: Implement init time detection of perf watchdog/hardlockup/perf: Implement init time perf validation watchdog/core: Get rid of the racy update loop watchdog/core, powerpc: Make watchdog_nmi_reconfigure() two stage watchdog/sysctl: Clean up sysctl variable name space watchdog/sysctl: Get rid of the #ifdeffery watchdog/core: Clean up header mess watchdog/core: Further simplify sysctl handling watchdog/core: Get rid of the thread teardown/setup dance ...
2017-09-25smp/hotplug: Hotplug state fail injectionPeter Zijlstra1-1/+59
Add a sysfs file to one-time fail a specific state. This can be used to test the state rollback code paths. Something like this (hotplug-up.sh): #!/bin/bash echo 0 > /debug/sched_debug echo 1 > /debug/tracing/events/cpuhp/enable ALL_STATES=`cat /sys/devices/system/cpu/hotplug/states | cut -d':' -f1` STATES=${1:-$ALL_STATES} for state in $STATES do echo 0 > /sys/devices/system/cpu/cpu1/online echo 0 > /debug/tracing/trace echo Fail state: $state echo $state > /sys/devices/system/cpu/cpu1/hotplug/fail cat /sys/devices/system/cpu/cpu1/hotplug/fail echo 1 > /sys/devices/system/cpu/cpu1/online cat /debug/tracing/trace > hotfail-${state}.trace sleep 1 done Can be used to test for all possible rollback (barring multi-instance) scenarios on CPU-up, CPU-down is a trivial modification of the above. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: bigeasy@linutronix.de Cc: efault@gmx.de Cc: rostedt@goodmis.org Cc: max.byungchul.park@gmail.com Link: https://lkml.kernel.org/r/20170920170546.972581715@infradead.org
2017-09-25smp/hotplug: Differentiate the AP completion between up and downPeter Zijlstra1-17/+32
With lockdep-crossrelease we get deadlock reports that span cpu-up and cpu-down chains. Such deadlocks cannot possibly happen because cpu-up and cpu-down are globally serialized. takedown_cpu() irq_lock_sparse() wait_for_completion(&st->done) cpuhp_thread_fun cpuhp_up_callback cpuhp_invoke_callback irq_affinity_online_cpu irq_local_spare() irq_unlock_sparse() complete(&st->done) Now that we have consistent AP state, we can trivially separate the AP completion between up and down using st->bringup. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: max.byungchul.park@gmail.com Cc: bigeasy@linutronix.de Cc: efault@gmx.de Cc: rostedt@goodmis.org Link: https://lkml.kernel.org/r/20170920170546.872472799@infradead.org
2017-09-25smp/hotplug: Differentiate the AP-work lockdep class between up and downPeter Zijlstra1-9/+32
With lockdep-crossrelease we get deadlock reports that span cpu-up and cpu-down chains. Such deadlocks cannot possibly happen because cpu-up and cpu-down are globally serialized. CPU0 CPU1 CPU2 cpuhp_up_callbacks: takedown_cpu: cpuhp_thread_fun: cpuhp_state irq_lock_sparse() irq_lock_sparse() wait_for_completion() cpuhp_state complete() Now that we have consistent AP state, we can trivially separate the AP-work class between up and down using st->bringup. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: max.byungchul.park@gmail.com Cc: bigeasy@linutronix.de Cc: efault@gmx.de Cc: rostedt@goodmis.org Link: https://lkml.kernel.org/r/20170920170546.922524234@infradead.org
2017-09-25smp/hotplug: Callback vs state-machine consistencyPeter Zijlstra1-4/+22
While the generic callback functions have an 'int' return and thus appear to be allowed to return error, this is not true for all states. Specifically, what used to be STARTING/DYING are ran with IRQs disabled from critical parts of CPU bringup/teardown and are not allowed to fail. Add WARNs to enforce this rule. But since some callbacks are indeed allowed to fail, we have the situation where a state-machine rollback encounters a failure, in this case we're stuck, we can't go forward and we can't go back. Also add a WARN for that case. AFAICT this is a fundamental 'problem' with no real obvious solution. We want the 'prepare' callbacks to allow failure on either up or down. Typically on prepare-up this would be things like -ENOMEM from resource allocations, and the typical usage in prepare-down would be something like -EBUSY to avoid CPUs being taken away. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: bigeasy@linutronix.de Cc: efault@gmx.de Cc: rostedt@goodmis.org Cc: max.byungchul.park@gmail.com Link: https://lkml.kernel.org/r/20170920170546.819539119@infradead.org
2017-09-25smp/hotplug: Rewrite AP state machine corePeter Zijlstra1-115/+206
There is currently no explicit state change on rollback. That is, st->bringup, st->rollback and st->target are not consistent when doing the rollback. Rework the AP state handling to be more coherent. This does mean we have to do a second AP kick-and-wait for rollback, but since rollback is the slow path of a slowpath, this really should not matter. Take this opportunity to simplify the AP thread function to only run a single callback per invocation. This unifies the three single/up/down modes is supports. The looping it used to do for up/down are achieved by retaining should_run and relying on the main smpboot_thread_fn() loop. (I have most of a patch that does the same for the BP state handling, but that's not critical and gets a little complicated because CPUHP_BRINGUP_CPU does the AP handoff from a callback, which gets recursive @st usage, I still have de-fugly that.) [ tglx: Move cpuhp_down_callbacks() et al. into the HOTPLUG_CPU section to avoid gcc complaining about unused functions. Make the HOTPLUG_CPU one piece instead of having two consecutive ifdef sections of the same type. ] Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: bigeasy@linutronix.de Cc: efault@gmx.de Cc: rostedt@goodmis.org Cc: max.byungchul.park@gmail.com Link: https://lkml.kernel.org/r/20170920170546.769658088@infradead.org
2017-09-25smp/hotplug: Allow external multi-instance rollbackPeter Zijlstra1-15/+32
Currently the rollback of multi-instance states is handled inside cpuhp_invoke_callback(). The problem is that when we want to allow an explicit state change for rollback, we need to return from the function without doing the rollback. Change cpuhp_invoke_callback() to optionally return the multi-instance state, such that rollback can be done from a subsequent call. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: bigeasy@linutronix.de Cc: efault@gmx.de Cc: rostedt@goodmis.org Cc: max.byungchul.park@gmail.com Link: https://lkml.kernel.org/r/20170920170546.720361181@infradead.org
2017-09-14watchdog/hardlockup/perf: Prevent CPU hotplug deadlockThomas Gleixner1-0/+6
The following deadlock is possible in the watchdog hotplug code: cpus_write_lock() ... takedown_cpu() smpboot_park_threads() smpboot_park_thread() kthread_park() ->park() := watchdog_disable() watchdog_nmi_disable() perf_event_release_kernel(); put_event() _free_event() ->destroy() := hw_perf_event_destroy() x86_release_hardware() release_ds_buffers() get_online_cpus() when a per cpu watchdog perf event is destroyed which drops the last reference to the PMU hardware. The cleanup code there invokes get_online_cpus() which instantly deadlocks because the hotplug percpu rwsem is write locked. To solve this add a deferring mechanism: cpus_write_lock() kthread_park() watchdog_nmi_disable(deferred) perf_event_disable(event); move_event_to_deferred(event); .... cpus_write_unlock() cleaup_deferred_events() perf_event_release_kernel() This is still properly serialized against concurrent hotplug via the cpu_add_remove_lock, which is held by the task which initiated the hotplug event. This is also used to handle event destruction when the watchdog threads are parked via other mechanisms than CPU hotplug. Analyzed-by: Peter Zijlstra <peterz@infradead.org> Reported-by: Borislav Petkov <bp@alien8.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Don Zickus <dzickus@redhat.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Chris Metcalf <cmetcalf@mellanox.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Sebastian Siewior <bigeasy@linutronix.de> Cc: Ulrich Obergfell <uobergfe@redhat.com> Link: http://lkml.kernel.org/r/20170912194146.884469246@linutronix.de Signed-off-by: Ingo Molnar <mingo@kernel.org>
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-16 16:45:59 +0000