Implement the start, stop and disable operations of the HPET-based NMI watchdog. Given that a single timer is used to monitor all the CPUs in the system, it is necessary to define a cpumask that keeps track of the CPUs that can be monitored. This cpumask is protected with a spin lock.
As individual CPUs are put online and offline, this cpumask is updated. CPUs are unconditionally cleared from the mask when going offline. When going online, the CPU is set in the mask only if is one of the CPUs allowed to be monitored by the watchdog. It is not necessary to implement a start function. The NMI watchdog will be enabled when there is at least one CPU to monitor. The disable function clears the CPU mask and disables the timer. Cc: Ashok Raj <[email protected]> Cc: Andi Kleen <[email protected]> Cc: Tony Luck <[email protected]> Cc: Borislav Petkov <[email protected]> Cc: Jacob Pan <[email protected]> Cc: "Rafael J. Wysocki" <[email protected]> Cc: Don Zickus <[email protected]> Cc: Nicholas Piggin <[email protected]> Cc: Michael Ellerman <[email protected]> Cc: Frederic Weisbecker <[email protected]> Cc: Alexei Starovoitov <[email protected]> Cc: Babu Moger <[email protected]> Cc: Mathieu Desnoyers <[email protected]> Cc: Masami Hiramatsu <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Andrew Morton <[email protected]> Cc: Philippe Ombredanne <[email protected]> Cc: Colin Ian King <[email protected]> Cc: Byungchul Park <[email protected]> Cc: "Paul E. McKenney" <[email protected]> Cc: "Luis R. Rodriguez" <[email protected]> Cc: Waiman Long <[email protected]> Cc: Josh Poimboeuf <[email protected]> Cc: Randy Dunlap <[email protected]> Cc: Davidlohr Bueso <[email protected]> Cc: Christoffer Dall <[email protected]> Cc: Marc Zyngier <[email protected]> Cc: Kai-Heng Feng <[email protected]> Cc: Konrad Rzeszutek Wilk <[email protected]> Cc: David Rientjes <[email protected]> Cc: "Ravi V. Shankar" <[email protected]> Cc: [email protected] Cc: [email protected] Signed-off-by: Ricardo Neri <[email protected]> --- arch/x86/include/asm/hpet.h | 2 + include/linux/nmi.h | 1 + kernel/watchdog_hld_hpet.c | 98 +++++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 101 insertions(+) diff --git a/arch/x86/include/asm/hpet.h b/arch/x86/include/asm/hpet.h index 33309b7..6ace2d1 100644 --- a/arch/x86/include/asm/hpet.h +++ b/arch/x86/include/asm/hpet.h @@ -124,6 +124,8 @@ struct hpet_hld_data { u32 irq; u32 flags; u64 ticks_per_second; + struct cpumask monitored_mask; + spinlock_t lock; /* serialized access to monitored_mask */ }; extern struct hpet_hld_data *hpet_hardlockup_detector_assign_timer(void); diff --git a/include/linux/nmi.h b/include/linux/nmi.h index e608762..23e20d2 100644 --- a/include/linux/nmi.h +++ b/include/linux/nmi.h @@ -129,6 +129,7 @@ struct nmi_watchdog_ops { }; extern struct nmi_watchdog_ops hardlockup_detector_perf_ops; +extern struct nmi_watchdog_ops hardlockup_detector_hpet_ops; void watchdog_nmi_stop(void); void watchdog_nmi_start(void); diff --git a/kernel/watchdog_hld_hpet.c b/kernel/watchdog_hld_hpet.c index 3bedffa..857e051 100644 --- a/kernel/watchdog_hld_hpet.c +++ b/kernel/watchdog_hld_hpet.c @@ -345,6 +345,91 @@ static int setup_hpet_irq(struct hpet_hld_data *hdata) } /** + * hardlockup_detector_hpet_enable() - Enable the hardlockup detector + * + * The hardlockup detector is enabled for the CPU that executes the + * function. It is only enabled if such CPU is allowed to be monitored + * by the lockup detector. + * + * Returns: + * + * None + * + */ +static void hardlockup_detector_hpet_enable(void) +{ + struct cpumask *allowed = watchdog_get_allowed_cpumask(); + unsigned int cpu = smp_processor_id(); + + if (!hld_data) + return; + + if (!cpumask_test_cpu(cpu, allowed)) + return; + + spin_lock(&hld_data->lock); + + cpumask_set_cpu(cpu, &hld_data->monitored_mask); + + /* + * If this is the first CPU to be monitored, set everything in motion: + * move the interrupt to this CPU, kick and enable the timer. + */ + if (cpumask_weight(&hld_data->monitored_mask) == 1) { + if (irq_set_affinity(hld_data->irq, cpumask_of(cpu))) { + spin_unlock(&hld_data->lock); + pr_err("Unable to enable on CPU %d.!\n", cpu); + return; + } + + kick_timer(hld_data); + enable(hld_data); + } + + spin_unlock(&hld_data->lock); +} + +/** + * hardlockup_detector_hpet_disable() - Disable the hardlockup detector + * + * The hardlockup detector is disabled for the CPU that executes the + * function. + * + * None + */ +static void hardlockup_detector_hpet_disable(void) +{ + if (!hld_data) + return; + + spin_lock(&hld_data->lock); + + cpumask_clear_cpu(smp_processor_id(), &hld_data->monitored_mask); + + /* Only disable the timer if there are no more CPUs to monitor. */ + if (!cpumask_weight(&hld_data->monitored_mask)) + disable(hld_data); + + spin_unlock(&hld_data->lock); +} + +/** + * hardlockup_detector_hpet_stop() - Stop the NMI watchdog on all CPUs + * + * Returns: + * + * None + */ +static void hardlockup_detector_hpet_stop(void) +{ + disable(hld_data); + + spin_lock(&hld_data->lock); + cpumask_clear(&hld_data->monitored_mask); + spin_unlock(&hld_data->lock); +} + +/** * hardlockup_detector_hpet_init() - Initialize the hardlockup detector * * Only initialize and configure the detector if an HPET is available on the @@ -383,5 +468,18 @@ static int __init hardlockup_detector_hpet_init(void) */ disable(hld_data); + spin_lock_init(&hld_data->lock); + + spin_lock(&hld_data->lock); + cpumask_clear(&hld_data->monitored_mask); + spin_unlock(&hld_data->lock); + return 0; } + +struct nmi_watchdog_ops hardlockup_detector_hpet_ops = { + .init = hardlockup_detector_hpet_init, + .enable = hardlockup_detector_hpet_enable, + .disable = hardlockup_detector_hpet_disable, + .stop = hardlockup_detector_hpet_stop +}; -- 2.7.4 _______________________________________________ iommu mailing list [email protected] https://lists.linuxfoundation.org/mailman/listinfo/iommu
