diff options
Diffstat (limited to 'arch/x86/kernel/smp.c')
| -rw-r--r-- | arch/x86/kernel/smp.c | 61 |
1 files changed, 56 insertions, 5 deletions
diff --git a/arch/x86/kernel/smp.c b/arch/x86/kernel/smp.c index 6d20f523bc4e..228e7405511a 100644 --- a/arch/x86/kernel/smp.c +++ b/arch/x86/kernel/smp.c @@ -29,6 +29,7 @@ #include <asm/mmu_context.h> #include <asm/proto.h> #include <asm/apic.h> +#include <asm/nmi.h> /* * Some notes on x86 processor bugs affecting SMP operation: * @@ -108,6 +109,8 @@ * about nothing of note with C stepping upwards. */ +static atomic_t stopping_cpu = ATOMIC_INIT(-1); + /* * this function sends a 'reschedule' IPI to another CPU. * it goes straight through and wastes no time serializing @@ -148,6 +151,17 @@ void native_send_call_func_ipi(const struct cpumask *mask) free_cpumask_var(allbutself); } +static int smp_stop_nmi_callback(unsigned int val, struct pt_regs *regs) +{ + /* We are registered on stopping cpu too, avoid spurious NMI */ + if (raw_smp_processor_id() == atomic_read(&stopping_cpu)) + return NMI_HANDLED; + + stop_this_cpu(NULL); + + return NMI_HANDLED; +} + /* * this function calls the 'stop' function on all other CPUs in the system. */ @@ -171,13 +185,25 @@ static void native_stop_other_cpus(int wait) /* * Use an own vector here because smp_call_function * does lots of things not suitable in a panic situation. - * On most systems we could also use an NMI here, - * but there are a few systems around where NMI - * is problematic so stay with an non NMI for now - * (this implies we cannot stop CPUs spinning with irq off - * currently) + */ + + /* + * We start by using the REBOOT_VECTOR irq. + * The irq is treated as a sync point to allow critical + * regions of code on other cpus to release their spin locks + * and re-enable irqs. Jumping straight to an NMI might + * accidentally cause deadlocks with further shutdown/panic + * code. By syncing, we give the cpus up to one second to + * finish their work before we force them off with the NMI. */ if (num_online_cpus() > 1) { + /* did someone beat us here? */ + if (atomic_cmpxchg(&stopping_cpu, -1, safe_smp_processor_id()) != -1) + return; + + /* sync above data before sending IRQ */ + wmb(); + apic->send_IPI_allbutself(REBOOT_VECTOR); /* @@ -188,7 +214,32 @@ static void native_stop_other_cpus(int wait) while (num_online_cpus() > 1 && (wait || timeout--)) udelay(1); } + + /* if the REBOOT_VECTOR didn't work, try with the NMI */ + if ((num_online_cpus() > 1)) { + if (register_nmi_handler(NMI_LOCAL, smp_stop_nmi_callback, + NMI_FLAG_FIRST, "smp_stop")) + /* Note: we ignore failures here */ + /* Hope the REBOOT_IRQ is good enough */ + goto finish; + + /* sync above data before sending IRQ */ + wmb(); + + pr_emerg("Shutting down cpus with NMI\n"); + + apic->send_IPI_allbutself(NMI_VECTOR); + + /* + * Don't wait longer than a 10 ms if the caller + * didn't ask us to wait. + */ + timeout = USEC_PER_MSEC * 10; + while (num_online_cpus() > 1 && (wait || timeout--)) + udelay(1); + } +finish: local_irq_save(flags); disable_local_APIC(); local_irq_restore(flags); |