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Diffstat (limited to 'arch/x86/kernel/smp.c')
| -rw-r--r-- | arch/x86/kernel/smp.c | 297 |
1 files changed, 297 insertions, 0 deletions
diff --git a/arch/x86/kernel/smp.c b/arch/x86/kernel/smp.c new file mode 100644 index 000000000..96a771f9f --- /dev/null +++ b/arch/x86/kernel/smp.c @@ -0,0 +1,297 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Intel SMP support routines. + * + * (c) 1995 Alan Cox, Building #3 <alan@lxorguk.ukuu.org.uk> + * (c) 1998-99, 2000, 2009 Ingo Molnar <mingo@redhat.com> + * (c) 2002,2003 Andi Kleen, SuSE Labs. + * + * i386 and x86_64 integration by Glauber Costa <gcosta@redhat.com> + */ + +#include <linux/init.h> + +#include <linux/mm.h> +#include <linux/delay.h> +#include <linux/spinlock.h> +#include <linux/export.h> +#include <linux/kernel_stat.h> +#include <linux/mc146818rtc.h> +#include <linux/cache.h> +#include <linux/interrupt.h> +#include <linux/cpu.h> +#include <linux/gfp.h> +#include <linux/kexec.h> + +#include <asm/mtrr.h> +#include <asm/tlbflush.h> +#include <asm/mmu_context.h> +#include <asm/proto.h> +#include <asm/apic.h> +#include <asm/cpu.h> +#include <asm/idtentry.h> +#include <asm/nmi.h> +#include <asm/mce.h> +#include <asm/trace/irq_vectors.h> +#include <asm/kexec.h> +#include <asm/reboot.h> + +/* + * Some notes on x86 processor bugs affecting SMP operation: + * + * Pentium, Pentium Pro, II, III (and all CPUs) have bugs. + * The Linux implications for SMP are handled as follows: + * + * Pentium III / [Xeon] + * None of the E1AP-E3AP errata are visible to the user. + * + * E1AP. see PII A1AP + * E2AP. see PII A2AP + * E3AP. see PII A3AP + * + * Pentium II / [Xeon] + * None of the A1AP-A3AP errata are visible to the user. + * + * A1AP. see PPro 1AP + * A2AP. see PPro 2AP + * A3AP. see PPro 7AP + * + * Pentium Pro + * None of 1AP-9AP errata are visible to the normal user, + * except occasional delivery of 'spurious interrupt' as trap #15. + * This is very rare and a non-problem. + * + * 1AP. Linux maps APIC as non-cacheable + * 2AP. worked around in hardware + * 3AP. fixed in C0 and above steppings microcode update. + * Linux does not use excessive STARTUP_IPIs. + * 4AP. worked around in hardware + * 5AP. symmetric IO mode (normal Linux operation) not affected. + * 'noapic' mode has vector 0xf filled out properly. + * 6AP. 'noapic' mode might be affected - fixed in later steppings + * 7AP. We do not assume writes to the LVT deasserting IRQs + * 8AP. We do not enable low power mode (deep sleep) during MP bootup + * 9AP. We do not use mixed mode + * + * Pentium + * There is a marginal case where REP MOVS on 100MHz SMP + * machines with B stepping processors can fail. XXX should provide + * an L1cache=Writethrough or L1cache=off option. + * + * B stepping CPUs may hang. There are hardware work arounds + * for this. We warn about it in case your board doesn't have the work + * arounds. Basically that's so I can tell anyone with a B stepping + * CPU and SMP problems "tough". + * + * Specific items [From Pentium Processor Specification Update] + * + * 1AP. Linux doesn't use remote read + * 2AP. Linux doesn't trust APIC errors + * 3AP. We work around this + * 4AP. Linux never generated 3 interrupts of the same priority + * to cause a lost local interrupt. + * 5AP. Remote read is never used + * 6AP. not affected - worked around in hardware + * 7AP. not affected - worked around in hardware + * 8AP. worked around in hardware - we get explicit CS errors if not + * 9AP. only 'noapic' mode affected. Might generate spurious + * interrupts, we log only the first one and count the + * rest silently. + * 10AP. not affected - worked around in hardware + * 11AP. Linux reads the APIC between writes to avoid this, as per + * the documentation. Make sure you preserve this as it affects + * the C stepping chips too. + * 12AP. not affected - worked around in hardware + * 13AP. not affected - worked around in hardware + * 14AP. we always deassert INIT during bootup + * 15AP. not affected - worked around in hardware + * 16AP. not affected - worked around in hardware + * 17AP. not affected - worked around in hardware + * 18AP. not affected - worked around in hardware + * 19AP. not affected - worked around in BIOS + * + * If this sounds worrying believe me these bugs are either ___RARE___, + * or are signal timing bugs worked around in hardware and there's + * about nothing of note with C stepping upwards. + */ + +static atomic_t stopping_cpu = ATOMIC_INIT(-1); +static bool smp_no_nmi_ipi = false; + +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; + + cpu_emergency_disable_virtualization(); + stop_this_cpu(NULL); + + return NMI_HANDLED; +} + +/* + * this function calls the 'stop' function on all other CPUs in the system. + */ +DEFINE_IDTENTRY_SYSVEC(sysvec_reboot) +{ + apic_eoi(); + cpu_emergency_disable_virtualization(); + stop_this_cpu(NULL); +} + +static int register_stop_handler(void) +{ + return register_nmi_handler(NMI_LOCAL, smp_stop_nmi_callback, + NMI_FLAG_FIRST, "smp_stop"); +} + +static void native_stop_other_cpus(int wait) +{ + unsigned int cpu = smp_processor_id(); + unsigned long flags, timeout; + + if (reboot_force) + return; + + /* Only proceed if this is the first CPU to reach this code */ + if (atomic_cmpxchg(&stopping_cpu, -1, cpu) != -1) + return; + + /* For kexec, ensure that offline CPUs are out of MWAIT and in HLT */ + if (kexec_in_progress) + smp_kick_mwait_play_dead(); + + /* + * 1) Send an IPI on the reboot vector to all other CPUs. + * + * The other CPUs should react on it after leaving critical + * sections and re-enabling interrupts. They might still hold + * locks, but there is nothing which can be done about that. + * + * 2) Wait for all other CPUs to report that they reached the + * HLT loop in stop_this_cpu() + * + * 3) If #2 timed out send an NMI to the CPUs which did not + * yet report + * + * 4) Wait for all other CPUs to report that they reached the + * HLT loop in stop_this_cpu() + * + * #3 can obviously race against a CPU reaching the HLT loop late. + * That CPU will have reported already and the "have all CPUs + * reached HLT" condition will be true despite the fact that the + * other CPU is still handling the NMI. Again, there is no + * protection against that as "disabled" APICs still respond to + * NMIs. + */ + cpumask_copy(&cpus_stop_mask, cpu_online_mask); + cpumask_clear_cpu(cpu, &cpus_stop_mask); + + if (!cpumask_empty(&cpus_stop_mask)) { + apic_send_IPI_allbutself(REBOOT_VECTOR); + + /* + * Don't wait longer than a second for IPI completion. The + * wait request is not checked here because that would + * prevent an NMI shutdown attempt in case that not all + * CPUs reach shutdown state. + */ + timeout = USEC_PER_SEC; + while (!cpumask_empty(&cpus_stop_mask) && timeout--) + udelay(1); + } + + /* if the REBOOT_VECTOR didn't work, try with the NMI */ + if (!cpumask_empty(&cpus_stop_mask)) { + /* + * If NMI IPI is enabled, try to register the stop handler + * and send the IPI. In any case try to wait for the other + * CPUs to stop. + */ + if (!smp_no_nmi_ipi && !register_stop_handler()) { + pr_emerg("Shutting down cpus with NMI\n"); + + for_each_cpu(cpu, &cpus_stop_mask) + __apic_send_IPI(cpu, NMI_VECTOR); + } + /* + * Don't wait longer than 10 ms if the caller didn't + * request it. If wait is true, the machine hangs here if + * one or more CPUs do not reach shutdown state. + */ + timeout = USEC_PER_MSEC * 10; + while (!cpumask_empty(&cpus_stop_mask) && (wait || timeout--)) + udelay(1); + } + + local_irq_save(flags); + disable_local_APIC(); + mcheck_cpu_clear(this_cpu_ptr(&cpu_info)); + local_irq_restore(flags); + + /* + * Ensure that the cpus_stop_mask cache lines are invalidated on + * the other CPUs. See comment vs. SME in stop_this_cpu(). + */ + cpumask_clear(&cpus_stop_mask); +} + +/* + * Reschedule call back. KVM uses this interrupt to force a cpu out of + * guest mode. + */ +DEFINE_IDTENTRY_SYSVEC_SIMPLE(sysvec_reschedule_ipi) +{ + apic_eoi(); + trace_reschedule_entry(RESCHEDULE_VECTOR); + inc_irq_stat(irq_resched_count); + scheduler_ipi(); + trace_reschedule_exit(RESCHEDULE_VECTOR); +} + +DEFINE_IDTENTRY_SYSVEC(sysvec_call_function) +{ + apic_eoi(); + trace_call_function_entry(CALL_FUNCTION_VECTOR); + inc_irq_stat(irq_call_count); + generic_smp_call_function_interrupt(); + trace_call_function_exit(CALL_FUNCTION_VECTOR); +} + +DEFINE_IDTENTRY_SYSVEC(sysvec_call_function_single) +{ + apic_eoi(); + trace_call_function_single_entry(CALL_FUNCTION_SINGLE_VECTOR); + inc_irq_stat(irq_call_count); + generic_smp_call_function_single_interrupt(); + trace_call_function_single_exit(CALL_FUNCTION_SINGLE_VECTOR); +} + +static int __init nonmi_ipi_setup(char *str) +{ + smp_no_nmi_ipi = true; + return 1; +} + +__setup("nonmi_ipi", nonmi_ipi_setup); + +struct smp_ops smp_ops = { + .smp_prepare_boot_cpu = native_smp_prepare_boot_cpu, + .smp_prepare_cpus = native_smp_prepare_cpus, + .smp_cpus_done = native_smp_cpus_done, + + .stop_other_cpus = native_stop_other_cpus, +#if defined(CONFIG_KEXEC_CORE) + .crash_stop_other_cpus = kdump_nmi_shootdown_cpus, +#endif + .smp_send_reschedule = native_smp_send_reschedule, + + .kick_ap_alive = native_kick_ap, + .cpu_disable = native_cpu_disable, + .play_dead = native_play_dead, + + .send_call_func_ipi = native_send_call_func_ipi, + .send_call_func_single_ipi = native_send_call_func_single_ipi, +}; +EXPORT_SYMBOL_GPL(smp_ops); |