x86/irq: Remove an old outdated comment about context tracking races

[mirror_ubuntu-bionic-kernel.git] / arch / x86 / kernel / irq.c

/*
 * Common interrupt code for 32 and 64 bit
 */
#include <linux/cpu.h>
#include <linux/interrupt.h>
#include <linux/kernel_stat.h>
#include <linux/of.h>
#include <linux/seq_file.h>
#include <linux/smp.h>
#include <linux/ftrace.h>
#include <linux/delay.h>
#include <linux/export.h>

#include <asm/apic.h>
#include <asm/io_apic.h>
#include <asm/irq.h>
#include <asm/mce.h>
#include <asm/hw_irq.h>
#include <asm/desc.h>

#define CREATE_TRACE_POINTS
#include <asm/trace/irq_vectors.h>

DEFINE_PER_CPU_SHARED_ALIGNED(irq_cpustat_t, irq_stat);
EXPORT_PER_CPU_SYMBOL(irq_stat);

DEFINE_PER_CPU(struct pt_regs *, irq_regs);
EXPORT_PER_CPU_SYMBOL(irq_regs);

atomic_t irq_err_count;

/*
 * 'what should we do if we get a hw irq event on an illegal vector'.
 * each architecture has to answer this themselves.
 */
void ack_bad_irq(unsigned int irq)
{
        if (printk_ratelimit())
                pr_err("unexpected IRQ trap at vector %02x\n", irq);

        /*
         * Currently unexpected vectors happen only on SMP and APIC.
         * We _must_ ack these because every local APIC has only N
         * irq slots per priority level, and a 'hanging, unacked' IRQ
         * holds up an irq slot - in excessive cases (when multiple
         * unexpected vectors occur) that might lock up the APIC
         * completely.
         * But only ack when the APIC is enabled -AK
         */
        ack_APIC_irq();
}

#define irq_stats(x)            (&per_cpu(irq_stat, x))
/*
 * /proc/interrupts printing for arch specific interrupts
 */
int arch_show_interrupts(struct seq_file *p, int prec)
{
        int j;

        seq_printf(p, "%*s: ", prec, "NMI");
        for_each_online_cpu(j)
                seq_printf(p, "%10u ", irq_stats(j)->__nmi_count);
        seq_puts(p, "  Non-maskable interrupts\n");
#ifdef CONFIG_X86_LOCAL_APIC
        seq_printf(p, "%*s: ", prec, "LOC");
        for_each_online_cpu(j)
                seq_printf(p, "%10u ", irq_stats(j)->apic_timer_irqs);
        seq_puts(p, "  Local timer interrupts\n");

        seq_printf(p, "%*s: ", prec, "SPU");
        for_each_online_cpu(j)
                seq_printf(p, "%10u ", irq_stats(j)->irq_spurious_count);
        seq_puts(p, "  Spurious interrupts\n");
        seq_printf(p, "%*s: ", prec, "PMI");
        for_each_online_cpu(j)
                seq_printf(p, "%10u ", irq_stats(j)->apic_perf_irqs);
        seq_puts(p, "  Performance monitoring interrupts\n");
        seq_printf(p, "%*s: ", prec, "IWI");
        for_each_online_cpu(j)
                seq_printf(p, "%10u ", irq_stats(j)->apic_irq_work_irqs);
        seq_puts(p, "  IRQ work interrupts\n");
        seq_printf(p, "%*s: ", prec, "RTR");
        for_each_online_cpu(j)
                seq_printf(p, "%10u ", irq_stats(j)->icr_read_retry_count);
        seq_puts(p, "  APIC ICR read retries\n");
        if (x86_platform_ipi_callback) {
                seq_printf(p, "%*s: ", prec, "PLT");
                for_each_online_cpu(j)
                        seq_printf(p, "%10u ", irq_stats(j)->x86_platform_ipis);
                seq_puts(p, "  Platform interrupts\n");
        }
#endif
#ifdef CONFIG_SMP
        seq_printf(p, "%*s: ", prec, "RES");
        for_each_online_cpu(j)
                seq_printf(p, "%10u ", irq_stats(j)->irq_resched_count);
        seq_puts(p, "  Rescheduling interrupts\n");
        seq_printf(p, "%*s: ", prec, "CAL");
        for_each_online_cpu(j)
                seq_printf(p, "%10u ", irq_stats(j)->irq_call_count);
        seq_puts(p, "  Function call interrupts\n");
        seq_printf(p, "%*s: ", prec, "TLB");
        for_each_online_cpu(j)
                seq_printf(p, "%10u ", irq_stats(j)->irq_tlb_count);
        seq_puts(p, "  TLB shootdowns\n");
#endif
#ifdef CONFIG_X86_THERMAL_VECTOR
        seq_printf(p, "%*s: ", prec, "TRM");
        for_each_online_cpu(j)
                seq_printf(p, "%10u ", irq_stats(j)->irq_thermal_count);
        seq_puts(p, "  Thermal event interrupts\n");
#endif
#ifdef CONFIG_X86_MCE_THRESHOLD
        seq_printf(p, "%*s: ", prec, "THR");
        for_each_online_cpu(j)
                seq_printf(p, "%10u ", irq_stats(j)->irq_threshold_count);
        seq_puts(p, "  Threshold APIC interrupts\n");
#endif
#ifdef CONFIG_X86_MCE_AMD
        seq_printf(p, "%*s: ", prec, "DFR");
        for_each_online_cpu(j)
                seq_printf(p, "%10u ", irq_stats(j)->irq_deferred_error_count);
        seq_puts(p, "  Deferred Error APIC interrupts\n");
#endif
#ifdef CONFIG_X86_MCE
        seq_printf(p, "%*s: ", prec, "MCE");
        for_each_online_cpu(j)
                seq_printf(p, "%10u ", per_cpu(mce_exception_count, j));
        seq_puts(p, "  Machine check exceptions\n");
        seq_printf(p, "%*s: ", prec, "MCP");
        for_each_online_cpu(j)
                seq_printf(p, "%10u ", per_cpu(mce_poll_count, j));
        seq_puts(p, "  Machine check polls\n");
#endif
#if IS_ENABLED(CONFIG_HYPERV) || defined(CONFIG_XEN)
        if (test_bit(HYPERVISOR_CALLBACK_VECTOR, used_vectors)) {
                seq_printf(p, "%*s: ", prec, "HYP");
                for_each_online_cpu(j)
                        seq_printf(p, "%10u ",
                                   irq_stats(j)->irq_hv_callback_count);
                seq_puts(p, "  Hypervisor callback interrupts\n");
        }
#endif
        seq_printf(p, "%*s: %10u\n", prec, "ERR", atomic_read(&irq_err_count));
#if defined(CONFIG_X86_IO_APIC)
        seq_printf(p, "%*s: %10u\n", prec, "MIS", atomic_read(&irq_mis_count));
#endif
#ifdef CONFIG_HAVE_KVM
        seq_printf(p, "%*s: ", prec, "PIN");
        for_each_online_cpu(j)
                seq_printf(p, "%10u ", irq_stats(j)->kvm_posted_intr_ipis);
        seq_puts(p, "  Posted-interrupt notification event\n");

        seq_printf(p, "%*s: ", prec, "NPI");
        for_each_online_cpu(j)
                seq_printf(p, "%10u ",
                           irq_stats(j)->kvm_posted_intr_nested_ipis);
        seq_puts(p, "  Nested posted-interrupt event\n");

        seq_printf(p, "%*s: ", prec, "PIW");
        for_each_online_cpu(j)
                seq_printf(p, "%10u ",
                           irq_stats(j)->kvm_posted_intr_wakeup_ipis);
        seq_puts(p, "  Posted-interrupt wakeup event\n");
#endif
        return 0;
}

/*
 * /proc/stat helpers
 */
u64 arch_irq_stat_cpu(unsigned int cpu)
{
        u64 sum = irq_stats(cpu)->__nmi_count;

#ifdef CONFIG_X86_LOCAL_APIC
        sum += irq_stats(cpu)->apic_timer_irqs;
        sum += irq_stats(cpu)->irq_spurious_count;
        sum += irq_stats(cpu)->apic_perf_irqs;
        sum += irq_stats(cpu)->apic_irq_work_irqs;
        sum += irq_stats(cpu)->icr_read_retry_count;
        if (x86_platform_ipi_callback)
                sum += irq_stats(cpu)->x86_platform_ipis;
#endif
#ifdef CONFIG_SMP
        sum += irq_stats(cpu)->irq_resched_count;
        sum += irq_stats(cpu)->irq_call_count;
#endif
#ifdef CONFIG_X86_THERMAL_VECTOR
        sum += irq_stats(cpu)->irq_thermal_count;
#endif
#ifdef CONFIG_X86_MCE_THRESHOLD
        sum += irq_stats(cpu)->irq_threshold_count;
#endif
#ifdef CONFIG_X86_MCE
        sum += per_cpu(mce_exception_count, cpu);
        sum += per_cpu(mce_poll_count, cpu);
#endif
        return sum;
}

u64 arch_irq_stat(void)
{
        u64 sum = atomic_read(&irq_err_count);
        return sum;
}


/*
 * do_IRQ handles all normal device IRQ's (the special
 * SMP cross-CPU interrupts have their own specific
 * handlers).
 */
__visible unsigned int __irq_entry do_IRQ(struct pt_regs *regs)
{
        struct pt_regs *old_regs = set_irq_regs(regs);
        struct irq_desc * desc;
        /* high bit used in ret_from_ code  */
        unsigned vector = ~regs->orig_ax;

        entering_irq();

        /* entering_irq() tells RCU that we're not quiescent.  Check it. */
        RCU_LOCKDEP_WARN(!rcu_is_watching(), "IRQ failed to wake up RCU");

        desc = __this_cpu_read(vector_irq[vector]);

        if (!handle_irq(desc, regs)) {
                ack_APIC_irq();

                if (desc != VECTOR_RETRIGGERED) {
                        pr_emerg_ratelimited("%s: %d.%d No irq handler for vector\n",
                                             __func__, smp_processor_id(),
                                             vector);
                } else {
                        __this_cpu_write(vector_irq[vector], VECTOR_UNUSED);
                }
        }

        exiting_irq();

        set_irq_regs(old_regs);
        return 1;
}

#ifdef CONFIG_X86_LOCAL_APIC
/* Function pointer for generic interrupt vector handling */
void (*x86_platform_ipi_callback)(void) = NULL;
/*
 * Handler for X86_PLATFORM_IPI_VECTOR.
 */
__visible void __irq_entry smp_x86_platform_ipi(struct pt_regs *regs)
{
        struct pt_regs *old_regs = set_irq_regs(regs);

        entering_ack_irq();
        trace_x86_platform_ipi_entry(X86_PLATFORM_IPI_VECTOR);
        inc_irq_stat(x86_platform_ipis);
        if (x86_platform_ipi_callback)
                x86_platform_ipi_callback();
        trace_x86_platform_ipi_exit(X86_PLATFORM_IPI_VECTOR);
        exiting_irq();
        set_irq_regs(old_regs);
}
#endif

#ifdef CONFIG_HAVE_KVM
static void dummy_handler(void) {}
static void (*kvm_posted_intr_wakeup_handler)(void) = dummy_handler;

void kvm_set_posted_intr_wakeup_handler(void (*handler)(void))
{
        if (handler)
                kvm_posted_intr_wakeup_handler = handler;
        else
                kvm_posted_intr_wakeup_handler = dummy_handler;
}
EXPORT_SYMBOL_GPL(kvm_set_posted_intr_wakeup_handler);

/*
 * Handler for POSTED_INTERRUPT_VECTOR.
 */
__visible void smp_kvm_posted_intr_ipi(struct pt_regs *regs)
{
        struct pt_regs *old_regs = set_irq_regs(regs);

        entering_ack_irq();
        inc_irq_stat(kvm_posted_intr_ipis);
        exiting_irq();
        set_irq_regs(old_regs);
}

/*
 * Handler for POSTED_INTERRUPT_WAKEUP_VECTOR.
 */
__visible void smp_kvm_posted_intr_wakeup_ipi(struct pt_regs *regs)
{
        struct pt_regs *old_regs = set_irq_regs(regs);

        entering_ack_irq();
        inc_irq_stat(kvm_posted_intr_wakeup_ipis);
        kvm_posted_intr_wakeup_handler();
        exiting_irq();
        set_irq_regs(old_regs);
}

/*
 * Handler for POSTED_INTERRUPT_NESTED_VECTOR.
 */
__visible void smp_kvm_posted_intr_nested_ipi(struct pt_regs *regs)
{
        struct pt_regs *old_regs = set_irq_regs(regs);

        entering_ack_irq();
        inc_irq_stat(kvm_posted_intr_nested_ipis);
        exiting_irq();
        set_irq_regs(old_regs);
}
#endif


#ifdef CONFIG_HOTPLUG_CPU

/* These two declarations are only used in check_irq_vectors_for_cpu_disable()
 * below, which is protected by stop_machine().  Putting them on the stack
 * results in a stack frame overflow.  Dynamically allocating could result in a
 * failure so declare these two cpumasks as global.
 */
static struct cpumask affinity_new, online_new;

/*
 * This cpu is going to be removed and its vectors migrated to the remaining
 * online cpus.  Check to see if there are enough vectors in the remaining cpus.
 * This function is protected by stop_machine().
 */
int check_irq_vectors_for_cpu_disable(void)
{
        unsigned int this_cpu, vector, this_count, count;
        struct irq_desc *desc;
        struct irq_data *data;
        int cpu;

        this_cpu = smp_processor_id();
        cpumask_copy(&online_new, cpu_online_mask);
        cpumask_clear_cpu(this_cpu, &online_new);

        this_count = 0;
        for (vector = FIRST_EXTERNAL_VECTOR; vector < NR_VECTORS; vector++) {
                desc = __this_cpu_read(vector_irq[vector]);
                if (IS_ERR_OR_NULL(desc))
                        continue;
                /*
                 * Protect against concurrent action removal, affinity
                 * changes etc.
                 */
                raw_spin_lock(&desc->lock);
                data = irq_desc_get_irq_data(desc);
                cpumask_copy(&affinity_new,
                             irq_data_get_affinity_mask(data));
                cpumask_clear_cpu(this_cpu, &affinity_new);

                /* Do not count inactive or per-cpu irqs. */
                if (!irq_desc_has_action(desc) || irqd_is_per_cpu(data)) {
                        raw_spin_unlock(&desc->lock);
                        continue;
                }

                raw_spin_unlock(&desc->lock);
                /*
                 * A single irq may be mapped to multiple cpu's
                 * vector_irq[] (for example IOAPIC cluster mode).  In
                 * this case we have two possibilities:
                 *
                 * 1) the resulting affinity mask is empty; that is
                 * this the down'd cpu is the last cpu in the irq's
                 * affinity mask, or
                 *
                 * 2) the resulting affinity mask is no longer a
                 * subset of the online cpus but the affinity mask is
                 * not zero; that is the down'd cpu is the last online
                 * cpu in a user set affinity mask.
                 */
                if (cpumask_empty(&affinity_new) ||
                    !cpumask_subset(&affinity_new, &online_new))
                        this_count++;
        }
        /* No need to check any further. */
        if (!this_count)
                return 0;

        count = 0;
        for_each_online_cpu(cpu) {
                if (cpu == this_cpu)
                        continue;
                /*
                 * We scan from FIRST_EXTERNAL_VECTOR to first system
                 * vector. If the vector is marked in the used vectors
                 * bitmap or an irq is assigned to it, we don't count
                 * it as available.
                 *
                 * As this is an inaccurate snapshot anyway, we can do
                 * this w/o holding vector_lock.
                 */
                for (vector = FIRST_EXTERNAL_VECTOR;
                     vector < FIRST_SYSTEM_VECTOR; vector++) {
                        if (!test_bit(vector, used_vectors) &&
                            IS_ERR_OR_NULL(per_cpu(vector_irq, cpu)[vector])) {
                                if (++count == this_count)
                                        return 0;
                        }
                }
        }

        if (count < this_count) {
                pr_warn("CPU %d disable failed: CPU has %u vectors assigned and there are only %u available.\n",
                        this_cpu, this_count, count);
                return -ERANGE;
        }
        return 0;
}

/* A cpu has been removed from cpu_online_mask.  Reset irq affinities. */
void fixup_irqs(void)
{
        unsigned int irr, vector;
        struct irq_desc *desc;
        struct irq_data *data;
        struct irq_chip *chip;

        irq_migrate_all_off_this_cpu();

        /*
         * We can remove mdelay() and then send spuriuous interrupts to
         * new cpu targets for all the irqs that were handled previously by
         * this cpu. While it works, I have seen spurious interrupt messages
         * (nothing wrong but still...).
         *
         * So for now, retain mdelay(1) and check the IRR and then send those
         * interrupts to new targets as this cpu is already offlined...
         */
        mdelay(1);

        /*
         * We can walk the vector array of this cpu without holding
         * vector_lock because the cpu is already marked !online, so
         * nothing else will touch it.
         */
        for (vector = FIRST_EXTERNAL_VECTOR; vector < NR_VECTORS; vector++) {
                if (IS_ERR_OR_NULL(__this_cpu_read(vector_irq[vector])))
                        continue;

                irr = apic_read(APIC_IRR + (vector / 32 * 0x10));
                if (irr  & (1 << (vector % 32))) {
                        desc = __this_cpu_read(vector_irq[vector]);

                        raw_spin_lock(&desc->lock);
                        data = irq_desc_get_irq_data(desc);
                        chip = irq_data_get_irq_chip(data);
                        if (chip->irq_retrigger) {
                                chip->irq_retrigger(data);
                                __this_cpu_write(vector_irq[vector], VECTOR_RETRIGGERED);
                        }
                        raw_spin_unlock(&desc->lock);
                }
                if (__this_cpu_read(vector_irq[vector]) != VECTOR_RETRIGGERED)
                        __this_cpu_write(vector_irq[vector], VECTOR_UNUSED);
        }
}
#endif