// SPDX-License-Identifier: GPL-2.0

#include <linux/cpumask.h>
#include <linux/smp.h>

#include "local.h"

DEFINE_STATIC_KEY_FALSE(apic_use_ipi_shorthand);

#ifdef CONFIG_SMP
static int apic_ipi_shorthand_off __ro_after_init;

static __init int apic_ipi_shorthand(char *str)
{
        get_option(&str, &apic_ipi_shorthand_off);
        return 1;
}
__setup("no_ipi_broadcast=", apic_ipi_shorthand);

static int __init print_ipi_mode(void)
{
        pr_info("IPI shorthand broadcast: %s\n",
                apic_ipi_shorthand_off ? "disabled" : "enabled");
        return 0;
}
late_initcall(print_ipi_mode);

void apic_smt_update(void)
{
        /*
         * Do not switch to broadcast mode if:
         * - Disabled on the command line
         * - Only a single CPU is online
         * - Not all present CPUs have been at least booted once
         *
         * The latter is important as the local APIC might be in some
         * random state and a broadcast might cause havoc. That's
         * especially true for NMI broadcasting.
         */
        if (apic_ipi_shorthand_off || num_online_cpus() == 1 ||
            !cpumask_equal(cpu_present_mask, &cpus_booted_once_mask)) {
                static_branch_disable(&apic_use_ipi_shorthand);
        } else {
                static_branch_enable(&apic_use_ipi_shorthand);
        }
}

void apic_send_IPI_allbutself(unsigned int vector)
{
        if (num_online_cpus() < 2)
                return;

        if (static_branch_likely(&apic_use_ipi_shorthand))
                apic->send_IPI_allbutself(vector);
        else
                apic->send_IPI_mask_allbutself(cpu_online_mask, vector);
}

/*
 * Send a 'reschedule' IPI to another CPU. It goes straight through and
 * wastes no time serializing anything. Worst case is that we lose a
 * reschedule ...
 */
void native_smp_send_reschedule(int cpu)
{
        if (unlikely(cpu_is_offline(cpu))) {
                WARN(1, "sched: Unexpected reschedule of offline CPU#%d!\n", cpu);
                return;
        }
        apic->send_IPI(cpu, RESCHEDULE_VECTOR);
}

void native_send_call_func_single_ipi(int cpu)
{
        apic->send_IPI(cpu, CALL_FUNCTION_SINGLE_VECTOR);
}

void native_send_call_func_ipi(const struct cpumask *mask)
{
        if (static_branch_likely(&apic_use_ipi_shorthand)) {
                unsigned int cpu = smp_processor_id();

                if (!cpumask_or_equal(mask, cpumask_of(cpu), cpu_online_mask))
                        goto sendmask;

                if (cpumask_test_cpu(cpu, mask))
                        apic->send_IPI_all(CALL_FUNCTION_VECTOR);
                else if (num_online_cpus() > 1)
                        apic->send_IPI_allbutself(CALL_FUNCTION_VECTOR);
                return;
        }

sendmask:
        apic->send_IPI_mask(mask, CALL_FUNCTION_VECTOR);
}

#endif /* CONFIG_SMP */

static inline int __prepare_ICR2(unsigned int mask)
{
        return SET_APIC_DEST_FIELD(mask);
}

static inline void __xapic_wait_icr_idle(void)
{
        while (native_apic_mem_read(APIC_ICR) & APIC_ICR_BUSY)
                cpu_relax();
}

void __default_send_IPI_shortcut(unsigned int shortcut, int vector)
{
        /*
         * Subtle. In the case of the 'never do double writes' workaround
         * we have to lock out interrupts to be safe.  As we don't care
         * of the value read we use an atomic rmw access to avoid costly
         * cli/sti.  Otherwise we use an even cheaper single atomic write
         * to the APIC.
         */
        unsigned int cfg;

        /*
         * Wait for idle.
         */
        if (unlikely(vector == NMI_VECTOR))
                safe_apic_wait_icr_idle();
        else
                __xapic_wait_icr_idle();

        /*
         * No need to touch the target chip field. Also the destination
         * mode is ignored when a shorthand is used.
         */
        cfg = __prepare_ICR(shortcut, vector, 0);

        /*
         * Send the IPI. The write to APIC_ICR fires this off.
         */
        native_apic_mem_write(APIC_ICR, cfg);
}

/*
 * This is used to send an IPI with no shorthand notation (the destination is
 * specified in bits 56 to 63 of the ICR).
 */
void __default_send_IPI_dest_field(unsigned int mask, int vector, unsigned int dest)
{
        unsigned long cfg;

        /*
         * Wait for idle.
         */
        if (unlikely(vector == NMI_VECTOR))
                safe_apic_wait_icr_idle();
        else
                __xapic_wait_icr_idle();

        /*
         * prepare target chip field
         */
        cfg = __prepare_ICR2(mask);
        native_apic_mem_write(APIC_ICR2, cfg);

        /*
         * program the ICR
         */
        cfg = __prepare_ICR(0, vector, dest);

        /*
         * Send the IPI. The write to APIC_ICR fires this off.
         */
        native_apic_mem_write(APIC_ICR, cfg);
}

void default_send_IPI_single_phys(int cpu, int vector)
{
        unsigned long flags;

        local_irq_save(flags);
        __default_send_IPI_dest_field(per_cpu(x86_cpu_to_apicid, cpu),
                                      vector, APIC_DEST_PHYSICAL);
        local_irq_restore(flags);
}

void default_send_IPI_mask_sequence_phys(const struct cpumask *mask, int vector)
{
        unsigned long query_cpu;
        unsigned long flags;

        /*
         * Hack. The clustered APIC addressing mode doesn't allow us to send
         * to an arbitrary mask, so I do a unicast to each CPU instead.
         * - mbligh
         */
        local_irq_save(flags);
        for_each_cpu(query_cpu, mask) {
                __default_send_IPI_dest_field(per_cpu(x86_cpu_to_apicid,
                                query_cpu), vector, APIC_DEST_PHYSICAL);
        }
        local_irq_restore(flags);
}

void default_send_IPI_mask_allbutself_phys(const struct cpumask *mask,
                                                 int vector)
{
        unsigned int this_cpu = smp_processor_id();
        unsigned int query_cpu;
        unsigned long flags;

        /* See Hack comment above */

        local_irq_save(flags);
        for_each_cpu(query_cpu, mask) {
                if (query_cpu == this_cpu)
                        continue;
                __default_send_IPI_dest_field(per_cpu(x86_cpu_to_apicid,
                                 query_cpu), vector, APIC_DEST_PHYSICAL);
        }
        local_irq_restore(flags);
}

/*
 * Helper function for APICs which insist on cpumasks
 */
void default_send_IPI_single(int cpu, int vector)
{
        apic->send_IPI_mask(cpumask_of(cpu), vector);
}

void default_send_IPI_allbutself(int vector)
{
        __default_send_IPI_shortcut(APIC_DEST_ALLBUT, vector);
}

void default_send_IPI_all(int vector)
{
        __default_send_IPI_shortcut(APIC_DEST_ALLINC, vector);
}

void default_send_IPI_self(int vector)
{
        __default_send_IPI_shortcut(APIC_DEST_SELF, vector);
}

#ifdef CONFIG_X86_32

void default_send_IPI_mask_sequence_logical(const struct cpumask *mask,
                                                 int vector)
{
        unsigned long flags;
        unsigned int query_cpu;

        /*
         * Hack. The clustered APIC addressing mode doesn't allow us to send
         * to an arbitrary mask, so I do a unicasts to each CPU instead. This
         * should be modified to do 1 message per cluster ID - mbligh
         */

        local_irq_save(flags);
        for_each_cpu(query_cpu, mask)
                __default_send_IPI_dest_field(
                        early_per_cpu(x86_cpu_to_logical_apicid, query_cpu),
                        vector, apic->dest_logical);
        local_irq_restore(flags);
}

void default_send_IPI_mask_allbutself_logical(const struct cpumask *mask,
                                                 int vector)
{
        unsigned long flags;
        unsigned int query_cpu;
        unsigned int this_cpu = smp_processor_id();

        /* See Hack comment above */

        local_irq_save(flags);
        for_each_cpu(query_cpu, mask) {
                if (query_cpu == this_cpu)
                        continue;
                __default_send_IPI_dest_field(
                        early_per_cpu(x86_cpu_to_logical_apicid, query_cpu),
                        vector, apic->dest_logical);
                }
        local_irq_restore(flags);
}

/*
 * This is only used on smaller machines.
 */
void default_send_IPI_mask_logical(const struct cpumask *cpumask, int vector)
{
        unsigned long mask = cpumask_bits(cpumask)[0];
        unsigned long flags;

        if (!mask)
                return;

        local_irq_save(flags);
        WARN_ON(mask & ~cpumask_bits(cpu_online_mask)[0]);
        __default_send_IPI_dest_field(mask, vector, apic->dest_logical);
        local_irq_restore(flags);
}

/* must come after the send_IPI functions above for inlining */
static int convert_apicid_to_cpu(int apic_id)
{
        int i;

        for_each_possible_cpu(i) {
                if (per_cpu(x86_cpu_to_apicid, i) == apic_id)
                        return i;
        }
        return -1;
}

int safe_smp_processor_id(void)
{
        int apicid, cpuid;

        if (!boot_cpu_has(X86_FEATURE_APIC))
                return 0;

        apicid = hard_smp_processor_id();
        if (apicid == BAD_APICID)
                return 0;

        cpuid = convert_apicid_to_cpu(apicid);

        return cpuid >= 0 ? cpuid : 0;
}
#endif