// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *      SGI UltraViolet TLB flush routines.
 *
 *      (c) 2008-2014 Cliff Wickman <cpw@sgi.com>, SGI.
 */
#include <linux/seq_file.h>
#include <linux/proc_fs.h>
#include <linux/debugfs.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/delay.h>

#include <asm/mmu_context.h>
#include <asm/uv/uv.h>
#include <asm/uv/uv_mmrs.h>
#include <asm/uv/uv_hub.h>
#include <asm/uv/uv_bau.h>
#include <asm/apic.h>
#include <asm/tsc.h>
#include <asm/irq_vectors.h>
#include <asm/timer.h>

static struct bau_operations ops __ro_after_init;

static int timeout_us;
static bool nobau = true;
static int nobau_perm;

/* tunables: */
static int max_concurr          = MAX_BAU_CONCURRENT;
static int max_concurr_const    = MAX_BAU_CONCURRENT;
static int plugged_delay        = PLUGGED_DELAY;
static int plugsb4reset         = PLUGSB4RESET;
static int giveup_limit         = GIVEUP_LIMIT;
static int timeoutsb4reset      = TIMEOUTSB4RESET;
static int ipi_reset_limit      = IPI_RESET_LIMIT;
static int complete_threshold   = COMPLETE_THRESHOLD;
static int congested_respns_us  = CONGESTED_RESPONSE_US;
static int congested_reps       = CONGESTED_REPS;
static int disabled_period      = DISABLED_PERIOD;

static struct tunables tunables[] = {
        {&max_concurr,           MAX_BAU_CONCURRENT}, /* must be [0] */
        {&plugged_delay,         PLUGGED_DELAY},
        {&plugsb4reset,          PLUGSB4RESET},
        {&timeoutsb4reset,       TIMEOUTSB4RESET},
        {&ipi_reset_limit,       IPI_RESET_LIMIT},
        {&complete_threshold,    COMPLETE_THRESHOLD},
        {&congested_respns_us,   CONGESTED_RESPONSE_US},
        {&congested_reps,        CONGESTED_REPS},
        {&disabled_period,       DISABLED_PERIOD},
        {&giveup_limit,          GIVEUP_LIMIT}
};

static struct dentry *tunables_dir;

/* these correspond to the statistics printed by ptc_seq_show() */
static char *stat_description[] = {
        "sent:     number of shootdown messages sent",
        "stime:    time spent sending messages",
        "numuvhubs: number of hubs targeted with shootdown",
        "numuvhubs16: number times 16 or more hubs targeted",
        "numuvhubs8: number times 8 or more hubs targeted",
        "numuvhubs4: number times 4 or more hubs targeted",
        "numuvhubs2: number times 2 or more hubs targeted",
        "numuvhubs1: number times 1 hub targeted",
        "numcpus:  number of cpus targeted with shootdown",
        "dto:      number of destination timeouts",
        "retries:  destination timeout retries sent",
        "rok:   :  destination timeouts successfully retried",
        "resetp:   ipi-style resource resets for plugs",
        "resett:   ipi-style resource resets for timeouts",
        "giveup:   fall-backs to ipi-style shootdowns",
        "sto:      number of source timeouts",
        "bz:       number of stay-busy's",
        "throt:    number times spun in throttle",
        "swack:   image of UVH_LB_BAU_INTD_SOFTWARE_ACKNOWLEDGE",
        "recv:     shootdown messages received",
        "rtime:    time spent processing messages",
        "all:      shootdown all-tlb messages",
        "one:      shootdown one-tlb messages",
        "mult:     interrupts that found multiple messages",
        "none:     interrupts that found no messages",
        "retry:    number of retry messages processed",
        "canc:     number messages canceled by retries",
        "nocan:    number retries that found nothing to cancel",
        "reset:    number of ipi-style reset requests processed",
        "rcan:     number messages canceled by reset requests",
        "disable:  number times use of the BAU was disabled",
        "enable:   number times use of the BAU was re-enabled"
};

static int __init setup_bau(char *arg)
{
        int result;

        if (!arg)
                return -EINVAL;

        result = strtobool(arg, &nobau);
        if (result)
                return result;

        /* we need to flip the logic here, so that bau=y sets nobau to false */
        nobau = !nobau;

        if (!nobau)
                pr_info("UV BAU Enabled\n");
        else
                pr_info("UV BAU Disabled\n");

        return 0;
}
early_param("bau", setup_bau);

/* base pnode in this partition */
static int uv_base_pnode __read_mostly;

static DEFINE_PER_CPU(struct ptc_stats, ptcstats);
static DEFINE_PER_CPU(struct bau_control, bau_control);
static DEFINE_PER_CPU(cpumask_var_t, uv_flush_tlb_mask);

static void
set_bau_on(void)
{
        int cpu;
        struct bau_control *bcp;

        if (nobau_perm) {
                pr_info("BAU not initialized; cannot be turned on\n");
                return;
        }
        nobau = false;
        for_each_present_cpu(cpu) {
                bcp = &per_cpu(bau_control, cpu);
                bcp->nobau = false;
        }
        pr_info("BAU turned on\n");
        return;
}

static void
set_bau_off(void)
{
        int cpu;
        struct bau_control *bcp;

        nobau = true;
        for_each_present_cpu(cpu) {
                bcp = &per_cpu(bau_control, cpu);
                bcp->nobau = true;
        }
        pr_info("BAU turned off\n");
        return;
}

/*
 * Determine the first node on a uvhub. 'Nodes' are used for kernel
 * memory allocation.
 */
static int __init uvhub_to_first_node(int uvhub)
{
        int node, b;

        for_each_online_node(node) {
                b = uv_node_to_blade_id(node);
                if (uvhub == b)
                        return node;
        }
        return -1;
}

/*
 * Determine the apicid of the first cpu on a uvhub.
 */
static int __init uvhub_to_first_apicid(int uvhub)
{
        int cpu;

        for_each_present_cpu(cpu)
                if (uvhub == uv_cpu_to_blade_id(cpu))
                        return per_cpu(x86_cpu_to_apicid, cpu);
        return -1;
}

/*
 * Free a software acknowledge hardware resource by clearing its Pending
 * bit. This will return a reply to the sender.
 * If the message has timed out, a reply has already been sent by the
 * hardware but the resource has not been released. In that case our
 * clear of the Timeout bit (as well) will free the resource. No reply will
 * be sent (the hardware will only do one reply per message).
 */
static void reply_to_message(struct msg_desc *mdp, struct bau_control *bcp,
                                                int do_acknowledge)
{
        unsigned long dw;
        struct bau_pq_entry *msg;

        msg = mdp->msg;
        if (!msg->canceled && do_acknowledge) {
                dw = (msg->swack_vec << UV_SW_ACK_NPENDING) | msg->swack_vec;
                ops.write_l_sw_ack(dw);
        }
        msg->replied_to = 1;
        msg->swack_vec = 0;
}

/*
 * Process the receipt of a RETRY message
 */
static void bau_process_retry_msg(struct msg_desc *mdp,
                                        struct bau_control *bcp)
{
        int i;
        int cancel_count = 0;
        unsigned long msg_res;
        unsigned long mmr = 0;
        struct bau_pq_entry *msg = mdp->msg;
        struct bau_pq_entry *msg2;
        struct ptc_stats *stat = bcp->statp;

        stat->d_retries++;
        /*
         * cancel any message from msg+1 to the retry itself
         */
        for (msg2 = msg+1, i = 0; i < DEST_Q_SIZE; msg2++, i++) {
                if (msg2 > mdp->queue_last)
                        msg2 = mdp->queue_first;
                if (msg2 == msg)
                        break;

                /* same conditions for cancellation as do_reset */
                if ((msg2->replied_to == 0) && (msg2->canceled == 0) &&
                    (msg2->swack_vec) && ((msg2->swack_vec &
                        msg->swack_vec) == 0) &&
                    (msg2->sending_cpu == msg->sending_cpu) &&
                    (msg2->msg_type != MSG_NOOP)) {
                        mmr = ops.read_l_sw_ack();
                        msg_res = msg2->swack_vec;
                        /*
                         * This is a message retry; clear the resources held
                         * by the previous message only if they timed out.
                         * If it has not timed out we have an unexpected
                         * situation to report.
                         */
                        if (mmr & (msg_res << UV_SW_ACK_NPENDING)) {
                                unsigned long mr;
                                /*
                                 * Is the resource timed out?
                                 * Make everyone ignore the cancelled message.
                                 */
                                msg2->canceled = 1;
                                stat->d_canceled++;
                                cancel_count++;
                                mr = (msg_res << UV_SW_ACK_NPENDING) | msg_res;
                                ops.write_l_sw_ack(mr);
                        }
                }
        }
        if (!cancel_count)
                stat->d_nocanceled++;
}

/*
 * Do all the things a cpu should do for a TLB shootdown message.
 * Other cpu's may come here at the same time for this message.
 */
static void bau_process_message(struct msg_desc *mdp, struct bau_control *bcp,
                                                int do_acknowledge)
{
        short socket_ack_count = 0;
        short *sp;
        struct atomic_short *asp;
        struct ptc_stats *stat = bcp->statp;
        struct bau_pq_entry *msg = mdp->msg;
        struct bau_control *smaster = bcp->socket_master;

        /*
         * This must be a normal message, or retry of a normal message
         */
        if (msg->address == TLB_FLUSH_ALL) {
                flush_tlb_local();
                stat->d_alltlb++;
        } else {
                flush_tlb_one_user(msg->address);
                stat->d_onetlb++;
        }
        stat->d_requestee++;

        /*
         * One cpu on each uvhub has the additional job on a RETRY
         * of releasing the resource held by the message that is
         * being retried.  That message is identified by sending
         * cpu number.
         */
        if (msg->msg_type == MSG_RETRY && bcp == bcp->uvhub_master)
                bau_process_retry_msg(mdp, bcp);

        /*
         * This is a swack message, so we have to reply to it.
         * Count each responding cpu on the socket. This avoids
         * pinging the count's cache line back and forth between
         * the sockets.
         */
        sp = &smaster->socket_acknowledge_count[mdp->msg_slot];
        asp = (struct atomic_short *)sp;
        socket_ack_count = atom_asr(1, asp);
        if (socket_ack_count == bcp->cpus_in_socket) {
                int msg_ack_count;
                /*
                 * Both sockets dump their completed count total into
                 * the message's count.
                 */
                *sp = 0;
                asp = (struct atomic_short *)&msg->acknowledge_count;
                msg_ack_count = atom_asr(socket_ack_count, asp);

                if (msg_ack_count == bcp->cpus_in_uvhub) {
                        /*
                         * All cpus in uvhub saw it; reply
                         * (unless we are in the UV2 workaround)
                         */
                        reply_to_message(mdp, bcp, do_acknowledge);
                }
        }

        return;
}

/*
 * Determine the first cpu on a pnode.
 */
static int pnode_to_first_cpu(int pnode, struct bau_control *smaster)
{
        int cpu;
        struct hub_and_pnode *hpp;

        for_each_present_cpu(cpu) {
                hpp = &smaster->thp[cpu];
                if (pnode == hpp->pnode)
                        return cpu;
        }
        return -1;
}

/*
 * Last resort when we get a large number of destination timeouts is
 * to clear resources held by a given cpu.
 * Do this with IPI so that all messages in the BAU message queue
 * can be identified by their nonzero swack_vec field.
 *
 * This is entered for a single cpu on the uvhub.
 * The sender want's this uvhub to free a specific message's
 * swack resources.
 */
static void do_reset(void *ptr)
{
        int i;
        struct bau_control *bcp = &per_cpu(bau_control, smp_processor_id());
        struct reset_args *rap = (struct reset_args *)ptr;
        struct bau_pq_entry *msg;
        struct ptc_stats *stat = bcp->statp;

        stat->d_resets++;
        /*
         * We're looking for the given sender, and
         * will free its swack resource.
         * If all cpu's finally responded after the timeout, its
         * message 'replied_to' was set.
         */
        for (msg = bcp->queue_first, i = 0; i < DEST_Q_SIZE; msg++, i++) {
                unsigned long msg_res;
                /* do_reset: same conditions for cancellation as
                   bau_process_retry_msg() */
                if ((msg->replied_to == 0) &&
                    (msg->canceled == 0) &&
                    (msg->sending_cpu == rap->sender) &&
                    (msg->swack_vec) &&
                    (msg->msg_type != MSG_NOOP)) {
                        unsigned long mmr;
                        unsigned long mr;
                        /*
                         * make everyone else ignore this message
                         */
                        msg->canceled = 1;
                        /*
                         * only reset the resource if it is still pending
                         */
                        mmr = ops.read_l_sw_ack();
                        msg_res = msg->swack_vec;
                        mr = (msg_res << UV_SW_ACK_NPENDING) | msg_res;
                        if (mmr & msg_res) {
                                stat->d_rcanceled++;
                                ops.write_l_sw_ack(mr);
                        }
                }
        }
        return;
}

/*
 * Use IPI to get all target uvhubs to release resources held by
 * a given sending cpu number.
 */
static void reset_with_ipi(struct pnmask *distribution, struct bau_control *bcp)
{
        int pnode;
        int apnode;
        int maskbits;
        int sender = bcp->cpu;
        cpumask_t *mask = bcp->uvhub_master->cpumask;
        struct bau_control *smaster = bcp->socket_master;
        struct reset_args reset_args;

        reset_args.sender = sender;
        cpumask_clear(mask);
        /* find a single cpu for each uvhub in this distribution mask */
        maskbits = sizeof(struct pnmask) * BITSPERBYTE;
        /* each bit is a pnode relative to the partition base pnode */
        for (pnode = 0; pnode < maskbits; pnode++) {
                int cpu;
                if (!bau_uvhub_isset(pnode, distribution))
                        continue;
                apnode = pnode + bcp->partition_base_pnode;
                cpu = pnode_to_first_cpu(apnode, smaster);
                cpumask_set_cpu(cpu, mask);
        }

        /* IPI all cpus; preemption is already disabled */
        smp_call_function_many(mask, do_reset, (void *)&reset_args, 1);
        return;
}

/*
 * Not to be confused with cycles_2_ns() from tsc.c; this gives a relative
 * number, not an absolute. It converts a duration in cycles to a duration in
 * ns.
 */
static inline unsigned long long cycles_2_ns(unsigned long long cyc)
{
        struct cyc2ns_data data;
        unsigned long long ns;

        cyc2ns_read_begin(&data);
        ns = mul_u64_u32_shr(cyc, data.cyc2ns_mul, data.cyc2ns_shift);
        cyc2ns_read_end();

        return ns;
}

/*
 * The reverse of the above; converts a duration in ns to a duration in cycles.
 */
static inline unsigned long long ns_2_cycles(unsigned long long ns)
{
        struct cyc2ns_data data;
        unsigned long long cyc;

        cyc2ns_read_begin(&data);
        cyc = (ns << data.cyc2ns_shift) / data.cyc2ns_mul;
        cyc2ns_read_end();

        return cyc;
}

static inline unsigned long cycles_2_us(unsigned long long cyc)
{
        return cycles_2_ns(cyc) / NSEC_PER_USEC;
}

static inline cycles_t sec_2_cycles(unsigned long sec)
{
        return ns_2_cycles(sec * NSEC_PER_SEC);
}

static inline unsigned long long usec_2_cycles(unsigned long usec)
{
        return ns_2_cycles(usec * NSEC_PER_USEC);
}

/*
 * wait for all cpus on this hub to finish their sends and go quiet
 * leaves uvhub_quiesce set so that no new broadcasts are started by
 * bau_flush_send_and_wait()
 */
static inline void quiesce_local_uvhub(struct bau_control *hmaster)
{
        atom_asr(1, (struct atomic_short *)&hmaster->uvhub_quiesce);
}

/*
 * mark this quiet-requestor as done
 */
static inline void end_uvhub_quiesce(struct bau_control *hmaster)
{
        atom_asr(-1, (struct atomic_short *)&hmaster->uvhub_quiesce);
}

/*
 * UV2 could have an extra bit of status in the ACTIVATION_STATUS_2 register.
 * But not currently used.
 */
static unsigned long uv2_3_read_status(unsigned long offset, int rshft, int desc)
{
        return ((read_lmmr(offset) >> rshft) & UV_ACT_STATUS_MASK) << 1;
}

/*
 * Entered when a bau descriptor has gone into a permanent busy wait because
 * of a hardware bug.
 * Workaround the bug.
 */
static int handle_uv2_busy(struct bau_control *bcp)
{
        struct ptc_stats *stat = bcp->statp;

        stat->s_uv2_wars++;
        bcp->busy = 1;
        return FLUSH_GIVEUP;
}

static int uv2_3_wait_completion(struct bau_desc *bau_desc,
                                struct bau_control *bcp, long try)
{
        unsigned long descriptor_stat;
        cycles_t ttm;
        u64 mmr_offset = bcp->status_mmr;
        int right_shift = bcp->status_index;
        int desc = bcp->uvhub_cpu;
        long busy_reps = 0;
        struct ptc_stats *stat = bcp->statp;

        descriptor_stat = uv2_3_read_status(mmr_offset, right_shift, desc);

        /* spin on the status MMR, waiting for it to go idle */
        while (descriptor_stat != UV2H_DESC_IDLE) {
                if (descriptor_stat == UV2H_DESC_SOURCE_TIMEOUT) {
                        /*
                         * A h/w bug on the destination side may
                         * have prevented the message being marked
                         * pending, thus it doesn't get replied to
                         * and gets continually nacked until it times
                         * out with a SOURCE_TIMEOUT.
                         */
                        stat->s_stimeout++;
                        return FLUSH_GIVEUP;
                } else if (descriptor_stat == UV2H_DESC_DEST_TIMEOUT) {
                        ttm = get_cycles();

                        /*
                         * Our retries may be blocked by all destination
                         * swack resources being consumed, and a timeout
                         * pending.  In that case hardware returns the
                         * ERROR that looks like a destination timeout.
                         * Without using the extended status we have to
                         * deduce from the short time that this was a
                         * strong nack.
                         */
                        if (cycles_2_us(ttm - bcp->send_message) < timeout_us) {
                                bcp->conseccompletes = 0;
                                stat->s_plugged++;
                                /* FLUSH_RETRY_PLUGGED causes hang on boot */
                                return FLUSH_GIVEUP;
                        }
                        stat->s_dtimeout++;
                        bcp->conseccompletes = 0;
                        /* FLUSH_RETRY_TIMEOUT causes hang on boot */
                        return FLUSH_GIVEUP;
                } else {
                        busy_reps++;
                        if (busy_reps > 1000000) {
                                /* not to hammer on the clock */
                                busy_reps = 0;
                                ttm = get_cycles();
                                if ((ttm - bcp->send_message) > bcp->timeout_interval)
                                        return handle_uv2_busy(bcp);
                        }
                        /*
                         * descriptor_stat is still BUSY
                         */
                        cpu_relax();
                }
                descriptor_stat = uv2_3_read_status(mmr_offset, right_shift, desc);
        }
        bcp->conseccompletes++;
        return FLUSH_COMPLETE;
}

/*
 * Returns the status of current BAU message for cpu desc as a bit field
 * [Error][Busy][Aux]
 */
static u64 read_status(u64 status_mmr, int index, int desc)
{
        u64 stat;

        stat = ((read_lmmr(status_mmr) >> index) & UV_ACT_STATUS_MASK) << 1;
        stat |= (read_lmmr(UVH_LB_BAU_SB_ACTIVATION_STATUS_2) >> desc) & 0x1;

        return stat;
}

static int uv4_wait_completion(struct bau_desc *bau_desc,
                                struct bau_control *bcp, long try)
{
        struct ptc_stats *stat = bcp->statp;
        u64 descriptor_stat;
        u64 mmr = bcp->status_mmr;
        int index = bcp->status_index;
        int desc = bcp->uvhub_cpu;

        descriptor_stat = read_status(mmr, index, desc);

        /* spin on the status MMR, waiting for it to go idle */
        while (descriptor_stat != UV2H_DESC_IDLE) {
                switch (descriptor_stat) {
                case UV2H_DESC_SOURCE_TIMEOUT:
                        stat->s_stimeout++;
                        return FLUSH_GIVEUP;

                case UV2H_DESC_DEST_TIMEOUT:
                        stat->s_dtimeout++;
                        bcp->conseccompletes = 0;
                        return FLUSH_RETRY_TIMEOUT;

                case UV2H_DESC_DEST_STRONG_NACK:
                        stat->s_plugged++;
                        bcp->conseccompletes = 0;
                        return FLUSH_RETRY_PLUGGED;

                case UV2H_DESC_DEST_PUT_ERR:
                        bcp->conseccompletes = 0;
                        return FLUSH_GIVEUP;

                default:
                        /* descriptor_stat is still BUSY */
                        cpu_relax();
                }
                descriptor_stat = read_status(mmr, index, desc);
        }
        bcp->conseccompletes++;
        return FLUSH_COMPLETE;
}

/*
 * Our retries are blocked by all destination sw ack resources being
 * in use, and a timeout is pending. In that case hardware immediately
 * returns the ERROR that looks like a destination timeout.
 */
static void destination_plugged(struct bau_desc *bau_desc,
                        struct bau_control *bcp,
                        struct bau_control *hmaster, struct ptc_stats *stat)
{
        udelay(bcp->plugged_delay);
        bcp->plugged_tries++;

        if (bcp->plugged_tries >= bcp->plugsb4reset) {
                bcp->plugged_tries = 0;

                quiesce_local_uvhub(hmaster);

                spin_lock(&hmaster->queue_lock);
                reset_with_ipi(&bau_desc->distribution, bcp);
                spin_unlock(&hmaster->queue_lock);

                end_uvhub_quiesce(hmaster);

                bcp->ipi_attempts++;
                stat->s_resets_plug++;
        }
}

static void destination_timeout(struct bau_desc *bau_desc,
                        struct bau_control *bcp, struct bau_control *hmaster,
                        struct ptc_stats *stat)
{
        hmaster->max_concurr = 1;
        bcp->timeout_tries++;
        if (bcp->timeout_tries >= bcp->timeoutsb4reset) {
                bcp->timeout_tries = 0;

                quiesce_local_uvhub(hmaster);

                spin_lock(&hmaster->queue_lock);
                reset_with_ipi(&bau_desc->distribution, bcp);
                spin_unlock(&hmaster->queue_lock);

                end_uvhub_quiesce(hmaster);

                bcp->ipi_attempts++;
                stat->s_resets_timeout++;
        }
}

/*
 * Stop all cpus on a uvhub from using the BAU for a period of time.
 * This is reversed by check_enable.
 */
static void disable_for_period(struct bau_control *bcp, struct ptc_stats *stat)
{
        int tcpu;
        struct bau_control *tbcp;
        struct bau_control *hmaster;
        cycles_t tm1;

        hmaster = bcp->uvhub_master;
        spin_lock(&hmaster->disable_lock);
        if (!bcp->baudisabled) {
                stat->s_bau_disabled++;
                tm1 = get_cycles();
                for_each_present_cpu(tcpu) {
                        tbcp = &per_cpu(bau_control, tcpu);
                        if (tbcp->uvhub_master == hmaster) {
                                tbcp->baudisabled = 1;
                                tbcp->set_bau_on_time =
                                        tm1 + bcp->disabled_period;
                        }
                }
        }
        spin_unlock(&hmaster->disable_lock);
}

static void count_max_concurr(int stat, struct bau_control *bcp,
                                struct bau_control *hmaster)
{
        bcp->plugged_tries = 0;
        bcp->timeout_tries = 0;
        if (stat != FLUSH_COMPLETE)
                return;
        if (bcp->conseccompletes <= bcp->complete_threshold)
                return;
        if (hmaster->max_concurr >= hmaster->max_concurr_const)
                return;
        hmaster->max_concurr++;
}

static void record_send_stats(cycles_t time1, cycles_t time2,
                struct bau_control *bcp, struct ptc_stats *stat,
                int completion_status, int try)
{
        cycles_t elapsed;

        if (time2 > time1) {
                elapsed = time2 - time1;
                stat->s_time += elapsed;

                if ((completion_status == FLUSH_COMPLETE) && (try == 1)) {
                        bcp->period_requests++;
                        bcp->period_time += elapsed;
                        if ((elapsed > usec_2_cycles(bcp->cong_response_us)) &&
                            (bcp->period_requests > bcp->cong_reps) &&
                            ((bcp->period_time / bcp->period_requests) >
                                        usec_2_cycles(bcp->cong_response_us))) {
                                stat->s_congested++;
                                disable_for_period(bcp, stat);
                        }
                }
        } else
                stat->s_requestor--;

        if (completion_status == FLUSH_COMPLETE && try > 1)
                stat->s_retriesok++;
        else if (completion_status == FLUSH_GIVEUP) {
                stat->s_giveup++;
                if (get_cycles() > bcp->period_end)
                        bcp->period_giveups = 0;
                bcp->period_giveups++;
                if (bcp->period_giveups == 1)
                        bcp->period_end = get_cycles() + bcp->disabled_period;
                if (bcp->period_giveups > bcp->giveup_limit) {
                        disable_for_period(bcp, stat);
                        stat->s_giveuplimit++;
                }
        }
}

/*
 * Handle the completion status of a message send.
 */
static void handle_cmplt(int completion_status, struct bau_desc *bau_desc,
                        struct bau_control *bcp, struct bau_control *hmaster,
                        struct ptc_stats *stat)
{
        if (completion_status == FLUSH_RETRY_PLUGGED)
                destination_plugged(bau_desc, bcp, hmaster, stat);
        else if (completion_status == FLUSH_RETRY_TIMEOUT)
                destination_timeout(bau_desc, bcp, hmaster, stat);
}

/*
 * Send a broadcast and wait for it to complete.
 *
 * The flush_mask contains the cpus the broadcast is to be sent to including
 * cpus that are on the local uvhub.
 *
 * Returns 0 if all flushing represented in the mask was done.
 * Returns 1 if it gives up entirely and the original cpu mask is to be
 * returned to the kernel.
 */
static int uv_flush_send_and_wait(struct cpumask *flush_mask,
                                  struct bau_control *bcp,
                                  struct bau_desc *bau_desc)
{
        int seq_number = 0;
        int completion_stat = 0;
        long try = 0;
        unsigned long index;
        cycles_t time1;
        cycles_t time2;
        struct ptc_stats *stat = bcp->statp;
        struct bau_control *hmaster = bcp->uvhub_master;
        struct uv2_3_bau_msg_header *uv2_3_hdr = NULL;

        while (hmaster->uvhub_quiesce)
                cpu_relax();

        time1 = get_cycles();
        uv2_3_hdr = &bau_desc->header.uv2_3_hdr;

        do {
                if (try == 0) {
                        uv2_3_hdr->msg_type = MSG_REGULAR;
                        seq_number = bcp->message_number++;
                } else {
                        uv2_3_hdr->msg_type = MSG_RETRY;
                        stat->s_retry_messages++;
                }

                uv2_3_hdr->sequence = seq_number;
                index = (1UL << AS_PUSH_SHIFT) | bcp->uvhub_cpu;
                bcp->send_message = get_cycles();

                write_mmr_activation(index);

                try++;
                completion_stat = ops.wait_completion(bau_desc, bcp, try);

                handle_cmplt(completion_stat, bau_desc, bcp, hmaster, stat);

                if (bcp->ipi_attempts >= bcp->ipi_reset_limit) {
                        bcp->ipi_attempts = 0;
                        stat->s_overipilimit++;
                        completion_stat = FLUSH_GIVEUP;
                        break;
                }
                cpu_relax();
        } while ((completion_stat == FLUSH_RETRY_PLUGGED) ||
                 (completion_stat == FLUSH_RETRY_TIMEOUT));

        time2 = get_cycles();

        count_max_concurr(completion_stat, bcp, hmaster);

        while (hmaster->uvhub_quiesce)
                cpu_relax();

        atomic_dec(&hmaster->active_descriptor_count);

        record_send_stats(time1, time2, bcp, stat, completion_stat, try);

        if (completion_stat == FLUSH_GIVEUP)
                /* FLUSH_GIVEUP will fall back to using IPI's for tlb flush */
                return 1;
        return 0;
}

/*
 * The BAU is disabled for this uvhub. When the disabled time period has
 * expired re-enable it.
 * Return 0 if it is re-enabled for all cpus on this uvhub.
 */
static int check_enable(struct bau_control *bcp, struct ptc_stats *stat)
{
        int tcpu;
        struct bau_control *tbcp;
        struct bau_control *hmaster;

        hmaster = bcp->uvhub_master;
        spin_lock(&hmaster->disable_lock);
        if (bcp->baudisabled && (get_cycles() >= bcp->set_bau_on_time)) {
                stat->s_bau_reenabled++;
                for_each_present_cpu(tcpu) {
                        tbcp = &per_cpu(bau_control, tcpu);
                        if (tbcp->uvhub_master == hmaster) {
                                tbcp->baudisabled = 0;
                                tbcp->period_requests = 0;
                                tbcp->period_time = 0;
                                tbcp->period_giveups = 0;
                        }
                }
                spin_unlock(&hmaster->disable_lock);
                return 0;
        }
        spin_unlock(&hmaster->disable_lock);
        return -1;
}

static void record_send_statistics(struct ptc_stats *stat, int locals, int hubs,
                                int remotes, struct bau_desc *bau_desc)
{
        stat->s_requestor++;
        stat->s_ntargcpu += remotes + locals;
        stat->s_ntargremotes += remotes;
        stat->s_ntarglocals += locals;

        /* uvhub statistics */
        hubs = bau_uvhub_weight(&bau_desc->distribution);
        if (locals) {
                stat->s_ntarglocaluvhub++;
                stat->s_ntargremoteuvhub += (hubs - 1);
        } else
                stat->s_ntargremoteuvhub += hubs;

        stat->s_ntarguvhub += hubs;

        if (hubs >= 16)
                stat->s_ntarguvhub16++;
        else if (hubs >= 8)
                stat->s_ntarguvhub8++;
        else if (hubs >= 4)
                stat->s_ntarguvhub4++;
        else if (hubs >= 2)
                stat->s_ntarguvhub2++;
        else
                stat->s_ntarguvhub1++;
}

/*
 * Translate a cpu mask to the uvhub distribution mask in the BAU
 * activation descriptor.
 */
static int set_distrib_bits(struct cpumask *flush_mask, struct bau_control *bcp,
                        struct bau_desc *bau_desc, int *localsp, int *remotesp)
{
        int cpu;
        int pnode;
        int cnt = 0;
        struct hub_and_pnode *hpp;

        for_each_cpu(cpu, flush_mask) {
                /*
                 * The distribution vector is a bit map of pnodes, relative
                 * to the partition base pnode (and the partition base nasid
                 * in the header).
                 * Translate cpu to pnode and hub using a local memory array.
                 */
                hpp = &bcp->socket_master->thp[cpu];
                pnode = hpp->pnode - bcp->partition_base_pnode;
                bau_uvhub_set(pnode, &bau_desc->distribution);
                cnt++;
                if (hpp->uvhub == bcp->uvhub)
                        (*localsp)++;
                else
                        (*remotesp)++;
        }
        if (!cnt)
                return 1;
        return 0;
}

/*
 * globally purge translation cache of a virtual address or all TLB's
 * @cpumask: mask of all cpu's in which the address is to be removed
 * @mm: mm_struct containing virtual address range
 * @start: start virtual address to be removed from TLB
 * @end: end virtual address to be remove from TLB
 * @cpu: the current cpu
 *
 * This is the entry point for initiating any UV global TLB shootdown.
 *
 * Purges the translation caches of all specified processors of the given
 * virtual address, or purges all TLB's on specified processors.
 *
 * The caller has derived the cpumask from the mm_struct.  This function
 * is called only if there are bits set in the mask. (e.g. flush_tlb_page())
 *
 * The cpumask is converted into a uvhubmask of the uvhubs containing
 * those cpus.
 *
 * Note that this function should be called with preemption disabled.
 *
 * Returns NULL if all remote flushing was done.
 * Returns pointer to cpumask if some remote flushing remains to be
 * done.  The returned pointer is valid till preemption is re-enabled.
 */
const struct cpumask *uv_flush_tlb_others(const struct cpumask *cpumask,
                                          const struct flush_tlb_info *info)
{
        unsigned int cpu = smp_processor_id();
        int locals = 0, remotes = 0, hubs = 0;
        struct bau_desc *bau_desc;
        struct cpumask *flush_mask;
        struct ptc_stats *stat;
        struct bau_control *bcp;
        unsigned long descriptor_status, status, address;

        bcp = &per_cpu(bau_control, cpu);

        if (bcp->nobau)
                return cpumask;

        stat = bcp->statp;
        stat->s_enters++;

        if (bcp->busy) {
                descriptor_status =
                        read_lmmr(UVH_LB_BAU_SB_ACTIVATION_STATUS_0);
                status = ((descriptor_status >> (bcp->uvhub_cpu *
                        UV_ACT_STATUS_SIZE)) & UV_ACT_STATUS_MASK) << 1;
                if (status == UV2H_DESC_BUSY)
                        return cpumask;
                bcp->busy = 0;
        }

        /* bau was disabled due to slow response */
        if (bcp->baudisabled) {
                if (check_enable(bcp, stat)) {
                        stat->s_ipifordisabled++;
                        return cpumask;
                }
        }

        /*
         * Each sending cpu has a per-cpu mask which it fills from the caller's
         * cpu mask.  All cpus are converted to uvhubs and copied to the
         * activation descriptor.
         */
        flush_mask = (struct cpumask *)per_cpu(uv_flush_tlb_mask, cpu);
        /* don't actually do a shootdown of the local cpu */
        cpumask_andnot(flush_mask, cpumask, cpumask_of(cpu));

        if (cpumask_test_cpu(cpu, cpumask))
                stat->s_ntargself++;

        bau_desc = bcp->descriptor_base;
        bau_desc += (ITEMS_PER_DESC * bcp->uvhub_cpu);
        bau_uvhubs_clear(&bau_desc->distribution, UV_DISTRIBUTION_SIZE);
        if (set_distrib_bits(flush_mask, bcp, bau_desc, &locals, &remotes))
                return NULL;

        record_send_statistics(stat, locals, hubs, remotes, bau_desc);

        if (!info->end || (info->end - info->start) <= PAGE_SIZE)
                address = info->start;
        else
                address = TLB_FLUSH_ALL;

        switch (bcp->uvhub_version) {
        case UV_BAU_V2:
        case UV_BAU_V3:
                bau_desc->payload.uv2_3.address = address;
                bau_desc->payload.uv2_3.sending_cpu = cpu;
                break;
        case UV_BAU_V4:
                bau_desc->payload.uv4.address = address;
                bau_desc->payload.uv4.sending_cpu = cpu;
                bau_desc->payload.uv4.qualifier = BAU_DESC_QUALIFIER;
                break;
        }

        /*
         * uv_flush_send_and_wait returns 0 if all cpu's were messaged,
         * or 1 if it gave up and the original cpumask should be returned.
         */
        if (!uv_flush_send_and_wait(flush_mask, bcp, bau_desc))
                return NULL;
        else
                return cpumask;
}

/*
 * Search the message queue for any 'other' unprocessed message with the
 * same software acknowledge resource bit vector as the 'msg' message.
 */
static struct bau_pq_entry *find_another_by_swack(struct bau_pq_entry *msg,
                                                  struct bau_control *bcp)
{
        struct bau_pq_entry *msg_next = msg + 1;
        unsigned char swack_vec = msg->swack_vec;

        if (msg_next > bcp->queue_last)
                msg_next = bcp->queue_first;
        while (msg_next != msg) {
                if ((msg_next->canceled == 0) && (msg_next->replied_to == 0) &&
                                (msg_next->swack_vec == swack_vec))
                        return msg_next;
                msg_next++;
                if (msg_next > bcp->queue_last)
                        msg_next = bcp->queue_first;
        }
        return NULL;
}

/*
 * UV2 needs to work around a bug in which an arriving message has not
 * set a bit in the UVH_LB_BAU_INTD_SOFTWARE_ACKNOWLEDGE register.
 * Such a message must be ignored.
 */
static void process_uv2_message(struct msg_desc *mdp, struct bau_control *bcp)
{
        unsigned long mmr_image;
        unsigned char swack_vec;
        struct bau_pq_entry *msg = mdp->msg;
        struct bau_pq_entry *other_msg;

        mmr_image = ops.read_l_sw_ack();
        swack_vec = msg->swack_vec;

        if ((swack_vec & mmr_image) == 0) {
                /*
                 * This message was assigned a swack resource, but no
                 * reserved acknowlegment is pending.
                 * The bug has prevented this message from setting the MMR.
                 */
                /*
                 * Some message has set the MMR 'pending' bit; it might have
                 * been another message.  Look for that message.
                 */
                other_msg = find_another_by_swack(msg, bcp);
                if (other_msg) {
                        /*
                         * There is another. Process this one but do not
                         * ack it.
                         */
                        bau_process_message(mdp, bcp, 0);
                        /*
                         * Let the natural processing of that other message
                         * acknowledge it. Don't get the processing of sw_ack's
                         * out of order.
                         */
                        return;
                }
        }

        /*
         * Either the MMR shows this one pending a reply or there is no
         * other message using this sw_ack, so it is safe to acknowledge it.
         */
        bau_process_message(mdp, bcp, 1);

        return;
}

/*
 * The BAU message interrupt comes here. (registered by set_intr_gate)
 * See entry_64.S
 *
 * We received a broadcast assist message.
 *
 * Interrupts are disabled; this interrupt could represent
 * the receipt of several messages.
 *
 * All cores/threads on this hub get this interrupt.
 * The last one to see it does the software ack.
 * (the resource will not be freed until noninterruptable cpus see this
 *  interrupt; hardware may timeout the s/w ack and reply ERROR)
 */
DEFINE_IDTENTRY_SYSVEC(sysvec_uv_bau_message)
{
        int count = 0;
        cycles_t time_start;
        struct bau_pq_entry *msg;
        struct bau_control *bcp;
        struct ptc_stats *stat;
        struct msg_desc msgdesc;

        ack_APIC_irq();
        kvm_set_cpu_l1tf_flush_l1d();
        time_start = get_cycles();

        bcp = &per_cpu(bau_control, smp_processor_id());
        stat = bcp->statp;

        msgdesc.queue_first = bcp->queue_first;
        msgdesc.queue_last = bcp->queue_last;

        msg = bcp->bau_msg_head;
        while (msg->swack_vec) {
                count++;

                msgdesc.msg_slot = msg - msgdesc.queue_first;
                msgdesc.msg = msg;
                if (bcp->uvhub_version == UV_BAU_V2)
                        process_uv2_message(&msgdesc, bcp);
                else
                        /* no error workaround for uv3 */
                        bau_process_message(&msgdesc, bcp, 1);

                msg++;
                if (msg > msgdesc.queue_last)
                        msg = msgdesc.queue_first;
                bcp->bau_msg_head = msg;
        }
        stat->d_time += (get_cycles() - time_start);
        if (!count)
                stat->d_nomsg++;
        else if (count > 1)
                stat->d_multmsg++;
}

/*
 * Each target uvhub (i.e. a uvhub that has cpu's) needs to have
 * shootdown message timeouts enabled.  The timeout does not cause
 * an interrupt, but causes an error message to be returned to
 * the sender.
 */
static void __init enable_timeouts(void)
{
        int uvhub;
        int nuvhubs;
        int pnode;
        unsigned long mmr_image;

        nuvhubs = uv_num_possible_blades();

        for (uvhub = 0; uvhub < nuvhubs; uvhub++) {
                if (!uv_blade_nr_possible_cpus(uvhub))
                        continue;

                pnode = uv_blade_to_pnode(uvhub);
                mmr_image = read_mmr_misc_control(pnode);
                /*
                 * Set the timeout period and then lock it in, in three
                 * steps; captures and locks in the period.
                 *
                 * To program the period, the SOFT_ACK_MODE must be off.
                 */
                mmr_image &= ~(1L << SOFTACK_MSHIFT);
                write_mmr_misc_control(pnode, mmr_image);
                /*
                 * Set the 4-bit period.
                 */
                mmr_image &= ~((unsigned long)0xf << SOFTACK_PSHIFT);
                mmr_image |= (SOFTACK_TIMEOUT_PERIOD << SOFTACK_PSHIFT);
                write_mmr_misc_control(pnode, mmr_image);

                mmr_image |= (1L << SOFTACK_MSHIFT);
                if (is_uv2_hub()) {
                        /* do not touch the legacy mode bit */
                        /* hw bug workaround; do not use extended status */
                        mmr_image &= ~(1L << UV2_EXT_SHFT);
                } else if (is_uv3_hub()) {
                        mmr_image &= ~(1L << PREFETCH_HINT_SHFT);
                        mmr_image |= (1L << SB_STATUS_SHFT);
                }
                write_mmr_misc_control(pnode, mmr_image);
        }
}

static void *ptc_seq_start(struct seq_file *file, loff_t *offset)
{
        if (*offset < num_possible_cpus())
                return offset;
        return NULL;
}

static void *ptc_seq_next(struct seq_file *file, void *data, loff_t *offset)
{
        (*offset)++;
        if (*offset < num_possible_cpus())
                return offset;
        return NULL;
}

static void ptc_seq_stop(struct seq_file *file, void *data)
{
}

/*
 * Display the statistics thru /proc/sgi_uv/ptc_statistics
 * 'data' points to the cpu number
 * Note: see the descriptions in stat_description[].
 */
static int ptc_seq_show(struct seq_file *file, void *data)
{
        struct ptc_stats *stat;
        struct bau_control *bcp;
        int cpu;

        cpu = *(loff_t *)data;
        if (!cpu) {
                seq_puts(file,
                         "# cpu bauoff sent stime self locals remotes ncpus localhub ");
                seq_puts(file, "remotehub numuvhubs numuvhubs16 numuvhubs8 ");
                seq_puts(file,
                         "numuvhubs4 numuvhubs2 numuvhubs1 dto snacks retries ");
                seq_puts(file,
                         "rok resetp resett giveup sto bz throt disable ");
                seq_puts(file,
                         "enable wars warshw warwaits enters ipidis plugged ");
                seq_puts(file,
                         "ipiover glim cong swack recv rtime all one mult ");
                seq_puts(file, "none retry canc nocan reset rcan\n");
        }
        if (cpu < num_possible_cpus() && cpu_online(cpu)) {
                bcp = &per_cpu(bau_control, cpu);
                if (bcp->nobau) {
                        seq_printf(file, "cpu %d bau disabled\n", cpu);
                        return 0;
                }
                stat = bcp->statp;
                /* source side statistics */
                seq_printf(file,
                        "cpu %d %d %ld %ld %ld %ld %ld %ld %ld %ld %ld %ld ",
                           cpu, bcp->nobau, stat->s_requestor,
                           cycles_2_us(stat->s_time),
                           stat->s_ntargself, stat->s_ntarglocals,
                           stat->s_ntargremotes, stat->s_ntargcpu,
                           stat->s_ntarglocaluvhub, stat->s_ntargremoteuvhub,
                           stat->s_ntarguvhub, stat->s_ntarguvhub16);
                seq_printf(file, "%ld %ld %ld %ld %ld %ld ",
                           stat->s_ntarguvhub8, stat->s_ntarguvhub4,
                           stat->s_ntarguvhub2, stat->s_ntarguvhub1,
                           stat->s_dtimeout, stat->s_strongnacks);
                seq_printf(file, "%ld %ld %ld %ld %ld %ld %ld %ld ",
                           stat->s_retry_messages, stat->s_retriesok,
                           stat->s_resets_plug, stat->s_resets_timeout,
                           stat->s_giveup, stat->s_stimeout,
                           stat->s_busy, stat->s_throttles);
                seq_printf(file, "%ld %ld %ld %ld %ld %ld %ld %ld %ld %ld %ld ",
                           stat->s_bau_disabled, stat->s_bau_reenabled,
                           stat->s_uv2_wars, stat->s_uv2_wars_hw,
                           stat->s_uv2_war_waits, stat->s_enters,
                           stat->s_ipifordisabled, stat->s_plugged,
                           stat->s_overipilimit, stat->s_giveuplimit,
                           stat->s_congested);

                /* destination side statistics */
                seq_printf(file,
                        "%lx %ld %ld %ld %ld %ld %ld %ld %ld %ld %ld %ld\n",
                           ops.read_g_sw_ack(uv_cpu_to_pnode(cpu)),
                           stat->d_requestee, cycles_2_us(stat->d_time),
                           stat->d_alltlb, stat->d_onetlb, stat->d_multmsg,
                           stat->d_nomsg, stat->d_retries, stat->d_canceled,
                           stat->d_nocanceled, stat->d_resets,
                           stat->d_rcanceled);
        }
        return 0;
}

/*
 * Display the tunables thru debugfs
 */
static ssize_t tunables_read(struct file *file, char __user *userbuf,
                                size_t count, loff_t *ppos)
{
        char *buf;
        int ret;

        buf = kasprintf(GFP_KERNEL, "%s %s %s\n%d %d %d %d %d %d %d %d %d %d\n",
                "max_concur plugged_delay plugsb4reset timeoutsb4reset",
                "ipi_reset_limit complete_threshold congested_response_us",
                "congested_reps disabled_period giveup_limit",
                max_concurr, plugged_delay, plugsb4reset,
                timeoutsb4reset, ipi_reset_limit, complete_threshold,
                congested_respns_us, congested_reps, disabled_period,
                giveup_limit);

        if (!buf)
                return -ENOMEM;

        ret = simple_read_from_buffer(userbuf, count, ppos, buf, strlen(buf));
        kfree(buf);
        return ret;
}

/*
 * handle a write to /proc/sgi_uv/ptc_statistics
 * -1: reset the statistics
 *  0: display meaning of the statistics
 */
static ssize_t ptc_proc_write(struct file *file, const char __user *user,
                                size_t count, loff_t *data)
{
        int cpu;
        int i;
        int elements;
        long input_arg;
        char optstr[64];
        struct ptc_stats *stat;

        if (count == 0 || count > sizeof(optstr))
                return -EINVAL;
        if (copy_from_user(optstr, user, count))
                return -EFAULT;
        optstr[count - 1] = '\0';

        if (!strcmp(optstr, "on")) {
                set_bau_on();
                return count;
        } else if (!strcmp(optstr, "off")) {
                set_bau_off();
                return count;
        }

        if (kstrtol(optstr, 10, &input_arg) < 0) {
                pr_debug("%s is invalid\n", optstr);
                return -EINVAL;
        }

        if (input_arg == 0) {
                elements = ARRAY_SIZE(stat_description);
                pr_debug("# cpu:      cpu number\n");
                pr_debug("Sender statistics:\n");
                for (i = 0; i < elements; i++)
                        pr_debug("%s\n", stat_description[i]);
        } else if (input_arg == -1) {
                for_each_present_cpu(cpu) {
                        stat = &per_cpu(ptcstats, cpu);
                        memset(stat, 0, sizeof(struct ptc_stats));
                }
        }

        return count;
}

static int local_atoi(const char *name)
{
        int val = 0;

        for (;; name++) {
                switch (*name) {
                case '0' ... '9':
                        val = 10*val+(*name-'0');
                        break;
                default:
                        return val;
                }
        }
}

/*
 * Parse the values written to /sys/kernel/debug/sgi_uv/bau_tunables.
 * Zero values reset them to defaults.
 */
static int parse_tunables_write(struct bau_control *bcp, char *instr,
                                int count)
{
        char *p;
        char *q;
        int cnt = 0;
        int val;
        int e = ARRAY_SIZE(tunables);

        p = instr + strspn(instr, WHITESPACE);
        q = p;
        for (; *p; p = q + strspn(q, WHITESPACE)) {
                q = p + strcspn(p, WHITESPACE);
                cnt++;
                if (q == p)
                        break;
        }
        if (cnt != e) {
                pr_info("bau tunable error: should be %d values\n", e);
                return -EINVAL;
        }

        p = instr + strspn(instr, WHITESPACE);
        q = p;
        for (cnt = 0; *p; p = q + strspn(q, WHITESPACE), cnt++) {
                q = p + strcspn(p, WHITESPACE);
                val = local_atoi(p);
                switch (cnt) {
                case 0:
                        if (val == 0) {
                                max_concurr = MAX_BAU_CONCURRENT;
                                max_concurr_const = MAX_BAU_CONCURRENT;
                                continue;
                        }
                        if (val < 1 || val > bcp->cpus_in_uvhub) {
                                pr_debug(
                                "Error: BAU max concurrent %d is invalid\n",
                                val);
                                return -EINVAL;
                        }
                        max_concurr = val;
                        max_concurr_const = val;
                        continue;
                default:
                        if (val == 0)
                                *tunables[cnt].tunp = tunables[cnt].deflt;
                        else
                                *tunables[cnt].tunp = val;
                        continue;
                }
        }
        return 0;
}

/*
 * Handle a write to debugfs. (/sys/kernel/debug/sgi_uv/bau_tunables)
 */
static ssize_t tunables_write(struct file *file, const char __user *user,
                                size_t count, loff_t *data)
{
        int cpu;
        int ret;
        char instr[100];
        struct bau_control *bcp;

        if (count == 0 || count > sizeof(instr)-1)
                return -EINVAL;
        if (copy_from_user(instr, user, count))
                return -EFAULT;

        instr[count] = '\0';

        cpu = get_cpu();
        bcp = &per_cpu(bau_control, cpu);
        ret = parse_tunables_write(bcp, instr, count);
        put_cpu();
        if (ret)
                return ret;

        for_each_present_cpu(cpu) {
                bcp = &per_cpu(bau_control, cpu);
                bcp->max_concurr         = max_concurr;
                bcp->max_concurr_const   = max_concurr;
                bcp->plugged_delay       = plugged_delay;
                bcp->plugsb4reset        = plugsb4reset;
                bcp->timeoutsb4reset     = timeoutsb4reset;
                bcp->ipi_reset_limit     = ipi_reset_limit;
                bcp->complete_threshold  = complete_threshold;
                bcp->cong_response_us    = congested_respns_us;
                bcp->cong_reps           = congested_reps;
                bcp->disabled_period     = sec_2_cycles(disabled_period);
                bcp->giveup_limit        = giveup_limit;
        }
        return count;
}

static const struct seq_operations uv_ptc_seq_ops = {
        .start          = ptc_seq_start,
        .next           = ptc_seq_next,
        .stop           = ptc_seq_stop,
        .show           = ptc_seq_show
};

static int ptc_proc_open(struct inode *inode, struct file *file)
{
        return seq_open(file, &uv_ptc_seq_ops);
}

static int tunables_open(struct inode *inode, struct file *file)
{
        return 0;
}

static const struct proc_ops uv_ptc_proc_ops = {
        .proc_open      = ptc_proc_open,
        .proc_read      = seq_read,
        .proc_write     = ptc_proc_write,
        .proc_lseek     = seq_lseek,
        .proc_release   = seq_release,
};

static const struct file_operations tunables_fops = {
        .open           = tunables_open,
        .read           = tunables_read,
        .write          = tunables_write,
        .llseek         = default_llseek,
};

static int __init uv_ptc_init(void)
{
        struct proc_dir_entry *proc_uv_ptc;

        if (!is_uv_system())
                return 0;

        proc_uv_ptc = proc_create(UV_PTC_BASENAME, 0444, NULL,
                                  &uv_ptc_proc_ops);
        if (!proc_uv_ptc) {
                pr_err("unable to create %s proc entry\n",
                       UV_PTC_BASENAME);
                return -EINVAL;
        }

        tunables_dir = debugfs_create_dir(UV_BAU_TUNABLES_DIR, NULL);
        debugfs_create_file(UV_BAU_TUNABLES_FILE, 0600, tunables_dir, NULL,
                            &tunables_fops);
        return 0;
}

/*
 * Initialize the sending side's sending buffers.
 */
static void activation_descriptor_init(int node, int pnode, int base_pnode)
{
        int i;
        int cpu;
        unsigned long gpa;
        unsigned long m;
        unsigned long n;
        size_t dsize;
        struct bau_desc *bau_desc;
        struct bau_desc *bd2;
        struct uv2_3_bau_msg_header *uv2_3_hdr;
        struct bau_control *bcp;

        /*
         * each bau_desc is 64 bytes; there are 8 (ITEMS_PER_DESC)
         * per cpu; and one per cpu on the uvhub (ADP_SZ)
         */
        dsize = sizeof(struct bau_desc) * ADP_SZ * ITEMS_PER_DESC;
        bau_desc = kmalloc_node(dsize, GFP_KERNEL, node);
        BUG_ON(!bau_desc);

        gpa = uv_gpa(bau_desc);
        n = uv_gpa_to_gnode(gpa);
        m = ops.bau_gpa_to_offset(gpa);

        /* the 14-bit pnode */
        write_mmr_descriptor_base(pnode,
                (n << UVH_LB_BAU_SB_DESCRIPTOR_BASE_NODE_ID_SHFT | m));
        /*
         * Initializing all 8 (ITEMS_PER_DESC) descriptors for each
         * cpu even though we only use the first one; one descriptor can
         * describe a broadcast to 256 uv hubs.
         */
        for (i = 0, bd2 = bau_desc; i < (ADP_SZ * ITEMS_PER_DESC); i++, bd2++) {
                memset(bd2, 0, sizeof(struct bau_desc));
                /*
                 * BIOS uses legacy mode, but uv2 and uv3 hardware always
                 * uses native mode for selective broadcasts.
                 */
                uv2_3_hdr = &bd2->header.uv2_3_hdr;
                uv2_3_hdr->swack_flag      = 1;
                uv2_3_hdr->base_dest_nasid = UV_PNODE_TO_NASID(base_pnode);
                uv2_3_hdr->dest_subnodeid  = UV_LB_SUBNODEID;
                uv2_3_hdr->command         = UV_NET_ENDPOINT_INTD;
        }
        for_each_present_cpu(cpu) {
                if (pnode != uv_blade_to_pnode(uv_cpu_to_blade_id(cpu)))
                        continue;
                bcp = &per_cpu(bau_control, cpu);
                bcp->descriptor_base = bau_desc;
        }
}

/*
 * initialize the destination side's receiving buffers
 * entered for each uvhub in the partition
 * - node is first node (kernel memory notion) on the uvhub
 * - pnode is the uvhub's physical identifier
 */
static void pq_init(int node, int pnode)
{
        int cpu;
        size_t plsize;
        char *cp;
        void *vp;
        unsigned long gnode, first, last, tail;
        struct bau_pq_entry *pqp;
        struct bau_control *bcp;

        plsize = (DEST_Q_SIZE + 1) * sizeof(struct bau_pq_entry);
        vp = kmalloc_node(plsize, GFP_KERNEL, node);
        BUG_ON(!vp);

        pqp = (struct bau_pq_entry *)vp;
        cp = (char *)pqp + 31;
        pqp = (struct bau_pq_entry *)(((unsigned long)cp >> 5) << 5);

        for_each_present_cpu(cpu) {
                if (pnode != uv_cpu_to_pnode(cpu))
                        continue;
                /* for every cpu on this pnode: */
                bcp = &per_cpu(bau_control, cpu);
                bcp->queue_first        = pqp;
                bcp->bau_msg_head       = pqp;
                bcp->queue_last         = pqp + (DEST_Q_SIZE - 1);
        }

        first = ops.bau_gpa_to_offset(uv_gpa(pqp));
        last = ops.bau_gpa_to_offset(uv_gpa(pqp + (DEST_Q_SIZE - 1)));

        /*
         * Pre UV4, the gnode is required to locate the payload queue
         * and the payload queue tail must be maintained by the kernel.
         */
        bcp = &per_cpu(bau_control, smp_processor_id());
        if (bcp->uvhub_version <= UV_BAU_V3) {
                tail = first;
                gnode = uv_gpa_to_gnode(uv_gpa(pqp));
                first = (gnode << UV_PAYLOADQ_GNODE_SHIFT) | tail;
                write_mmr_payload_tail(pnode, tail);
        }

        ops.write_payload_first(pnode, first);
        ops.write_payload_last(pnode, last);

        /* in effect, all msg_type's are set to MSG_NOOP */
        memset(pqp, 0, sizeof(struct bau_pq_entry) * DEST_Q_SIZE);
}

/*
 * Initialization of each UV hub's structures
 */
static void __init init_uvhub(int uvhub, int vector, int base_pnode)
{
        int node;
        int pnode;
        unsigned long apicid;

        node = uvhub_to_first_node(uvhub);
        pnode = uv_blade_to_pnode(uvhub);

        activation_descriptor_init(node, pnode, base_pnode);

        pq_init(node, pnode);
        /*
         * The below initialization can't be in firmware because the
         * messaging IRQ will be determined by the OS.
         */
        apicid = uvhub_to_first_apicid(uvhub);
        write_mmr_data_config(pnode, ((apicid << 32) | vector));
}

/*
 * We will set BAU_MISC_CONTROL with a timeout period.
 * But the BIOS has set UVH_AGING_PRESCALE_SEL and UVH_TRANSACTION_TIMEOUT.
 * So the destination timeout period has to be calculated from them.
 */
static int calculate_destination_timeout(void)
{
        unsigned long mmr_image;
        int mult1;
        int base;
        int ret;

        /* same destination timeout for uv2 and uv3 */
        /* 4 bits  0/1 for 10/80us base, 3 bits of multiplier */
        mmr_image = uv_read_local_mmr(UVH_LB_BAU_MISC_CONTROL);
        mmr_image = (mmr_image & UV_SA_MASK) >> UV_SA_SHFT;
        if (mmr_image & (1L << UV2_ACK_UNITS_SHFT))
                base = 80;
        else
                base = 10;
        mult1 = mmr_image & UV2_ACK_MASK;
        ret = mult1 * base;

        return ret;
}

static void __init init_per_cpu_tunables(void)
{
        int cpu;
        struct bau_control *bcp;

        for_each_present_cpu(cpu) {
                bcp = &per_cpu(bau_control, cpu);
                bcp->baudisabled                = 0;
                if (nobau)
                        bcp->nobau              = true;
                bcp->statp                      = &per_cpu(ptcstats, cpu);
                /* time interval to catch a hardware stay-busy bug */
                bcp->timeout_interval           = usec_2_cycles(2*timeout_us);
                bcp->max_concurr                = max_concurr;
                bcp->max_concurr_const          = max_concurr;
                bcp->plugged_delay              = plugged_delay;
                bcp->plugsb4reset               = plugsb4reset;
                bcp->timeoutsb4reset            = timeoutsb4reset;
                bcp->ipi_reset_limit            = ipi_reset_limit;
                bcp->complete_threshold         = complete_threshold;
                bcp->cong_response_us           = congested_respns_us;
                bcp->cong_reps                  = congested_reps;
                bcp->disabled_period            = sec_2_cycles(disabled_period);
                bcp->giveup_limit               = giveup_limit;
                spin_lock_init(&bcp->queue_lock);
                spin_lock_init(&bcp->uvhub_lock);
                spin_lock_init(&bcp->disable_lock);
        }
}

/*
 * Scan all cpus to collect blade and socket summaries.
 */
static int __init get_cpu_topology(int base_pnode,
                                        struct uvhub_desc *uvhub_descs,
                                        unsigned char *uvhub_mask)
{
        int cpu;
        int pnode;
        int uvhub;
        int socket;
        struct bau_control *bcp;
        struct uvhub_desc *bdp;
        struct socket_desc *sdp;

        for_each_present_cpu(cpu) {
                bcp = &per_cpu(bau_control, cpu);

                memset(bcp, 0, sizeof(struct bau_control));

                pnode = uv_cpu_hub_info(cpu)->pnode;
                if ((pnode - base_pnode) >= UV_DISTRIBUTION_SIZE) {
                        pr_emerg(
                                "cpu %d pnode %d-%d beyond %d; BAU disabled\n",
                                cpu, pnode, base_pnode, UV_DISTRIBUTION_SIZE);
                        return 1;
                }

                bcp->osnode = cpu_to_node(cpu);
                bcp->partition_base_pnode = base_pnode;

                uvhub = uv_cpu_hub_info(cpu)->numa_blade_id;
                *(uvhub_mask + (uvhub/8)) |= (1 << (uvhub%8));
                bdp = &uvhub_descs[uvhub];

                bdp->num_cpus++;
                bdp->uvhub = uvhub;
                bdp->pnode = pnode;

                /* kludge: 'assuming' one node per socket, and assuming that
                   disabling a socket just leaves a gap in node numbers */
                socket = bcp->osnode & 1;
                bdp->socket_mask |= (1 << socket);
                sdp = &bdp->socket[socket];
                sdp->cpu_number[sdp->num_cpus] = cpu;
                sdp->num_cpus++;
                if (sdp->num_cpus > MAX_CPUS_PER_SOCKET) {
                        pr_emerg("%d cpus per socket invalid\n",
                                sdp->num_cpus);
                        return 1;
                }
        }
        return 0;
}

/*
 * Each socket is to get a local array of pnodes/hubs.
 */
static void make_per_cpu_thp(struct bau_control *smaster)
{
        int cpu;
        size_t hpsz = sizeof(struct hub_and_pnode) * num_possible_cpus();

        smaster->thp = kzalloc_node(hpsz, GFP_KERNEL, smaster->osnode);
        for_each_present_cpu(cpu) {
                smaster->thp[cpu].pnode = uv_cpu_hub_info(cpu)->pnode;
                smaster->thp[cpu].uvhub = uv_cpu_hub_info(cpu)->numa_blade_id;
        }
}

/*
 * Each uvhub is to get a local cpumask.
 */
static void make_per_hub_cpumask(struct bau_control *hmaster)
{
        int sz = sizeof(cpumask_t);

        hmaster->cpumask = kzalloc_node(sz, GFP_KERNEL, hmaster->osnode);
}

/*
 * Initialize all the per_cpu information for the cpu's on a given socket,
 * given what has been gathered into the socket_desc struct.
 * And reports the chosen hub and socket masters back to the caller.
 */
static int scan_sock(struct socket_desc *sdp, struct uvhub_desc *bdp,
                        struct bau_control **smasterp,
                        struct bau_control **hmasterp)
{
        int i, cpu, uvhub_cpu;
        struct bau_control *bcp;

        for (i = 0; i < sdp->num_cpus; i++) {
                cpu = sdp->cpu_number[i];
                bcp = &per_cpu(bau_control, cpu);
                bcp->cpu = cpu;
                if (i == 0) {
                        *smasterp = bcp;
                        if (!(*hmasterp))
                                *hmasterp = bcp;
                }
                bcp->cpus_in_uvhub = bdp->num_cpus;
                bcp->cpus_in_socket = sdp->num_cpus;
                bcp->socket_master = *smasterp;
                bcp->uvhub = bdp->uvhub;
                if (is_uv2_hub())
                        bcp->uvhub_version = UV_BAU_V2;
                else if (is_uv3_hub())
                        bcp->uvhub_version = UV_BAU_V3;
                else if (is_uv4_hub())
                        bcp->uvhub_version = UV_BAU_V4;
                else {
                        pr_emerg("uvhub version not 1, 2, 3, or 4\n");
                        return 1;
                }
                bcp->uvhub_master = *hmasterp;
                uvhub_cpu = uv_cpu_blade_processor_id(cpu);
                bcp->uvhub_cpu = uvhub_cpu;

                /*
                 * The ERROR and BUSY status registers are located pairwise over
                 * the STATUS_0 and STATUS_1 mmrs; each an array[32] of 2 bits.
                 */
                if (uvhub_cpu < UV_CPUS_PER_AS) {
                        bcp->status_mmr = UVH_LB_BAU_SB_ACTIVATION_STATUS_0;
                        bcp->status_index = uvhub_cpu * UV_ACT_STATUS_SIZE;
                } else {
                        bcp->status_mmr = UVH_LB_BAU_SB_ACTIVATION_STATUS_1;
                        bcp->status_index = (uvhub_cpu - UV_CPUS_PER_AS)
                                                * UV_ACT_STATUS_SIZE;
                }

                if (bcp->uvhub_cpu >= MAX_CPUS_PER_UVHUB) {
                        pr_emerg("%d cpus per uvhub invalid\n",
                                bcp->uvhub_cpu);
                        return 1;
                }
        }
        return 0;
}

/*
 * Summarize the blade and socket topology into the per_cpu structures.
 */
static int __init summarize_uvhub_sockets(int nuvhubs,
                        struct uvhub_desc *uvhub_descs,
                        unsigned char *uvhub_mask)
{
        int socket;
        int uvhub;
        unsigned short socket_mask;

        for (uvhub = 0; uvhub < nuvhubs; uvhub++) {
                struct uvhub_desc *bdp;
                struct bau_control *smaster = NULL;
                struct bau_control *hmaster = NULL;

                if (!(*(uvhub_mask + (uvhub/8)) & (1 << (uvhub%8))))
                        continue;

                bdp = &uvhub_descs[uvhub];
                socket_mask = bdp->socket_mask;
                socket = 0;
                while (socket_mask) {
                        struct socket_desc *sdp;
                        if ((socket_mask & 1)) {
                                sdp = &bdp->socket[socket];
                                if (scan_sock(sdp, bdp, &smaster, &hmaster))
                                        return 1;
                                make_per_cpu_thp(smaster);
                        }
                        socket++;
                        socket_mask = (socket_mask >> 1);
                }
                make_per_hub_cpumask(hmaster);
        }
        return 0;
}

/*
 * initialize the bau_control structure for each cpu
 */
static int __init init_per_cpu(int nuvhubs, int base_part_pnode)
{
        struct uvhub_desc *uvhub_descs;
        unsigned char *uvhub_mask = NULL;

        if (is_uv3_hub() || is_uv2_hub())
                timeout_us = calculate_destination_timeout();

        uvhub_descs = kcalloc(nuvhubs, sizeof(struct uvhub_desc), GFP_KERNEL);
        if (!uvhub_descs)
                goto fail;

        uvhub_mask = kzalloc((nuvhubs+7)/8, GFP_KERNEL);
        if (!uvhub_mask)
                goto fail;

        if (get_cpu_topology(base_part_pnode, uvhub_descs, uvhub_mask))
                goto fail;

        if (summarize_uvhub_sockets(nuvhubs, uvhub_descs, uvhub_mask))
                goto fail;

        kfree(uvhub_descs);
        kfree(uvhub_mask);
        init_per_cpu_tunables();
        return 0;

fail:
        kfree(uvhub_descs);
        kfree(uvhub_mask);
        return 1;
}

static const struct bau_operations uv2_3_bau_ops __initconst = {
        .bau_gpa_to_offset       = uv_gpa_to_offset,
        .read_l_sw_ack           = read_mmr_sw_ack,
        .read_g_sw_ack           = read_gmmr_sw_ack,
        .write_l_sw_ack          = write_mmr_sw_ack,
        .write_g_sw_ack          = write_gmmr_sw_ack,
        .write_payload_first     = write_mmr_payload_first,
        .write_payload_last      = write_mmr_payload_last,

        .wait_completion         = uv2_3_wait_completion,
};

static const struct bau_operations uv4_bau_ops __initconst = {
        .bau_gpa_to_offset       = uv_gpa_to_soc_phys_ram,
        .read_l_sw_ack           = read_mmr_proc_sw_ack,
        .read_g_sw_ack           = read_gmmr_proc_sw_ack,
        .write_l_sw_ack          = write_mmr_proc_sw_ack,
        .write_g_sw_ack          = write_gmmr_proc_sw_ack,
        .write_payload_first     = write_mmr_proc_payload_first,
        .write_payload_last      = write_mmr_proc_payload_last,
        .wait_completion         = uv4_wait_completion,
};

/*
 * Initialization of BAU-related structures
 */
static int __init uv_bau_init(void)
{
        int uvhub;
        int pnode;
        int nuvhubs;
        int cur_cpu;
        int cpus;
        int vector;
        cpumask_var_t *mask;

        if (!is_uv_system())
                return 0;

        if (is_uv4_hub())
                ops = uv4_bau_ops;
        else if (is_uv3_hub())
                ops = uv2_3_bau_ops;
        else if (is_uv2_hub())
                ops = uv2_3_bau_ops;

        nuvhubs = uv_num_possible_blades();
        if (nuvhubs < 2) {
                pr_crit("UV: BAU disabled - insufficient hub count\n");
                goto err_bau_disable;
        }

        for_each_possible_cpu(cur_cpu) {
                mask = &per_cpu(uv_flush_tlb_mask, cur_cpu);
                zalloc_cpumask_var_node(mask, GFP_KERNEL, cpu_to_node(cur_cpu));
        }

        uv_base_pnode = 0x7fffffff;
        for (uvhub = 0; uvhub < nuvhubs; uvhub++) {
                cpus = uv_blade_nr_possible_cpus(uvhub);
                if (cpus && (uv_blade_to_pnode(uvhub) < uv_base_pnode))
                        uv_base_pnode = uv_blade_to_pnode(uvhub);
        }

        /* software timeouts are not supported on UV4 */
        if (is_uv3_hub() || is_uv2_hub())
                enable_timeouts();

        if (init_per_cpu(nuvhubs, uv_base_pnode)) {
                pr_crit("UV: BAU disabled - per CPU init failed\n");
                goto err_bau_disable;
        }

        vector = UV_BAU_MESSAGE;
        for_each_possible_blade(uvhub) {
                if (uv_blade_nr_possible_cpus(uvhub))
                        init_uvhub(uvhub, vector, uv_base_pnode);
        }

        for_each_possible_blade(uvhub) {
                if (uv_blade_nr_possible_cpus(uvhub)) {
                        unsigned long val;
                        unsigned long mmr;
                        pnode = uv_blade_to_pnode(uvhub);
                        /* INIT the bau */
                        val = 1L << 63;
                        write_gmmr_activation(pnode, val);
                        mmr = 1; /* should be 1 to broadcast to both sockets */
                        write_mmr_data_broadcast(pnode, mmr);
                }
        }

        return 0;

err_bau_disable:

        for_each_possible_cpu(cur_cpu)
                free_cpumask_var(per_cpu(uv_flush_tlb_mask, cur_cpu));

        set_bau_off();
        nobau_perm = 1;

        return -EINVAL;
}
core_initcall(uv_bau_init);
fs_initcall(uv_ptc_init);