tlb_uv.c

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/*
 *  SGI UltraViolet TLB flush routines.
 *
 *  (c) 2008-2012 Cliff Wickman <[email protected]>, SGI.
 *
 *  This code is released under the GNU General Public License version 2 or
 *  later.
 */
#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/idle.h>
#include <asm/tsc.h>
#include <asm/irq_vectors.h>
#include <asm/timer.h>

/* timeouts in nanoseconds (indexed by UVH_AGING_PRESCALE_SEL urgency7 30:28) */
static int timeout_base_ns[] = {
        20,
        160,
        1280,
        10240,
        81920,
        655360,
        5242880,
        167772160
};

static int timeout_us;
static int nobau;
static int nobau_perm;
static cycles_t congested_cycles;

/* 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;
static struct dentry *tunables_file;

/* 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_nobau(char *arg)
{
    nobau = 1;
    return 0;
}
early_param("nobau", setup_nobau);

/* 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 = 0;
    for_each_present_cpu(cpu) {
        bcp = &per_cpu(bau_control, cpu);
        bcp->nobau = 0;
    }
    pr_info("BAU turned on\n");
    return;
}

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

    nobau = 1;
    for_each_present_cpu(cpu) {
        bcp = &per_cpu(bau_control, cpu);
        bcp->nobau = 1;
    }
    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;
        write_mmr_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 = read_mmr_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;
                write_mmr_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) {
        local_flush_tlb();
        stat->d_alltlb++;
    } else {
        __flush_tlb_one(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 = read_mmr_sw_ack();
            msg_res = msg->swack_vec;
            mr = (msg_res << UV_SW_ACK_NPENDING) | msg_res;
            if (mmr & msg_res) {
                stat->d_rcanceled++;
                write_mmr_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;
    cpus_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);
        cpu_set(cpu, *mask);
    }

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

static inline unsigned long cycles_2_us(unsigned long long cyc)
{
    unsigned long long ns;
    unsigned long us;
    int cpu = smp_processor_id();

    ns =  (cyc * per_cpu(cyc2ns, cpu)) >> CYC2NS_SCALE_FACTOR;
    us = ns / 1000;
    return us;
}

/*
 * 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);
}

static unsigned long uv1_read_status(unsigned long mmr_offset, int right_shift)
{
    unsigned long descriptor_status;

    descriptor_status = uv_read_local_mmr(mmr_offset);
    descriptor_status >>= right_shift;
    descriptor_status &= UV_ACT_STATUS_MASK;
    return descriptor_status;
}

/*
 * Wait for completion of a broadcast software ack message
 * return COMPLETE, RETRY(PLUGGED or TIMEOUT) or GIVEUP
 */
static int uv1_wait_completion(struct bau_desc *bau_desc,
                unsigned long mmr_offset, int right_shift,
                struct bau_control *bcp, long try)
{
    unsigned long descriptor_status;
    cycles_t ttm;
    struct ptc_stats *stat = bcp->statp;

    descriptor_status = uv1_read_status(mmr_offset, right_shift);
    /* spin on the status MMR, waiting for it to go idle */
    while ((descriptor_status != DS_IDLE)) {
        /*
         * Our software ack messages may be blocked because
         * there are no swack resources available.  As long
         * as none of them has timed out hardware will NACK
         * our message and its state will stay IDLE.
         */
        if (descriptor_status == DS_SOURCE_TIMEOUT) {
            stat->s_stimeout++;
            return FLUSH_GIVEUP;
        } else if (descriptor_status == DS_DESTINATION_TIMEOUT) {
            stat->s_dtimeout++;
            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.
             */
            if (cycles_2_us(ttm - bcp->send_message) < timeout_us) {
                bcp->conseccompletes = 0;
                return FLUSH_RETRY_PLUGGED;
            }

            bcp->conseccompletes = 0;
            return FLUSH_RETRY_TIMEOUT;
        } else {
            /*
             * descriptor_status is still BUSY
             */
            cpu_relax();
        }
        descriptor_status = uv1_read_status(mmr_offset, right_shift);
    }
    bcp->conseccompletes++;
    return FLUSH_COMPLETE;
}

/*
 * UV2 could have an extra bit of status in the ACTIVATION_STATUS_2 register.
 * But not currently used.
 */
static unsigned long uv2_read_status(unsigned long offset, int rshft, int desc)
{
    unsigned long descriptor_status;

    descriptor_status =
        ((read_lmmr(offset) >> rshft) & UV_ACT_STATUS_MASK) << 1;
    return descriptor_status;
}

/*
 * Return whether the status of the descriptor that is normally used for this
 * cpu (the one indexed by its hub-relative cpu number) is busy.
 * The status of the original 32 descriptors is always reflected in the 64
 * bits of UVH_LB_BAU_SB_ACTIVATION_STATUS_0.
 * The bit provided by the activation_status_2 register is irrelevant to
 * the status if it is only being tested for busy or not busy.
 */
int normal_busy(struct bau_control *bcp)
{
    int cpu = bcp->uvhub_cpu;
    int mmr_offset;
    int right_shift;

    mmr_offset = UVH_LB_BAU_SB_ACTIVATION_STATUS_0;
    right_shift = cpu * UV_ACT_STATUS_SIZE;
    return (((((read_lmmr(mmr_offset) >> right_shift) &
                UV_ACT_STATUS_MASK)) << 1) == UV2H_DESC_BUSY);
}

/*
 * Entered when a bau descriptor has gone into a permanent busy wait because
 * of a hardware bug.
 * Workaround the bug.
 */
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_wait_completion(struct bau_desc *bau_desc,
                unsigned long mmr_offset, int right_shift,
                struct bau_control *bcp, long try)
{
    unsigned long descriptor_stat;
    cycles_t ttm;
    int desc = bcp->uvhub_cpu;
    long busy_reps = 0;
    struct ptc_stats *stat = bcp->statp;

    descriptor_stat = uv2_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_read_status(mmr_offset, right_shift,
                                    desc);
    }
    bcp->conseccompletes++;
    return FLUSH_COMPLETE;
}

/*
 * There are 2 status registers; each and array[32] of 2 bits. Set up for
 * which register to read and position in that register based on cpu in
 * current hub.
 */
static int wait_completion(struct bau_desc *bau_desc,
                struct bau_control *bcp, long try)
{
    int right_shift;
    unsigned long mmr_offset;
    int desc = bcp->uvhub_cpu;

    if (desc < UV_CPUS_PER_AS) {
        mmr_offset = UVH_LB_BAU_SB_ACTIVATION_STATUS_0;
        right_shift = desc * UV_ACT_STATUS_SIZE;
    } else {
        mmr_offset = UVH_LB_BAU_SB_ACTIVATION_STATUS_1;
        right_shift = ((desc - UV_CPUS_PER_AS) * UV_ACT_STATUS_SIZE);
    }

    if (bcp->uvhub_version == 1)
        return uv1_wait_completion(bau_desc, mmr_offset, right_shift,
                                bcp, try);
    else
        return uv2_wait_completion(bau_desc, mmr_offset, right_shift,
                                bcp, try);
}

static inline cycles_t sec_2_cycles(unsigned long sec)
{
    unsigned long ns;
    cycles_t cyc;

    ns = sec * 1000000000;
    cyc = (ns << CYC2NS_SCALE_FACTOR)/(per_cpu(cyc2ns, smp_processor_id()));
    return cyc;
}

/*
 * 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 > congested_cycles) &&
                (bcp->period_requests > bcp->cong_reps) &&
                ((bcp->period_time / bcp->period_requests) >
                            congested_cycles)) {
                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++;
        }
    }
}

/*
 * Because of a uv1 hardware bug only a limited number of concurrent
 * requests can be made.
 */
static void uv1_throttle(struct bau_control *hmaster, struct ptc_stats *stat)
{
    spinlock_t *lock = &hmaster->uvhub_lock;
    atomic_t *v;

    v = &hmaster->active_descriptor_count;
    if (!atomic_inc_unless_ge(lock, v, hmaster->max_concurr)) {
        stat->s_throttles++;
        do {
            cpu_relax();
        } while (!atomic_inc_unless_ge(lock, v, hmaster->max_concurr));
    }
}

/*
 * 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.
 */
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;
    int uv1 = 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 uv1_bau_msg_header *uv1_hdr = NULL;
    struct uv2_bau_msg_header *uv2_hdr = NULL;

    if (bcp->uvhub_version == 1) {
        uv1 = 1;
        uv1_throttle(hmaster, stat);
    }

    while (hmaster->uvhub_quiesce)
        cpu_relax();

    time1 = get_cycles();
    if (uv1)
        uv1_hdr = &bau_desc->header.uv1_hdr;
    else
        uv2_hdr = &bau_desc->header.uv2_hdr;

    do {
        if (try == 0) {
            if (uv1)
                uv1_hdr->msg_type = MSG_REGULAR;
            else
                uv2_hdr->msg_type = MSG_REGULAR;
            seq_number = bcp->message_number++;
        } else {
            if (uv1)
                uv1_hdr->msg_type = MSG_RETRY;
            else
                uv2_hdr->msg_type = MSG_RETRY;
            stat->s_retry_messages++;
        }

        if (uv1)
            uv1_hdr->sequence = seq_number;
        else
            uv2_hdr->sequence = seq_number;
        index = (1UL << AS_PUSH_SHIFT) | bcp->uvhub_cpu;
        bcp->send_message = get_cycles();

        write_mmr_activation(index);

        try++;
        completion_stat = 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
 * @va: virtual address to be removed (or TLB_FLUSH_ALL for all TLB's on cpu)
 * @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,
                struct mm_struct *mm, unsigned long start,
                unsigned end, unsigned int cpu)
{
    int locals = 0;
    int remotes = 0;
    int hubs = 0;
    struct bau_desc *bau_desc;
    struct cpumask *flush_mask;
    struct ptc_stats *stat;
    struct bau_control *bcp;
    unsigned long descriptor_status;
    unsigned long status;

    bcp = &per_cpu(bau_control, cpu);
    stat = bcp->statp;
    stat->s_enters++;

    if (bcp->nobau)
        return cpumask;

    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 (cpu_isset(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);

    bau_desc->payload.address = start;
    bau_desc->payload.sending_cpu = cpu;
    /*
     * 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.
 */
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.
 */
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 = read_mmr_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)
 */
void uv_bau_message_interrupt(struct pt_regs *regs)
{
    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();
    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 == 2)
            process_uv2_message(&msgdesc, bcp);
        else
            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);
        /*
         * UV1:
         * Subsequent reversals of the timebase bit (3) cause an
         * immediate timeout of one or all INTD resources as
         * indicated in bits 2:0 (7 causes all of them to timeout).
         */
        mmr_image |= (1L << SOFTACK_MSHIFT);
        if (is_uv2_hub()) {
            /* hw bug workaround; do not use extended status */
            mmr_image &= ~(1L << UV2_EXT_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)
{
}

static inline unsigned long long usec_2_cycles(unsigned long microsec)
{
    unsigned long ns;
    unsigned long long cyc;

    ns = microsec * 1000;
    cyc = (ns << CYC2NS_SCALE_FACTOR)/(per_cpu(cyc2ns, smp_processor_id()));
    return cyc;
}

/*
 * 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_printf(file,
         "# cpu bauoff sent stime self locals remotes ncpus localhub ");
        seq_printf(file,
            "remotehub numuvhubs numuvhubs16 numuvhubs8 ");
        seq_printf(file,
            "numuvhubs4 numuvhubs2 numuvhubs1 dto snacks retries ");
        seq_printf(file,
            "rok resetp resett giveup sto bz throt disable ");
        seq_printf(file,
            "enable wars warshw warwaits enters ipidis plugged ");
        seq_printf(file,
            "ipiover glim cong swack recv rtime all one mult ");
        seq_printf(file,
            "none retry canc nocan reset rcan\n");
    }
    if (cpu < num_possible_cpus() && cpu_online(cpu)) {
        bcp = &per_cpu(bau_control, cpu);
        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",
               read_gmmr_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 (strict_strtol(optstr, 10, &input_arg) < 0) {
        printk(KERN_DEBUG "%s is invalid\n", optstr);
        return -EINVAL;
    }

    if (input_arg == 0) {
        elements = sizeof(stat_description)/sizeof(*stat_description);
        printk(KERN_DEBUG "# cpu:      cpu number\n");
        printk(KERN_DEBUG "Sender statistics:\n");
        for (i = 0; i < elements; i++)
            printk(KERN_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 = sizeof(tunables) / sizeof(*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) {
        printk(KERN_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) {
                printk(KERN_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;
        }
        if (q == p)
            break;
    }
    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 file_operations proc_uv_ptc_operations = {
    .open       = ptc_proc_open,
    .read       = seq_read,
    .write      = ptc_proc_write,
    .llseek     = seq_lseek,
    .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,
                  &proc_uv_ptc_operations);
    if (!proc_uv_ptc) {
        printk(KERN_ERR "unable to create %s proc entry\n",
               UV_PTC_BASENAME);
        return -EINVAL;
    }

    tunables_dir = debugfs_create_dir(UV_BAU_TUNABLES_DIR, NULL);
    if (!tunables_dir) {
        printk(KERN_ERR "unable to create debugfs directory %s\n",
               UV_BAU_TUNABLES_DIR);
        return -EINVAL;
    }
    tunables_file = debugfs_create_file(UV_BAU_TUNABLES_FILE, 0600,
                    tunables_dir, NULL, &tunables_fops);
    if (!tunables_file) {
        printk(KERN_ERR "unable to create debugfs file %s\n",
               UV_BAU_TUNABLES_FILE);
        return -EINVAL;
    }
    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;
    int uv1 = 0;
    unsigned long gpa;
    unsigned long m;
    unsigned long n;
    size_t dsize;
    struct bau_desc *bau_desc;
    struct bau_desc *bd2;
    struct uv1_bau_msg_header *uv1_hdr;
    struct uv2_bau_msg_header *uv2_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 = uv_gpa_to_offset(gpa);
    if (is_uv1_hub())
        uv1 = 1;

    /* the 14-bit pnode */
    write_mmr_descriptor_base(pnode, (n << UV_DESC_PSHIFT | 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));
        if (uv1) {
            uv1_hdr = &bd2->header.uv1_hdr;
            uv1_hdr->swack_flag =   1;
            /*
             * The base_dest_nasid set in the message header
             * is the nasid of the first uvhub in the partition.
             * The bit map will indicate destination pnode numbers
             * relative to that base. They may not be consecutive
             * if nasid striding is being used.
             */
            uv1_hdr->base_dest_nasid =
                        UV_PNODE_TO_NASID(base_pnode);
            uv1_hdr->dest_subnodeid =   UV_LB_SUBNODEID;
            uv1_hdr->command =      UV_NET_ENDPOINT_INTD;
            uv1_hdr->int_both =     1;
            /*
             * all others need to be set to zero:
             *   fairness chaining multilevel count replied_to
             */
        } else {
            /*
             * BIOS uses legacy mode, but UV2 hardware always
             * uses native mode for selective broadcasts.
             */
            uv2_hdr = &bd2->header.uv2_hdr;
            uv2_hdr->swack_flag =   1;
            uv2_hdr->base_dest_nasid =
                        UV_PNODE_TO_NASID(base_pnode);
            uv2_hdr->dest_subnodeid =   UV_LB_SUBNODEID;
            uv2_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 pn;
    unsigned long first;
    unsigned long pn_first;
    unsigned long last;
    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);
    pqp = (struct bau_pq_entry *)vp;
    BUG_ON(!pqp);

    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);
    }
    /*
     * need the gnode of where the memory was really allocated
     */
    pn = uv_gpa_to_gnode(uv_gpa(pqp));
    first = uv_physnodeaddr(pqp);
    pn_first = ((unsigned long)pn << UV_PAYLOADQ_PNODE_SHIFT) | first;
    last = uv_physnodeaddr(pqp + (DEST_Q_SIZE - 1));
    write_mmr_payload_first(pnode, pn_first);
    write_mmr_payload_tail(pnode, first);
    write_mmr_payload_last(pnode, last);
    write_gmmr_sw_ack(pnode, 0xffffUL);

    /* 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) | uv_apicid_hibits;
    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 mult2;
    int index;
    int base;
    int ret;
    unsigned long ts_ns;

    if (is_uv1_hub()) {
        mult1 = SOFTACK_TIMEOUT_PERIOD & BAU_MISC_CONTROL_MULT_MASK;
        mmr_image = uv_read_local_mmr(UVH_AGING_PRESCALE_SEL);
        index = (mmr_image >> BAU_URGENCY_7_SHIFT) & BAU_URGENCY_7_MASK;
        mmr_image = uv_read_local_mmr(UVH_TRANSACTION_TIMEOUT);
        mult2 = (mmr_image >> BAU_TRANS_SHIFT) & BAU_TRANS_MASK;
        ts_ns = timeout_base_ns[index];
        ts_ns *= (mult1 * mult2);
        ret = ts_ns / 1000;
    } else {
        /* 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      = 1;
        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) {
            printk(KERN_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) {
            printk(KERN_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 = kmalloc_node(hpsz, GFP_KERNEL, smaster->osnode);
    memset(smaster->thp, 0, hpsz);
    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;
    int 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_uv1_hub())
            bcp->uvhub_version = 1;
        else if (is_uv2_hub())
            bcp->uvhub_version = 2;
        else {
            printk(KERN_EMERG "uvhub version not 1 or 2\n");
            return 1;
        }
        bcp->uvhub_master = *hmasterp;
        bcp->uvhub_cpu = uv_cpu_hub_info(cpu)->blade_processor_id;
        if (bcp->uvhub_cpu >= MAX_CPUS_PER_UVHUB) {
            printk(KERN_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)
{
    unsigned char *uvhub_mask;
    void *vp;
    struct uvhub_desc *uvhub_descs;

    timeout_us = calculate_destination_timeout();

    vp = kmalloc(nuvhubs * sizeof(struct uvhub_desc), GFP_KERNEL);
    uvhub_descs = (struct uvhub_desc *)vp;
    memset(uvhub_descs, 0, nuvhubs * sizeof(struct uvhub_desc));
    uvhub_mask = kzalloc((nuvhubs+7)/8, GFP_KERNEL);

    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;
}

/*
 * 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;

    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));
    }

    nuvhubs = uv_num_possible_blades();
    congested_cycles = usec_2_cycles(congested_respns_us);

    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);
    }

    enable_timeouts();

    if (init_per_cpu(nuvhubs, uv_base_pnode)) {
        set_bau_off();
        nobau_perm = 1;
        return 0;
    }

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

    alloc_intr_gate(vector, uv_bau_message_intr1);

    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 */
            if (!is_uv1_hub())
                write_mmr_data_broadcast(pnode, mmr);
        }
    }

    return 0;
}
core_initcall(uv_bau_init);
fs_initcall(uv_ptc_init);