x86, UV: cpu_relax in uv_wait_completion

[linux-2.6/mini2440.git] / arch / x86 / kernel / tlb_uv.c

/*
 *      SGI UltraViolet TLB flush routines.
 *
 *      (c) 2008 Cliff Wickman <cpw@sgi.com>, 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/kernel.h>

#include <asm/mmu_context.h>
#include <asm/uv/uv_mmrs.h>
#include <asm/uv/uv_hub.h>
#include <asm/uv/uv_bau.h>
#include <asm/genapic.h>
#include <asm/idle.h>
#include <asm/tsc.h>
#include <asm/irq_vectors.h>

#include <mach_apic.h>

static struct bau_control       **uv_bau_table_bases __read_mostly;
static int                      uv_bau_retry_limit __read_mostly;

/* position of pnode (which is nasid>>1): */
static int                      uv_nshift __read_mostly;

static unsigned long            uv_mmask __read_mostly;

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

/*
 * 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 uv_reply_to_message(int resource,
                                struct bau_payload_queue_entry *msg,
                                struct bau_msg_status *msp)
{
        unsigned long dw;

        dw = (1 << (resource + UV_SW_ACK_NPENDING)) | (1 << resource);
        msg->replied_to = 1;
        msg->sw_ack_vector = 0;
        if (msp)
                msp->seen_by.bits = 0;
        uv_write_local_mmr(UVH_LB_BAU_INTD_SOFTWARE_ACKNOWLEDGE_ALIAS, dw);
}

/*
 * 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 uv_bau_process_message(struct bau_payload_queue_entry *msg,
                                   int msg_slot, int sw_ack_slot)
{
        unsigned long this_cpu_mask;
        struct bau_msg_status *msp;
        int cpu;

        msp = __get_cpu_var(bau_control).msg_statuses + msg_slot;
        cpu = uv_blade_processor_id();
        msg->number_of_cpus =
            uv_blade_nr_online_cpus(uv_node_to_blade_id(numa_node_id()));
        this_cpu_mask = 1UL << cpu;
        if (msp->seen_by.bits & this_cpu_mask)
                return;
        atomic_or_long(&msp->seen_by.bits, this_cpu_mask);

        if (msg->replied_to == 1)
                return;

        if (msg->address == TLB_FLUSH_ALL) {
                local_flush_tlb();
                __get_cpu_var(ptcstats).alltlb++;
        } else {
                __flush_tlb_one(msg->address);
                __get_cpu_var(ptcstats).onetlb++;
        }

        __get_cpu_var(ptcstats).requestee++;

        atomic_inc_short(&msg->acknowledge_count);
        if (msg->number_of_cpus == msg->acknowledge_count)
                uv_reply_to_message(sw_ack_slot, msg, msp);
}

/*
 * Examine the payload queue on one distribution node to see
 * which messages have not been seen, and which cpu(s) have not seen them.
 *
 * Returns the number of cpu's that have not responded.
 */
static int uv_examine_destination(struct bau_control *bau_tablesp, int sender)
{
        struct bau_payload_queue_entry *msg;
        struct bau_msg_status *msp;
        int count = 0;
        int i;
        int j;

        for (msg = bau_tablesp->va_queue_first, i = 0; i < DEST_Q_SIZE;
             msg++, i++) {
                if ((msg->sending_cpu == sender) && (!msg->replied_to)) {
                        msp = bau_tablesp->msg_statuses + i;
                        printk(KERN_DEBUG
                               "blade %d: address:%#lx %d of %d, not cpu(s): ",
                               i, msg->address, msg->acknowledge_count,
                               msg->number_of_cpus);
                        for (j = 0; j < msg->number_of_cpus; j++) {
                                if (!((1L << j) & msp->seen_by.bits)) {
                                        count++;
                                        printk("%d ", j);
                                }
                        }
                        printk("\n");
                }
        }
        return count;
}

/*
 * Examine the payload queue on all the distribution nodes to see
 * which messages have not been seen, and which cpu(s) have not seen them.
 *
 * Returns the number of cpu's that have not responded.
 */
static int uv_examine_destinations(struct bau_target_nodemask *distribution)
{
        int sender;
        int i;
        int count = 0;

        sender = smp_processor_id();
        for (i = 0; i < sizeof(struct bau_target_nodemask) * BITSPERBYTE; i++) {
                if (!bau_node_isset(i, distribution))
                        continue;
                count += uv_examine_destination(uv_bau_table_bases[i], sender);
        }
        return count;
}

/*
 * wait for completion of a broadcast message
 *
 * return COMPLETE, RETRY or GIVEUP
 */
static int uv_wait_completion(struct bau_desc *bau_desc,
                              unsigned long mmr_offset, int right_shift)
{
        int exams = 0;
        long destination_timeouts = 0;
        long source_timeouts = 0;
        unsigned long descriptor_status;

        while ((descriptor_status = (((unsigned long)
                uv_read_local_mmr(mmr_offset) >>
                        right_shift) & UV_ACT_STATUS_MASK)) !=
                        DESC_STATUS_IDLE) {
                if (descriptor_status == DESC_STATUS_SOURCE_TIMEOUT) {
                        source_timeouts++;
                        if (source_timeouts > SOURCE_TIMEOUT_LIMIT)
                                source_timeouts = 0;
                        __get_cpu_var(ptcstats).s_retry++;
                        return FLUSH_RETRY;
                }
                /*
                 * spin here looking for progress at the destinations
                 */
                if (descriptor_status == DESC_STATUS_DESTINATION_TIMEOUT) {
                        destination_timeouts++;
                        if (destination_timeouts > DESTINATION_TIMEOUT_LIMIT) {
                                /*
                                 * returns number of cpus not responding
                                 */
                                if (uv_examine_destinations
                                    (&bau_desc->distribution) == 0) {
                                        __get_cpu_var(ptcstats).d_retry++;
                                        return FLUSH_RETRY;
                                }
                                exams++;
                                if (exams >= uv_bau_retry_limit) {
                                        printk(KERN_DEBUG
                                               "uv_flush_tlb_others");
                                        printk("giving up on cpu %d\n",
                                               smp_processor_id());
                                        return FLUSH_GIVEUP;
                                }
                                /*
                                 * delays can hang the simulator
                                   udelay(1000);
                                 */
                                destination_timeouts = 0;
                        }
                }
                cpu_relax();
        }
        return FLUSH_COMPLETE;
}

/**
 * uv_flush_send_and_wait
 *
 * Send a broadcast and wait for a broadcast message to complete.
 *
 * The cpumaskp mask contains the cpus the broadcast was sent to.
 *
 * Returns 1 if all remote flushing was done. The mask is zeroed.
 * Returns 0 if some remote flushing remains to be done. The mask is left
 * unchanged.
 */
int uv_flush_send_and_wait(int cpu, int this_blade, struct bau_desc *bau_desc,
                           cpumask_t *cpumaskp)
{
        int completion_status = 0;
        int right_shift;
        int tries = 0;
        int blade;
        int bit;
        unsigned long mmr_offset;
        unsigned long index;
        cycles_t time1;
        cycles_t time2;

        if (cpu < UV_CPUS_PER_ACT_STATUS) {
                mmr_offset = UVH_LB_BAU_SB_ACTIVATION_STATUS_0;
                right_shift = cpu * UV_ACT_STATUS_SIZE;
        } else {
                mmr_offset = UVH_LB_BAU_SB_ACTIVATION_STATUS_1;
                right_shift =
                    ((cpu - UV_CPUS_PER_ACT_STATUS) * UV_ACT_STATUS_SIZE);
        }
        time1 = get_cycles();
        do {
                tries++;
                index = (1UL << UVH_LB_BAU_SB_ACTIVATION_CONTROL_PUSH_SHFT) |
                        cpu;
                uv_write_local_mmr(UVH_LB_BAU_SB_ACTIVATION_CONTROL, index);
                completion_status = uv_wait_completion(bau_desc, mmr_offset,
                                        right_shift);
        } while (completion_status == FLUSH_RETRY);
        time2 = get_cycles();
        __get_cpu_var(ptcstats).sflush += (time2 - time1);
        if (tries > 1)
                __get_cpu_var(ptcstats).retriesok++;

        if (completion_status == FLUSH_GIVEUP) {
                /*
                 * Cause the caller to do an IPI-style TLB shootdown on
                 * the cpu's, all of which are still in the mask.
                 */
                __get_cpu_var(ptcstats).ptc_i++;
                return 0;
        }

        /*
         * Success, so clear the remote cpu's from the mask so we don't
         * use the IPI method of shootdown on them.
         */
        for_each_cpu_mask(bit, *cpumaskp) {
                blade = uv_cpu_to_blade_id(bit);
                if (blade == this_blade)
                        continue;
                cpu_clear(bit, *cpumaskp);
        }
        if (!cpus_empty(*cpumaskp))
                return 0;
        return 1;
}

/**
 * uv_flush_tlb_others - globally purge translation cache of a virtual
 * address or all TLB's
 * @cpumaskp: 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)
 *
 * 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 cpumaskp from the mm_struct and has subtracted
 * the local cpu from the mask.  This function is called only if there
 * are bits set in the mask. (e.g. flush_tlb_page())
 *
 * The cpumaskp is converted into a nodemask of the nodes containing
 * the cpus.
 *
 * Returns 1 if all remote flushing was done.
 * Returns 0 if some remote flushing remains to be done.
 */
int uv_flush_tlb_others(cpumask_t *cpumaskp, struct mm_struct *mm,
                        unsigned long va)
{
        int i;
        int bit;
        int blade;
        int cpu;
        int this_blade;
        int locals = 0;
        struct bau_desc *bau_desc;

        cpu = uv_blade_processor_id();
        this_blade = uv_numa_blade_id();
        bau_desc = __get_cpu_var(bau_control).descriptor_base;
        bau_desc += UV_ITEMS_PER_DESCRIPTOR * cpu;

        bau_nodes_clear(&bau_desc->distribution, UV_DISTRIBUTION_SIZE);

        i = 0;
        for_each_cpu_mask(bit, *cpumaskp) {
                blade = uv_cpu_to_blade_id(bit);
                BUG_ON(blade > (UV_DISTRIBUTION_SIZE - 1));
                if (blade == this_blade) {
                        locals++;
                        continue;
                }
                bau_node_set(blade, &bau_desc->distribution);
                i++;
        }
        if (i == 0) {
                /*
                 * no off_node flushing; return status for local node
                 */
                if (locals)
                        return 0;
                else
                        return 1;
        }
        __get_cpu_var(ptcstats).requestor++;
        __get_cpu_var(ptcstats).ntargeted += i;

        bau_desc->payload.address = va;
        bau_desc->payload.sending_cpu = smp_processor_id();

        return uv_flush_send_and_wait(cpu, this_blade, bau_desc, cpumaskp);
}

/*
 * The BAU message interrupt comes here. (registered by set_intr_gate)
 * See entry_64.S
 *
 * We received a broadcast assist message.
 *
 * Interrupts may have been disabled; this interrupt could represent
 * the receipt of several messages.
 *
 * All cores/threads on this node get this interrupt.
 * The last one to see it does the s/w ack.
 * (the resource will not be freed until noninterruptable cpus see this
 *  interrupt; hardware will timeout the s/w ack and reply ERROR)
 */
void uv_bau_message_interrupt(struct pt_regs *regs)
{
        struct bau_payload_queue_entry *va_queue_first;
        struct bau_payload_queue_entry *va_queue_last;
        struct bau_payload_queue_entry *msg;
        struct pt_regs *old_regs = set_irq_regs(regs);
        cycles_t time1;
        cycles_t time2;
        int msg_slot;
        int sw_ack_slot;
        int fw;
        int count = 0;
        unsigned long local_pnode;

        ack_APIC_irq();
        exit_idle();
        irq_enter();

        time1 = get_cycles();

        local_pnode = uv_blade_to_pnode(uv_numa_blade_id());

        va_queue_first = __get_cpu_var(bau_control).va_queue_first;
        va_queue_last = __get_cpu_var(bau_control).va_queue_last;

        msg = __get_cpu_var(bau_control).bau_msg_head;
        while (msg->sw_ack_vector) {
                count++;
                fw = msg->sw_ack_vector;
                msg_slot = msg - va_queue_first;
                sw_ack_slot = ffs(fw) - 1;

                uv_bau_process_message(msg, msg_slot, sw_ack_slot);

                msg++;
                if (msg > va_queue_last)
                        msg = va_queue_first;
                __get_cpu_var(bau_control).bau_msg_head = msg;
        }
        if (!count)
                __get_cpu_var(ptcstats).nomsg++;
        else if (count > 1)
                __get_cpu_var(ptcstats).multmsg++;

        time2 = get_cycles();
        __get_cpu_var(ptcstats).dflush += (time2 - time1);

        irq_exit();
        set_irq_regs(old_regs);
}

static void uv_enable_timeouts(void)
{
        int i;
        int blade;
        int last_blade;
        int pnode;
        int cur_cpu = 0;
        unsigned long apicid;

        last_blade = -1;
        for_each_online_node(i) {
                blade = uv_node_to_blade_id(i);
                if (blade == last_blade)
                        continue;
                last_blade = blade;
                apicid = per_cpu(x86_cpu_to_apicid, cur_cpu);
                pnode = uv_blade_to_pnode(blade);
                cur_cpu += uv_blade_nr_possible_cpus(i);
        }
}

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

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

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

/*
 * Display the statistics thru /proc
 * data points to the cpu number
 */
static int uv_ptc_seq_show(struct seq_file *file, void *data)
{
        struct ptc_stats *stat;
        int cpu;

        cpu = *(loff_t *)data;

        if (!cpu) {
                seq_printf(file,
                "# cpu requestor requestee one all sretry dretry ptc_i ");
                seq_printf(file,
                "sw_ack sflush dflush sok dnomsg dmult starget\n");
        }
        if (cpu < num_possible_cpus() && cpu_online(cpu)) {
                stat = &per_cpu(ptcstats, cpu);
                seq_printf(file, "cpu %d %ld %ld %ld %ld %ld %ld %ld ",
                           cpu, stat->requestor,
                           stat->requestee, stat->onetlb, stat->alltlb,
                           stat->s_retry, stat->d_retry, stat->ptc_i);
                seq_printf(file, "%lx %ld %ld %ld %ld %ld %ld\n",
                           uv_read_global_mmr64(uv_blade_to_pnode
                                        (uv_cpu_to_blade_id(cpu)),
                                        UVH_LB_BAU_INTD_SOFTWARE_ACKNOWLEDGE),
                           stat->sflush, stat->dflush,
                           stat->retriesok, stat->nomsg,
                           stat->multmsg, stat->ntargeted);
        }

        return 0;
}

/*
 *  0: display meaning of the statistics
 * >0: retry limit
 */
static ssize_t uv_ptc_proc_write(struct file *file, const char __user *user,
                                 size_t count, loff_t *data)
{
        long newmode;
        char optstr[64];

        if (count == 0 || count > sizeof(optstr))
                return -EINVAL;
        if (copy_from_user(optstr, user, count))
                return -EFAULT;
        optstr[count - 1] = '\0';
        if (strict_strtoul(optstr, 10, &newmode) < 0) {
                printk(KERN_DEBUG "%s is invalid\n", optstr);
                return -EINVAL;
        }

        if (newmode == 0) {
                printk(KERN_DEBUG "# cpu:      cpu number\n");
                printk(KERN_DEBUG
                "requestor:  times this cpu was the flush requestor\n");
                printk(KERN_DEBUG
                "requestee:  times this cpu was requested to flush its TLBs\n");
                printk(KERN_DEBUG
                "one:        times requested to flush a single address\n");
                printk(KERN_DEBUG
                "all:        times requested to flush all TLB's\n");
                printk(KERN_DEBUG
                "sretry:     number of retries of source-side timeouts\n");
                printk(KERN_DEBUG
                "dretry:     number of retries of destination-side timeouts\n");
                printk(KERN_DEBUG
                "ptc_i:      times UV fell through to IPI-style flushes\n");
                printk(KERN_DEBUG
                "sw_ack:     image of UVH_LB_BAU_INTD_SOFTWARE_ACKNOWLEDGE\n");
                printk(KERN_DEBUG
                "sflush_us:  cycles spent in uv_flush_tlb_others()\n");
                printk(KERN_DEBUG
                "dflush_us:  cycles spent in handling flush requests\n");
                printk(KERN_DEBUG "sok:        successes on retry\n");
                printk(KERN_DEBUG "dnomsg:     interrupts with no message\n");
                printk(KERN_DEBUG
                "dmult:      interrupts with multiple messages\n");
                printk(KERN_DEBUG "starget:    nodes targeted\n");
        } else {
                uv_bau_retry_limit = newmode;
                printk(KERN_DEBUG "timeout retry limit:%d\n",
                       uv_bau_retry_limit);
        }

        return count;
}

static const struct seq_operations uv_ptc_seq_ops = {
        .start          = uv_ptc_seq_start,
        .next           = uv_ptc_seq_next,
        .stop           = uv_ptc_seq_stop,
        .show           = uv_ptc_seq_show
};

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

static const struct file_operations proc_uv_ptc_operations = {
        .open           = uv_ptc_proc_open,
        .read           = seq_read,
        .write          = uv_ptc_proc_write,
        .llseek         = seq_lseek,
        .release        = seq_release,
};

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

        if (!is_uv_system())
                return 0;

        proc_uv_ptc = create_proc_entry(UV_PTC_BASENAME, 0444, NULL);
        if (!proc_uv_ptc) {
                printk(KERN_ERR "unable to create %s proc entry\n",
                       UV_PTC_BASENAME);
                return -EINVAL;
        }
        proc_uv_ptc->proc_fops = &proc_uv_ptc_operations;
        return 0;
}

/*
 * begin the initialization of the per-blade control structures
 */
static struct bau_control * __init uv_table_bases_init(int blade, int node)
{
        int i;
        struct bau_msg_status *msp;
        struct bau_control *bau_tabp;

        bau_tabp =
            kmalloc_node(sizeof(struct bau_control), GFP_KERNEL, node);
        BUG_ON(!bau_tabp);

        bau_tabp->msg_statuses =
            kmalloc_node(sizeof(struct bau_msg_status) *
                         DEST_Q_SIZE, GFP_KERNEL, node);
        BUG_ON(!bau_tabp->msg_statuses);

        for (i = 0, msp = bau_tabp->msg_statuses; i < DEST_Q_SIZE; i++, msp++)
                bau_cpubits_clear(&msp->seen_by, (int)
                                  uv_blade_nr_possible_cpus(blade));

        uv_bau_table_bases[blade] = bau_tabp;

        return bau_tabp;
}

/*
 * finish the initialization of the per-blade control structures
 */
static void __init
uv_table_bases_finish(int blade, int node, int cur_cpu,
                      struct bau_control *bau_tablesp,
                      struct bau_desc *adp)
{
        struct bau_control *bcp;
        int i;

        for (i = cur_cpu; i < cur_cpu + uv_blade_nr_possible_cpus(blade); i++) {
                bcp = (struct bau_control *)&per_cpu(bau_control, i);

                bcp->bau_msg_head       = bau_tablesp->va_queue_first;
                bcp->va_queue_first     = bau_tablesp->va_queue_first;
                bcp->va_queue_last      = bau_tablesp->va_queue_last;
                bcp->msg_statuses       = bau_tablesp->msg_statuses;
                bcp->descriptor_base    = adp;
        }
}

/*
 * initialize the sending side's sending buffers
 */
static struct bau_desc * __init
uv_activation_descriptor_init(int node, int pnode)
{
        int i;
        unsigned long pa;
        unsigned long m;
        unsigned long n;
        unsigned long mmr_image;
        struct bau_desc *adp;
        struct bau_desc *ad2;

        adp = (struct bau_desc *)
            kmalloc_node(16384, GFP_KERNEL, node);
        BUG_ON(!adp);

        pa = __pa((unsigned long)adp);
        n = pa >> uv_nshift;
        m = pa & uv_mmask;

        mmr_image = uv_read_global_mmr64(pnode, UVH_LB_BAU_SB_DESCRIPTOR_BASE);
        if (mmr_image) {
                uv_write_global_mmr64(pnode, (unsigned long)
                                      UVH_LB_BAU_SB_DESCRIPTOR_BASE,
                                      (n << UV_DESC_BASE_PNODE_SHIFT | m));
        }

        for (i = 0, ad2 = adp; i < UV_ACTIVATION_DESCRIPTOR_SIZE; i++, ad2++) {
                memset(ad2, 0, sizeof(struct bau_desc));
                ad2->header.sw_ack_flag = 1;
                ad2->header.base_dest_nodeid =
                    uv_blade_to_pnode(uv_cpu_to_blade_id(0));
                ad2->header.command = UV_NET_ENDPOINT_INTD;
                ad2->header.int_both = 1;
                /*
                 * all others need to be set to zero:
                 *   fairness chaining multilevel count replied_to
                 */
        }
        return adp;
}

/*
 * initialize the destination side's receiving buffers
 */
static struct bau_payload_queue_entry * __init
uv_payload_queue_init(int node, int pnode, struct bau_control *bau_tablesp)
{
        struct bau_payload_queue_entry *pqp;
        char *cp;

        pqp = (struct bau_payload_queue_entry *) kmalloc_node(
                (DEST_Q_SIZE + 1) * sizeof(struct bau_payload_queue_entry),
                GFP_KERNEL, node);
        BUG_ON(!pqp);

        cp = (char *)pqp + 31;
        pqp = (struct bau_payload_queue_entry *)(((unsigned long)cp >> 5) << 5);
        bau_tablesp->va_queue_first = pqp;
        uv_write_global_mmr64(pnode,
                              UVH_LB_BAU_INTD_PAYLOAD_QUEUE_FIRST,
                              ((unsigned long)pnode <<
                               UV_PAYLOADQ_PNODE_SHIFT) |
                              uv_physnodeaddr(pqp));
        uv_write_global_mmr64(pnode, UVH_LB_BAU_INTD_PAYLOAD_QUEUE_TAIL,
                              uv_physnodeaddr(pqp));
        bau_tablesp->va_queue_last = pqp + (DEST_Q_SIZE - 1);
        uv_write_global_mmr64(pnode, UVH_LB_BAU_INTD_PAYLOAD_QUEUE_LAST,
                              (unsigned long)
                              uv_physnodeaddr(bau_tablesp->va_queue_last));
        memset(pqp, 0, sizeof(struct bau_payload_queue_entry) * DEST_Q_SIZE);

        return pqp;
}

/*
 * Initialization of each UV blade's structures
 */
static int __init uv_init_blade(int blade, int node, int cur_cpu)
{
        int pnode;
        unsigned long pa;
        unsigned long apicid;
        struct bau_desc *adp;
        struct bau_payload_queue_entry *pqp;
        struct bau_control *bau_tablesp;

        bau_tablesp = uv_table_bases_init(blade, node);
        pnode = uv_blade_to_pnode(blade);
        adp = uv_activation_descriptor_init(node, pnode);
        pqp = uv_payload_queue_init(node, pnode, bau_tablesp);
        uv_table_bases_finish(blade, node, cur_cpu, bau_tablesp, adp);
        /*
         * the below initialization can't be in firmware because the
         * messaging IRQ will be determined by the OS
         */
        apicid = per_cpu(x86_cpu_to_apicid, cur_cpu);
        pa = uv_read_global_mmr64(pnode, UVH_BAU_DATA_CONFIG);
        if ((pa & 0xff) != UV_BAU_MESSAGE) {
                uv_write_global_mmr64(pnode, UVH_BAU_DATA_CONFIG,
                                      ((apicid << 32) | UV_BAU_MESSAGE));
        }
        return 0;
}

/*
 * Initialization of BAU-related structures
 */
static int __init uv_bau_init(void)
{
        int blade;
        int node;
        int nblades;
        int last_blade;
        int cur_cpu = 0;

        if (!is_uv_system())
                return 0;

        uv_bau_retry_limit = 1;
        uv_nshift = uv_hub_info->n_val;
        uv_mmask = (1UL << uv_hub_info->n_val) - 1;
        nblades = 0;
        last_blade = -1;
        for_each_online_node(node) {
                blade = uv_node_to_blade_id(node);
                if (blade == last_blade)
                        continue;
                last_blade = blade;
                nblades++;
        }
        uv_bau_table_bases = (struct bau_control **)
            kmalloc(nblades * sizeof(struct bau_control *), GFP_KERNEL);
        BUG_ON(!uv_bau_table_bases);

        last_blade = -1;
        for_each_online_node(node) {
                blade = uv_node_to_blade_id(node);
                if (blade == last_blade)
                        continue;
                last_blade = blade;
                uv_init_blade(blade, node, cur_cpu);
                cur_cpu += uv_blade_nr_possible_cpus(blade);
        }
        alloc_intr_gate(UV_BAU_MESSAGE, uv_bau_message_intr1);
        uv_enable_timeouts();

        return 0;
}
__initcall(uv_bau_init);
__initcall(uv_ptc_init);