grukservices.c

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/*
 * SN Platform GRU Driver
 *
 *              KERNEL SERVICES THAT USE THE GRU
 *
 *  Copyright (c) 2008 Silicon Graphics, Inc.  All Rights Reserved.
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
 */

#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/slab.h>
#include <linux/mm.h>
#include <linux/spinlock.h>
#include <linux/device.h>
#include <linux/miscdevice.h>
#include <linux/proc_fs.h>
#include <linux/interrupt.h>
#include <linux/uaccess.h>
#include <linux/delay.h>
#include <linux/export.h>
#include <asm/io_apic.h>
#include "gru.h"
#include "grulib.h"
#include "grutables.h"
#include "grukservices.h"
#include "gru_instructions.h"
#include <asm/uv/uv_hub.h>

/*
 * Kernel GRU Usage
 *
 * The following is an interim algorithm for management of kernel GRU
 * resources. This will likely be replaced when we better understand the
 * kernel/user requirements.
 *
 * Blade percpu resources reserved for kernel use. These resources are
 * reserved whenever the the kernel context for the blade is loaded. Note
 * that the kernel context is not guaranteed to be always available. It is
 * loaded on demand & can be stolen by a user if the user demand exceeds the
 * kernel demand. The kernel can always reload the kernel context but
 * a SLEEP may be required!!!.
 *
 * Async Overview:
 *
 *  Each blade has one "kernel context" that owns GRU kernel resources
 *  located on the blade. Kernel drivers use GRU resources in this context
 *  for sending messages, zeroing memory, etc.
 *
 *  The kernel context is dynamically loaded on demand. If it is not in
 *  use by the kernel, the kernel context can be unloaded & given to a user.
 *  The kernel context will be reloaded when needed. This may require that
 *  a context be stolen from a user.
 *      NOTE: frequent unloading/reloading of the kernel context is
 *      expensive. We are depending on batch schedulers, cpusets, sane
 *      drivers or some other mechanism to prevent the need for frequent
 *      stealing/reloading.
 *
 *  The kernel context consists of two parts:
 *      - 1 CB & a few DSRs that are reserved for each cpu on the blade.
 *        Each cpu has it's own private resources & does not share them
 *        with other cpus. These resources are used serially, ie,
 *        locked, used & unlocked  on each call to a function in
 *        grukservices.
 *          (Now that we have dynamic loading of kernel contexts, I
 *           may rethink this & allow sharing between cpus....)
 *
 *      - Additional resources can be reserved long term & used directly
 *        by UV drivers located in the kernel. Drivers using these GRU
 *        resources can use asynchronous GRU instructions that send
 *        interrupts on completion.
 *          - these resources must be explicitly locked/unlocked
 *          - locked resources prevent (obviously) the kernel
 *            context from being unloaded.
 *          - drivers using these resource directly issue their own
 *            GRU instruction and must wait/check completion.
 *
 *        When these resources are reserved, the caller can optionally
 *        associate a wait_queue with the resources and use asynchronous
 *        GRU instructions. When an async GRU instruction completes, the
 *        driver will do a wakeup on the event.
 *
 */


#define ASYNC_HAN_TO_BID(h) ((h) - 1)
#define ASYNC_BID_TO_HAN(b) ((b) + 1)
#define ASYNC_HAN_TO_BS(h)  gru_base[ASYNC_HAN_TO_BID(h)]

#define GRU_NUM_KERNEL_CBR  1
#define GRU_NUM_KERNEL_DSR_BYTES 256
#define GRU_NUM_KERNEL_DSR_CL   (GRU_NUM_KERNEL_DSR_BYTES /     \
                    GRU_CACHE_LINE_BYTES)

/* GRU instruction attributes for all instructions */
#define IMA         IMA_CB_DELAY

/* GRU cacheline size is always 64 bytes - even on arches with 128 byte lines */
#define __gru_cacheline_aligned__                               \
    __attribute__((__aligned__(GRU_CACHE_LINE_BYTES)))

#define MAGIC   0x1234567887654321UL

/* Default retry count for GRU errors on kernel instructions */
#define EXCEPTION_RETRY_LIMIT   3

/* Status of message queue sections */
#define MQS_EMPTY       0
#define MQS_FULL        1
#define MQS_NOOP        2

/*----------------- RESOURCE MANAGEMENT -------------------------------------*/
/* optimized for x86_64 */
struct message_queue {
    union gru_mesqhead  head __gru_cacheline_aligned__; /* CL 0 */
    int         qlines;             /* DW 1 */
    long            hstatus[2];
    void            *next __gru_cacheline_aligned__;/* CL 1 */
    void            *limit;
    void            *start;
    void            *start2;
    char            data ____cacheline_aligned; /* CL 2 */
};

/* First word in every message - used by mesq interface */
struct message_header {
    char    present;
    char    present2;
    char    lines;
    char    fill;
};

#define HSTATUS(mq, h)  ((mq) + offsetof(struct message_queue, hstatus[h]))

/*
 * Reload the blade's kernel context into a GRU chiplet. Called holding
 * the bs_kgts_sema for READ. Will steal user contexts if necessary.
 */
static void gru_load_kernel_context(struct gru_blade_state *bs, int blade_id)
{
    struct gru_state *gru;
    struct gru_thread_state *kgts;
    void *vaddr;
    int ctxnum, ncpus;

    up_read(&bs->bs_kgts_sema);
    down_write(&bs->bs_kgts_sema);

    if (!bs->bs_kgts) {
        bs->bs_kgts = gru_alloc_gts(NULL, 0, 0, 0, 0, 0);
        bs->bs_kgts->ts_user_blade_id = blade_id;
    }
    kgts = bs->bs_kgts;

    if (!kgts->ts_gru) {
        STAT(load_kernel_context);
        ncpus = uv_blade_nr_possible_cpus(blade_id);
        kgts->ts_cbr_au_count = GRU_CB_COUNT_TO_AU(
            GRU_NUM_KERNEL_CBR * ncpus + bs->bs_async_cbrs);
        kgts->ts_dsr_au_count = GRU_DS_BYTES_TO_AU(
            GRU_NUM_KERNEL_DSR_BYTES * ncpus +
                bs->bs_async_dsr_bytes);
        while (!gru_assign_gru_context(kgts)) {
            msleep(1);
            gru_steal_context(kgts);
        }
        gru_load_context(kgts);
        gru = bs->bs_kgts->ts_gru;
        vaddr = gru->gs_gru_base_vaddr;
        ctxnum = kgts->ts_ctxnum;
        bs->kernel_cb = get_gseg_base_address_cb(vaddr, ctxnum, 0);
        bs->kernel_dsr = get_gseg_base_address_ds(vaddr, ctxnum, 0);
    }
    downgrade_write(&bs->bs_kgts_sema);
}

/*
 * Free all kernel contexts that are not currently in use.
 *   Returns 0 if all freed, else number of inuse context.
 */
static int gru_free_kernel_contexts(void)
{
    struct gru_blade_state *bs;
    struct gru_thread_state *kgts;
    int bid, ret = 0;

    for (bid = 0; bid < GRU_MAX_BLADES; bid++) {
        bs = gru_base[bid];
        if (!bs)
            continue;

        /* Ignore busy contexts. Don't want to block here.  */
        if (down_write_trylock(&bs->bs_kgts_sema)) {
            kgts = bs->bs_kgts;
            if (kgts && kgts->ts_gru)
                gru_unload_context(kgts, 0);
            bs->bs_kgts = NULL;
            up_write(&bs->bs_kgts_sema);
            kfree(kgts);
        } else {
            ret++;
        }
    }
    return ret;
}

/*
 * Lock & load the kernel context for the specified blade.
 */
static struct gru_blade_state *gru_lock_kernel_context(int blade_id)
{
    struct gru_blade_state *bs;
    int bid;

    STAT(lock_kernel_context);
again:
    bid = blade_id < 0 ? uv_numa_blade_id() : blade_id;
    bs = gru_base[bid];

    /* Handle the case where migration occurred while waiting for the sema */
    down_read(&bs->bs_kgts_sema);
    if (blade_id < 0 && bid != uv_numa_blade_id()) {
        up_read(&bs->bs_kgts_sema);
        goto again;
    }
    if (!bs->bs_kgts || !bs->bs_kgts->ts_gru)
        gru_load_kernel_context(bs, bid);
    return bs;

}

/*
 * Unlock the kernel context for the specified blade. Context is not
 * unloaded but may be stolen before next use.
 */
static void gru_unlock_kernel_context(int blade_id)
{
    struct gru_blade_state *bs;

    bs = gru_base[blade_id];
    up_read(&bs->bs_kgts_sema);
    STAT(unlock_kernel_context);
}

/*
 * Reserve & get pointers to the DSR/CBRs reserved for the current cpu.
 *  - returns with preemption disabled
 */
static int gru_get_cpu_resources(int dsr_bytes, void **cb, void **dsr)
{
    struct gru_blade_state *bs;
    int lcpu;

    BUG_ON(dsr_bytes > GRU_NUM_KERNEL_DSR_BYTES);
    preempt_disable();
    bs = gru_lock_kernel_context(-1);
    lcpu = uv_blade_processor_id();
    *cb = bs->kernel_cb + lcpu * GRU_HANDLE_STRIDE;
    *dsr = bs->kernel_dsr + lcpu * GRU_NUM_KERNEL_DSR_BYTES;
    return 0;
}

/*
 * Free the current cpus reserved DSR/CBR resources.
 */
static void gru_free_cpu_resources(void *cb, void *dsr)
{
    gru_unlock_kernel_context(uv_numa_blade_id());
    preempt_enable();
}

/*
 * Reserve GRU resources to be used asynchronously.
 *   Note: currently supports only 1 reservation per blade.
 *
 *  input:
 *      blade_id  - blade on which resources should be reserved
 *      cbrs      - number of CBRs
 *      dsr_bytes - number of DSR bytes needed
 *  output:
 *      handle to identify resource
 *      (0 = async resources already reserved)
 */
unsigned long gru_reserve_async_resources(int blade_id, int cbrs, int dsr_bytes,
            struct completion *cmp)
{
    struct gru_blade_state *bs;
    struct gru_thread_state *kgts;
    int ret = 0;

    bs = gru_base[blade_id];

    down_write(&bs->bs_kgts_sema);

    /* Verify no resources already reserved */
    if (bs->bs_async_dsr_bytes + bs->bs_async_cbrs)
        goto done;
    bs->bs_async_dsr_bytes = dsr_bytes;
    bs->bs_async_cbrs = cbrs;
    bs->bs_async_wq = cmp;
    kgts = bs->bs_kgts;

    /* Resources changed. Unload context if already loaded */
    if (kgts && kgts->ts_gru)
        gru_unload_context(kgts, 0);
    ret = ASYNC_BID_TO_HAN(blade_id);

done:
    up_write(&bs->bs_kgts_sema);
    return ret;
}

/*
 * Release async resources previously reserved.
 *
 *  input:
 *      han - handle to identify resources
 */
void gru_release_async_resources(unsigned long han)
{
    struct gru_blade_state *bs = ASYNC_HAN_TO_BS(han);

    down_write(&bs->bs_kgts_sema);
    bs->bs_async_dsr_bytes = 0;
    bs->bs_async_cbrs = 0;
    bs->bs_async_wq = NULL;
    up_write(&bs->bs_kgts_sema);
}

/*
 * Wait for async GRU instructions to complete.
 *
 *  input:
 *      han - handle to identify resources
 */
void gru_wait_async_cbr(unsigned long han)
{
    struct gru_blade_state *bs = ASYNC_HAN_TO_BS(han);

    wait_for_completion(bs->bs_async_wq);
    mb();
}

/*
 * Lock previous reserved async GRU resources
 *
 *  input:
 *      han - handle to identify resources
 *  output:
 *      cb  - pointer to first CBR
 *      dsr - pointer to first DSR
 */
void gru_lock_async_resource(unsigned long han,  void **cb, void **dsr)
{
    struct gru_blade_state *bs = ASYNC_HAN_TO_BS(han);
    int blade_id = ASYNC_HAN_TO_BID(han);
    int ncpus;

    gru_lock_kernel_context(blade_id);
    ncpus = uv_blade_nr_possible_cpus(blade_id);
    if (cb)
        *cb = bs->kernel_cb + ncpus * GRU_HANDLE_STRIDE;
    if (dsr)
        *dsr = bs->kernel_dsr + ncpus * GRU_NUM_KERNEL_DSR_BYTES;
}

/*
 * Unlock previous reserved async GRU resources
 *
 *  input:
 *      han - handle to identify resources
 */
void gru_unlock_async_resource(unsigned long han)
{
    int blade_id = ASYNC_HAN_TO_BID(han);

    gru_unlock_kernel_context(blade_id);
}

/*----------------------------------------------------------------------*/
int gru_get_cb_exception_detail(void *cb,
        struct control_block_extended_exc_detail *excdet)
{
    struct gru_control_block_extended *cbe;
    struct gru_thread_state *kgts = NULL;
    unsigned long off;
    int cbrnum, bid;

    /*
     * Locate kgts for cb. This algorithm is SLOW but
     * this function is rarely called (ie., almost never).
     * Performance does not matter.
     */
    for_each_possible_blade(bid) {
        if (!gru_base[bid])
            break;
        kgts = gru_base[bid]->bs_kgts;
        if (!kgts || !kgts->ts_gru)
            continue;
        off = cb - kgts->ts_gru->gs_gru_base_vaddr;
        if (off < GRU_SIZE)
            break;
        kgts = NULL;
    }
    BUG_ON(!kgts);
    cbrnum = thread_cbr_number(kgts, get_cb_number(cb));
    cbe = get_cbe(GRUBASE(cb), cbrnum);
    gru_flush_cache(cbe);   /* CBE not coherent */
    sync_core();
    excdet->opc = cbe->opccpy;
    excdet->exopc = cbe->exopccpy;
    excdet->ecause = cbe->ecause;
    excdet->exceptdet0 = cbe->idef1upd;
    excdet->exceptdet1 = cbe->idef3upd;
    gru_flush_cache(cbe);
    return 0;
}

char *gru_get_cb_exception_detail_str(int ret, void *cb,
                      char *buf, int size)
{
    struct gru_control_block_status *gen = (void *)cb;
    struct control_block_extended_exc_detail excdet;

    if (ret > 0 && gen->istatus == CBS_EXCEPTION) {
        gru_get_cb_exception_detail(cb, &excdet);
        snprintf(buf, size,
            "GRU:%d exception: cb %p, opc %d, exopc %d, ecause 0x%x,"
            "excdet0 0x%lx, excdet1 0x%x", smp_processor_id(),
            gen, excdet.opc, excdet.exopc, excdet.ecause,
            excdet.exceptdet0, excdet.exceptdet1);
    } else {
        snprintf(buf, size, "No exception");
    }
    return buf;
}

static int gru_wait_idle_or_exception(struct gru_control_block_status *gen)
{
    while (gen->istatus >= CBS_ACTIVE) {
        cpu_relax();
        barrier();
    }
    return gen->istatus;
}

static int gru_retry_exception(void *cb)
{
    struct gru_control_block_status *gen = (void *)cb;
    struct control_block_extended_exc_detail excdet;
    int retry = EXCEPTION_RETRY_LIMIT;

    while (1)  {
        if (gru_wait_idle_or_exception(gen) == CBS_IDLE)
            return CBS_IDLE;
        if (gru_get_cb_message_queue_substatus(cb))
            return CBS_EXCEPTION;
        gru_get_cb_exception_detail(cb, &excdet);
        if ((excdet.ecause & ~EXCEPTION_RETRY_BITS) ||
                (excdet.cbrexecstatus & CBR_EXS_ABORT_OCC))
            break;
        if (retry-- == 0)
            break;
        gen->icmd = 1;
        gru_flush_cache(gen);
    }
    return CBS_EXCEPTION;
}

int gru_check_status_proc(void *cb)
{
    struct gru_control_block_status *gen = (void *)cb;
    int ret;

    ret = gen->istatus;
    if (ret == CBS_EXCEPTION)
        ret = gru_retry_exception(cb);
    rmb();
    return ret;

}

int gru_wait_proc(void *cb)
{
    struct gru_control_block_status *gen = (void *)cb;
    int ret;

    ret = gru_wait_idle_or_exception(gen);
    if (ret == CBS_EXCEPTION)
        ret = gru_retry_exception(cb);
    rmb();
    return ret;
}

void gru_abort(int ret, void *cb, char *str)
{
    char buf[GRU_EXC_STR_SIZE];

    panic("GRU FATAL ERROR: %s - %s\n", str,
          gru_get_cb_exception_detail_str(ret, cb, buf, sizeof(buf)));
}

void gru_wait_abort_proc(void *cb)
{
    int ret;

    ret = gru_wait_proc(cb);
    if (ret)
        gru_abort(ret, cb, "gru_wait_abort");
}


/*------------------------------ MESSAGE QUEUES -----------------------------*/

/* Internal status . These are NOT returned to the user. */
#define MQIE_AGAIN      -1  /* try again */


/*
 * Save/restore the "present" flag that is in the second line of 2-line
 * messages
 */
static inline int get_present2(void *p)
{
    struct message_header *mhdr = p + GRU_CACHE_LINE_BYTES;
    return mhdr->present;
}

static inline void restore_present2(void *p, int val)
{
    struct message_header *mhdr = p + GRU_CACHE_LINE_BYTES;
    mhdr->present = val;
}

/*
 * Create a message queue.
 *  qlines - message queue size in cache lines. Includes 2-line header.
 */
int gru_create_message_queue(struct gru_message_queue_desc *mqd,
        void *p, unsigned int bytes, int nasid, int vector, int apicid)
{
    struct message_queue *mq = p;
    unsigned int qlines;

    qlines = bytes / GRU_CACHE_LINE_BYTES - 2;
    memset(mq, 0, bytes);
    mq->start = &mq->data;
    mq->start2 = &mq->data + (qlines / 2 - 1) * GRU_CACHE_LINE_BYTES;
    mq->next = &mq->data;
    mq->limit = &mq->data + (qlines - 2) * GRU_CACHE_LINE_BYTES;
    mq->qlines = qlines;
    mq->hstatus[0] = 0;
    mq->hstatus[1] = 1;
    mq->head = gru_mesq_head(2, qlines / 2 + 1);
    mqd->mq = mq;
    mqd->mq_gpa = uv_gpa(mq);
    mqd->qlines = qlines;
    mqd->interrupt_pnode = nasid >> 1;
    mqd->interrupt_vector = vector;
    mqd->interrupt_apicid = apicid;
    return 0;
}
EXPORT_SYMBOL_GPL(gru_create_message_queue);

/*
 * Send a NOOP message to a message queue
 *  Returns:
 *       0 - if queue is full after the send. This is the normal case
 *           but various races can change this.
 *      -1 - if mesq sent successfully but queue not full
 *      >0 - unexpected error. MQE_xxx returned
 */
static int send_noop_message(void *cb, struct gru_message_queue_desc *mqd,
                void *mesg)
{
    const struct message_header noop_header = {
                    .present = MQS_NOOP, .lines = 1};
    unsigned long m;
    int substatus, ret;
    struct message_header save_mhdr, *mhdr = mesg;

    STAT(mesq_noop);
    save_mhdr = *mhdr;
    *mhdr = noop_header;
    gru_mesq(cb, mqd->mq_gpa, gru_get_tri(mhdr), 1, IMA);
    ret = gru_wait(cb);

    if (ret) {
        substatus = gru_get_cb_message_queue_substatus(cb);
        switch (substatus) {
        case CBSS_NO_ERROR:
            STAT(mesq_noop_unexpected_error);
            ret = MQE_UNEXPECTED_CB_ERR;
            break;
        case CBSS_LB_OVERFLOWED:
            STAT(mesq_noop_lb_overflow);
            ret = MQE_CONGESTION;
            break;
        case CBSS_QLIMIT_REACHED:
            STAT(mesq_noop_qlimit_reached);
            ret = 0;
            break;
        case CBSS_AMO_NACKED:
            STAT(mesq_noop_amo_nacked);
            ret = MQE_CONGESTION;
            break;
        case CBSS_PUT_NACKED:
            STAT(mesq_noop_put_nacked);
            m = mqd->mq_gpa + (gru_get_amo_value_head(cb) << 6);
            gru_vstore(cb, m, gru_get_tri(mesg), XTYPE_CL, 1, 1,
                        IMA);
            if (gru_wait(cb) == CBS_IDLE)
                ret = MQIE_AGAIN;
            else
                ret = MQE_UNEXPECTED_CB_ERR;
            break;
        case CBSS_PAGE_OVERFLOW:
            STAT(mesq_noop_page_overflow);
            /* fallthru */
        default:
            BUG();
        }
    }
    *mhdr = save_mhdr;
    return ret;
}

/*
 * Handle a gru_mesq full.
 */
static int send_message_queue_full(void *cb, struct gru_message_queue_desc *mqd,
                void *mesg, int lines)
{
    union gru_mesqhead mqh;
    unsigned int limit, head;
    unsigned long avalue;
    int half, qlines;

    /* Determine if switching to first/second half of q */
    avalue = gru_get_amo_value(cb);
    head = gru_get_amo_value_head(cb);
    limit = gru_get_amo_value_limit(cb);

    qlines = mqd->qlines;
    half = (limit != qlines);

    if (half)
        mqh = gru_mesq_head(qlines / 2 + 1, qlines);
    else
        mqh = gru_mesq_head(2, qlines / 2 + 1);

    /* Try to get lock for switching head pointer */
    gru_gamir(cb, EOP_IR_CLR, HSTATUS(mqd->mq_gpa, half), XTYPE_DW, IMA);
    if (gru_wait(cb) != CBS_IDLE)
        goto cberr;
    if (!gru_get_amo_value(cb)) {
        STAT(mesq_qf_locked);
        return MQE_QUEUE_FULL;
    }

    /* Got the lock. Send optional NOP if queue not full, */
    if (head != limit) {
        if (send_noop_message(cb, mqd, mesg)) {
            gru_gamir(cb, EOP_IR_INC, HSTATUS(mqd->mq_gpa, half),
                    XTYPE_DW, IMA);
            if (gru_wait(cb) != CBS_IDLE)
                goto cberr;
            STAT(mesq_qf_noop_not_full);
            return MQIE_AGAIN;
        }
        avalue++;
    }

    /* Then flip queuehead to other half of queue. */
    gru_gamer(cb, EOP_ERR_CSWAP, mqd->mq_gpa, XTYPE_DW, mqh.val, avalue,
                            IMA);
    if (gru_wait(cb) != CBS_IDLE)
        goto cberr;

    /* If not successfully in swapping queue head, clear the hstatus lock */
    if (gru_get_amo_value(cb) != avalue) {
        STAT(mesq_qf_switch_head_failed);
        gru_gamir(cb, EOP_IR_INC, HSTATUS(mqd->mq_gpa, half), XTYPE_DW,
                            IMA);
        if (gru_wait(cb) != CBS_IDLE)
            goto cberr;
    }
    return MQIE_AGAIN;
cberr:
    STAT(mesq_qf_unexpected_error);
    return MQE_UNEXPECTED_CB_ERR;
}

/*
 * Handle a PUT failure. Note: if message was a 2-line message, one of the
 * lines might have successfully have been written. Before sending the
 * message, "present" must be cleared in BOTH lines to prevent the receiver
 * from prematurely seeing the full message.
 */
static int send_message_put_nacked(void *cb, struct gru_message_queue_desc *mqd,
            void *mesg, int lines)
{
    unsigned long m, *val = mesg, gpa, save;
    int ret;

    m = mqd->mq_gpa + (gru_get_amo_value_head(cb) << 6);
    if (lines == 2) {
        gru_vset(cb, m, 0, XTYPE_CL, lines, 1, IMA);
        if (gru_wait(cb) != CBS_IDLE)
            return MQE_UNEXPECTED_CB_ERR;
    }
    gru_vstore(cb, m, gru_get_tri(mesg), XTYPE_CL, lines, 1, IMA);
    if (gru_wait(cb) != CBS_IDLE)
        return MQE_UNEXPECTED_CB_ERR;

    if (!mqd->interrupt_vector)
        return MQE_OK;

    /*
     * Send a cross-partition interrupt to the SSI that contains the target
     * message queue. Normally, the interrupt is automatically delivered by
     * hardware but some error conditions require explicit delivery.
     * Use the GRU to deliver the interrupt. Otherwise partition failures
     * could cause unrecovered errors.
     */
    gpa = uv_global_gru_mmr_address(mqd->interrupt_pnode, UVH_IPI_INT);
    save = *val;
    *val = uv_hub_ipi_value(mqd->interrupt_apicid, mqd->interrupt_vector,
                dest_Fixed);
    gru_vstore_phys(cb, gpa, gru_get_tri(mesg), IAA_REGISTER, IMA);
    ret = gru_wait(cb);
    *val = save;
    if (ret != CBS_IDLE)
        return MQE_UNEXPECTED_CB_ERR;
    return MQE_OK;
}

/*
 * Handle a gru_mesq failure. Some of these failures are software recoverable
 * or retryable.
 */
static int send_message_failure(void *cb, struct gru_message_queue_desc *mqd,
                void *mesg, int lines)
{
    int substatus, ret = 0;

    substatus = gru_get_cb_message_queue_substatus(cb);
    switch (substatus) {
    case CBSS_NO_ERROR:
        STAT(mesq_send_unexpected_error);
        ret = MQE_UNEXPECTED_CB_ERR;
        break;
    case CBSS_LB_OVERFLOWED:
        STAT(mesq_send_lb_overflow);
        ret = MQE_CONGESTION;
        break;
    case CBSS_QLIMIT_REACHED:
        STAT(mesq_send_qlimit_reached);
        ret = send_message_queue_full(cb, mqd, mesg, lines);
        break;
    case CBSS_AMO_NACKED:
        STAT(mesq_send_amo_nacked);
        ret = MQE_CONGESTION;
        break;
    case CBSS_PUT_NACKED:
        STAT(mesq_send_put_nacked);
        ret = send_message_put_nacked(cb, mqd, mesg, lines);
        break;
    case CBSS_PAGE_OVERFLOW:
        STAT(mesq_page_overflow);
        /* fallthru */
    default:
        BUG();
    }
    return ret;
}

/*
 * Send a message to a message queue
 *  mqd message queue descriptor
 *  mesg    message. ust be vaddr within a GSEG
 *  bytes   message size (<= 2 CL)
 */
int gru_send_message_gpa(struct gru_message_queue_desc *mqd, void *mesg,
                unsigned int bytes)
{
    struct message_header *mhdr;
    void *cb;
    void *dsr;
    int istatus, clines, ret;

    STAT(mesq_send);
    BUG_ON(bytes < sizeof(int) || bytes > 2 * GRU_CACHE_LINE_BYTES);

    clines = DIV_ROUND_UP(bytes, GRU_CACHE_LINE_BYTES);
    if (gru_get_cpu_resources(bytes, &cb, &dsr))
        return MQE_BUG_NO_RESOURCES;
    memcpy(dsr, mesg, bytes);
    mhdr = dsr;
    mhdr->present = MQS_FULL;
    mhdr->lines = clines;
    if (clines == 2) {
        mhdr->present2 = get_present2(mhdr);
        restore_present2(mhdr, MQS_FULL);
    }

    do {
        ret = MQE_OK;
        gru_mesq(cb, mqd->mq_gpa, gru_get_tri(mhdr), clines, IMA);
        istatus = gru_wait(cb);
        if (istatus != CBS_IDLE)
            ret = send_message_failure(cb, mqd, dsr, clines);
    } while (ret == MQIE_AGAIN);
    gru_free_cpu_resources(cb, dsr);

    if (ret)
        STAT(mesq_send_failed);
    return ret;
}
EXPORT_SYMBOL_GPL(gru_send_message_gpa);

/*
 * Advance the receive pointer for the queue to the next message.
 */
void gru_free_message(struct gru_message_queue_desc *mqd, void *mesg)
{
    struct message_queue *mq = mqd->mq;
    struct message_header *mhdr = mq->next;
    void *next, *pnext;
    int half = -1;
    int lines = mhdr->lines;

    if (lines == 2)
        restore_present2(mhdr, MQS_EMPTY);
    mhdr->present = MQS_EMPTY;

    pnext = mq->next;
    next = pnext + GRU_CACHE_LINE_BYTES * lines;
    if (next == mq->limit) {
        next = mq->start;
        half = 1;
    } else if (pnext < mq->start2 && next >= mq->start2) {
        half = 0;
    }

    if (half >= 0)
        mq->hstatus[half] = 1;
    mq->next = next;
}
EXPORT_SYMBOL_GPL(gru_free_message);

/*
 * Get next message from message queue. Return NULL if no message
 * present. User must call next_message() to move to next message.
 *  rmq message queue
 */
void *gru_get_next_message(struct gru_message_queue_desc *mqd)
{
    struct message_queue *mq = mqd->mq;
    struct message_header *mhdr = mq->next;
    int present = mhdr->present;

    /* skip NOOP messages */
    while (present == MQS_NOOP) {
        gru_free_message(mqd, mhdr);
        mhdr = mq->next;
        present = mhdr->present;
    }

    /* Wait for both halves of 2 line messages */
    if (present == MQS_FULL && mhdr->lines == 2 &&
                get_present2(mhdr) == MQS_EMPTY)
        present = MQS_EMPTY;

    if (!present) {
        STAT(mesq_receive_none);
        return NULL;
    }

    if (mhdr->lines == 2)
        restore_present2(mhdr, mhdr->present2);

    STAT(mesq_receive);
    return mhdr;
}
EXPORT_SYMBOL_GPL(gru_get_next_message);

/* ---------------------- GRU DATA COPY FUNCTIONS ---------------------------*/

/*
 * Load a DW from a global GPA. The GPA can be a memory or MMR address.
 */
int gru_read_gpa(unsigned long *value, unsigned long gpa)
{
    void *cb;
    void *dsr;
    int ret, iaa;

    STAT(read_gpa);
    if (gru_get_cpu_resources(GRU_NUM_KERNEL_DSR_BYTES, &cb, &dsr))
        return MQE_BUG_NO_RESOURCES;
    iaa = gpa >> 62;
    gru_vload_phys(cb, gpa, gru_get_tri(dsr), iaa, IMA);
    ret = gru_wait(cb);
    if (ret == CBS_IDLE)
        *value = *(unsigned long *)dsr;
    gru_free_cpu_resources(cb, dsr);
    return ret;
}
EXPORT_SYMBOL_GPL(gru_read_gpa);


/*
 * Copy a block of data using the GRU resources
 */
int gru_copy_gpa(unsigned long dest_gpa, unsigned long src_gpa,
                unsigned int bytes)
{
    void *cb;
    void *dsr;
    int ret;

    STAT(copy_gpa);
    if (gru_get_cpu_resources(GRU_NUM_KERNEL_DSR_BYTES, &cb, &dsr))
        return MQE_BUG_NO_RESOURCES;
    gru_bcopy(cb, src_gpa, dest_gpa, gru_get_tri(dsr),
          XTYPE_B, bytes, GRU_NUM_KERNEL_DSR_CL, IMA);
    ret = gru_wait(cb);
    gru_free_cpu_resources(cb, dsr);
    return ret;
}
EXPORT_SYMBOL_GPL(gru_copy_gpa);

/* ------------------- KERNEL QUICKTESTS RUN AT STARTUP ----------------*/
/*  Temp - will delete after we gain confidence in the GRU      */

static int quicktest0(unsigned long arg)
{
    unsigned long word0;
    unsigned long word1;
    void *cb;
    void *dsr;
    unsigned long *p;
    int ret = -EIO;

    if (gru_get_cpu_resources(GRU_CACHE_LINE_BYTES, &cb, &dsr))
        return MQE_BUG_NO_RESOURCES;
    p = dsr;
    word0 = MAGIC;
    word1 = 0;

    gru_vload(cb, uv_gpa(&word0), gru_get_tri(dsr), XTYPE_DW, 1, 1, IMA);
    if (gru_wait(cb) != CBS_IDLE) {
        printk(KERN_DEBUG "GRU:%d quicktest0: CBR failure 1\n", smp_processor_id());
        goto done;
    }

    if (*p != MAGIC) {
        printk(KERN_DEBUG "GRU:%d quicktest0 bad magic 0x%lx\n", smp_processor_id(), *p);
        goto done;
    }
    gru_vstore(cb, uv_gpa(&word1), gru_get_tri(dsr), XTYPE_DW, 1, 1, IMA);
    if (gru_wait(cb) != CBS_IDLE) {
        printk(KERN_DEBUG "GRU:%d quicktest0: CBR failure 2\n", smp_processor_id());
        goto done;
    }

    if (word0 != word1 || word1 != MAGIC) {
        printk(KERN_DEBUG
               "GRU:%d quicktest0 err: found 0x%lx, expected 0x%lx\n",
             smp_processor_id(), word1, MAGIC);
        goto done;
    }
    ret = 0;

done:
    gru_free_cpu_resources(cb, dsr);
    return ret;
}

#define ALIGNUP(p, q)   ((void *)(((unsigned long)(p) + (q) - 1) & ~(q - 1)))

static int quicktest1(unsigned long arg)
{
    struct gru_message_queue_desc mqd;
    void *p, *mq;
    unsigned long *dw;
    int i, ret = -EIO;
    char mes[GRU_CACHE_LINE_BYTES], *m;

    /* Need  1K cacheline aligned that does not cross page boundary */
    p = kmalloc(4096, 0);
    if (p == NULL)
        return -ENOMEM;
    mq = ALIGNUP(p, 1024);
    memset(mes, 0xee, sizeof(mes));
    dw = mq;

    gru_create_message_queue(&mqd, mq, 8 * GRU_CACHE_LINE_BYTES, 0, 0, 0);
    for (i = 0; i < 6; i++) {
        mes[8] = i;
        do {
            ret = gru_send_message_gpa(&mqd, mes, sizeof(mes));
        } while (ret == MQE_CONGESTION);
        if (ret)
            break;
    }
    if (ret != MQE_QUEUE_FULL || i != 4) {
        printk(KERN_DEBUG "GRU:%d quicktest1: unexpect status %d, i %d\n",
               smp_processor_id(), ret, i);
        goto done;
    }

    for (i = 0; i < 6; i++) {
        m = gru_get_next_message(&mqd);
        if (!m || m[8] != i)
            break;
        gru_free_message(&mqd, m);
    }
    if (i != 4) {
        printk(KERN_DEBUG "GRU:%d quicktest2: bad message, i %d, m %p, m8 %d\n",
            smp_processor_id(), i, m, m ? m[8] : -1);
        goto done;
    }
    ret = 0;

done:
    kfree(p);
    return ret;
}

static int quicktest2(unsigned long arg)
{
    static DECLARE_COMPLETION(cmp);
    unsigned long han;
    int blade_id = 0;
    int numcb = 4;
    int ret = 0;
    unsigned long *buf;
    void *cb0, *cb;
    struct gru_control_block_status *gen;
    int i, k, istatus, bytes;

    bytes = numcb * 4 * 8;
    buf = kmalloc(bytes, GFP_KERNEL);
    if (!buf)
        return -ENOMEM;

    ret = -EBUSY;
    han = gru_reserve_async_resources(blade_id, numcb, 0, &cmp);
    if (!han)
        goto done;

    gru_lock_async_resource(han, &cb0, NULL);
    memset(buf, 0xee, bytes);
    for (i = 0; i < numcb; i++)
        gru_vset(cb0 + i * GRU_HANDLE_STRIDE, uv_gpa(&buf[i * 4]), 0,
                XTYPE_DW, 4, 1, IMA_INTERRUPT);

    ret = 0;
    k = numcb;
    do {
        gru_wait_async_cbr(han);
        for (i = 0; i < numcb; i++) {
            cb = cb0 + i * GRU_HANDLE_STRIDE;
            istatus = gru_check_status(cb);
            if (istatus != CBS_ACTIVE && istatus != CBS_CALL_OS)
                break;
        }
        if (i == numcb)
            continue;
        if (istatus != CBS_IDLE) {
            printk(KERN_DEBUG "GRU:%d quicktest2: cb %d, exception\n", smp_processor_id(), i);
            ret = -EFAULT;
        } else if (buf[4 * i] || buf[4 * i + 1] || buf[4 * i + 2] ||
                buf[4 * i + 3]) {
            printk(KERN_DEBUG "GRU:%d quicktest2:cb %d,  buf 0x%lx, 0x%lx, 0x%lx, 0x%lx\n",
                   smp_processor_id(), i, buf[4 * i], buf[4 * i + 1], buf[4 * i + 2], buf[4 * i + 3]);
            ret = -EIO;
        }
        k--;
        gen = cb;
        gen->istatus = CBS_CALL_OS; /* don't handle this CBR again */
    } while (k);
    BUG_ON(cmp.done);

    gru_unlock_async_resource(han);
    gru_release_async_resources(han);
done:
    kfree(buf);
    return ret;
}

#define BUFSIZE 200
static int quicktest3(unsigned long arg)
{
    char buf1[BUFSIZE], buf2[BUFSIZE];
    int ret = 0;

    memset(buf2, 0, sizeof(buf2));
    memset(buf1, get_cycles() & 255, sizeof(buf1));
    gru_copy_gpa(uv_gpa(buf2), uv_gpa(buf1), BUFSIZE);
    if (memcmp(buf1, buf2, BUFSIZE)) {
        printk(KERN_DEBUG "GRU:%d quicktest3 error\n", smp_processor_id());
        ret = -EIO;
    }
    return ret;
}

/*
 * Debugging only. User hook for various kernel tests
 * of driver & gru.
 */
int gru_ktest(unsigned long arg)
{
    int ret = -EINVAL;

    switch (arg & 0xff) {
    case 0:
        ret = quicktest0(arg);
        break;
    case 1:
        ret = quicktest1(arg);
        break;
    case 2:
        ret = quicktest2(arg);
        break;
    case 3:
        ret = quicktest3(arg);
        break;
    case 99:
        ret = gru_free_kernel_contexts();
        break;
    }
    return ret;

}

int gru_kservices_init(void)
{
    return 0;
}

void gru_kservices_exit(void)
{
    if (gru_free_kernel_contexts())
        BUG();
}