/*
   * 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
  ", 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
  ", smp_processor_id());
  		goto done;
  	}
  
  	if (*p != MAGIC) {
  		printk(KERN_DEBUG "GRU:%d quicktest0 bad magic 0x%lx
  ", 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
  ", smp_processor_id());
  		goto done;
  	}
  
  	if (word0 != word1 || word1 != MAGIC) {
  		printk(KERN_DEBUG
  		       "GRU:%d quicktest0 err: found 0x%lx, expected 0x%lx
  ",
  		     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
  ",
  		       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
  ",
  			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
  ", 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
  ",
  			       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
  ", 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();
  }