GRU Driver: kernel services provide by driver

This file contains functions for handling services provided to other
kernel modules that use the GRU.

Signed-off-by: Jack Steiner <steiner@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 679 insertions, 0 deletions

diff --git a/drivers/misc/sgi-gru/grukservices.c b/drivers/misc/sgi-gru/grukservices.c
new file mode 100644
index 0000000..234d165
--- /dev/null
+++ b/drivers/misc/sgi-gru/grukservices.c
@@ -0,0 +1,679 @@
+/*
+ * 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/smp_lock.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 "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.
+ *
+ * At boot time, the kernel permanently reserves a fixed number of
+ * CBRs/DSRs for each cpu to use. The resources are all taken from
+ * the GRU chiplet 1 on the blade. This leaves the full set of resources
+ * of chiplet 0 available to be allocated to a single user.
+ */
+
+/* Blade percpu resources PERMANENTLY reserved for kernel use */
+#define GRU_NUM_KERNEL_CBR      1
+#define GRU_NUM_KERNEL_DSR_BYTES 256
+#define KERNEL_CTXNUM           15
+
+/* 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 QLINES(mq)	((mq) + offsetof(struct message_queue, qlines))
+#define HSTATUS(mq, h)	((mq) + offsetof(struct message_queue, hstatus[h]))
+
+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_base[uv_numa_blade_id()];
+	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;
+}
+
+static void gru_free_cpu_resources(void *cb, void *dsr)
+{
+	preempt_enable();
+}
+
+int gru_get_cb_exception_detail(void *cb,
+		struct control_block_extended_exc_detail *excdet)
+{
+	struct gru_control_block_extended *cbe;
+
+	cbe = get_cbe(GRUBASE(cb), get_cb_number(cb));
+	excdet->opc = cbe->opccpy;
+	excdet->exopc = cbe->exopccpy;
+	excdet->ecause = cbe->ecause;
+	excdet->exceptdet0 = cbe->idef1upd;
+	excdet->exceptdet1 = cbe->idef3upd;
+	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 exception: cb %p, opc %d, exopc %d, ecause 0x%x,"
+			"excdet0 0x%lx, excdet1 0x%x",
+			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_get_cb_message_queue_substatus(cb))
+			break;
+		if (gru_wait_idle_or_exception(gen) == CBS_IDLE)
+			return CBS_IDLE;
+
+		gru_get_cb_exception_detail(cb, &excdet);
+		if (excdet.ecause & ~EXCEPTION_RETRY_BITS)
+			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)
+		return ret;
+	return gru_retry_exception(cb);
+
+}
+
+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);
+
+	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(void *p, unsigned int bytes)
+{
+	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);
+	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,
+				unsigned long mq, 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, mq, 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 = mq + (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:
+		default:
+			BUG();
+		}
+	}
+	*mhdr = save_mhdr;
+	return ret;
+}
+
+/*
+ * Handle a gru_mesq full.
+ */
+static int send_message_queue_full(void *cb,
+			   unsigned long mq, void *mesg, int lines)
+{
+	union gru_mesqhead mqh;
+	unsigned int limit, head;
+	unsigned long avalue;
+	int half, qlines, save;
+
+	/* 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);
+
+	/*
+	 * Fetch "qlines" from the queue header. Since the queue may be
+	 * in memory that can't be accessed using socket addresses, use
+	 * the GRU to access the data. Use DSR space from the message.
+	 */
+	save = *(int *)mesg;
+	gru_vload(cb, QLINES(mq), gru_get_tri(mesg), XTYPE_W, 1, 1, IMA);
+	if (gru_wait(cb) != CBS_IDLE)
+		goto cberr;
+	qlines = *(int *)mesg;
+	*(int *)mesg = save;
+	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(mq, 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, mq, mesg)) {
+			gru_gamir(cb, EOP_IR_INC, HSTATUS(mq, 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, mq, 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(mq, 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 gru_mesq failure. Some of these failures are software recoverable
+ * or retryable.
+ */
+static int send_message_failure(void *cb,
+				unsigned long mq,
+				void *mesg,
+				int lines)
+{
+	int substatus, ret = 0;
+	unsigned long m;
+
+	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, mq, 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);
+		m =mq + (gru_get_amo_value_head(cb) << 6);
+		gru_vstore(cb, m, gru_get_tri(mesg), XTYPE_CL, lines, 1, IMA);
+		if (gru_wait(cb) == CBS_IDLE)
+			ret = MQE_OK;
+		else
+			ret = MQE_UNEXPECTED_CB_ERR;
+		break;
+	default:
+		BUG();
+	}
+	return ret;
+}
+
+/*
+ * Send a message to a message queue
+ * 	cb	GRU control block to use to send message
+ * 	mq	message queue
+ * 	mesg	message. ust be vaddr within a GSEG
+ * 	bytes	message size (<= 2 CL)
+ */
+int gru_send_message_gpa(unsigned long mq, 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 = (bytes + GRU_CACHE_LINE_BYTES - 1) / 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, mq, gru_get_tri(mhdr), clines, IMA);
+		istatus = gru_wait(cb);
+		if (istatus != CBS_IDLE)
+			ret = send_message_failure(cb, mq, 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(void *rmq, void *mesg)
+{
+	struct message_queue *mq = rmq;
+	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(void *rmq)
+{
+	struct message_queue *mq = rmq;
+	struct message_header *mhdr = mq->next;
+	int present = mhdr->present;
+
+	/* skip NOOP messages */
+	STAT(mesq_receive);
+	while (present == MQS_NOOP) {
+		gru_free_message(rmq, 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);
+
+	return mhdr;
+}
+EXPORT_SYMBOL_GPL(gru_get_next_message);
+
+/* ---------------------- GRU DATA COPY FUNCTIONS ---------------------------*/
+
+/*
+ * 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_BYTES, 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 __cacheline_aligned unsigned long word0;
+static __cacheline_aligned unsigned long word1;
+
+static int quicktest(struct gru_state *gru)
+{
+	void *cb;
+	void *ds;
+	unsigned long *p;
+
+	cb = get_gseg_base_address_cb(gru->gs_gru_base_vaddr, KERNEL_CTXNUM, 0);
+	ds = get_gseg_base_address_ds(gru->gs_gru_base_vaddr, KERNEL_CTXNUM, 0);
+	p = ds;
+	word0 = MAGIC;
+
+	gru_vload(cb, uv_gpa(&word0), 0, XTYPE_DW, 1, 1, IMA);
+	if (gru_wait(cb) != CBS_IDLE)
+		BUG();
+
+	if (*(unsigned long *)ds != MAGIC)
+		BUG();
+	gru_vstore(cb, uv_gpa(&word1), 0, XTYPE_DW, 1, 1, IMA);
+	if (gru_wait(cb) != CBS_IDLE)
+		BUG();
+
+	if (word0 != word1 || word0 != MAGIC) {
+		printk
+		    ("GRU quicktest err: gru %d, found 0x%lx, expected 0x%lx\n",
+		     gru->gs_gid, word1, MAGIC);
+		BUG();		/* ZZZ should not be fatal */
+	}
+
+	return 0;
+}
+
+
+int gru_kservices_init(struct gru_state *gru)
+{
+	struct gru_blade_state *bs;
+	struct gru_context_configuration_handle *cch;
+	unsigned long cbr_map, dsr_map;
+	int err, num, cpus_possible;
+
+	/*
+	 * Currently, resources are reserved ONLY on the second chiplet
+	 * on each blade. This leaves ALL resources on chiplet 0 available
+	 * for user code.
+	 */
+	bs = gru->gs_blade;
+	if (gru != &bs->bs_grus[1])
+		return 0;
+
+	cpus_possible = uv_blade_nr_possible_cpus(gru->gs_blade_id);
+
+	num = GRU_NUM_KERNEL_CBR * cpus_possible;
+	cbr_map = reserve_gru_cb_resources(gru, GRU_CB_COUNT_TO_AU(num), NULL);
+	gru->gs_reserved_cbrs += num;
+
+	num = GRU_NUM_KERNEL_DSR_BYTES * cpus_possible;
+	dsr_map = reserve_gru_ds_resources(gru, GRU_DS_BYTES_TO_AU(num), NULL);
+	gru->gs_reserved_dsr_bytes += num;
+
+	gru->gs_active_contexts++;
+	__set_bit(KERNEL_CTXNUM, &gru->gs_context_map);
+	cch = get_cch(gru->gs_gru_base_vaddr, KERNEL_CTXNUM);
+
+	bs->kernel_cb = get_gseg_base_address_cb(gru->gs_gru_base_vaddr,
+					KERNEL_CTXNUM, 0);
+	bs->kernel_dsr = get_gseg_base_address_ds(gru->gs_gru_base_vaddr,
+					KERNEL_CTXNUM, 0);
+
+	lock_cch_handle(cch);
+	cch->tfm_fault_bit_enable = 0;
+	cch->tlb_int_enable = 0;
+	cch->tfm_done_bit_enable = 0;
+	cch->unmap_enable = 1;
+	err = cch_allocate(cch, 0, cbr_map, dsr_map);
+	if (err) {
+		gru_dbg(grudev,
+			"Unable to allocate kernel CCH: gru %d, err %d\n",
+			gru->gs_gid, err);
+		BUG();
+	}
+	if (cch_start(cch)) {
+		gru_dbg(grudev, "Unable to start kernel CCH: gru %d, err %d\n",
+			gru->gs_gid, err);
+		BUG();
+	}
+	unlock_cch_handle(cch);
+
+	if (options & GRU_QUICKLOOK)
+		quicktest(gru);
+	return 0;
+}