xref: /netbsd-src/sys/dev/pci/vioscsi.c (revision f21b7d7f2cbdd5c14b3882c4e8a3d43580d460a6)
1 /*	$NetBSD: vioscsi.c,v 1.8 2016/10/04 18:23:24 jdolecek Exp $	*/
2 /*	$OpenBSD: vioscsi.c,v 1.3 2015/03/14 03:38:49 jsg Exp $	*/
3 
4 /*
5  * Copyright (c) 2013 Google Inc.
6  *
7  * Permission to use, copy, modify, and distribute this software for any
8  * purpose with or without fee is hereby granted, provided that the above
9  * copyright notice and this permission notice appear in all copies.
10  *
11  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
12  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
13  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
14  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
15  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
16  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
17  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
18  */
19 
20 #include <sys/cdefs.h>
21 __KERNEL_RCSID(0, "$NetBSD: vioscsi.c,v 1.8 2016/10/04 18:23:24 jdolecek Exp $");
22 
23 #include <sys/param.h>
24 #include <sys/systm.h>
25 #include <sys/device.h>
26 #include <sys/bus.h>
27 #include <sys/buf.h>
28 
29 #include <dev/pci/pcidevs.h>
30 #include <dev/pci/pcireg.h>
31 #include <dev/pci/pcivar.h>
32 
33 #include <dev/pci/vioscsireg.h>
34 #include <dev/pci/virtiovar.h>
35 
36 #include <dev/scsipi/scsi_all.h>
37 #include <dev/scsipi/scsiconf.h>
38 
39 #ifdef VIOSCSI_DEBUG
40 static int vioscsi_debug = 1;
41 #define DPRINTF(f) do { if (vioscsi_debug) printf f; } while (/*CONSTCOND*/0)
42 #else
43 #define DPRINTF(f) ((void)0)
44 #endif
45 
46 struct vioscsi_req {
47 	struct virtio_scsi_req_hdr	 vr_req;
48 	struct virtio_scsi_res_hdr	 vr_res;
49 	struct scsipi_xfer		*vr_xs;
50 	bus_dmamap_t			 vr_control;
51 	bus_dmamap_t			 vr_data;
52 };
53 
54 struct vioscsi_softc {
55 	device_t 		 sc_dev;
56 	struct scsipi_adapter	 sc_adapter;
57 	struct scsipi_channel 	 sc_channel;
58 
59 	struct virtqueue	 sc_vqs[3];
60 	struct vioscsi_req	*sc_reqs;
61 	bus_dma_segment_t        sc_reqs_segs[1];
62 
63 	u_int32_t		 sc_seg_max;
64 };
65 
66 /*
67  * Each block request uses at least two segments - one for the header
68  * and one for the status.
69 */
70 #define VIRTIO_SCSI_MIN_SEGMENTS 2
71 
72 static int	 vioscsi_match(device_t, cfdata_t, void *);
73 static void	 vioscsi_attach(device_t, device_t, void *);
74 
75 static int	 vioscsi_alloc_reqs(struct vioscsi_softc *,
76     struct virtio_softc *, int, uint32_t);
77 static void	 vioscsi_scsipi_request(struct scsipi_channel *,
78     scsipi_adapter_req_t, void *);
79 static int	 vioscsi_vq_done(struct virtqueue *);
80 static void	 vioscsi_req_done(struct vioscsi_softc *, struct virtio_softc *,
81     struct vioscsi_req *);
82 static struct vioscsi_req *vioscsi_req_get(struct vioscsi_softc *);
83 static void	 vioscsi_req_put(struct vioscsi_softc *, struct vioscsi_req *);
84 
85 static const char *const vioscsi_vq_names[] = {
86 	"control",
87 	"event",
88 	"request",
89 };
90 
91 CFATTACH_DECL_NEW(vioscsi, sizeof(struct vioscsi_softc),
92     vioscsi_match, vioscsi_attach, NULL, NULL);
93 
94 static int
95 vioscsi_match(device_t parent, cfdata_t match, void *aux)
96 {
97 	struct virtio_softc *va = aux;
98 
99 	if (va->sc_childdevid == PCI_PRODUCT_VIRTIO_SCSI)
100 		return 1;
101 	return 0;
102 }
103 
104 static void
105 vioscsi_attach(device_t parent, device_t self, void *aux)
106 {
107 	struct vioscsi_softc *sc = device_private(self);
108 	struct virtio_softc *vsc = device_private(parent);
109 	struct scsipi_adapter *adapt = &sc->sc_adapter;
110 	struct scsipi_channel *chan = &sc->sc_channel;
111 	uint32_t features;
112 	char buf[256];
113 	int rv;
114 
115 	if (vsc->sc_child != NULL) {
116 		aprint_error(": parent %s already has a child\n",
117 		    device_xname(parent));
118 		return;
119 	}
120 
121 	sc->sc_dev = self;
122 
123 	vsc->sc_child = self;
124 	vsc->sc_ipl = IPL_BIO;
125 	vsc->sc_vqs = sc->sc_vqs;
126 	vsc->sc_nvqs = __arraycount(sc->sc_vqs);
127 	vsc->sc_config_change = NULL;
128 	vsc->sc_intrhand = virtio_vq_intr;
129 	vsc->sc_flags = 0;
130 
131 	features = virtio_negotiate_features(vsc, 0);
132 	snprintb(buf, sizeof(buf), VIRTIO_COMMON_FLAG_BITS, features);
133 	aprint_normal(": Features: %s\n", buf);
134 	aprint_naive("\n");
135 
136 	uint32_t cmd_per_lun = virtio_read_device_config_4(vsc,
137 	    VIRTIO_SCSI_CONFIG_CMD_PER_LUN);
138 
139 	uint32_t seg_max = virtio_read_device_config_4(vsc,
140 	    VIRTIO_SCSI_CONFIG_SEG_MAX);
141 
142 	uint16_t max_target = virtio_read_device_config_2(vsc,
143 	    VIRTIO_SCSI_CONFIG_MAX_TARGET);
144 
145 	uint16_t max_channel = virtio_read_device_config_2(vsc,
146 	    VIRTIO_SCSI_CONFIG_MAX_CHANNEL);
147 
148 	uint32_t max_lun = virtio_read_device_config_4(vsc,
149 	    VIRTIO_SCSI_CONFIG_MAX_LUN);
150 
151 	sc->sc_seg_max = seg_max;
152 
153 	for (size_t i = 0; i < __arraycount(sc->sc_vqs); i++) {
154 		rv = virtio_alloc_vq(vsc, &sc->sc_vqs[i], i, MAXPHYS,
155 		    1 + howmany(MAXPHYS, NBPG), vioscsi_vq_names[i]);
156 		if (rv) {
157 			aprint_error_dev(sc->sc_dev,
158 			    "failed to allocate virtqueue %zu\n", i);
159 			return;
160 		}
161 		sc->sc_vqs[i].vq_done = vioscsi_vq_done;
162 	}
163 
164 	int qsize = sc->sc_vqs[2].vq_num;
165 	aprint_normal_dev(sc->sc_dev, "qsize %d\n", qsize);
166 	if (vioscsi_alloc_reqs(sc, vsc, qsize, seg_max))
167 		return;
168 
169 	/*
170 	 * Fill in the scsipi_adapter.
171 	 */
172 	memset(adapt, 0, sizeof(*adapt));
173 	adapt->adapt_dev = sc->sc_dev;
174 	adapt->adapt_nchannels = max_channel;
175 	adapt->adapt_openings = cmd_per_lun;
176 	adapt->adapt_max_periph = adapt->adapt_openings;
177 	adapt->adapt_request = vioscsi_scsipi_request;
178 	adapt->adapt_minphys = minphys;
179 
180 	/*
181 	 * Fill in the scsipi_channel.
182 	 */
183 	memset(chan, 0, sizeof(*chan));
184 	chan->chan_adapter = adapt;
185 	chan->chan_bustype = &scsi_bustype;
186 	chan->chan_channel = 0;
187 	chan->chan_ntargets = max_target;
188 	chan->chan_nluns = max_lun;
189 	chan->chan_id = 0;
190 	chan->chan_flags = SCSIPI_CHAN_NOSETTLE;
191 
192 	config_found(sc->sc_dev, &sc->sc_channel, scsiprint);
193 }
194 
195 #define XS2DMA(xs) \
196     ((((xs)->xs_control & XS_CTL_DATA_IN) ? BUS_DMA_READ : BUS_DMA_WRITE) | \
197     (((xs)->xs_control & XS_CTL_NOSLEEP) ? BUS_DMA_NOWAIT : BUS_DMA_WAITOK) | \
198     BUS_DMA_STREAMING)
199 
200 #define XS2DMAPRE(xs) (((xs)->xs_control & XS_CTL_DATA_IN) ? \
201     BUS_DMASYNC_PREREAD : BUS_DMASYNC_PREWRITE)
202 
203 #define XS2DMAPOST(xs) (((xs)->xs_control & XS_CTL_DATA_IN) ? \
204     BUS_DMASYNC_POSTREAD : BUS_DMASYNC_POSTWRITE)
205 
206 static void
207 vioscsi_scsipi_request(struct scsipi_channel *chan, scsipi_adapter_req_t
208     request, void *arg)
209 {
210 	struct vioscsi_softc *sc =
211 	    device_private(chan->chan_adapter->adapt_dev);
212 	struct virtio_softc *vsc = device_private(device_parent(sc->sc_dev));
213 	struct scsipi_xfer *xs;
214 	struct scsipi_periph *periph;
215 	struct vioscsi_req *vr;
216 	struct virtio_scsi_req_hdr *req;
217 	struct virtqueue *vq = &sc->sc_vqs[2];
218 	int slot, error;
219 
220 	DPRINTF(("%s: enter\n", __func__));
221 
222 	switch (request) {
223 	case ADAPTER_REQ_RUN_XFER:
224 		break;
225 	case ADAPTER_REQ_SET_XFER_MODE:
226 	{
227 		struct scsipi_xfer_mode *xm = arg;
228 		xm->xm_mode = PERIPH_CAP_TQING;
229 		xm->xm_period = 0;
230 		xm->xm_offset = 0;
231 		scsipi_async_event(chan, ASYNC_EVENT_XFER_MODE, xm);
232 		return;
233 	}
234 	default:
235 		DPRINTF(("%s: unhandled %d\n", __func__, request));
236 		return;
237 	}
238 
239 	xs = arg;
240 	periph = xs->xs_periph;
241 
242 	vr = vioscsi_req_get(sc);
243 	/*
244 	 * This can happen when we run out of queue slots.
245 	 */
246 	if (vr == NULL) {
247 		xs->error = XS_RESOURCE_SHORTAGE;
248 		scsipi_done(xs);
249 		return;
250 	}
251 
252 	req = &vr->vr_req;
253 	slot = vr - sc->sc_reqs;
254 
255 	vr->vr_xs = xs;
256 
257 	/*
258 	 * "The only supported format for the LUN field is: first byte set to
259 	 * 1, second byte set to target, third and fourth byte representing a
260 	 * single level LUN structure, followed by four zero bytes."
261 	 */
262 	if (periph->periph_target >= 256 || periph->periph_lun >= 16384) {
263 		DPRINTF(("%s: bad target %u or lun %u\n", __func__,
264 		    periph->periph_target, periph->periph_lun));
265 		goto stuffup;
266 	}
267 	req->lun[0] = 1;
268 	req->lun[1] = periph->periph_target - 1;
269 	req->lun[2] = 0x40 | (periph->periph_lun >> 8);
270 	req->lun[3] = periph->periph_lun;
271 	memset(req->lun + 4, 0, 4);
272 	DPRINTF(("%s: command for %u:%u at slot %d\n", __func__,
273 	    periph->periph_target - 1, periph->periph_lun, slot));
274 
275 	/* tag */
276 	switch (XS_CTL_TAGTYPE(xs)) {
277 	case XS_CTL_HEAD_TAG:
278 		req->task_attr = VIRTIO_SCSI_S_HEAD;
279 		break;
280 
281 #if 0	/* XXX */
282 	case XS_CTL_ACA_TAG:
283 		req->task_attr = VIRTIO_SCSI_S_ACA;
284 		break;
285 #endif
286 
287 	case XS_CTL_ORDERED_TAG:
288 		req->task_attr = VIRTIO_SCSI_S_ORDERED;
289 		break;
290 
291 	case XS_CTL_SIMPLE_TAG:
292 	default:
293 		req->task_attr = VIRTIO_SCSI_S_SIMPLE;
294 		break;
295 	}
296 	req->id = (intptr_t)vr;
297 
298 	if ((size_t)xs->cmdlen > sizeof(req->cdb)) {
299 		DPRINTF(("%s: bad cmdlen %zu > %zu\n", __func__,
300 		    (size_t)xs->cmdlen, sizeof(req->cdb)));
301 		goto stuffup;
302 	}
303 
304 	memset(req->cdb, 0, sizeof(req->cdb));
305 	memcpy(req->cdb, xs->cmd, xs->cmdlen);
306 
307 	error = bus_dmamap_load(vsc->sc_dmat, vr->vr_data,
308 	    xs->data, xs->datalen, NULL, XS2DMA(xs));
309 	switch (error) {
310 	case 0:
311 		break;
312 	case ENOMEM:
313 	case EAGAIN:
314 		xs->error = XS_RESOURCE_SHORTAGE;
315 		goto nomore;
316 	default:
317 		aprint_error_dev(sc->sc_dev, "error %d loading DMA map\n",
318 		    error);
319 	stuffup:
320 		xs->error = XS_DRIVER_STUFFUP;
321 nomore:
322 		vioscsi_req_put(sc, vr);
323 		scsipi_done(xs);
324 		return;
325 	}
326 
327 	int nsegs = VIRTIO_SCSI_MIN_SEGMENTS;
328 	if ((xs->xs_control & (XS_CTL_DATA_IN|XS_CTL_DATA_OUT)) != 0)
329 		nsegs += vr->vr_data->dm_nsegs;
330 
331 	error = virtio_enqueue_reserve(vsc, vq, slot, nsegs);
332 	if (error) {
333 		DPRINTF(("%s: error reserving %d\n", __func__, error));
334 		goto stuffup;
335 	}
336 
337 	bus_dmamap_sync(vsc->sc_dmat, vr->vr_control,
338 	    offsetof(struct vioscsi_req, vr_req),
339 	    sizeof(struct virtio_scsi_req_hdr),
340 	    BUS_DMASYNC_PREWRITE);
341 	bus_dmamap_sync(vsc->sc_dmat, vr->vr_control,
342 	    offsetof(struct vioscsi_req, vr_res),
343             sizeof(struct virtio_scsi_res_hdr),
344 	    BUS_DMASYNC_PREREAD);
345 	if ((xs->xs_control & (XS_CTL_DATA_IN|XS_CTL_DATA_OUT)) != 0)
346 		bus_dmamap_sync(vsc->sc_dmat, vr->vr_data, 0, xs->datalen,
347 		    XS2DMAPRE(xs));
348 
349 	virtio_enqueue_p(vsc, vq, slot, vr->vr_control,
350 	    offsetof(struct vioscsi_req, vr_req),
351             sizeof(struct virtio_scsi_req_hdr), 1);
352 	if (xs->xs_control & XS_CTL_DATA_OUT)
353 		virtio_enqueue(vsc, vq, slot, vr->vr_data, 1);
354 	virtio_enqueue_p(vsc, vq, slot, vr->vr_control,
355 	    offsetof(struct vioscsi_req, vr_res),
356             sizeof(struct virtio_scsi_res_hdr), 0);
357 	if (xs->xs_control & XS_CTL_DATA_IN)
358 		virtio_enqueue(vsc, vq, slot, vr->vr_data, 0);
359 	virtio_enqueue_commit(vsc, vq, slot, 1);
360 
361 	if ((xs->xs_control & XS_CTL_POLL) == 0)
362 		return;
363 
364 	DPRINTF(("%s: polling...\n", __func__));
365 	// XXX: do this better.
366 	int timeout = 1000;
367 	do {
368 		(*vsc->sc_intrhand)(vsc);
369 		if (vr->vr_xs != xs)
370 			break;
371 		delay(1000);
372 	} while (--timeout > 0);
373 
374 	if (vr->vr_xs == xs) {
375 		// XXX: Abort!
376 		xs->error = XS_TIMEOUT;
377 		xs->resid = xs->datalen;
378 		DPRINTF(("%s: polling timeout\n", __func__));
379 		scsipi_done(xs);
380 	}
381 	DPRINTF(("%s: done (timeout=%d)\n", __func__, timeout));
382 }
383 
384 static void
385 vioscsi_req_done(struct vioscsi_softc *sc, struct virtio_softc *vsc,
386     struct vioscsi_req *vr)
387 {
388 	struct scsipi_xfer *xs = vr->vr_xs;
389 	struct scsi_sense_data *sense = &xs->sense.scsi_sense;
390 	size_t sense_len;
391 
392 	DPRINTF(("%s: enter\n", __func__));
393 
394 	bus_dmamap_sync(vsc->sc_dmat, vr->vr_control,
395 	    offsetof(struct vioscsi_req, vr_req),
396 	    sizeof(struct virtio_scsi_req_hdr),
397 	    BUS_DMASYNC_POSTWRITE);
398 	bus_dmamap_sync(vsc->sc_dmat, vr->vr_control,
399 	    offsetof(struct vioscsi_req, vr_res),
400 	    sizeof(struct virtio_scsi_res_hdr),
401 	    BUS_DMASYNC_POSTREAD);
402 	bus_dmamap_sync(vsc->sc_dmat, vr->vr_data, 0, xs->datalen,
403 	    XS2DMAPOST(xs));
404 
405 	switch (vr->vr_res.response) {
406 	case VIRTIO_SCSI_S_OK:
407 		sense_len = MIN(sizeof(xs->sense), vr->vr_res.sense_len);
408 		memcpy(&xs->sense, vr->vr_res.sense, sense_len);
409 		xs->error = (sense_len == 0) ? XS_NOERROR : XS_SENSE;
410 		break;
411 	case VIRTIO_SCSI_S_BAD_TARGET:
412 		DPRINTF(("%s: bad target\n", __func__));
413 		memset(sense, 0, sizeof(*sense));
414 		sense->response_code = 0x70;
415 		sense->flags = SKEY_ILLEGAL_REQUEST;
416 		xs->error = XS_SENSE;
417 		xs->status = 0;
418 		xs->resid = 0;
419 		break;
420 	default:
421 		DPRINTF(("%s: stuffup: %d\n", __func__, vr->vr_res.response));
422 		xs->error = XS_DRIVER_STUFFUP;
423 		xs->resid = xs->datalen;
424 		break;
425 	}
426 
427 	xs->status = vr->vr_res.status;
428 	xs->resid = vr->vr_res.residual;
429 
430 	DPRINTF(("%s: done %d, %d, %d\n", __func__,
431 	    xs->error, xs->status, xs->resid));
432 
433 	vr->vr_xs = NULL;
434 	vioscsi_req_put(sc, vr);
435 	scsipi_done(xs);
436 }
437 
438 static int
439 vioscsi_vq_done(struct virtqueue *vq)
440 {
441 	struct virtio_softc *vsc = vq->vq_owner;
442 	struct vioscsi_softc *sc = device_private(vsc->sc_child);
443 	int ret = 0;
444 
445 	DPRINTF(("%s: enter\n", __func__));
446 
447 	for (;;) {
448 		int r, slot;
449 		r = virtio_dequeue(vsc, vq, &slot, NULL);
450 		if (r != 0)
451 			break;
452 
453 		DPRINTF(("%s: slot=%d\n", __func__, slot));
454 		vioscsi_req_done(sc, vsc, &sc->sc_reqs[slot]);
455 		ret = 1;
456 	}
457 
458 	DPRINTF(("%s: exit %d\n", __func__, ret));
459 
460 	return ret;
461 }
462 
463 static struct vioscsi_req *
464 vioscsi_req_get(struct vioscsi_softc *sc)
465 {
466 	struct virtio_softc *vsc = device_private(device_parent(sc->sc_dev));
467 	struct virtqueue *vq = &sc->sc_vqs[2];
468 	struct vioscsi_req *vr;
469 	int r, slot;
470 
471 	if ((r = virtio_enqueue_prep(vsc, vq, &slot)) != 0) {
472 		DPRINTF(("%s: virtio_enqueue_get error %d\n", __func__, r));
473 		goto err1;
474 	}
475 	vr = &sc->sc_reqs[slot];
476 
477 	vr->vr_req.id = slot;
478 	vr->vr_req.task_attr = VIRTIO_SCSI_S_SIMPLE;
479 
480 	r = bus_dmamap_create(vsc->sc_dmat,
481 	    offsetof(struct vioscsi_req, vr_xs), 1,
482 	    offsetof(struct vioscsi_req, vr_xs), 0,
483 	    BUS_DMA_NOWAIT|BUS_DMA_ALLOCNOW, &vr->vr_control);
484 	if (r != 0) {
485 		DPRINTF(("%s: bus_dmamap_create xs error %d\n", __func__, r));
486 		goto err2;
487 	}
488 	r = bus_dmamap_create(vsc->sc_dmat, MAXPHYS, sc->sc_seg_max,
489 	    MAXPHYS, 0, BUS_DMA_NOWAIT|BUS_DMA_ALLOCNOW, &vr->vr_data);
490 	if (r != 0) {
491 		DPRINTF(("%s: bus_dmamap_create data error %d\n", __func__, r));
492 		goto err3;
493 	}
494 	r = bus_dmamap_load(vsc->sc_dmat, vr->vr_control,
495 	    vr, offsetof(struct vioscsi_req, vr_xs), NULL,
496 	    BUS_DMA_NOWAIT);
497 	if (r != 0) {
498 		DPRINTF(("%s: bus_dmamap_create ctrl error %d\n", __func__, r));
499 		goto err4;
500 	}
501 
502 	DPRINTF(("%s: %p, %d\n", __func__, vr, slot));
503 
504 	return vr;
505 
506 err4:
507 	bus_dmamap_destroy(vsc->sc_dmat, vr->vr_data);
508 err3:
509 	bus_dmamap_destroy(vsc->sc_dmat, vr->vr_control);
510 err2:
511 	virtio_enqueue_abort(vsc, vq, slot);
512 err1:
513 	return NULL;
514 }
515 
516 static void
517 vioscsi_req_put(struct vioscsi_softc *sc, struct vioscsi_req *vr)
518 {
519 	struct virtio_softc *vsc = device_private(device_parent(sc->sc_dev));
520 	struct virtqueue *vq = &sc->sc_vqs[2];
521 	int slot = vr - sc->sc_reqs;
522 
523 	DPRINTF(("%s: %p, %d\n", __func__, vr, slot));
524 
525 	bus_dmamap_destroy(vsc->sc_dmat, vr->vr_control);
526 	bus_dmamap_destroy(vsc->sc_dmat, vr->vr_data);
527 
528 	virtio_dequeue_commit(vsc, vq, slot);
529 }
530 
531 int
532 vioscsi_alloc_reqs(struct vioscsi_softc *sc, struct virtio_softc *vsc,
533     int qsize, uint32_t seg_max)
534 {
535 	size_t allocsize;
536 	int r, rsegs;
537 	void *vaddr;
538 
539 	allocsize = qsize * sizeof(struct vioscsi_req);
540 	r = bus_dmamem_alloc(vsc->sc_dmat, allocsize, 0, 0,
541 	    &sc->sc_reqs_segs[0], 1, &rsegs, BUS_DMA_NOWAIT);
542 	if (r != 0) {
543 		aprint_error_dev(sc->sc_dev,
544 		    "%s: bus_dmamem_alloc, size %zu, error %d\n", __func__,
545 		    allocsize, r);
546 		return 1;
547 	}
548 	r = bus_dmamem_map(vsc->sc_dmat, &sc->sc_reqs_segs[0], 1,
549 	    allocsize, &vaddr, BUS_DMA_NOWAIT);
550 	if (r != 0) {
551 		aprint_error_dev(sc->sc_dev,
552 		    "%s: bus_dmamem_map failed, error %d\n", __func__, r);
553 		bus_dmamem_free(vsc->sc_dmat, &sc->sc_reqs_segs[0], 1);
554 		return 1;
555 	}
556 	sc->sc_reqs = vaddr;
557 	memset(vaddr, 0, allocsize);
558 	return 0;
559 }
560