xref: /netbsd-src/sys/dev/pci/ld_virtio.c (revision e89934bbf778a6d6d6894877c4da59d0c7835b0f)
1 /*	$NetBSD: ld_virtio.c,v 1.13 2016/11/30 01:36:38 christos Exp $	*/
2 
3 /*
4  * Copyright (c) 2010 Minoura Makoto.
5  * All rights reserved.
6  *
7  * Redistribution and use in source and binary forms, with or without
8  * modification, are permitted provided that the following conditions
9  * are met:
10  * 1. Redistributions of source code must retain the above copyright
11  *    notice, this list of conditions and the following disclaimer.
12  * 2. Redistributions in binary form must reproduce the above copyright
13  *    notice, this list of conditions and the following disclaimer in the
14  *    documentation and/or other materials provided with the distribution.
15  *
16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
17  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
18  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
19  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
20  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
21  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
22  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
23  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
24  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
25  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
26  */
27 
28 #include <sys/cdefs.h>
29 __KERNEL_RCSID(0, "$NetBSD: ld_virtio.c,v 1.13 2016/11/30 01:36:38 christos Exp $");
30 
31 #include <sys/param.h>
32 #include <sys/systm.h>
33 #include <sys/kernel.h>
34 #include <sys/buf.h>
35 #include <sys/bufq.h>
36 #include <sys/bus.h>
37 #include <sys/device.h>
38 #include <sys/disk.h>
39 #include <sys/mutex.h>
40 #include <sys/module.h>
41 
42 #include <dev/pci/pcidevs.h>
43 #include <dev/pci/pcireg.h>
44 #include <dev/pci/pcivar.h>
45 
46 #include <dev/ldvar.h>
47 #include <dev/pci/virtioreg.h>
48 #include <dev/pci/virtiovar.h>
49 
50 #include "ioconf.h"
51 
52 /*
53  * ld_virtioreg:
54  */
55 /* Configuration registers */
56 #define VIRTIO_BLK_CONFIG_CAPACITY	0 /* 64bit */
57 #define VIRTIO_BLK_CONFIG_SIZE_MAX	8 /* 32bit */
58 #define VIRTIO_BLK_CONFIG_SEG_MAX	12 /* 32bit */
59 #define VIRTIO_BLK_CONFIG_GEOMETRY_C	16 /* 16bit */
60 #define VIRTIO_BLK_CONFIG_GEOMETRY_H	18 /* 8bit */
61 #define VIRTIO_BLK_CONFIG_GEOMETRY_S	19 /* 8bit */
62 #define VIRTIO_BLK_CONFIG_BLK_SIZE	20 /* 32bit */
63 
64 /* Feature bits */
65 #define VIRTIO_BLK_F_BARRIER	(1<<0)
66 #define VIRTIO_BLK_F_SIZE_MAX	(1<<1)
67 #define VIRTIO_BLK_F_SEG_MAX	(1<<2)
68 #define VIRTIO_BLK_F_GEOMETRY	(1<<4)
69 #define VIRTIO_BLK_F_RO		(1<<5)
70 #define VIRTIO_BLK_F_BLK_SIZE	(1<<6)
71 #define VIRTIO_BLK_F_SCSI	(1<<7)
72 #define VIRTIO_BLK_F_FLUSH	(1<<9)
73 
74 /*
75  * Each block request uses at least two segments - one for the header
76  * and one for the status.
77 */
78 #define	VIRTIO_BLK_MIN_SEGMENTS	2
79 
80 #define VIRTIO_BLK_FLAG_BITS \
81 	VIRTIO_COMMON_FLAG_BITS \
82 	"\x0a""FLUSH" \
83 	"\x08""SCSI" \
84 	"\x07""BLK_SIZE" \
85 	"\x06""RO" \
86 	"\x05""GEOMETRY" \
87 	"\x03""SEG_MAX" \
88 	"\x02""SIZE_MAX" \
89 	"\x01""BARRIER"
90 
91 /* Command */
92 #define VIRTIO_BLK_T_IN		0
93 #define VIRTIO_BLK_T_OUT	1
94 #define VIRTIO_BLK_T_BARRIER	0x80000000
95 
96 /* Status */
97 #define VIRTIO_BLK_S_OK		0
98 #define VIRTIO_BLK_S_IOERR	1
99 
100 /* Request header structure */
101 struct virtio_blk_req_hdr {
102 	uint32_t	type;	/* VIRTIO_BLK_T_* */
103 	uint32_t	ioprio;
104 	uint64_t	sector;
105 } __packed;
106 /* 512*virtio_blk_req_hdr.sector byte payload and 1 byte status follows */
107 
108 
109 /*
110  * ld_virtiovar:
111  */
112 struct virtio_blk_req {
113 	struct virtio_blk_req_hdr	vr_hdr;
114 	uint8_t				vr_status;
115 	struct buf			*vr_bp;
116 	bus_dmamap_t			vr_cmdsts;
117 	bus_dmamap_t			vr_payload;
118 };
119 
120 struct ld_virtio_softc {
121 	struct ld_softc		sc_ld;
122 	device_t		sc_dev;
123 
124 	struct virtio_softc	*sc_virtio;
125 	struct virtqueue	sc_vq;
126 
127 	struct virtio_blk_req	*sc_reqs;
128 	bus_dma_segment_t	sc_reqs_seg;
129 
130 	int			sc_readonly;
131 };
132 
133 static int	ld_virtio_match(device_t, cfdata_t, void *);
134 static void	ld_virtio_attach(device_t, device_t, void *);
135 static int	ld_virtio_detach(device_t, int);
136 
137 CFATTACH_DECL_NEW(ld_virtio, sizeof(struct ld_virtio_softc),
138     ld_virtio_match, ld_virtio_attach, ld_virtio_detach, NULL);
139 
140 static int
141 ld_virtio_match(device_t parent, cfdata_t match, void *aux)
142 {
143 	struct virtio_softc *va = aux;
144 
145 	if (va->sc_childdevid == PCI_PRODUCT_VIRTIO_BLOCK)
146 		return 1;
147 
148 	return 0;
149 }
150 
151 static int ld_virtio_vq_done(struct virtqueue *);
152 static int ld_virtio_dump(struct ld_softc *, void *, int, int);
153 static int ld_virtio_start(struct ld_softc *, struct buf *);
154 
155 static int
156 ld_virtio_alloc_reqs(struct ld_virtio_softc *sc, int qsize)
157 {
158 	int allocsize, r, rsegs, i;
159 	struct ld_softc *ld = &sc->sc_ld;
160 	void *vaddr;
161 
162 	allocsize = sizeof(struct virtio_blk_req) * qsize;
163 	r = bus_dmamem_alloc(sc->sc_virtio->sc_dmat, allocsize, 0, 0,
164 			     &sc->sc_reqs_seg, 1, &rsegs, BUS_DMA_NOWAIT);
165 	if (r != 0) {
166 		aprint_error_dev(sc->sc_dev,
167 				 "DMA memory allocation failed, size %d, "
168 				 "error code %d\n", allocsize, r);
169 		goto err_none;
170 	}
171 	r = bus_dmamem_map(sc->sc_virtio->sc_dmat,
172 			   &sc->sc_reqs_seg, 1, allocsize,
173 			   &vaddr, BUS_DMA_NOWAIT);
174 	if (r != 0) {
175 		aprint_error_dev(sc->sc_dev,
176 				 "DMA memory map failed, "
177 				 "error code %d\n", r);
178 		goto err_dmamem_alloc;
179 	}
180 	sc->sc_reqs = vaddr;
181 	memset(vaddr, 0, allocsize);
182 	for (i = 0; i < qsize; i++) {
183 		struct virtio_blk_req *vr = &sc->sc_reqs[i];
184 		r = bus_dmamap_create(sc->sc_virtio->sc_dmat,
185 				      offsetof(struct virtio_blk_req, vr_bp),
186 				      1,
187 				      offsetof(struct virtio_blk_req, vr_bp),
188 				      0,
189 				      BUS_DMA_NOWAIT|BUS_DMA_ALLOCNOW,
190 				      &vr->vr_cmdsts);
191 		if (r != 0) {
192 			aprint_error_dev(sc->sc_dev,
193 					 "command dmamap creation failed, "
194 					 "error code %d\n", r);
195 			goto err_reqs;
196 		}
197 		r = bus_dmamap_load(sc->sc_virtio->sc_dmat, vr->vr_cmdsts,
198 				    &vr->vr_hdr,
199 				    offsetof(struct virtio_blk_req, vr_bp),
200 				    NULL, BUS_DMA_NOWAIT);
201 		if (r != 0) {
202 			aprint_error_dev(sc->sc_dev,
203 					 "command dmamap load failed, "
204 					 "error code %d\n", r);
205 			goto err_reqs;
206 		}
207 		r = bus_dmamap_create(sc->sc_virtio->sc_dmat,
208 				      ld->sc_maxxfer,
209 				      (ld->sc_maxxfer / NBPG) +
210 				      VIRTIO_BLK_MIN_SEGMENTS,
211 				      ld->sc_maxxfer,
212 				      0,
213 				      BUS_DMA_NOWAIT|BUS_DMA_ALLOCNOW,
214 				      &vr->vr_payload);
215 		if (r != 0) {
216 			aprint_error_dev(sc->sc_dev,
217 					 "payload dmamap creation failed, "
218 					 "error code %d\n", r);
219 			goto err_reqs;
220 		}
221 	}
222 	return 0;
223 
224 err_reqs:
225 	for (i = 0; i < qsize; i++) {
226 		struct virtio_blk_req *vr = &sc->sc_reqs[i];
227 		if (vr->vr_cmdsts) {
228 			bus_dmamap_destroy(sc->sc_virtio->sc_dmat,
229 					   vr->vr_cmdsts);
230 			vr->vr_cmdsts = 0;
231 		}
232 		if (vr->vr_payload) {
233 			bus_dmamap_destroy(sc->sc_virtio->sc_dmat,
234 					   vr->vr_payload);
235 			vr->vr_payload = 0;
236 		}
237 	}
238 	bus_dmamem_unmap(sc->sc_virtio->sc_dmat, sc->sc_reqs, allocsize);
239 err_dmamem_alloc:
240 	bus_dmamem_free(sc->sc_virtio->sc_dmat, &sc->sc_reqs_seg, 1);
241 err_none:
242 	return -1;
243 }
244 
245 static void
246 ld_virtio_attach(device_t parent, device_t self, void *aux)
247 {
248 	struct ld_virtio_softc *sc = device_private(self);
249 	struct ld_softc *ld = &sc->sc_ld;
250 	struct virtio_softc *vsc = device_private(parent);
251 	uint32_t features;
252 	char buf[256];
253 	int qsize, maxxfersize, maxnsegs;
254 
255 	if (vsc->sc_child != NULL) {
256 		aprint_normal(": child already attached for %s; "
257 			      "something wrong...\n", device_xname(parent));
258 		return;
259 	}
260 
261 	sc->sc_dev = self;
262 	sc->sc_virtio = vsc;
263 
264 	vsc->sc_child = self;
265 	vsc->sc_ipl = IPL_BIO;
266 	vsc->sc_vqs = &sc->sc_vq;
267 	vsc->sc_nvqs = 1;
268 	vsc->sc_config_change = NULL;
269 	vsc->sc_intrhand = virtio_vq_intr;
270 	vsc->sc_flags = 0;
271 
272 	features = virtio_negotiate_features(vsc,
273 					     (VIRTIO_BLK_F_SIZE_MAX |
274 					      VIRTIO_BLK_F_SEG_MAX |
275 					      VIRTIO_BLK_F_GEOMETRY |
276 					      VIRTIO_BLK_F_RO |
277 					      VIRTIO_BLK_F_BLK_SIZE));
278 	if (features & VIRTIO_BLK_F_RO)
279 		sc->sc_readonly = 1;
280 	else
281 		sc->sc_readonly = 0;
282 
283 	snprintb(buf, sizeof(buf), VIRTIO_BLK_FLAG_BITS, features);
284 	aprint_normal(": Features: %s\n", buf);
285 	aprint_naive("\n");
286 	if (features & VIRTIO_BLK_F_BLK_SIZE) {
287 		ld->sc_secsize = virtio_read_device_config_4(vsc,
288 					VIRTIO_BLK_CONFIG_BLK_SIZE);
289 	} else
290 		ld->sc_secsize = 512;
291 
292 	/* At least genfs_io assumes maxxfer == MAXPHYS. */
293 	if (features & VIRTIO_BLK_F_SIZE_MAX) {
294 		maxxfersize = virtio_read_device_config_4(vsc,
295 		    VIRTIO_BLK_CONFIG_SIZE_MAX);
296 		if (maxxfersize < MAXPHYS) {
297 			aprint_error_dev(sc->sc_dev,
298 			    "Too small SIZE_MAX %dK minimum is %dK\n",
299 			    maxxfersize / 1024, MAXPHYS / 1024);
300 			// goto err;
301 			maxxfersize = MAXPHYS;
302 		} else if (maxxfersize > MAXPHYS) {
303 			aprint_normal_dev(sc->sc_dev,
304 			    "Clip SEG_MAX from %dK to %dK\n",
305 			    maxxfersize / 1024,
306 			    MAXPHYS / 1024);
307 			maxxfersize = MAXPHYS;
308 		}
309 	} else
310 		maxxfersize = MAXPHYS;
311 
312 	if (features & VIRTIO_BLK_F_SEG_MAX) {
313 		maxnsegs = virtio_read_device_config_4(vsc,
314 		    VIRTIO_BLK_CONFIG_SEG_MAX);
315 		if (maxnsegs < VIRTIO_BLK_MIN_SEGMENTS) {
316 			aprint_error_dev(sc->sc_dev,
317 			    "Too small SEG_MAX %d minimum is %d\n",
318 			    maxnsegs, VIRTIO_BLK_MIN_SEGMENTS);
319 			maxnsegs = maxxfersize / NBPG;
320 			// goto err;
321 		}
322 	} else
323 		maxnsegs = maxxfersize / NBPG;
324 
325 	/* 2 for the minimum size */
326 	maxnsegs += VIRTIO_BLK_MIN_SEGMENTS;
327 
328 	if (virtio_alloc_vq(vsc, &sc->sc_vq, 0, maxxfersize, maxnsegs,
329 	    "I/O request") != 0) {
330 		goto err;
331 	}
332 	qsize = sc->sc_vq.vq_num;
333 	sc->sc_vq.vq_done = ld_virtio_vq_done;
334 
335 	ld->sc_dv = self;
336 	ld->sc_secperunit = virtio_read_device_config_8(vsc,
337 				VIRTIO_BLK_CONFIG_CAPACITY);
338 	ld->sc_maxxfer = maxxfersize;
339 	if (features & VIRTIO_BLK_F_GEOMETRY) {
340 		ld->sc_ncylinders = virtio_read_device_config_2(vsc,
341 					VIRTIO_BLK_CONFIG_GEOMETRY_C);
342 		ld->sc_nheads     = virtio_read_device_config_1(vsc,
343 					VIRTIO_BLK_CONFIG_GEOMETRY_H);
344 		ld->sc_nsectors   = virtio_read_device_config_1(vsc,
345 					VIRTIO_BLK_CONFIG_GEOMETRY_S);
346 	}
347 	ld->sc_maxqueuecnt = qsize;
348 
349 	if (ld_virtio_alloc_reqs(sc, qsize) < 0)
350 		goto err;
351 
352 	ld->sc_dump = ld_virtio_dump;
353 	ld->sc_flush = NULL;
354 	ld->sc_start = ld_virtio_start;
355 
356 	ld->sc_flags = LDF_ENABLED;
357 	ldattach(ld, BUFQ_DISK_DEFAULT_STRAT);
358 
359 	return;
360 
361 err:
362 	vsc->sc_child = (void*)1;
363 	return;
364 }
365 
366 static int
367 ld_virtio_start(struct ld_softc *ld, struct buf *bp)
368 {
369 	/* splbio */
370 	struct ld_virtio_softc *sc = device_private(ld->sc_dv);
371 	struct virtio_softc *vsc = sc->sc_virtio;
372 	struct virtqueue *vq = &sc->sc_vq;
373 	struct virtio_blk_req *vr;
374 	int r;
375 	int isread = (bp->b_flags & B_READ);
376 	int slot;
377 
378 	if (sc->sc_readonly && !isread)
379 		return EIO;
380 
381 	r = virtio_enqueue_prep(vsc, vq, &slot);
382 	if (r != 0)
383 		return r;
384 
385 	vr = &sc->sc_reqs[slot];
386 	KASSERT(vr->vr_bp == NULL);
387 
388 	r = bus_dmamap_load(vsc->sc_dmat, vr->vr_payload,
389 			    bp->b_data, bp->b_bcount, NULL,
390 			    ((isread?BUS_DMA_READ:BUS_DMA_WRITE)
391 			     |BUS_DMA_NOWAIT));
392 	if (r != 0) {
393 		aprint_error_dev(sc->sc_dev,
394 		    "payload dmamap failed, error code %d\n", r);
395 		virtio_enqueue_abort(vsc, vq, slot);
396 		return r;
397 	}
398 
399 	r = virtio_enqueue_reserve(vsc, vq, slot, vr->vr_payload->dm_nsegs +
400 	    VIRTIO_BLK_MIN_SEGMENTS);
401 	if (r != 0) {
402 		bus_dmamap_unload(vsc->sc_dmat, vr->vr_payload);
403 		return r;
404 	}
405 
406 	vr->vr_bp = bp;
407 	vr->vr_hdr.type = isread?VIRTIO_BLK_T_IN:VIRTIO_BLK_T_OUT;
408 	vr->vr_hdr.ioprio = 0;
409 	vr->vr_hdr.sector = bp->b_rawblkno * sc->sc_ld.sc_secsize / 512;
410 
411 	bus_dmamap_sync(vsc->sc_dmat, vr->vr_cmdsts,
412 			0, sizeof(struct virtio_blk_req_hdr),
413 			BUS_DMASYNC_PREWRITE);
414 	bus_dmamap_sync(vsc->sc_dmat, vr->vr_payload,
415 			0, bp->b_bcount,
416 			isread?BUS_DMASYNC_PREREAD:BUS_DMASYNC_PREWRITE);
417 	bus_dmamap_sync(vsc->sc_dmat, vr->vr_cmdsts,
418 			offsetof(struct virtio_blk_req, vr_status),
419 			sizeof(uint8_t),
420 			BUS_DMASYNC_PREREAD);
421 
422 	virtio_enqueue_p(vsc, vq, slot, vr->vr_cmdsts,
423 			 0, sizeof(struct virtio_blk_req_hdr),
424 			 true);
425 	virtio_enqueue(vsc, vq, slot, vr->vr_payload, !isread);
426 	virtio_enqueue_p(vsc, vq, slot, vr->vr_cmdsts,
427 			 offsetof(struct virtio_blk_req, vr_status),
428 			 sizeof(uint8_t),
429 			 false);
430 	virtio_enqueue_commit(vsc, vq, slot, true);
431 
432 	return 0;
433 }
434 
435 static void
436 ld_virtio_vq_done1(struct ld_virtio_softc *sc, struct virtio_softc *vsc,
437 		   struct virtqueue *vq, int slot)
438 {
439 	struct virtio_blk_req *vr = &sc->sc_reqs[slot];
440 	struct buf *bp = vr->vr_bp;
441 
442 	vr->vr_bp = NULL;
443 
444 	bus_dmamap_sync(vsc->sc_dmat, vr->vr_cmdsts,
445 			0, sizeof(struct virtio_blk_req_hdr),
446 			BUS_DMASYNC_POSTWRITE);
447 	bus_dmamap_sync(vsc->sc_dmat, vr->vr_payload,
448 			0, bp->b_bcount,
449 			(bp->b_flags & B_READ)?BUS_DMASYNC_POSTREAD
450 					      :BUS_DMASYNC_POSTWRITE);
451 	bus_dmamap_sync(vsc->sc_dmat, vr->vr_cmdsts,
452 			sizeof(struct virtio_blk_req_hdr), sizeof(uint8_t),
453 			BUS_DMASYNC_POSTREAD);
454 
455 	if (vr->vr_status != VIRTIO_BLK_S_OK) {
456 		bp->b_error = EIO;
457 		bp->b_resid = bp->b_bcount;
458 	} else {
459 		bp->b_error = 0;
460 		bp->b_resid = 0;
461 	}
462 
463 	virtio_dequeue_commit(vsc, vq, slot);
464 
465 	lddone(&sc->sc_ld, bp);
466 }
467 
468 static int
469 ld_virtio_vq_done(struct virtqueue *vq)
470 {
471 	struct virtio_softc *vsc = vq->vq_owner;
472 	struct ld_virtio_softc *sc = device_private(vsc->sc_child);
473 	int r = 0;
474 	int slot;
475 
476 again:
477 	if (virtio_dequeue(vsc, vq, &slot, NULL))
478 		return r;
479 	r = 1;
480 
481 	ld_virtio_vq_done1(sc, vsc, vq, slot);
482 	goto again;
483 }
484 
485 static int
486 ld_virtio_dump(struct ld_softc *ld, void *data, int blkno, int blkcnt)
487 {
488 	struct ld_virtio_softc *sc = device_private(ld->sc_dv);
489 	struct virtio_softc *vsc = sc->sc_virtio;
490 	struct virtqueue *vq = &sc->sc_vq;
491 	struct virtio_blk_req *vr;
492 	int slot, r;
493 
494 	if (sc->sc_readonly)
495 		return EIO;
496 
497 	r = virtio_enqueue_prep(vsc, vq, &slot);
498 	if (r != 0) {
499 		if (r == EAGAIN) { /* no free slot; dequeue first */
500 			delay(100);
501 			ld_virtio_vq_done(vq);
502 			r = virtio_enqueue_prep(vsc, vq, &slot);
503 			if (r != 0)
504 				return r;
505 		}
506 		return r;
507 	}
508 	vr = &sc->sc_reqs[slot];
509 	r = bus_dmamap_load(vsc->sc_dmat, vr->vr_payload,
510 			    data, blkcnt*ld->sc_secsize, NULL,
511 			    BUS_DMA_WRITE|BUS_DMA_NOWAIT);
512 	if (r != 0)
513 		return r;
514 
515 	r = virtio_enqueue_reserve(vsc, vq, slot, vr->vr_payload->dm_nsegs +
516 	    VIRTIO_BLK_MIN_SEGMENTS);
517 	if (r != 0) {
518 		bus_dmamap_unload(vsc->sc_dmat, vr->vr_payload);
519 		return r;
520 	}
521 
522 	vr->vr_bp = (void*)0xdeadbeef;
523 	vr->vr_hdr.type = VIRTIO_BLK_T_OUT;
524 	vr->vr_hdr.ioprio = 0;
525 	vr->vr_hdr.sector = (daddr_t) blkno * ld->sc_secsize / 512;
526 
527 	bus_dmamap_sync(vsc->sc_dmat, vr->vr_cmdsts,
528 			0, sizeof(struct virtio_blk_req_hdr),
529 			BUS_DMASYNC_PREWRITE);
530 	bus_dmamap_sync(vsc->sc_dmat, vr->vr_payload,
531 			0, blkcnt*ld->sc_secsize,
532 			BUS_DMASYNC_PREWRITE);
533 	bus_dmamap_sync(vsc->sc_dmat, vr->vr_cmdsts,
534 			offsetof(struct virtio_blk_req, vr_status),
535 			sizeof(uint8_t),
536 			BUS_DMASYNC_PREREAD);
537 
538 	virtio_enqueue_p(vsc, vq, slot, vr->vr_cmdsts,
539 			 0, sizeof(struct virtio_blk_req_hdr),
540 			 true);
541 	virtio_enqueue(vsc, vq, slot, vr->vr_payload, true);
542 	virtio_enqueue_p(vsc, vq, slot, vr->vr_cmdsts,
543 			 offsetof(struct virtio_blk_req, vr_status),
544 			 sizeof(uint8_t),
545 			 false);
546 	virtio_enqueue_commit(vsc, vq, slot, true);
547 
548 	for ( ; ; ) {
549 		int dslot;
550 
551 		r = virtio_dequeue(vsc, vq, &dslot, NULL);
552 		if (r != 0)
553 			continue;
554 		if (dslot != slot) {
555 			ld_virtio_vq_done1(sc, vsc, vq, dslot);
556 			continue;
557 		} else
558 			break;
559 	}
560 
561 	bus_dmamap_sync(vsc->sc_dmat, vr->vr_cmdsts,
562 			0, sizeof(struct virtio_blk_req_hdr),
563 			BUS_DMASYNC_POSTWRITE);
564 	bus_dmamap_sync(vsc->sc_dmat, vr->vr_payload,
565 			0, blkcnt*ld->sc_secsize,
566 			BUS_DMASYNC_POSTWRITE);
567 	bus_dmamap_sync(vsc->sc_dmat, vr->vr_cmdsts,
568 			offsetof(struct virtio_blk_req, vr_status),
569 			sizeof(uint8_t),
570 			BUS_DMASYNC_POSTREAD);
571 	if (vr->vr_status == VIRTIO_BLK_S_OK)
572 		r = 0;
573 	else
574 		r = EIO;
575 	virtio_dequeue_commit(vsc, vq, slot);
576 
577 	return r;
578 }
579 
580 static int
581 ld_virtio_detach(device_t self, int flags)
582 {
583 	struct ld_virtio_softc *sc = device_private(self);
584 	struct ld_softc *ld = &sc->sc_ld;
585 	bus_dma_tag_t dmat = sc->sc_virtio->sc_dmat;
586 	int r, i, qsize;
587 
588 	qsize = sc->sc_vq.vq_num;
589 	r = ldbegindetach(ld, flags);
590 	if (r != 0)
591 		return r;
592 	virtio_reset(sc->sc_virtio);
593 	virtio_free_vq(sc->sc_virtio, &sc->sc_vq);
594 
595 	for (i = 0; i < qsize; i++) {
596 		bus_dmamap_destroy(dmat,
597 				   sc->sc_reqs[i].vr_cmdsts);
598 		bus_dmamap_destroy(dmat,
599 				   sc->sc_reqs[i].vr_payload);
600 	}
601 	bus_dmamem_unmap(dmat, sc->sc_reqs,
602 			 sizeof(struct virtio_blk_req) * qsize);
603 	bus_dmamem_free(dmat, &sc->sc_reqs_seg, 1);
604 
605 	ldenddetach(ld);
606 
607 	return 0;
608 }
609 
610 MODULE(MODULE_CLASS_DRIVER, ld_virtio, "ld,virtio");
611 
612 #ifdef _MODULE
613 /*
614  * XXX Don't allow ioconf.c to redefine the "struct cfdriver ld_cd"
615  * XXX it will be defined in the common-code module
616  */
617 #undef  CFDRIVER_DECL
618 #define CFDRIVER_DECL(name, class, attr)
619 #include "ioconf.c"
620 #endif
621 
622 static int
623 ld_virtio_modcmd(modcmd_t cmd, void *opaque)
624 {
625 #ifdef _MODULE
626 	/*
627 	 * We ignore the cfdriver_vec[] that ioconf provides, since
628 	 * the cfdrivers are attached already.
629 	 */
630 	static struct cfdriver * const no_cfdriver_vec[] = { NULL };
631 #endif
632 	int error = 0;
633 
634 #ifdef _MODULE
635 	switch (cmd) {
636 	case MODULE_CMD_INIT:
637 		error = config_init_component(no_cfdriver_vec,
638 		    cfattach_ioconf_ld_virtio, cfdata_ioconf_ld_virtio);
639 		break;
640 	case MODULE_CMD_FINI:
641 		error = config_fini_component(no_cfdriver_vec,
642 		    cfattach_ioconf_ld_virtio, cfdata_ioconf_ld_virtio);
643 		break;
644 	default:
645 		error = ENOTTY;
646 		break;
647 	}
648 #endif
649 
650 	return error;
651 }
652