xref: /freebsd/sys/dev/virtio/mmio/virtio_mmio.c (revision 8df8b2d3e51d1b816201d8a1fe8bc29fe192e562)
1 /*-
2  * Copyright (c) 2014 Ruslan Bukin <br@bsdpad.com>
3  * Copyright (c) 2014 The FreeBSD Foundation
4  * All rights reserved.
5  *
6  * This software was developed by SRI International and the University of
7  * Cambridge Computer Laboratory under DARPA/AFRL contract (FA8750-10-C-0237)
8  * ("CTSRD"), as part of the DARPA CRASH research programme.
9  *
10  * Portions of this software were developed by Andrew Turner
11  * under sponsorship from the FreeBSD Foundation.
12  *
13  * Redistribution and use in source and binary forms, with or without
14  * modification, are permitted provided that the following conditions
15  * are met:
16  * 1. Redistributions of source code must retain the above copyright
17  *    notice, this list of conditions and the following disclaimer.
18  * 2. Redistributions in binary form must reproduce the above copyright
19  *    notice, this list of conditions and the following disclaimer in the
20  *    documentation and/or other materials provided with the distribution.
21  *
22  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32  * SUCH DAMAGE.
33  */
34 
35 /*
36  * VirtIO MMIO interface.
37  * This driver is heavily based on VirtIO PCI interface driver.
38  */
39 
40 #include <sys/cdefs.h>
41 __FBSDID("$FreeBSD$");
42 
43 #include <sys/param.h>
44 #include <sys/systm.h>
45 #include <sys/bus.h>
46 #include <sys/kernel.h>
47 #include <sys/module.h>
48 #include <sys/malloc.h>
49 #include <sys/rman.h>
50 
51 #include <machine/bus.h>
52 #include <machine/resource.h>
53 
54 #include <dev/virtio/virtio.h>
55 #include <dev/virtio/virtqueue.h>
56 #include <dev/virtio/mmio/virtio_mmio.h>
57 
58 #include "virtio_mmio_if.h"
59 #include "virtio_bus_if.h"
60 #include "virtio_if.h"
61 
62 #define	PAGE_SHIFT	12
63 
64 struct vtmmio_virtqueue {
65 	struct virtqueue	*vtv_vq;
66 	int			 vtv_no_intr;
67 };
68 
69 static int	vtmmio_detach(device_t);
70 static int	vtmmio_suspend(device_t);
71 static int	vtmmio_resume(device_t);
72 static int	vtmmio_shutdown(device_t);
73 static void	vtmmio_driver_added(device_t, driver_t *);
74 static void	vtmmio_child_detached(device_t, device_t);
75 static int	vtmmio_read_ivar(device_t, device_t, int, uintptr_t *);
76 static int	vtmmio_write_ivar(device_t, device_t, int, uintptr_t);
77 static uint64_t	vtmmio_negotiate_features(device_t, uint64_t);
78 static int	vtmmio_with_feature(device_t, uint64_t);
79 static int	vtmmio_alloc_virtqueues(device_t, int, int,
80 		    struct vq_alloc_info *);
81 static int	vtmmio_setup_intr(device_t, enum intr_type);
82 static void	vtmmio_stop(device_t);
83 static void	vtmmio_poll(device_t);
84 static int	vtmmio_reinit(device_t, uint64_t);
85 static void	vtmmio_reinit_complete(device_t);
86 static void	vtmmio_notify_virtqueue(device_t, uint16_t);
87 static uint8_t	vtmmio_get_status(device_t);
88 static void	vtmmio_set_status(device_t, uint8_t);
89 static void	vtmmio_read_dev_config(device_t, bus_size_t, void *, int);
90 static void	vtmmio_write_dev_config(device_t, bus_size_t, void *, int);
91 static void	vtmmio_describe_features(struct vtmmio_softc *, const char *,
92 		    uint64_t);
93 static void	vtmmio_probe_and_attach_child(struct vtmmio_softc *);
94 static int	vtmmio_reinit_virtqueue(struct vtmmio_softc *, int);
95 static void	vtmmio_free_interrupts(struct vtmmio_softc *);
96 static void	vtmmio_free_virtqueues(struct vtmmio_softc *);
97 static void	vtmmio_release_child_resources(struct vtmmio_softc *);
98 static void	vtmmio_reset(struct vtmmio_softc *);
99 static void	vtmmio_select_virtqueue(struct vtmmio_softc *, int);
100 static void	vtmmio_vq_intr(void *);
101 
102 /*
103  * I/O port read/write wrappers.
104  */
105 #define vtmmio_write_config_1(sc, o, v)				\
106 do {								\
107 	if (sc->platform != NULL)				\
108 		VIRTIO_MMIO_PREWRITE(sc->platform, (o), (v));	\
109 	bus_write_1((sc)->res[0], (o), (v)); 			\
110 	if (sc->platform != NULL)				\
111 		VIRTIO_MMIO_NOTE(sc->platform, (o), (v));	\
112 } while (0)
113 #define vtmmio_write_config_2(sc, o, v)				\
114 do {								\
115 	if (sc->platform != NULL)				\
116 		VIRTIO_MMIO_PREWRITE(sc->platform, (o), (v));	\
117 	bus_write_2((sc)->res[0], (o), (v));			\
118 	if (sc->platform != NULL)				\
119 		VIRTIO_MMIO_NOTE(sc->platform, (o), (v));	\
120 } while (0)
121 #define vtmmio_write_config_4(sc, o, v)				\
122 do {								\
123 	if (sc->platform != NULL)				\
124 		VIRTIO_MMIO_PREWRITE(sc->platform, (o), (v));	\
125 	bus_write_4((sc)->res[0], (o), (v));			\
126 	if (sc->platform != NULL)				\
127 		VIRTIO_MMIO_NOTE(sc->platform, (o), (v));	\
128 } while (0)
129 
130 #define vtmmio_read_config_1(sc, o) \
131 	bus_read_1((sc)->res[0], (o))
132 #define vtmmio_read_config_2(sc, o) \
133 	bus_read_2((sc)->res[0], (o))
134 #define vtmmio_read_config_4(sc, o) \
135 	bus_read_4((sc)->res[0], (o))
136 
137 static device_method_t vtmmio_methods[] = {
138 	/* Device interface. */
139 	DEVMETHOD(device_attach,		  vtmmio_attach),
140 	DEVMETHOD(device_detach,		  vtmmio_detach),
141 	DEVMETHOD(device_suspend,		  vtmmio_suspend),
142 	DEVMETHOD(device_resume,		  vtmmio_resume),
143 	DEVMETHOD(device_shutdown,		  vtmmio_shutdown),
144 
145 	/* Bus interface. */
146 	DEVMETHOD(bus_driver_added,		  vtmmio_driver_added),
147 	DEVMETHOD(bus_child_detached,		  vtmmio_child_detached),
148 	DEVMETHOD(bus_read_ivar,		  vtmmio_read_ivar),
149 	DEVMETHOD(bus_write_ivar,		  vtmmio_write_ivar),
150 
151 	/* VirtIO bus interface. */
152 	DEVMETHOD(virtio_bus_negotiate_features,  vtmmio_negotiate_features),
153 	DEVMETHOD(virtio_bus_with_feature,	  vtmmio_with_feature),
154 	DEVMETHOD(virtio_bus_alloc_virtqueues,	  vtmmio_alloc_virtqueues),
155 	DEVMETHOD(virtio_bus_setup_intr,	  vtmmio_setup_intr),
156 	DEVMETHOD(virtio_bus_stop,		  vtmmio_stop),
157 	DEVMETHOD(virtio_bus_poll,		  vtmmio_poll),
158 	DEVMETHOD(virtio_bus_reinit,		  vtmmio_reinit),
159 	DEVMETHOD(virtio_bus_reinit_complete,	  vtmmio_reinit_complete),
160 	DEVMETHOD(virtio_bus_notify_vq,		  vtmmio_notify_virtqueue),
161 	DEVMETHOD(virtio_bus_read_device_config,  vtmmio_read_dev_config),
162 	DEVMETHOD(virtio_bus_write_device_config, vtmmio_write_dev_config),
163 
164 	DEVMETHOD_END
165 };
166 
167 DEFINE_CLASS_0(virtio_mmio, vtmmio_driver, vtmmio_methods,
168     sizeof(struct vtmmio_softc));
169 
170 MODULE_VERSION(virtio_mmio, 1);
171 
172 static int
173 vtmmio_setup_intr(device_t dev, enum intr_type type)
174 {
175 	struct vtmmio_softc *sc;
176 	int rid;
177 	int err;
178 
179 	sc = device_get_softc(dev);
180 
181 	if (sc->platform != NULL) {
182 		err = VIRTIO_MMIO_SETUP_INTR(sc->platform, sc->dev,
183 					vtmmio_vq_intr, sc);
184 		if (err == 0) {
185 			/* Okay we have backend-specific interrupts */
186 			return (0);
187 		}
188 	}
189 
190 	rid = 0;
191 	sc->res[1] = bus_alloc_resource_any(dev, SYS_RES_IRQ, &rid,
192 		RF_ACTIVE);
193 	if (!sc->res[1]) {
194 		device_printf(dev, "Can't allocate interrupt\n");
195 		return (ENXIO);
196 	}
197 
198 	if (bus_setup_intr(dev, sc->res[1], INTR_TYPE_MISC | INTR_MPSAFE,
199 		NULL, vtmmio_vq_intr, sc, &sc->ih)) {
200 		device_printf(dev, "Can't setup the interrupt\n");
201 		return (ENXIO);
202 	}
203 
204 	return (0);
205 }
206 
207 int
208 vtmmio_attach(device_t dev)
209 {
210 	struct vtmmio_softc *sc;
211 	device_t child;
212 	int rid;
213 
214 	sc = device_get_softc(dev);
215 	sc->dev = dev;
216 
217 	rid = 0;
218 	sc->res[0] = bus_alloc_resource_any(dev, SYS_RES_MEMORY, &rid,
219 			RF_ACTIVE);
220 	if (!sc->res[0]) {
221 		device_printf(dev, "Cannot allocate memory window.\n");
222 		return (ENXIO);
223 	}
224 
225 	vtmmio_reset(sc);
226 
227 	/* Tell the host we've noticed this device. */
228 	vtmmio_set_status(dev, VIRTIO_CONFIG_STATUS_ACK);
229 
230 	if ((child = device_add_child(dev, NULL, -1)) == NULL) {
231 		device_printf(dev, "Cannot create child device.\n");
232 		vtmmio_set_status(dev, VIRTIO_CONFIG_STATUS_FAILED);
233 		vtmmio_detach(dev);
234 		return (ENOMEM);
235 	}
236 
237 	sc->vtmmio_child_dev = child;
238 	vtmmio_probe_and_attach_child(sc);
239 
240 	return (0);
241 }
242 
243 static int
244 vtmmio_detach(device_t dev)
245 {
246 	struct vtmmio_softc *sc;
247 	device_t child;
248 	int error;
249 
250 	sc = device_get_softc(dev);
251 
252 	if ((child = sc->vtmmio_child_dev) != NULL) {
253 		error = device_delete_child(dev, child);
254 		if (error)
255 			return (error);
256 		sc->vtmmio_child_dev = NULL;
257 	}
258 
259 	vtmmio_reset(sc);
260 
261 	if (sc->res[0] != NULL) {
262 		bus_release_resource(dev, SYS_RES_MEMORY, 0,
263 		    sc->res[0]);
264 		sc->res[0] = NULL;
265 	}
266 
267 	return (0);
268 }
269 
270 static int
271 vtmmio_suspend(device_t dev)
272 {
273 
274 	return (bus_generic_suspend(dev));
275 }
276 
277 static int
278 vtmmio_resume(device_t dev)
279 {
280 
281 	return (bus_generic_resume(dev));
282 }
283 
284 static int
285 vtmmio_shutdown(device_t dev)
286 {
287 
288 	(void) bus_generic_shutdown(dev);
289 
290 	/* Forcibly stop the host device. */
291 	vtmmio_stop(dev);
292 
293 	return (0);
294 }
295 
296 static void
297 vtmmio_driver_added(device_t dev, driver_t *driver)
298 {
299 	struct vtmmio_softc *sc;
300 
301 	sc = device_get_softc(dev);
302 
303 	vtmmio_probe_and_attach_child(sc);
304 }
305 
306 static void
307 vtmmio_child_detached(device_t dev, device_t child)
308 {
309 	struct vtmmio_softc *sc;
310 
311 	sc = device_get_softc(dev);
312 
313 	vtmmio_reset(sc);
314 	vtmmio_release_child_resources(sc);
315 }
316 
317 static int
318 vtmmio_read_ivar(device_t dev, device_t child, int index, uintptr_t *result)
319 {
320 	struct vtmmio_softc *sc;
321 
322 	sc = device_get_softc(dev);
323 
324 	if (sc->vtmmio_child_dev != child)
325 		return (ENOENT);
326 
327 	switch (index) {
328 	case VIRTIO_IVAR_DEVTYPE:
329 	case VIRTIO_IVAR_SUBDEVICE:
330 		*result = vtmmio_read_config_4(sc, VIRTIO_MMIO_DEVICE_ID);
331 		break;
332 	case VIRTIO_IVAR_VENDOR:
333 		*result = vtmmio_read_config_4(sc, VIRTIO_MMIO_VENDOR_ID);
334 		break;
335 	default:
336 		return (ENOENT);
337 	}
338 
339 	return (0);
340 }
341 
342 static int
343 vtmmio_write_ivar(device_t dev, device_t child, int index, uintptr_t value)
344 {
345 	struct vtmmio_softc *sc;
346 
347 	sc = device_get_softc(dev);
348 
349 	if (sc->vtmmio_child_dev != child)
350 		return (ENOENT);
351 
352 	switch (index) {
353 	case VIRTIO_IVAR_FEATURE_DESC:
354 		sc->vtmmio_child_feat_desc = (void *) value;
355 		break;
356 	default:
357 		return (ENOENT);
358 	}
359 
360 	return (0);
361 }
362 
363 static uint64_t
364 vtmmio_negotiate_features(device_t dev, uint64_t child_features)
365 {
366 	struct vtmmio_softc *sc;
367 	uint64_t host_features, features;
368 
369 	sc = device_get_softc(dev);
370 
371 	host_features = vtmmio_read_config_4(sc, VIRTIO_MMIO_HOST_FEATURES);
372 	vtmmio_describe_features(sc, "host", host_features);
373 
374 	/*
375 	 * Limit negotiated features to what the driver, virtqueue, and
376 	 * host all support.
377 	 */
378 	features = host_features & child_features;
379 	features = virtqueue_filter_features(features);
380 	sc->vtmmio_features = features;
381 
382 	vtmmio_describe_features(sc, "negotiated", features);
383 	vtmmio_write_config_4(sc, VIRTIO_MMIO_GUEST_FEATURES, features);
384 
385 	return (features);
386 }
387 
388 static int
389 vtmmio_with_feature(device_t dev, uint64_t feature)
390 {
391 	struct vtmmio_softc *sc;
392 
393 	sc = device_get_softc(dev);
394 
395 	return ((sc->vtmmio_features & feature) != 0);
396 }
397 
398 static int
399 vtmmio_alloc_virtqueues(device_t dev, int flags, int nvqs,
400     struct vq_alloc_info *vq_info)
401 {
402 	struct vtmmio_virtqueue *vqx;
403 	struct vq_alloc_info *info;
404 	struct vtmmio_softc *sc;
405 	struct virtqueue *vq;
406 	uint32_t size;
407 	int idx, error;
408 
409 	sc = device_get_softc(dev);
410 
411 	if (sc->vtmmio_nvqs != 0)
412 		return (EALREADY);
413 	if (nvqs <= 0)
414 		return (EINVAL);
415 
416 	sc->vtmmio_vqs = malloc(nvqs * sizeof(struct vtmmio_virtqueue),
417 	    M_DEVBUF, M_NOWAIT | M_ZERO);
418 	if (sc->vtmmio_vqs == NULL)
419 		return (ENOMEM);
420 
421 	vtmmio_write_config_4(sc, VIRTIO_MMIO_GUEST_PAGE_SIZE,
422 	    (1 << PAGE_SHIFT));
423 
424 	for (idx = 0; idx < nvqs; idx++) {
425 		vqx = &sc->vtmmio_vqs[idx];
426 		info = &vq_info[idx];
427 
428 		vtmmio_write_config_4(sc, VIRTIO_MMIO_QUEUE_SEL, idx);
429 
430 		vtmmio_select_virtqueue(sc, idx);
431 		size = vtmmio_read_config_4(sc, VIRTIO_MMIO_QUEUE_NUM_MAX);
432 
433 		error = virtqueue_alloc(dev, idx, size,
434 		    VIRTIO_MMIO_VRING_ALIGN, 0xFFFFFFFFUL, info, &vq);
435 		if (error) {
436 			device_printf(dev,
437 			    "cannot allocate virtqueue %d: %d\n",
438 			    idx, error);
439 			break;
440 		}
441 
442 		vtmmio_write_config_4(sc, VIRTIO_MMIO_QUEUE_NUM, size);
443 		vtmmio_write_config_4(sc, VIRTIO_MMIO_QUEUE_ALIGN,
444 		    VIRTIO_MMIO_VRING_ALIGN);
445 #if 0
446 		device_printf(dev, "virtqueue paddr 0x%08lx\n",
447 		    (uint64_t)virtqueue_paddr(vq));
448 #endif
449 		vtmmio_write_config_4(sc, VIRTIO_MMIO_QUEUE_PFN,
450 		    virtqueue_paddr(vq) >> PAGE_SHIFT);
451 
452 		vqx->vtv_vq = *info->vqai_vq = vq;
453 		vqx->vtv_no_intr = info->vqai_intr == NULL;
454 
455 		sc->vtmmio_nvqs++;
456 	}
457 
458 	if (error)
459 		vtmmio_free_virtqueues(sc);
460 
461 	return (error);
462 }
463 
464 static void
465 vtmmio_stop(device_t dev)
466 {
467 
468 	vtmmio_reset(device_get_softc(dev));
469 }
470 
471 static void
472 vtmmio_poll(device_t dev)
473 {
474 	struct vtmmio_softc *sc;
475 
476 	sc = device_get_softc(dev);
477 
478 	if (sc->platform != NULL)
479 		VIRTIO_MMIO_POLL(sc->platform);
480 }
481 
482 static int
483 vtmmio_reinit(device_t dev, uint64_t features)
484 {
485 	struct vtmmio_softc *sc;
486 	int idx, error;
487 
488 	sc = device_get_softc(dev);
489 
490 	if (vtmmio_get_status(dev) != VIRTIO_CONFIG_STATUS_RESET)
491 		vtmmio_stop(dev);
492 
493 	/*
494 	 * Quickly drive the status through ACK and DRIVER. The device
495 	 * does not become usable again until vtmmio_reinit_complete().
496 	 */
497 	vtmmio_set_status(dev, VIRTIO_CONFIG_STATUS_ACK);
498 	vtmmio_set_status(dev, VIRTIO_CONFIG_STATUS_DRIVER);
499 
500 	vtmmio_negotiate_features(dev, features);
501 
502 	vtmmio_write_config_4(sc, VIRTIO_MMIO_GUEST_PAGE_SIZE,
503 	    (1 << PAGE_SHIFT));
504 
505 	for (idx = 0; idx < sc->vtmmio_nvqs; idx++) {
506 		error = vtmmio_reinit_virtqueue(sc, idx);
507 		if (error)
508 			return (error);
509 	}
510 
511 	return (0);
512 }
513 
514 static void
515 vtmmio_reinit_complete(device_t dev)
516 {
517 
518 	vtmmio_set_status(dev, VIRTIO_CONFIG_STATUS_DRIVER_OK);
519 }
520 
521 static void
522 vtmmio_notify_virtqueue(device_t dev, uint16_t queue)
523 {
524 	struct vtmmio_softc *sc;
525 
526 	sc = device_get_softc(dev);
527 
528 	vtmmio_write_config_4(sc, VIRTIO_MMIO_QUEUE_NOTIFY, queue);
529 }
530 
531 static uint8_t
532 vtmmio_get_status(device_t dev)
533 {
534 	struct vtmmio_softc *sc;
535 
536 	sc = device_get_softc(dev);
537 
538 	return (vtmmio_read_config_4(sc, VIRTIO_MMIO_STATUS));
539 }
540 
541 static void
542 vtmmio_set_status(device_t dev, uint8_t status)
543 {
544 	struct vtmmio_softc *sc;
545 
546 	sc = device_get_softc(dev);
547 
548 	if (status != VIRTIO_CONFIG_STATUS_RESET)
549 		status |= vtmmio_get_status(dev);
550 
551 	vtmmio_write_config_4(sc, VIRTIO_MMIO_STATUS, status);
552 }
553 
554 static void
555 vtmmio_read_dev_config(device_t dev, bus_size_t offset,
556     void *dst, int length)
557 {
558 	struct vtmmio_softc *sc;
559 	bus_size_t off;
560 	uint8_t *d;
561 	int size;
562 
563 	sc = device_get_softc(dev);
564 	off = VIRTIO_MMIO_CONFIG + offset;
565 
566 	for (d = dst; length > 0; d += size, off += size, length -= size) {
567 #ifdef ALLOW_WORD_ALIGNED_ACCESS
568 		if (length >= 4) {
569 			size = 4;
570 			*(uint32_t *)d = vtmmio_read_config_4(sc, off);
571 		} else if (length >= 2) {
572 			size = 2;
573 			*(uint16_t *)d = vtmmio_read_config_2(sc, off);
574 		} else
575 #endif
576 		{
577 			size = 1;
578 			*d = vtmmio_read_config_1(sc, off);
579 		}
580 	}
581 }
582 
583 static void
584 vtmmio_write_dev_config(device_t dev, bus_size_t offset,
585     void *src, int length)
586 {
587 	struct vtmmio_softc *sc;
588 	bus_size_t off;
589 	uint8_t *s;
590 	int size;
591 
592 	sc = device_get_softc(dev);
593 	off = VIRTIO_MMIO_CONFIG + offset;
594 
595 	for (s = src; length > 0; s += size, off += size, length -= size) {
596 #ifdef ALLOW_WORD_ALIGNED_ACCESS
597 		if (length >= 4) {
598 			size = 4;
599 			vtmmio_write_config_4(sc, off, *(uint32_t *)s);
600 		} else if (length >= 2) {
601 			size = 2;
602 			vtmmio_write_config_2(sc, off, *(uint16_t *)s);
603 		} else
604 #endif
605 		{
606 			size = 1;
607 			vtmmio_write_config_1(sc, off, *s);
608 		}
609 	}
610 }
611 
612 static void
613 vtmmio_describe_features(struct vtmmio_softc *sc, const char *msg,
614     uint64_t features)
615 {
616 	device_t dev, child;
617 
618 	dev = sc->dev;
619 	child = sc->vtmmio_child_dev;
620 
621 	if (device_is_attached(child) || bootverbose == 0)
622 		return;
623 
624 	virtio_describe(dev, msg, features, sc->vtmmio_child_feat_desc);
625 }
626 
627 static void
628 vtmmio_probe_and_attach_child(struct vtmmio_softc *sc)
629 {
630 	device_t dev, child;
631 
632 	dev = sc->dev;
633 	child = sc->vtmmio_child_dev;
634 
635 	if (child == NULL)
636 		return;
637 
638 	if (device_get_state(child) != DS_NOTPRESENT) {
639 		return;
640 	}
641 
642 	if (device_probe(child) != 0) {
643 		return;
644 	}
645 
646 	vtmmio_set_status(dev, VIRTIO_CONFIG_STATUS_DRIVER);
647 	if (device_attach(child) != 0) {
648 		vtmmio_set_status(dev, VIRTIO_CONFIG_STATUS_FAILED);
649 		vtmmio_reset(sc);
650 		vtmmio_release_child_resources(sc);
651 		/* Reset status for future attempt. */
652 		vtmmio_set_status(dev, VIRTIO_CONFIG_STATUS_ACK);
653 	} else {
654 		vtmmio_set_status(dev, VIRTIO_CONFIG_STATUS_DRIVER_OK);
655 		VIRTIO_ATTACH_COMPLETED(child);
656 	}
657 }
658 
659 static int
660 vtmmio_reinit_virtqueue(struct vtmmio_softc *sc, int idx)
661 {
662 	struct vtmmio_virtqueue *vqx;
663 	struct virtqueue *vq;
664 	int error;
665 	uint16_t size;
666 
667 	vqx = &sc->vtmmio_vqs[idx];
668 	vq = vqx->vtv_vq;
669 
670 	KASSERT(vq != NULL, ("%s: vq %d not allocated", __func__, idx));
671 
672 	vtmmio_select_virtqueue(sc, idx);
673 	size = vtmmio_read_config_4(sc, VIRTIO_MMIO_QUEUE_NUM_MAX);
674 
675 	error = virtqueue_reinit(vq, size);
676 	if (error)
677 		return (error);
678 
679 	vtmmio_write_config_4(sc, VIRTIO_MMIO_QUEUE_NUM, size);
680 	vtmmio_write_config_4(sc, VIRTIO_MMIO_QUEUE_ALIGN,
681 	    VIRTIO_MMIO_VRING_ALIGN);
682 #if 0
683 	device_printf(sc->dev, "virtqueue paddr 0x%08lx\n",
684 	    (uint64_t)virtqueue_paddr(vq));
685 #endif
686 	vtmmio_write_config_4(sc, VIRTIO_MMIO_QUEUE_PFN,
687 	    virtqueue_paddr(vq) >> PAGE_SHIFT);
688 
689 	return (0);
690 }
691 
692 static void
693 vtmmio_free_interrupts(struct vtmmio_softc *sc)
694 {
695 
696 	if (sc->ih != NULL)
697 		bus_teardown_intr(sc->dev, sc->res[1], sc->ih);
698 
699 	if (sc->res[1] != NULL)
700 		bus_release_resource(sc->dev, SYS_RES_IRQ, 0, sc->res[1]);
701 }
702 
703 static void
704 vtmmio_free_virtqueues(struct vtmmio_softc *sc)
705 {
706 	struct vtmmio_virtqueue *vqx;
707 	int idx;
708 
709 	for (idx = 0; idx < sc->vtmmio_nvqs; idx++) {
710 		vqx = &sc->vtmmio_vqs[idx];
711 
712 		vtmmio_select_virtqueue(sc, idx);
713 		vtmmio_write_config_4(sc, VIRTIO_MMIO_QUEUE_PFN, 0);
714 
715 		virtqueue_free(vqx->vtv_vq);
716 		vqx->vtv_vq = NULL;
717 	}
718 
719 	free(sc->vtmmio_vqs, M_DEVBUF);
720 	sc->vtmmio_vqs = NULL;
721 	sc->vtmmio_nvqs = 0;
722 }
723 
724 static void
725 vtmmio_release_child_resources(struct vtmmio_softc *sc)
726 {
727 
728 	vtmmio_free_interrupts(sc);
729 	vtmmio_free_virtqueues(sc);
730 }
731 
732 static void
733 vtmmio_reset(struct vtmmio_softc *sc)
734 {
735 
736 	/*
737 	 * Setting the status to RESET sets the host device to
738 	 * the original, uninitialized state.
739 	 */
740 	vtmmio_set_status(sc->dev, VIRTIO_CONFIG_STATUS_RESET);
741 }
742 
743 static void
744 vtmmio_select_virtqueue(struct vtmmio_softc *sc, int idx)
745 {
746 
747 	vtmmio_write_config_4(sc, VIRTIO_MMIO_QUEUE_SEL, idx);
748 }
749 
750 static void
751 vtmmio_vq_intr(void *arg)
752 {
753 	struct vtmmio_virtqueue *vqx;
754 	struct vtmmio_softc *sc;
755 	struct virtqueue *vq;
756 	uint32_t status;
757 	int idx;
758 
759 	sc = arg;
760 
761 	status = vtmmio_read_config_4(sc, VIRTIO_MMIO_INTERRUPT_STATUS);
762 	vtmmio_write_config_4(sc, VIRTIO_MMIO_INTERRUPT_ACK, status);
763 
764 	/* The config changed */
765 	if (status & VIRTIO_MMIO_INT_CONFIG)
766 		if (sc->vtmmio_child_dev != NULL)
767 			VIRTIO_CONFIG_CHANGE(sc->vtmmio_child_dev);
768 
769 	/* Notify all virtqueues. */
770 	if (status & VIRTIO_MMIO_INT_VRING) {
771 		for (idx = 0; idx < sc->vtmmio_nvqs; idx++) {
772 			vqx = &sc->vtmmio_vqs[idx];
773 			if (vqx->vtv_no_intr == 0) {
774 				vq = vqx->vtv_vq;
775 				virtqueue_intr(vq);
776 			}
777 		}
778 	}
779 }
780