xref: /freebsd/sys/dev/virtio/mmio/virtio_mmio.c (revision 4e99f45480598189d49d45a825533a6c9e12f02c)
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 #include <sys/endian.h>
51 
52 #include <machine/bus.h>
53 #include <machine/resource.h>
54 
55 #include <dev/virtio/virtio.h>
56 #include <dev/virtio/virtqueue.h>
57 #include <dev/virtio/mmio/virtio_mmio.h>
58 
59 #include "virtio_mmio_if.h"
60 #include "virtio_bus_if.h"
61 #include "virtio_if.h"
62 
63 #define	PAGE_SHIFT	12
64 
65 struct vtmmio_virtqueue {
66 	struct virtqueue	*vtv_vq;
67 	int			 vtv_no_intr;
68 };
69 
70 static int	vtmmio_detach(device_t);
71 static int	vtmmio_suspend(device_t);
72 static int	vtmmio_resume(device_t);
73 static int	vtmmio_shutdown(device_t);
74 static void	vtmmio_driver_added(device_t, driver_t *);
75 static void	vtmmio_child_detached(device_t, device_t);
76 static int	vtmmio_read_ivar(device_t, device_t, int, uintptr_t *);
77 static int	vtmmio_write_ivar(device_t, device_t, int, uintptr_t);
78 static uint64_t	vtmmio_negotiate_features(device_t, uint64_t);
79 static int	vtmmio_with_feature(device_t, uint64_t);
80 static void	vtmmio_set_virtqueue(struct vtmmio_softc *sc,
81 		    struct virtqueue *vq, uint32_t size);
82 static int	vtmmio_alloc_virtqueues(device_t, int, int,
83 		    struct vq_alloc_info *);
84 static int	vtmmio_setup_intr(device_t, enum intr_type);
85 static void	vtmmio_stop(device_t);
86 static void	vtmmio_poll(device_t);
87 static int	vtmmio_reinit(device_t, uint64_t);
88 static void	vtmmio_reinit_complete(device_t);
89 static void	vtmmio_notify_virtqueue(device_t, uint16_t);
90 static uint8_t	vtmmio_get_status(device_t);
91 static void	vtmmio_set_status(device_t, uint8_t);
92 static void	vtmmio_read_dev_config(device_t, bus_size_t, void *, int);
93 static void	vtmmio_write_dev_config(device_t, bus_size_t, void *, int);
94 static void	vtmmio_describe_features(struct vtmmio_softc *, const char *,
95 		    uint64_t);
96 static void	vtmmio_probe_and_attach_child(struct vtmmio_softc *);
97 static int	vtmmio_reinit_virtqueue(struct vtmmio_softc *, int);
98 static void	vtmmio_free_interrupts(struct vtmmio_softc *);
99 static void	vtmmio_free_virtqueues(struct vtmmio_softc *);
100 static void	vtmmio_release_child_resources(struct vtmmio_softc *);
101 static void	vtmmio_reset(struct vtmmio_softc *);
102 static void	vtmmio_select_virtqueue(struct vtmmio_softc *, int);
103 static void	vtmmio_vq_intr(void *);
104 
105 /*
106  * I/O port read/write wrappers.
107  */
108 #define vtmmio_write_config_1(sc, o, v)				\
109 do {								\
110 	if (sc->platform != NULL)				\
111 		VIRTIO_MMIO_PREWRITE(sc->platform, (o), (v));	\
112 	bus_write_1((sc)->res[0], (o), (v)); 			\
113 	if (sc->platform != NULL)				\
114 		VIRTIO_MMIO_NOTE(sc->platform, (o), (v));	\
115 } while (0)
116 #define vtmmio_write_config_2(sc, o, v)				\
117 do {								\
118 	if (sc->platform != NULL)				\
119 		VIRTIO_MMIO_PREWRITE(sc->platform, (o), (v));	\
120 	bus_write_2((sc)->res[0], (o), (v));			\
121 	if (sc->platform != NULL)				\
122 		VIRTIO_MMIO_NOTE(sc->platform, (o), (v));	\
123 } while (0)
124 #define vtmmio_write_config_4(sc, o, v)				\
125 do {								\
126 	if (sc->platform != NULL)				\
127 		VIRTIO_MMIO_PREWRITE(sc->platform, (o), (v));	\
128 	bus_write_4((sc)->res[0], (o), (v));			\
129 	if (sc->platform != NULL)				\
130 		VIRTIO_MMIO_NOTE(sc->platform, (o), (v));	\
131 } while (0)
132 
133 #define vtmmio_read_config_1(sc, o) \
134 	bus_read_1((sc)->res[0], (o))
135 #define vtmmio_read_config_2(sc, o) \
136 	bus_read_2((sc)->res[0], (o))
137 #define vtmmio_read_config_4(sc, o) \
138 	bus_read_4((sc)->res[0], (o))
139 
140 static device_method_t vtmmio_methods[] = {
141 	/* Device interface. */
142 	DEVMETHOD(device_attach,		  vtmmio_attach),
143 	DEVMETHOD(device_detach,		  vtmmio_detach),
144 	DEVMETHOD(device_suspend,		  vtmmio_suspend),
145 	DEVMETHOD(device_resume,		  vtmmio_resume),
146 	DEVMETHOD(device_shutdown,		  vtmmio_shutdown),
147 
148 	/* Bus interface. */
149 	DEVMETHOD(bus_driver_added,		  vtmmio_driver_added),
150 	DEVMETHOD(bus_child_detached,		  vtmmio_child_detached),
151 	DEVMETHOD(bus_child_pnpinfo_str,	  virtio_child_pnpinfo_str),
152 	DEVMETHOD(bus_read_ivar,		  vtmmio_read_ivar),
153 	DEVMETHOD(bus_write_ivar,		  vtmmio_write_ivar),
154 
155 	/* VirtIO bus interface. */
156 	DEVMETHOD(virtio_bus_negotiate_features,  vtmmio_negotiate_features),
157 	DEVMETHOD(virtio_bus_with_feature,	  vtmmio_with_feature),
158 	DEVMETHOD(virtio_bus_alloc_virtqueues,	  vtmmio_alloc_virtqueues),
159 	DEVMETHOD(virtio_bus_setup_intr,	  vtmmio_setup_intr),
160 	DEVMETHOD(virtio_bus_stop,		  vtmmio_stop),
161 	DEVMETHOD(virtio_bus_poll,		  vtmmio_poll),
162 	DEVMETHOD(virtio_bus_reinit,		  vtmmio_reinit),
163 	DEVMETHOD(virtio_bus_reinit_complete,	  vtmmio_reinit_complete),
164 	DEVMETHOD(virtio_bus_notify_vq,		  vtmmio_notify_virtqueue),
165 	DEVMETHOD(virtio_bus_read_device_config,  vtmmio_read_dev_config),
166 	DEVMETHOD(virtio_bus_write_device_config, vtmmio_write_dev_config),
167 
168 	DEVMETHOD_END
169 };
170 
171 DEFINE_CLASS_0(virtio_mmio, vtmmio_driver, vtmmio_methods,
172     sizeof(struct vtmmio_softc));
173 
174 MODULE_VERSION(virtio_mmio, 1);
175 
176 static int
177 vtmmio_setup_intr(device_t dev, enum intr_type type)
178 {
179 	struct vtmmio_softc *sc;
180 	int rid;
181 	int err;
182 
183 	sc = device_get_softc(dev);
184 
185 	if (sc->platform != NULL) {
186 		err = VIRTIO_MMIO_SETUP_INTR(sc->platform, sc->dev,
187 					vtmmio_vq_intr, sc);
188 		if (err == 0) {
189 			/* Okay we have backend-specific interrupts */
190 			return (0);
191 		}
192 	}
193 
194 	rid = 0;
195 	sc->res[1] = bus_alloc_resource_any(dev, SYS_RES_IRQ, &rid,
196 		RF_ACTIVE);
197 	if (!sc->res[1]) {
198 		device_printf(dev, "Can't allocate interrupt\n");
199 		return (ENXIO);
200 	}
201 
202 	if (bus_setup_intr(dev, sc->res[1], type | INTR_MPSAFE,
203 		NULL, vtmmio_vq_intr, sc, &sc->ih)) {
204 		device_printf(dev, "Can't setup the interrupt\n");
205 		return (ENXIO);
206 	}
207 
208 	return (0);
209 }
210 
211 int
212 vtmmio_attach(device_t dev)
213 {
214 	struct vtmmio_softc *sc;
215 	device_t child;
216 	int rid;
217 
218 	sc = device_get_softc(dev);
219 	sc->dev = dev;
220 
221 	rid = 0;
222 	sc->res[0] = bus_alloc_resource_any(dev, SYS_RES_MEMORY, &rid,
223 			RF_ACTIVE);
224 	if (!sc->res[0]) {
225 		device_printf(dev, "Cannot allocate memory window.\n");
226 		return (ENXIO);
227 	}
228 
229 	sc->vtmmio_version = vtmmio_read_config_4(sc, VIRTIO_MMIO_VERSION);
230 	if (sc->vtmmio_version < 1 || sc->vtmmio_version > 2) {
231 		device_printf(dev, "Unsupported version: %x\n",
232 		    sc->vtmmio_version);
233 		bus_release_resource(dev, SYS_RES_MEMORY, 0,
234 		    sc->res[0]);
235 		sc->res[0] = NULL;
236 		return (ENXIO);
237 	}
238 
239 	vtmmio_reset(sc);
240 
241 	/* Tell the host we've noticed this device. */
242 	vtmmio_set_status(dev, VIRTIO_CONFIG_STATUS_ACK);
243 
244 	if ((child = device_add_child(dev, NULL, -1)) == NULL) {
245 		device_printf(dev, "Cannot create child device.\n");
246 		vtmmio_set_status(dev, VIRTIO_CONFIG_STATUS_FAILED);
247 		vtmmio_detach(dev);
248 		return (ENOMEM);
249 	}
250 
251 	sc->vtmmio_child_dev = child;
252 	vtmmio_probe_and_attach_child(sc);
253 
254 	return (0);
255 }
256 
257 static int
258 vtmmio_detach(device_t dev)
259 {
260 	struct vtmmio_softc *sc;
261 	device_t child;
262 	int error;
263 
264 	sc = device_get_softc(dev);
265 
266 	if ((child = sc->vtmmio_child_dev) != NULL) {
267 		error = device_delete_child(dev, child);
268 		if (error)
269 			return (error);
270 		sc->vtmmio_child_dev = NULL;
271 	}
272 
273 	vtmmio_reset(sc);
274 
275 	if (sc->res[0] != NULL) {
276 		bus_release_resource(dev, SYS_RES_MEMORY, 0,
277 		    sc->res[0]);
278 		sc->res[0] = NULL;
279 	}
280 
281 	return (0);
282 }
283 
284 static int
285 vtmmio_suspend(device_t dev)
286 {
287 
288 	return (bus_generic_suspend(dev));
289 }
290 
291 static int
292 vtmmio_resume(device_t dev)
293 {
294 
295 	return (bus_generic_resume(dev));
296 }
297 
298 static int
299 vtmmio_shutdown(device_t dev)
300 {
301 
302 	(void) bus_generic_shutdown(dev);
303 
304 	/* Forcibly stop the host device. */
305 	vtmmio_stop(dev);
306 
307 	return (0);
308 }
309 
310 static void
311 vtmmio_driver_added(device_t dev, driver_t *driver)
312 {
313 	struct vtmmio_softc *sc;
314 
315 	sc = device_get_softc(dev);
316 
317 	vtmmio_probe_and_attach_child(sc);
318 }
319 
320 static void
321 vtmmio_child_detached(device_t dev, device_t child)
322 {
323 	struct vtmmio_softc *sc;
324 
325 	sc = device_get_softc(dev);
326 
327 	vtmmio_reset(sc);
328 	vtmmio_release_child_resources(sc);
329 }
330 
331 static int
332 vtmmio_read_ivar(device_t dev, device_t child, int index, uintptr_t *result)
333 {
334 	struct vtmmio_softc *sc;
335 
336 	sc = device_get_softc(dev);
337 
338 	if (sc->vtmmio_child_dev != child)
339 		return (ENOENT);
340 
341 	switch (index) {
342 	case VIRTIO_IVAR_DEVTYPE:
343 	case VIRTIO_IVAR_SUBDEVICE:
344 		*result = vtmmio_read_config_4(sc, VIRTIO_MMIO_DEVICE_ID);
345 		break;
346 	case VIRTIO_IVAR_VENDOR:
347 		*result = vtmmio_read_config_4(sc, VIRTIO_MMIO_VENDOR_ID);
348 		break;
349 	case VIRTIO_IVAR_SUBVENDOR:
350 	case VIRTIO_IVAR_DEVICE:
351 		/*
352 		 * Dummy value for fields not present in this bus.  Used by
353 		 * bus-agnostic virtio_child_pnpinfo_str.
354 		 */
355 		*result = 0;
356 		break;
357 	default:
358 		return (ENOENT);
359 	}
360 
361 	return (0);
362 }
363 
364 static int
365 vtmmio_write_ivar(device_t dev, device_t child, int index, uintptr_t value)
366 {
367 	struct vtmmio_softc *sc;
368 
369 	sc = device_get_softc(dev);
370 
371 	if (sc->vtmmio_child_dev != child)
372 		return (ENOENT);
373 
374 	switch (index) {
375 	case VIRTIO_IVAR_FEATURE_DESC:
376 		sc->vtmmio_child_feat_desc = (void *) value;
377 		break;
378 	default:
379 		return (ENOENT);
380 	}
381 
382 	return (0);
383 }
384 
385 static uint64_t
386 vtmmio_negotiate_features(device_t dev, uint64_t child_features)
387 {
388 	struct vtmmio_softc *sc;
389 	uint64_t host_features, features;
390 
391 	sc = device_get_softc(dev);
392 
393 	host_features = vtmmio_read_config_4(sc, VIRTIO_MMIO_HOST_FEATURES);
394 	vtmmio_describe_features(sc, "host", host_features);
395 
396 	/*
397 	 * Limit negotiated features to what the driver, virtqueue, and
398 	 * host all support.
399 	 */
400 	features = host_features & child_features;
401 	features = virtqueue_filter_features(features);
402 	sc->vtmmio_features = features;
403 
404 	vtmmio_describe_features(sc, "negotiated", features);
405 	vtmmio_write_config_4(sc, VIRTIO_MMIO_GUEST_FEATURES, features);
406 
407 	return (features);
408 }
409 
410 static int
411 vtmmio_with_feature(device_t dev, uint64_t feature)
412 {
413 	struct vtmmio_softc *sc;
414 
415 	sc = device_get_softc(dev);
416 
417 	return ((sc->vtmmio_features & feature) != 0);
418 }
419 
420 static void
421 vtmmio_set_virtqueue(struct vtmmio_softc *sc, struct virtqueue *vq,
422     uint32_t size)
423 {
424 	vm_paddr_t paddr;
425 
426 	vtmmio_write_config_4(sc, VIRTIO_MMIO_QUEUE_NUM, size);
427 #if 0
428 	device_printf(dev, "virtqueue paddr 0x%08lx\n",
429 	    (uint64_t)paddr);
430 #endif
431 	if (sc->vtmmio_version == 1) {
432 		vtmmio_write_config_4(sc, VIRTIO_MMIO_QUEUE_ALIGN,
433 		    VIRTIO_MMIO_VRING_ALIGN);
434 		paddr = virtqueue_paddr(vq);
435 		vtmmio_write_config_4(sc, VIRTIO_MMIO_QUEUE_PFN,
436 		    paddr >> PAGE_SHIFT);
437 	} else {
438 		paddr = virtqueue_desc_paddr(vq);
439 		vtmmio_write_config_4(sc, VIRTIO_MMIO_QUEUE_DESC_LOW,
440 		    paddr);
441 		vtmmio_write_config_4(sc, VIRTIO_MMIO_QUEUE_DESC_HIGH,
442 		    ((uint64_t)paddr) >> 32);
443 
444 		paddr = virtqueue_avail_paddr(vq);
445 		vtmmio_write_config_4(sc, VIRTIO_MMIO_QUEUE_AVAIL_LOW,
446 		    paddr);
447 		vtmmio_write_config_4(sc, VIRTIO_MMIO_QUEUE_AVAIL_HIGH,
448 		    ((uint64_t)paddr) >> 32);
449 
450 		paddr = virtqueue_used_paddr(vq);
451 		vtmmio_write_config_4(sc, VIRTIO_MMIO_QUEUE_USED_LOW,
452 		    paddr);
453 		vtmmio_write_config_4(sc, VIRTIO_MMIO_QUEUE_USED_HIGH,
454 		    ((uint64_t)paddr) >> 32);
455 
456 		vtmmio_write_config_4(sc, VIRTIO_MMIO_QUEUE_READY, 1);
457 	}
458 }
459 
460 static int
461 vtmmio_alloc_virtqueues(device_t dev, int flags, int nvqs,
462     struct vq_alloc_info *vq_info)
463 {
464 	struct vtmmio_virtqueue *vqx;
465 	struct vq_alloc_info *info;
466 	struct vtmmio_softc *sc;
467 	struct virtqueue *vq;
468 	uint32_t size;
469 	int idx, error;
470 
471 	sc = device_get_softc(dev);
472 
473 	if (sc->vtmmio_nvqs != 0)
474 		return (EALREADY);
475 	if (nvqs <= 0)
476 		return (EINVAL);
477 
478 	sc->vtmmio_vqs = malloc(nvqs * sizeof(struct vtmmio_virtqueue),
479 	    M_DEVBUF, M_NOWAIT | M_ZERO);
480 	if (sc->vtmmio_vqs == NULL)
481 		return (ENOMEM);
482 
483 	vtmmio_write_config_4(sc, VIRTIO_MMIO_GUEST_PAGE_SIZE,
484 	    (1 << PAGE_SHIFT));
485 
486 	for (idx = 0; idx < nvqs; idx++) {
487 		vqx = &sc->vtmmio_vqs[idx];
488 		info = &vq_info[idx];
489 
490 		vtmmio_write_config_4(sc, VIRTIO_MMIO_QUEUE_SEL, idx);
491 
492 		vtmmio_select_virtqueue(sc, idx);
493 		size = vtmmio_read_config_4(sc, VIRTIO_MMIO_QUEUE_NUM_MAX);
494 
495 		error = virtqueue_alloc(dev, idx, size,
496 		    VIRTIO_MMIO_VRING_ALIGN, ~(vm_paddr_t)0, info, &vq);
497 		if (error) {
498 			device_printf(dev,
499 			    "cannot allocate virtqueue %d: %d\n",
500 			    idx, error);
501 			break;
502 		}
503 
504 		vtmmio_set_virtqueue(sc, vq, size);
505 
506 		vqx->vtv_vq = *info->vqai_vq = vq;
507 		vqx->vtv_no_intr = info->vqai_intr == NULL;
508 
509 		sc->vtmmio_nvqs++;
510 	}
511 
512 	if (error)
513 		vtmmio_free_virtqueues(sc);
514 
515 	return (error);
516 }
517 
518 static void
519 vtmmio_stop(device_t dev)
520 {
521 
522 	vtmmio_reset(device_get_softc(dev));
523 }
524 
525 static void
526 vtmmio_poll(device_t dev)
527 {
528 	struct vtmmio_softc *sc;
529 
530 	sc = device_get_softc(dev);
531 
532 	if (sc->platform != NULL)
533 		VIRTIO_MMIO_POLL(sc->platform);
534 }
535 
536 static int
537 vtmmio_reinit(device_t dev, uint64_t features)
538 {
539 	struct vtmmio_softc *sc;
540 	int idx, error;
541 
542 	sc = device_get_softc(dev);
543 
544 	if (vtmmio_get_status(dev) != VIRTIO_CONFIG_STATUS_RESET)
545 		vtmmio_stop(dev);
546 
547 	/*
548 	 * Quickly drive the status through ACK and DRIVER. The device
549 	 * does not become usable again until vtmmio_reinit_complete().
550 	 */
551 	vtmmio_set_status(dev, VIRTIO_CONFIG_STATUS_ACK);
552 	vtmmio_set_status(dev, VIRTIO_CONFIG_STATUS_DRIVER);
553 
554 	vtmmio_negotiate_features(dev, features);
555 
556 	vtmmio_write_config_4(sc, VIRTIO_MMIO_GUEST_PAGE_SIZE,
557 	    (1 << PAGE_SHIFT));
558 
559 	for (idx = 0; idx < sc->vtmmio_nvqs; idx++) {
560 		error = vtmmio_reinit_virtqueue(sc, idx);
561 		if (error)
562 			return (error);
563 	}
564 
565 	return (0);
566 }
567 
568 static void
569 vtmmio_reinit_complete(device_t dev)
570 {
571 
572 	vtmmio_set_status(dev, VIRTIO_CONFIG_STATUS_DRIVER_OK);
573 }
574 
575 static void
576 vtmmio_notify_virtqueue(device_t dev, uint16_t queue)
577 {
578 	struct vtmmio_softc *sc;
579 
580 	sc = device_get_softc(dev);
581 
582 	vtmmio_write_config_4(sc, VIRTIO_MMIO_QUEUE_NOTIFY, queue);
583 }
584 
585 static uint8_t
586 vtmmio_get_status(device_t dev)
587 {
588 	struct vtmmio_softc *sc;
589 
590 	sc = device_get_softc(dev);
591 
592 	return (vtmmio_read_config_4(sc, VIRTIO_MMIO_STATUS));
593 }
594 
595 static void
596 vtmmio_set_status(device_t dev, uint8_t status)
597 {
598 	struct vtmmio_softc *sc;
599 
600 	sc = device_get_softc(dev);
601 
602 	if (status != VIRTIO_CONFIG_STATUS_RESET)
603 		status |= vtmmio_get_status(dev);
604 
605 	vtmmio_write_config_4(sc, VIRTIO_MMIO_STATUS, status);
606 }
607 
608 static void
609 vtmmio_read_dev_config(device_t dev, bus_size_t offset,
610     void *dst, int length)
611 {
612 	struct vtmmio_softc *sc;
613 	bus_size_t off;
614 	uint8_t *d;
615 	int size;
616 	uint64_t low32, high32;
617 
618 	sc = device_get_softc(dev);
619 	off = VIRTIO_MMIO_CONFIG + offset;
620 
621 	/*
622 	 * The non-legacy MMIO specification adds the following restriction:
623 	 *
624 	 *   4.2.2.2: For the device-specific configuration space, the driver
625 	 *   MUST use 8 bit wide accesses for 8 bit wide fields, 16 bit wide
626 	 *   and aligned accesses for 16 bit wide fields and 32 bit wide and
627 	 *   aligned accesses for 32 and 64 bit wide fields.
628 	 *
629 	 * The endianness also varies between non-legacy and legacy:
630 	 *
631 	 *   2.4: Note: The device configuration space uses the little-endian
632 	 *   format for multi-byte fields.
633 	 *
634 	 *   2.4.3: Note that for legacy interfaces, device configuration space
635 	 *   is generally the guest’s native endian, rather than PCI’s
636 	 *   little-endian. The correct endian-ness is documented for each
637 	 *   device.
638 	 */
639 	if (sc->vtmmio_version > 1) {
640 		switch (length) {
641 		case 1:
642 			*(uint8_t *)dst = vtmmio_read_config_1(sc, off);
643 			break;
644 		case 2:
645 			*(uint16_t *)dst =
646 			    le16toh(vtmmio_read_config_2(sc, off));
647 			break;
648 		case 4:
649 			*(uint32_t *)dst =
650 			    le32toh(vtmmio_read_config_4(sc, off));
651 			break;
652 		case 8:
653 			low32 = le32toh(vtmmio_read_config_4(sc, off));
654 			high32 = le32toh(vtmmio_read_config_4(sc, off + 4));
655 			*(uint64_t *)dst = (high32 << 32) | low32;
656 			break;
657 		default:
658 			panic("%s: invalid length %d\n", __func__, length);
659 		}
660 
661 		return;
662 	}
663 
664 	for (d = dst; length > 0; d += size, off += size, length -= size) {
665 #ifdef ALLOW_WORD_ALIGNED_ACCESS
666 		if (length >= 4) {
667 			size = 4;
668 			*(uint32_t *)d = vtmmio_read_config_4(sc, off);
669 		} else if (length >= 2) {
670 			size = 2;
671 			*(uint16_t *)d = vtmmio_read_config_2(sc, off);
672 		} else
673 #endif
674 		{
675 			size = 1;
676 			*d = vtmmio_read_config_1(sc, off);
677 		}
678 	}
679 }
680 
681 static void
682 vtmmio_write_dev_config(device_t dev, bus_size_t offset,
683     void *src, int length)
684 {
685 	struct vtmmio_softc *sc;
686 	bus_size_t off;
687 	uint8_t *s;
688 	int size;
689 
690 	sc = device_get_softc(dev);
691 	off = VIRTIO_MMIO_CONFIG + offset;
692 
693 	/*
694 	 * The non-legacy MMIO specification adds size and alignment
695 	 * restrctions. It also changes the endianness from native-endian to
696 	 * little-endian. See vtmmio_read_dev_config.
697 	 */
698 	if (sc->vtmmio_version > 1) {
699 		switch (length) {
700 		case 1:
701 			vtmmio_write_config_1(sc, off, *(uint8_t *)src);
702 			break;
703 		case 2:
704 			vtmmio_write_config_2(sc, off,
705 			    htole16(*(uint16_t *)src));
706 			break;
707 		case 4:
708 			vtmmio_write_config_4(sc, off,
709 			    htole32(*(uint32_t *)src));
710 			break;
711 		case 8:
712 			vtmmio_write_config_4(sc, off,
713 			    htole32(*(uint64_t *)src));
714 			vtmmio_write_config_4(sc, off + 4,
715 			    htole32((*(uint64_t *)src) >> 32));
716 			break;
717 		default:
718 			panic("%s: invalid length %d\n", __func__, length);
719 		}
720 
721 		return;
722 	}
723 
724 	for (s = src; length > 0; s += size, off += size, length -= size) {
725 #ifdef ALLOW_WORD_ALIGNED_ACCESS
726 		if (length >= 4) {
727 			size = 4;
728 			vtmmio_write_config_4(sc, off, *(uint32_t *)s);
729 		} else if (length >= 2) {
730 			size = 2;
731 			vtmmio_write_config_2(sc, off, *(uint16_t *)s);
732 		} else
733 #endif
734 		{
735 			size = 1;
736 			vtmmio_write_config_1(sc, off, *s);
737 		}
738 	}
739 }
740 
741 static void
742 vtmmio_describe_features(struct vtmmio_softc *sc, const char *msg,
743     uint64_t features)
744 {
745 	device_t dev, child;
746 
747 	dev = sc->dev;
748 	child = sc->vtmmio_child_dev;
749 
750 	if (device_is_attached(child) || bootverbose == 0)
751 		return;
752 
753 	virtio_describe(dev, msg, features, sc->vtmmio_child_feat_desc);
754 }
755 
756 static void
757 vtmmio_probe_and_attach_child(struct vtmmio_softc *sc)
758 {
759 	device_t dev, child;
760 
761 	dev = sc->dev;
762 	child = sc->vtmmio_child_dev;
763 
764 	if (child == NULL)
765 		return;
766 
767 	if (device_get_state(child) != DS_NOTPRESENT) {
768 		return;
769 	}
770 
771 	if (device_probe(child) != 0) {
772 		return;
773 	}
774 
775 	vtmmio_set_status(dev, VIRTIO_CONFIG_STATUS_DRIVER);
776 	if (device_attach(child) != 0) {
777 		vtmmio_set_status(dev, VIRTIO_CONFIG_STATUS_FAILED);
778 		vtmmio_reset(sc);
779 		vtmmio_release_child_resources(sc);
780 		/* Reset status for future attempt. */
781 		vtmmio_set_status(dev, VIRTIO_CONFIG_STATUS_ACK);
782 	} else {
783 		vtmmio_set_status(dev, VIRTIO_CONFIG_STATUS_DRIVER_OK);
784 		VIRTIO_ATTACH_COMPLETED(child);
785 	}
786 }
787 
788 static int
789 vtmmio_reinit_virtqueue(struct vtmmio_softc *sc, int idx)
790 {
791 	struct vtmmio_virtqueue *vqx;
792 	struct virtqueue *vq;
793 	int error;
794 	uint16_t size;
795 
796 	vqx = &sc->vtmmio_vqs[idx];
797 	vq = vqx->vtv_vq;
798 
799 	KASSERT(vq != NULL, ("%s: vq %d not allocated", __func__, idx));
800 
801 	vtmmio_select_virtqueue(sc, idx);
802 	size = vtmmio_read_config_4(sc, VIRTIO_MMIO_QUEUE_NUM_MAX);
803 
804 	error = virtqueue_reinit(vq, size);
805 	if (error)
806 		return (error);
807 
808 	vtmmio_set_virtqueue(sc, vq, size);
809 
810 	return (0);
811 }
812 
813 static void
814 vtmmio_free_interrupts(struct vtmmio_softc *sc)
815 {
816 
817 	if (sc->ih != NULL)
818 		bus_teardown_intr(sc->dev, sc->res[1], sc->ih);
819 
820 	if (sc->res[1] != NULL)
821 		bus_release_resource(sc->dev, SYS_RES_IRQ, 0, sc->res[1]);
822 }
823 
824 static void
825 vtmmio_free_virtqueues(struct vtmmio_softc *sc)
826 {
827 	struct vtmmio_virtqueue *vqx;
828 	int idx;
829 
830 	for (idx = 0; idx < sc->vtmmio_nvqs; idx++) {
831 		vqx = &sc->vtmmio_vqs[idx];
832 
833 		vtmmio_select_virtqueue(sc, idx);
834 		if (sc->vtmmio_version == 1)
835 			vtmmio_write_config_4(sc, VIRTIO_MMIO_QUEUE_PFN, 0);
836 		else
837 			vtmmio_write_config_4(sc, VIRTIO_MMIO_QUEUE_READY, 0);
838 
839 		virtqueue_free(vqx->vtv_vq);
840 		vqx->vtv_vq = NULL;
841 	}
842 
843 	free(sc->vtmmio_vqs, M_DEVBUF);
844 	sc->vtmmio_vqs = NULL;
845 	sc->vtmmio_nvqs = 0;
846 }
847 
848 static void
849 vtmmio_release_child_resources(struct vtmmio_softc *sc)
850 {
851 
852 	vtmmio_free_interrupts(sc);
853 	vtmmio_free_virtqueues(sc);
854 }
855 
856 static void
857 vtmmio_reset(struct vtmmio_softc *sc)
858 {
859 
860 	/*
861 	 * Setting the status to RESET sets the host device to
862 	 * the original, uninitialized state.
863 	 */
864 	vtmmio_set_status(sc->dev, VIRTIO_CONFIG_STATUS_RESET);
865 }
866 
867 static void
868 vtmmio_select_virtqueue(struct vtmmio_softc *sc, int idx)
869 {
870 
871 	vtmmio_write_config_4(sc, VIRTIO_MMIO_QUEUE_SEL, idx);
872 }
873 
874 static void
875 vtmmio_vq_intr(void *arg)
876 {
877 	struct vtmmio_virtqueue *vqx;
878 	struct vtmmio_softc *sc;
879 	struct virtqueue *vq;
880 	uint32_t status;
881 	int idx;
882 
883 	sc = arg;
884 
885 	status = vtmmio_read_config_4(sc, VIRTIO_MMIO_INTERRUPT_STATUS);
886 	vtmmio_write_config_4(sc, VIRTIO_MMIO_INTERRUPT_ACK, status);
887 
888 	/* The config changed */
889 	if (status & VIRTIO_MMIO_INT_CONFIG)
890 		if (sc->vtmmio_child_dev != NULL)
891 			VIRTIO_CONFIG_CHANGE(sc->vtmmio_child_dev);
892 
893 	/* Notify all virtqueues. */
894 	if (status & VIRTIO_MMIO_INT_VRING) {
895 		for (idx = 0; idx < sc->vtmmio_nvqs; idx++) {
896 			vqx = &sc->vtmmio_vqs[idx];
897 			if (vqx->vtv_no_intr == 0) {
898 				vq = vqx->vtv_vq;
899 				virtqueue_intr(vq);
900 			}
901 		}
902 	}
903 }
904