xref: /freebsd/sys/dev/virtio/pci/virtio_pci_legacy.c (revision cfd6422a5217410fbd66f7a7a8a64d9d85e61229)
1 /*-
2  * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
3  *
4  * Copyright (c) 2011, Bryan Venteicher <bryanv@FreeBSD.org>
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 unmodified, this list of conditions, and the following
12  *    disclaimer.
13  * 2. Redistributions in binary form must reproduce the above copyright
14  *    notice, this list of conditions and the following disclaimer in the
15  *    documentation and/or other materials provided with the distribution.
16  *
17  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
18  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
19  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
20  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
21  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
22  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
26  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27  */
28 
29 /* Driver for the legacy VirtIO PCI interface. */
30 
31 #include <sys/cdefs.h>
32 __FBSDID("$FreeBSD$");
33 
34 #include <sys/param.h>
35 #include <sys/systm.h>
36 #include <sys/bus.h>
37 #include <sys/lock.h>
38 #include <sys/kernel.h>
39 #include <sys/module.h>
40 #include <sys/endian.h>
41 
42 #include <machine/bus.h>
43 #include <machine/resource.h>
44 #include <sys/bus.h>
45 #include <sys/rman.h>
46 
47 #include <dev/pci/pcivar.h>
48 #include <dev/pci/pcireg.h>
49 
50 #include <dev/virtio/virtio.h>
51 #include <dev/virtio/virtqueue.h>
52 #include <dev/virtio/pci/virtio_pci.h>
53 #include <dev/virtio/pci/virtio_pci_legacy_var.h>
54 
55 #include "virtio_bus_if.h"
56 #include "virtio_pci_if.h"
57 #include "virtio_if.h"
58 
59 struct vtpci_legacy_softc {
60 	device_t			 vtpci_dev;
61 	struct vtpci_common		 vtpci_common;
62 	struct resource			*vtpci_res;
63 	struct resource			*vtpci_msix_res;
64 };
65 
66 static int	vtpci_legacy_probe(device_t);
67 static int	vtpci_legacy_attach(device_t);
68 static int	vtpci_legacy_detach(device_t);
69 static int	vtpci_legacy_suspend(device_t);
70 static int	vtpci_legacy_resume(device_t);
71 static int	vtpci_legacy_shutdown(device_t);
72 
73 static void	vtpci_legacy_driver_added(device_t, driver_t *);
74 static void	vtpci_legacy_child_detached(device_t, device_t);
75 static int	vtpci_legacy_read_ivar(device_t, device_t, int, uintptr_t *);
76 static int	vtpci_legacy_write_ivar(device_t, device_t, int, uintptr_t);
77 
78 static uint8_t	vtpci_legacy_read_isr(device_t);
79 static uint16_t	vtpci_legacy_get_vq_size(device_t, int);
80 static bus_size_t vtpci_legacy_get_vq_notify_off(device_t, int);
81 static void	vtpci_legacy_set_vq(device_t, struct virtqueue *);
82 static void	vtpci_legacy_disable_vq(device_t, int);
83 static int	vtpci_legacy_register_cfg_msix(device_t,
84 		    struct vtpci_interrupt *);
85 static int	vtpci_legacy_register_vq_msix(device_t, int idx,
86 		    struct vtpci_interrupt *);
87 
88 static uint64_t	vtpci_legacy_negotiate_features(device_t, uint64_t);
89 static int	vtpci_legacy_with_feature(device_t, uint64_t);
90 static int	vtpci_legacy_alloc_virtqueues(device_t, int, int,
91 		    struct vq_alloc_info *);
92 static int	vtpci_legacy_setup_interrupts(device_t, enum intr_type);
93 static void	vtpci_legacy_stop(device_t);
94 static int	vtpci_legacy_reinit(device_t, uint64_t);
95 static void	vtpci_legacy_reinit_complete(device_t);
96 static void	vtpci_legacy_notify_vq(device_t, uint16_t, bus_size_t);
97 static void	vtpci_legacy_read_dev_config(device_t, bus_size_t, void *, int);
98 static void	vtpci_legacy_write_dev_config(device_t, bus_size_t, void *, int);
99 
100 static int	vtpci_legacy_alloc_resources(struct vtpci_legacy_softc *);
101 static void	vtpci_legacy_free_resources(struct vtpci_legacy_softc *);
102 
103 static void	vtpci_legacy_probe_and_attach_child(struct vtpci_legacy_softc *);
104 
105 static uint8_t	vtpci_legacy_get_status(struct vtpci_legacy_softc *);
106 static void	vtpci_legacy_set_status(struct vtpci_legacy_softc *, uint8_t);
107 static void	vtpci_legacy_select_virtqueue(struct vtpci_legacy_softc *, int);
108 static void	vtpci_legacy_reset(struct vtpci_legacy_softc *);
109 
110 #define VIRTIO_PCI_LEGACY_CONFIG(_sc) \
111     VIRTIO_PCI_CONFIG_OFF(vtpci_is_msix_enabled(&(_sc)->vtpci_common))
112 
113 #define vtpci_legacy_read_config_1(sc, o) \
114     bus_read_1((sc)->vtpci_res, (o))
115 #define vtpci_legacy_write_config_1(sc, o, v) \
116     bus_write_1((sc)->vtpci_res, (o), (v))
117 /*
118  * VirtIO specifies that PCI Configuration area is guest endian. However,
119  * since PCI devices are inherently little-endian, on big-endian systems
120  * the bus layer transparently converts it to BE. For virtio-legacy, this
121  * conversion is undesired, so an extra byte swap is required to fix it.
122  */
123 #define vtpci_legacy_read_config_2(sc, o) \
124     le16toh(bus_read_2((sc)->vtpci_res, (o)))
125 #define vtpci_legacy_read_config_4(sc, o) \
126     le32toh(bus_read_4((sc)->vtpci_res, (o)))
127 #define vtpci_legacy_write_config_2(sc, o, v) \
128     bus_write_2((sc)->vtpci_res, (o), (htole16(v)))
129 #define vtpci_legacy_write_config_4(sc, o, v) \
130     bus_write_4((sc)->vtpci_res, (o), (htole32(v)))
131 /* PCI Header LE. On BE systems the bus layer takes care of byte swapping. */
132 #define vtpci_legacy_read_header_2(sc, o) \
133     bus_read_2((sc)->vtpci_res, (o))
134 #define vtpci_legacy_read_header_4(sc, o) \
135     bus_read_4((sc)->vtpci_res, (o))
136 #define vtpci_legacy_write_header_2(sc, o, v) \
137     bus_write_2((sc)->vtpci_res, (o), (v))
138 #define vtpci_legacy_write_header_4(sc, o, v) \
139     bus_write_4((sc)->vtpci_res, (o), (v))
140 
141 static device_method_t vtpci_legacy_methods[] = {
142 	/* Device interface. */
143 	DEVMETHOD(device_probe,			  vtpci_legacy_probe),
144 	DEVMETHOD(device_attach,		  vtpci_legacy_attach),
145 	DEVMETHOD(device_detach,		  vtpci_legacy_detach),
146 	DEVMETHOD(device_suspend,		  vtpci_legacy_suspend),
147 	DEVMETHOD(device_resume,		  vtpci_legacy_resume),
148 	DEVMETHOD(device_shutdown,		  vtpci_legacy_shutdown),
149 
150 	/* Bus interface. */
151 	DEVMETHOD(bus_driver_added,		  vtpci_legacy_driver_added),
152 	DEVMETHOD(bus_child_detached,		  vtpci_legacy_child_detached),
153 	DEVMETHOD(bus_child_pnpinfo_str,	  virtio_child_pnpinfo_str),
154 	DEVMETHOD(bus_read_ivar,		  vtpci_legacy_read_ivar),
155 	DEVMETHOD(bus_write_ivar,		  vtpci_legacy_write_ivar),
156 
157 	/* VirtIO PCI interface. */
158 	DEVMETHOD(virtio_pci_read_isr,		 vtpci_legacy_read_isr),
159 	DEVMETHOD(virtio_pci_get_vq_size,	 vtpci_legacy_get_vq_size),
160 	DEVMETHOD(virtio_pci_get_vq_notify_off,	 vtpci_legacy_get_vq_notify_off),
161 	DEVMETHOD(virtio_pci_set_vq,		 vtpci_legacy_set_vq),
162 	DEVMETHOD(virtio_pci_disable_vq,	 vtpci_legacy_disable_vq),
163 	DEVMETHOD(virtio_pci_register_cfg_msix,  vtpci_legacy_register_cfg_msix),
164 	DEVMETHOD(virtio_pci_register_vq_msix,	 vtpci_legacy_register_vq_msix),
165 
166 	/* VirtIO bus interface. */
167 	DEVMETHOD(virtio_bus_negotiate_features,  vtpci_legacy_negotiate_features),
168 	DEVMETHOD(virtio_bus_with_feature,	  vtpci_legacy_with_feature),
169 	DEVMETHOD(virtio_bus_alloc_virtqueues,	  vtpci_legacy_alloc_virtqueues),
170 	DEVMETHOD(virtio_bus_setup_intr,	  vtpci_legacy_setup_interrupts),
171 	DEVMETHOD(virtio_bus_stop,		  vtpci_legacy_stop),
172 	DEVMETHOD(virtio_bus_reinit,		  vtpci_legacy_reinit),
173 	DEVMETHOD(virtio_bus_reinit_complete,	  vtpci_legacy_reinit_complete),
174 	DEVMETHOD(virtio_bus_notify_vq,		  vtpci_legacy_notify_vq),
175 	DEVMETHOD(virtio_bus_read_device_config,  vtpci_legacy_read_dev_config),
176 	DEVMETHOD(virtio_bus_write_device_config, vtpci_legacy_write_dev_config),
177 
178 	DEVMETHOD_END
179 };
180 
181 static driver_t vtpci_legacy_driver = {
182 	.name = "virtio_pci",
183 	.methods = vtpci_legacy_methods,
184 	.size = sizeof(struct vtpci_legacy_softc)
185 };
186 
187 devclass_t vtpci_legacy_devclass;
188 
189 DRIVER_MODULE(virtio_pci_legacy, pci, vtpci_legacy_driver,
190     vtpci_legacy_devclass, 0, 0);
191 
192 static int
193 vtpci_legacy_probe(device_t dev)
194 {
195 	char desc[64];
196 	const char *name;
197 
198 	if (pci_get_vendor(dev) != VIRTIO_PCI_VENDORID)
199 		return (ENXIO);
200 
201 	if (pci_get_device(dev) < VIRTIO_PCI_DEVICEID_MIN ||
202 	    pci_get_device(dev) > VIRTIO_PCI_DEVICEID_LEGACY_MAX)
203 		return (ENXIO);
204 
205 	if (pci_get_revid(dev) != VIRTIO_PCI_ABI_VERSION)
206 		return (ENXIO);
207 
208 	name = virtio_device_name(pci_get_subdevice(dev));
209 	if (name == NULL)
210 		name = "Unknown";
211 
212 	snprintf(desc, sizeof(desc), "VirtIO PCI (legacy) %s adapter", name);
213 	device_set_desc_copy(dev, desc);
214 
215 	/* Prefer transitional modern VirtIO PCI. */
216 	return (BUS_PROBE_LOW_PRIORITY);
217 }
218 
219 static int
220 vtpci_legacy_attach(device_t dev)
221 {
222 	struct vtpci_legacy_softc *sc;
223 	int error;
224 
225 	sc = device_get_softc(dev);
226 	sc->vtpci_dev = dev;
227 	vtpci_init(&sc->vtpci_common, dev, false);
228 
229 	error = vtpci_legacy_alloc_resources(sc);
230 	if (error) {
231 		device_printf(dev, "cannot map I/O space\n");
232 		return (error);
233 	}
234 
235 	vtpci_legacy_reset(sc);
236 
237 	/* Tell the host we've noticed this device. */
238 	vtpci_legacy_set_status(sc, VIRTIO_CONFIG_STATUS_ACK);
239 
240 	error = vtpci_add_child(&sc->vtpci_common);
241 	if (error)
242 		goto fail;
243 
244 	vtpci_legacy_probe_and_attach_child(sc);
245 
246 	return (0);
247 
248 fail:
249 	vtpci_legacy_set_status(sc, VIRTIO_CONFIG_STATUS_FAILED);
250 	vtpci_legacy_detach(dev);
251 
252 	return (error);
253 }
254 
255 static int
256 vtpci_legacy_detach(device_t dev)
257 {
258 	struct vtpci_legacy_softc *sc;
259 	int error;
260 
261 	sc = device_get_softc(dev);
262 
263 	error = vtpci_delete_child(&sc->vtpci_common);
264 	if (error)
265 		return (error);
266 
267 	vtpci_legacy_reset(sc);
268 	vtpci_legacy_free_resources(sc);
269 
270 	return (0);
271 }
272 
273 static int
274 vtpci_legacy_suspend(device_t dev)
275 {
276 	return (bus_generic_suspend(dev));
277 }
278 
279 static int
280 vtpci_legacy_resume(device_t dev)
281 {
282 	return (bus_generic_resume(dev));
283 }
284 
285 static int
286 vtpci_legacy_shutdown(device_t dev)
287 {
288 	(void) bus_generic_shutdown(dev);
289 	/* Forcibly stop the host device. */
290 	vtpci_legacy_stop(dev);
291 
292 	return (0);
293 }
294 
295 static void
296 vtpci_legacy_driver_added(device_t dev, driver_t *driver)
297 {
298 	vtpci_legacy_probe_and_attach_child(device_get_softc(dev));
299 }
300 
301 static void
302 vtpci_legacy_child_detached(device_t dev, device_t child)
303 {
304 	struct vtpci_legacy_softc *sc;
305 
306 	sc = device_get_softc(dev);
307 
308 	vtpci_legacy_reset(sc);
309 	vtpci_child_detached(&sc->vtpci_common);
310 
311 	/* After the reset, retell the host we've noticed this device. */
312 	vtpci_legacy_set_status(sc, VIRTIO_CONFIG_STATUS_ACK);
313 }
314 
315 static int
316 vtpci_legacy_read_ivar(device_t dev, device_t child, int index,
317     uintptr_t *result)
318 {
319 	struct vtpci_legacy_softc *sc;
320 	struct vtpci_common *cn;
321 
322 	sc = device_get_softc(dev);
323 	cn = &sc->vtpci_common;
324 
325 	if (vtpci_child_device(cn) != child)
326 		return (ENOENT);
327 
328 	switch (index) {
329 	case VIRTIO_IVAR_DEVTYPE:
330 		*result = pci_get_subdevice(dev);
331 		break;
332 	default:
333 		return (vtpci_read_ivar(cn, index, result));
334 	}
335 
336 	return (0);
337 }
338 
339 static int
340 vtpci_legacy_write_ivar(device_t dev, device_t child, int index, uintptr_t value)
341 {
342 	struct vtpci_legacy_softc *sc;
343 	struct vtpci_common *cn;
344 
345 	sc = device_get_softc(dev);
346 	cn = &sc->vtpci_common;
347 
348 	if (vtpci_child_device(cn) != child)
349 		return (ENOENT);
350 
351 	switch (index) {
352 	default:
353 		return (vtpci_write_ivar(cn, index, value));
354 	}
355 
356 	return (0);
357 }
358 
359 static uint64_t
360 vtpci_legacy_negotiate_features(device_t dev, uint64_t child_features)
361 {
362 	struct vtpci_legacy_softc *sc;
363 	uint64_t host_features, features;
364 
365 	sc = device_get_softc(dev);
366 	host_features = vtpci_legacy_read_header_4(sc, VIRTIO_PCI_HOST_FEATURES);
367 
368 	features = vtpci_negotiate_features(&sc->vtpci_common,
369 	    child_features, host_features);
370 	vtpci_legacy_write_header_4(sc, VIRTIO_PCI_GUEST_FEATURES, features);
371 
372 	return (features);
373 }
374 
375 static int
376 vtpci_legacy_with_feature(device_t dev, uint64_t feature)
377 {
378 	struct vtpci_legacy_softc *sc;
379 
380 	sc = device_get_softc(dev);
381 
382 	return (vtpci_with_feature(&sc->vtpci_common, feature));
383 }
384 
385 static int
386 vtpci_legacy_alloc_virtqueues(device_t dev, int flags, int nvqs,
387     struct vq_alloc_info *vq_info)
388 {
389 	struct vtpci_legacy_softc *sc;
390 	struct vtpci_common *cn;
391 
392 	sc = device_get_softc(dev);
393 	cn = &sc->vtpci_common;
394 
395 	return (vtpci_alloc_virtqueues(cn, flags, nvqs, vq_info));
396 }
397 
398 static int
399 vtpci_legacy_setup_interrupts(device_t dev, enum intr_type type)
400 {
401 	struct vtpci_legacy_softc *sc;
402 
403 	sc = device_get_softc(dev);
404 
405 	return (vtpci_setup_interrupts(&sc->vtpci_common, type));
406 }
407 
408 static void
409 vtpci_legacy_stop(device_t dev)
410 {
411 	vtpci_legacy_reset(device_get_softc(dev));
412 }
413 
414 static int
415 vtpci_legacy_reinit(device_t dev, uint64_t features)
416 {
417 	struct vtpci_legacy_softc *sc;
418 	struct vtpci_common *cn;
419 	int error;
420 
421 	sc = device_get_softc(dev);
422 	cn = &sc->vtpci_common;
423 
424 	/*
425 	 * Redrive the device initialization. This is a bit of an abuse of
426 	 * the specification, but VirtualBox, QEMU/KVM, and BHyVe seem to
427 	 * play nice.
428 	 *
429 	 * We do not allow the host device to change from what was originally
430 	 * negotiated beyond what the guest driver changed. MSIX state should
431 	 * not change, number of virtqueues and their size remain the same, etc.
432 	 * This will need to be rethought when we want to support migration.
433 	 */
434 
435 	if (vtpci_legacy_get_status(sc) != VIRTIO_CONFIG_STATUS_RESET)
436 		vtpci_legacy_stop(dev);
437 
438 	/*
439 	 * Quickly drive the status through ACK and DRIVER. The device does
440 	 * not become usable again until DRIVER_OK in reinit complete.
441 	 */
442 	vtpci_legacy_set_status(sc, VIRTIO_CONFIG_STATUS_ACK);
443 	vtpci_legacy_set_status(sc, VIRTIO_CONFIG_STATUS_DRIVER);
444 
445 	vtpci_legacy_negotiate_features(dev, features);
446 
447 	error = vtpci_reinit(cn);
448 	if (error)
449 		return (error);
450 
451 	return (0);
452 }
453 
454 static void
455 vtpci_legacy_reinit_complete(device_t dev)
456 {
457 	struct vtpci_legacy_softc *sc;
458 
459 	sc = device_get_softc(dev);
460 
461 	vtpci_legacy_set_status(sc, VIRTIO_CONFIG_STATUS_DRIVER_OK);
462 }
463 
464 static void
465 vtpci_legacy_notify_vq(device_t dev, uint16_t queue, bus_size_t offset)
466 {
467 	struct vtpci_legacy_softc *sc;
468 
469 	sc = device_get_softc(dev);
470 	MPASS(offset == VIRTIO_PCI_QUEUE_NOTIFY);
471 
472 	vtpci_legacy_write_header_2(sc, offset, queue);
473 }
474 
475 static uint8_t
476 vtpci_legacy_get_status(struct vtpci_legacy_softc *sc)
477 {
478 	return (vtpci_legacy_read_config_1(sc, VIRTIO_PCI_STATUS));
479 }
480 
481 static void
482 vtpci_legacy_set_status(struct vtpci_legacy_softc *sc, uint8_t status)
483 {
484 	if (status != VIRTIO_CONFIG_STATUS_RESET)
485 		status |= vtpci_legacy_get_status(sc);
486 
487 	vtpci_legacy_write_config_1(sc, VIRTIO_PCI_STATUS, status);
488 }
489 
490 static void
491 vtpci_legacy_read_dev_config(device_t dev, bus_size_t offset,
492     void *dst, int length)
493 {
494 	struct vtpci_legacy_softc *sc;
495 	bus_size_t off;
496 	uint8_t *d;
497 	int size;
498 
499 	sc = device_get_softc(dev);
500 	off = VIRTIO_PCI_LEGACY_CONFIG(sc) + offset;
501 
502 	for (d = dst; length > 0; d += size, off += size, length -= size) {
503 		if (length >= 4) {
504 			size = 4;
505 			*(uint32_t *)d = vtpci_legacy_read_config_4(sc, off);
506 		} else if (length >= 2) {
507 			size = 2;
508 			*(uint16_t *)d = vtpci_legacy_read_config_2(sc, off);
509 		} else {
510 			size = 1;
511 			*d = vtpci_legacy_read_config_1(sc, off);
512 		}
513 	}
514 }
515 
516 static void
517 vtpci_legacy_write_dev_config(device_t dev, bus_size_t offset,
518     void *src, int length)
519 {
520 	struct vtpci_legacy_softc *sc;
521 	bus_size_t off;
522 	uint8_t *s;
523 	int size;
524 
525 	sc = device_get_softc(dev);
526 	off = VIRTIO_PCI_LEGACY_CONFIG(sc) + offset;
527 
528 	for (s = src; length > 0; s += size, off += size, length -= size) {
529 		if (length >= 4) {
530 			size = 4;
531 			vtpci_legacy_write_config_4(sc, off, *(uint32_t *)s);
532 		} else if (length >= 2) {
533 			size = 2;
534 			vtpci_legacy_write_config_2(sc, off, *(uint16_t *)s);
535 		} else {
536 			size = 1;
537 			vtpci_legacy_write_config_1(sc, off, *s);
538 		}
539 	}
540 }
541 
542 static int
543 vtpci_legacy_alloc_resources(struct vtpci_legacy_softc *sc)
544 {
545 	device_t dev;
546 	int rid;
547 
548 	dev = sc->vtpci_dev;
549 
550 	rid = PCIR_BAR(0);
551 	if ((sc->vtpci_res = bus_alloc_resource_any(dev, SYS_RES_IOPORT,
552 	    &rid, RF_ACTIVE)) == NULL)
553 		return (ENXIO);
554 
555 	if (vtpci_is_msix_available(&sc->vtpci_common)) {
556 		rid = PCIR_BAR(1);
557 		if ((sc->vtpci_msix_res = bus_alloc_resource_any(dev,
558 		    SYS_RES_MEMORY, &rid, RF_ACTIVE)) == NULL)
559 			return (ENXIO);
560 	}
561 
562 	return (0);
563 }
564 
565 static void
566 vtpci_legacy_free_resources(struct vtpci_legacy_softc *sc)
567 {
568 	device_t dev;
569 
570 	dev = sc->vtpci_dev;
571 
572 	if (sc->vtpci_msix_res != NULL) {
573 		bus_release_resource(dev, SYS_RES_MEMORY, PCIR_BAR(1),
574 		    sc->vtpci_msix_res);
575 		sc->vtpci_msix_res = NULL;
576 	}
577 
578 	if (sc->vtpci_res != NULL) {
579 		bus_release_resource(dev, SYS_RES_IOPORT, PCIR_BAR(0),
580 		    sc->vtpci_res);
581 		sc->vtpci_res = NULL;
582 	}
583 }
584 
585 static void
586 vtpci_legacy_probe_and_attach_child(struct vtpci_legacy_softc *sc)
587 {
588 	device_t dev, child;
589 
590 	dev = sc->vtpci_dev;
591 	child = vtpci_child_device(&sc->vtpci_common);
592 
593 	if (child == NULL || device_get_state(child) != DS_NOTPRESENT)
594 		return;
595 
596 	if (device_probe(child) != 0)
597 		return;
598 
599 	vtpci_legacy_set_status(sc, VIRTIO_CONFIG_STATUS_DRIVER);
600 
601 	if (device_attach(child) != 0) {
602 		vtpci_legacy_set_status(sc, VIRTIO_CONFIG_STATUS_FAILED);
603 		/* Reset status for future attempt. */
604 		vtpci_legacy_child_detached(dev, child);
605 	} else {
606 		vtpci_legacy_set_status(sc, VIRTIO_CONFIG_STATUS_DRIVER_OK);
607 		VIRTIO_ATTACH_COMPLETED(child);
608 	}
609 }
610 
611 static int
612 vtpci_legacy_register_msix(struct vtpci_legacy_softc *sc, int offset,
613     struct vtpci_interrupt *intr)
614 {
615 	device_t dev;
616 	uint16_t vector;
617 
618 	dev = sc->vtpci_dev;
619 
620 	if (intr != NULL) {
621 		/* Map from guest rid to host vector. */
622 		vector = intr->vti_rid - 1;
623 	} else
624 		vector = VIRTIO_MSI_NO_VECTOR;
625 
626 	vtpci_legacy_write_header_2(sc, offset, vector);
627 	return (vtpci_legacy_read_header_2(sc, offset) == vector ? 0 : ENODEV);
628 }
629 
630 static int
631 vtpci_legacy_register_cfg_msix(device_t dev, struct vtpci_interrupt *intr)
632 {
633 	struct vtpci_legacy_softc *sc;
634 	int error;
635 
636 	sc = device_get_softc(dev);
637 
638 	error = vtpci_legacy_register_msix(sc, VIRTIO_MSI_CONFIG_VECTOR, intr);
639 	if (error) {
640 		device_printf(dev,
641 		    "unable to register config MSIX interrupt\n");
642 		return (error);
643 	}
644 
645 	return (0);
646 }
647 
648 static int
649 vtpci_legacy_register_vq_msix(device_t dev, int idx,
650     struct vtpci_interrupt *intr)
651 {
652 	struct vtpci_legacy_softc *sc;
653 	int error;
654 
655 	sc = device_get_softc(dev);
656 
657 	vtpci_legacy_select_virtqueue(sc, idx);
658 	error = vtpci_legacy_register_msix(sc, VIRTIO_MSI_QUEUE_VECTOR, intr);
659 	if (error) {
660 		device_printf(dev,
661 		    "unable to register virtqueue MSIX interrupt\n");
662 		return (error);
663 	}
664 
665 	return (0);
666 }
667 
668 static void
669 vtpci_legacy_reset(struct vtpci_legacy_softc *sc)
670 {
671 	/*
672 	 * Setting the status to RESET sets the host device to the
673 	 * original, uninitialized state.
674 	 */
675 	vtpci_legacy_set_status(sc, VIRTIO_CONFIG_STATUS_RESET);
676 	(void) vtpci_legacy_get_status(sc);
677 }
678 
679 static void
680 vtpci_legacy_select_virtqueue(struct vtpci_legacy_softc *sc, int idx)
681 {
682 	vtpci_legacy_write_header_2(sc, VIRTIO_PCI_QUEUE_SEL, idx);
683 }
684 
685 static uint8_t
686 vtpci_legacy_read_isr(device_t dev)
687 {
688 	struct vtpci_legacy_softc *sc;
689 
690 	sc = device_get_softc(dev);
691 
692 	return (vtpci_legacy_read_config_1(sc, VIRTIO_PCI_ISR));
693 }
694 
695 static uint16_t
696 vtpci_legacy_get_vq_size(device_t dev, int idx)
697 {
698 	struct vtpci_legacy_softc *sc;
699 
700 	sc = device_get_softc(dev);
701 
702 	vtpci_legacy_select_virtqueue(sc, idx);
703 	return (vtpci_legacy_read_header_2(sc, VIRTIO_PCI_QUEUE_NUM));
704 }
705 
706 static bus_size_t
707 vtpci_legacy_get_vq_notify_off(device_t dev, int idx)
708 {
709 	return (VIRTIO_PCI_QUEUE_NOTIFY);
710 }
711 
712 static void
713 vtpci_legacy_set_vq(device_t dev, struct virtqueue *vq)
714 {
715 	struct vtpci_legacy_softc *sc;
716 
717 	sc = device_get_softc(dev);
718 
719 	vtpci_legacy_select_virtqueue(sc, virtqueue_index(vq));
720 	vtpci_legacy_write_header_4(sc, VIRTIO_PCI_QUEUE_PFN,
721 	    virtqueue_paddr(vq) >> VIRTIO_PCI_QUEUE_ADDR_SHIFT);
722 }
723 
724 static void
725 vtpci_legacy_disable_vq(device_t dev, int idx)
726 {
727 	struct vtpci_legacy_softc *sc;
728 
729 	sc = device_get_softc(dev);
730 
731 	vtpci_legacy_select_virtqueue(sc, idx);
732 	vtpci_legacy_write_header_4(sc, VIRTIO_PCI_QUEUE_PFN, 0);
733 }
734