xref: /freebsd/sys/dev/virtio/pci/virtio_pci.c (revision 193d9e768ba63fcfb187cfd17f461f7d41345048)
1 /*-
2  * Copyright (c) 2011, Bryan Venteicher <bryanv@FreeBSD.org>
3  * All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions
7  * are met:
8  * 1. Redistributions of source code must retain the above copyright
9  *    notice unmodified, this list of conditions, and the following
10  *    disclaimer.
11  * 2. Redistributions in binary form must reproduce the above copyright
12  *    notice, this list of conditions and the following disclaimer in the
13  *    documentation and/or other materials provided with the distribution.
14  *
15  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
16  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
17  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
18  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
19  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
20  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
21  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
22  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
23  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
24  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
25  */
26 
27 /* Driver for the VirtIO PCI interface. */
28 
29 #include <sys/cdefs.h>
30 __FBSDID("$FreeBSD$");
31 
32 #include <sys/param.h>
33 #include <sys/systm.h>
34 #include <sys/bus.h>
35 #include <sys/kernel.h>
36 #include <sys/module.h>
37 #include <sys/malloc.h>
38 
39 #include <machine/bus.h>
40 #include <machine/resource.h>
41 #include <sys/bus.h>
42 #include <sys/rman.h>
43 
44 #include <dev/pci/pcivar.h>
45 #include <dev/pci/pcireg.h>
46 
47 #include <dev/virtio/virtio.h>
48 #include <dev/virtio/virtqueue.h>
49 #include <dev/virtio/pci/virtio_pci.h>
50 
51 #include "virtio_bus_if.h"
52 #include "virtio_if.h"
53 
54 struct vtpci_interrupt {
55 	struct resource		*vti_irq;
56 	int			 vti_rid;
57 	void			*vti_handler;
58 };
59 
60 struct vtpci_virtqueue {
61 	struct virtqueue	*vtv_vq;
62 	int			 vtv_no_intr;
63 };
64 
65 struct vtpci_softc {
66 	device_t			 vtpci_dev;
67 	struct resource			*vtpci_res;
68 	struct resource			*vtpci_msix_res;
69 	uint64_t			 vtpci_features;
70 	uint32_t			 vtpci_flags;
71 #define VTPCI_FLAG_NO_MSI		0x0001
72 #define VTPCI_FLAG_NO_MSIX		0x0002
73 #define VTPCI_FLAG_LEGACY		0x1000
74 #define VTPCI_FLAG_MSI			0x2000
75 #define VTPCI_FLAG_MSIX			0x4000
76 #define VTPCI_FLAG_SHARED_MSIX		0x8000
77 #define VTPCI_FLAG_ITYPE_MASK		0xF000
78 
79 	/* This "bus" will only ever have one child. */
80 	device_t			 vtpci_child_dev;
81 	struct virtio_feature_desc	*vtpci_child_feat_desc;
82 
83 	int				 vtpci_nvqs;
84 	struct vtpci_virtqueue		*vtpci_vqs;
85 
86 	/*
87 	 * Ideally, each virtqueue that the driver provides a callback for will
88 	 * receive its own MSIX vector. If there are not sufficient vectors
89 	 * available, then attempt to have all the VQs share one vector. For
90 	 * MSIX, the configuration changed notifications must be on their own
91 	 * vector.
92 	 *
93 	 * If MSIX is not available, we will attempt to have the whole device
94 	 * share one MSI vector, and then, finally, one legacy interrupt.
95 	 */
96 	struct vtpci_interrupt		 vtpci_device_interrupt;
97 	struct vtpci_interrupt		*vtpci_msix_vq_interrupts;
98 	int				 vtpci_nmsix_resources;
99 };
100 
101 static int	vtpci_probe(device_t);
102 static int	vtpci_attach(device_t);
103 static int	vtpci_detach(device_t);
104 static int	vtpci_suspend(device_t);
105 static int	vtpci_resume(device_t);
106 static int	vtpci_shutdown(device_t);
107 static void	vtpci_driver_added(device_t, driver_t *);
108 static void	vtpci_child_detached(device_t, device_t);
109 static int	vtpci_read_ivar(device_t, device_t, int, uintptr_t *);
110 static int	vtpci_write_ivar(device_t, device_t, int, uintptr_t);
111 
112 static uint64_t	vtpci_negotiate_features(device_t, uint64_t);
113 static int	vtpci_with_feature(device_t, uint64_t);
114 static int	vtpci_alloc_virtqueues(device_t, int, int,
115 		    struct vq_alloc_info *);
116 static int	vtpci_setup_intr(device_t, enum intr_type);
117 static void	vtpci_stop(device_t);
118 static int	vtpci_reinit(device_t, uint64_t);
119 static void	vtpci_reinit_complete(device_t);
120 static void	vtpci_notify_virtqueue(device_t, uint16_t);
121 static uint8_t	vtpci_get_status(device_t);
122 static void	vtpci_set_status(device_t, uint8_t);
123 static void	vtpci_read_dev_config(device_t, bus_size_t, void *, int);
124 static void	vtpci_write_dev_config(device_t, bus_size_t, void *, int);
125 
126 static void	vtpci_describe_features(struct vtpci_softc *, const char *,
127 		    uint64_t);
128 static void	vtpci_probe_and_attach_child(struct vtpci_softc *);
129 
130 static int	vtpci_alloc_msix(struct vtpci_softc *, int);
131 static int	vtpci_alloc_msi(struct vtpci_softc *);
132 static int	vtpci_alloc_intr_msix_pervq(struct vtpci_softc *);
133 static int	vtpci_alloc_intr_msix_shared(struct vtpci_softc *);
134 static int	vtpci_alloc_intr_msi(struct vtpci_softc *);
135 static int	vtpci_alloc_intr_legacy(struct vtpci_softc *);
136 static int	vtpci_alloc_interrupt(struct vtpci_softc *, int, int,
137 		    struct vtpci_interrupt *);
138 static int	vtpci_alloc_intr_resources(struct vtpci_softc *);
139 
140 static int	vtpci_setup_legacy_interrupt(struct vtpci_softc *,
141 		    enum intr_type);
142 static int	vtpci_setup_pervq_msix_interrupts(struct vtpci_softc *,
143 		    enum intr_type);
144 static int	vtpci_setup_msix_interrupts(struct vtpci_softc *,
145 		    enum intr_type);
146 static int	vtpci_setup_interrupts(struct vtpci_softc *, enum intr_type);
147 
148 static int	vtpci_register_msix_vector(struct vtpci_softc *, int,
149 		    struct vtpci_interrupt *);
150 static int	vtpci_set_host_msix_vectors(struct vtpci_softc *);
151 static int	vtpci_reinit_virtqueue(struct vtpci_softc *, int);
152 
153 static void	vtpci_free_interrupt(struct vtpci_softc *,
154 		    struct vtpci_interrupt *);
155 static void	vtpci_free_interrupts(struct vtpci_softc *);
156 static void	vtpci_free_virtqueues(struct vtpci_softc *);
157 static void	vtpci_release_child_resources(struct vtpci_softc *);
158 static void	vtpci_cleanup_setup_intr_attempt(struct vtpci_softc *);
159 static void	vtpci_reset(struct vtpci_softc *);
160 
161 static void	vtpci_select_virtqueue(struct vtpci_softc *, int);
162 
163 static void	vtpci_legacy_intr(void *);
164 static int	vtpci_vq_shared_intr_filter(void *);
165 static void	vtpci_vq_shared_intr(void *);
166 static int	vtpci_vq_intr_filter(void *);
167 static void	vtpci_vq_intr(void *);
168 static void	vtpci_config_intr(void *);
169 
170 #define vtpci_setup_msi_interrupt vtpci_setup_legacy_interrupt
171 
172 #define VIRTIO_PCI_CONFIG(_sc) \
173     VIRTIO_PCI_CONFIG_OFF((((_sc)->vtpci_flags & VTPCI_FLAG_MSIX)) != 0)
174 
175 /*
176  * I/O port read/write wrappers.
177  */
178 #define vtpci_read_config_1(sc, o)	bus_read_1((sc)->vtpci_res, (o))
179 #define vtpci_read_config_2(sc, o)	bus_read_2((sc)->vtpci_res, (o))
180 #define vtpci_read_config_4(sc, o)	bus_read_4((sc)->vtpci_res, (o))
181 #define vtpci_write_config_1(sc, o, v)	bus_write_1((sc)->vtpci_res, (o), (v))
182 #define vtpci_write_config_2(sc, o, v)	bus_write_2((sc)->vtpci_res, (o), (v))
183 #define vtpci_write_config_4(sc, o, v)	bus_write_4((sc)->vtpci_res, (o), (v))
184 
185 /* Tunables. */
186 static int vtpci_disable_msix = 0;
187 TUNABLE_INT("hw.virtio.pci.disable_msix", &vtpci_disable_msix);
188 
189 static device_method_t vtpci_methods[] = {
190 	/* Device interface. */
191 	DEVMETHOD(device_probe,			  vtpci_probe),
192 	DEVMETHOD(device_attach,		  vtpci_attach),
193 	DEVMETHOD(device_detach,		  vtpci_detach),
194 	DEVMETHOD(device_suspend,		  vtpci_suspend),
195 	DEVMETHOD(device_resume,		  vtpci_resume),
196 	DEVMETHOD(device_shutdown,		  vtpci_shutdown),
197 
198 	/* Bus interface. */
199 	DEVMETHOD(bus_driver_added,		  vtpci_driver_added),
200 	DEVMETHOD(bus_child_detached,		  vtpci_child_detached),
201 	DEVMETHOD(bus_read_ivar,		  vtpci_read_ivar),
202 	DEVMETHOD(bus_write_ivar,		  vtpci_write_ivar),
203 
204 	/* VirtIO bus interface. */
205 	DEVMETHOD(virtio_bus_negotiate_features,  vtpci_negotiate_features),
206 	DEVMETHOD(virtio_bus_with_feature,	  vtpci_with_feature),
207 	DEVMETHOD(virtio_bus_alloc_virtqueues,	  vtpci_alloc_virtqueues),
208 	DEVMETHOD(virtio_bus_setup_intr,	  vtpci_setup_intr),
209 	DEVMETHOD(virtio_bus_stop,		  vtpci_stop),
210 	DEVMETHOD(virtio_bus_reinit,		  vtpci_reinit),
211 	DEVMETHOD(virtio_bus_reinit_complete,	  vtpci_reinit_complete),
212 	DEVMETHOD(virtio_bus_notify_vq,		  vtpci_notify_virtqueue),
213 	DEVMETHOD(virtio_bus_read_device_config,  vtpci_read_dev_config),
214 	DEVMETHOD(virtio_bus_write_device_config, vtpci_write_dev_config),
215 
216 	DEVMETHOD_END
217 };
218 
219 static driver_t vtpci_driver = {
220 	"virtio_pci",
221 	vtpci_methods,
222 	sizeof(struct vtpci_softc)
223 };
224 
225 devclass_t vtpci_devclass;
226 
227 DRIVER_MODULE(virtio_pci, pci, vtpci_driver, vtpci_devclass, 0, 0);
228 MODULE_VERSION(virtio_pci, 1);
229 MODULE_DEPEND(virtio_pci, pci, 1, 1, 1);
230 MODULE_DEPEND(virtio_pci, virtio, 1, 1, 1);
231 
232 static int
233 vtpci_probe(device_t dev)
234 {
235 	char desc[36];
236 	const char *name;
237 
238 	if (pci_get_vendor(dev) != VIRTIO_PCI_VENDORID)
239 		return (ENXIO);
240 
241 	if (pci_get_device(dev) < VIRTIO_PCI_DEVICEID_MIN ||
242 	    pci_get_device(dev) > VIRTIO_PCI_DEVICEID_MAX)
243 		return (ENXIO);
244 
245 	if (pci_get_revid(dev) != VIRTIO_PCI_ABI_VERSION)
246 		return (ENXIO);
247 
248 	name = virtio_device_name(pci_get_subdevice(dev));
249 	if (name == NULL)
250 		name = "Unknown";
251 
252 	snprintf(desc, sizeof(desc), "VirtIO PCI %s adapter", name);
253 	device_set_desc_copy(dev, desc);
254 
255 	return (BUS_PROBE_DEFAULT);
256 }
257 
258 static int
259 vtpci_attach(device_t dev)
260 {
261 	struct vtpci_softc *sc;
262 	device_t child;
263 	int rid;
264 
265 	sc = device_get_softc(dev);
266 	sc->vtpci_dev = dev;
267 
268 	pci_enable_busmaster(dev);
269 
270 	rid = PCIR_BAR(0);
271 	sc->vtpci_res = bus_alloc_resource_any(dev, SYS_RES_IOPORT, &rid,
272 	    RF_ACTIVE);
273 	if (sc->vtpci_res == NULL) {
274 		device_printf(dev, "cannot map I/O space\n");
275 		return (ENXIO);
276 	}
277 
278 	if (pci_find_cap(dev, PCIY_MSI, NULL) != 0)
279 		sc->vtpci_flags |= VTPCI_FLAG_NO_MSI;
280 
281 	if (pci_find_cap(dev, PCIY_MSIX, NULL) == 0) {
282 		rid = PCIR_BAR(1);
283 		sc->vtpci_msix_res = bus_alloc_resource_any(dev,
284 		    SYS_RES_MEMORY, &rid, RF_ACTIVE);
285 	}
286 
287 	if (sc->vtpci_msix_res == NULL)
288 		sc->vtpci_flags |= VTPCI_FLAG_NO_MSIX;
289 
290 	vtpci_reset(sc);
291 
292 	/* Tell the host we've noticed this device. */
293 	vtpci_set_status(dev, VIRTIO_CONFIG_STATUS_ACK);
294 
295 	if ((child = device_add_child(dev, NULL, -1)) == NULL) {
296 		device_printf(dev, "cannot create child device\n");
297 		vtpci_set_status(dev, VIRTIO_CONFIG_STATUS_FAILED);
298 		vtpci_detach(dev);
299 		return (ENOMEM);
300 	}
301 
302 	sc->vtpci_child_dev = child;
303 	vtpci_probe_and_attach_child(sc);
304 
305 	return (0);
306 }
307 
308 static int
309 vtpci_detach(device_t dev)
310 {
311 	struct vtpci_softc *sc;
312 	device_t child;
313 	int error;
314 
315 	sc = device_get_softc(dev);
316 
317 	if ((child = sc->vtpci_child_dev) != NULL) {
318 		error = device_delete_child(dev, child);
319 		if (error)
320 			return (error);
321 		sc->vtpci_child_dev = NULL;
322 	}
323 
324 	vtpci_reset(sc);
325 
326 	if (sc->vtpci_msix_res != NULL) {
327 		bus_release_resource(dev, SYS_RES_MEMORY, PCIR_BAR(1),
328 		    sc->vtpci_msix_res);
329 		sc->vtpci_msix_res = NULL;
330 	}
331 
332 	if (sc->vtpci_res != NULL) {
333 		bus_release_resource(dev, SYS_RES_IOPORT, PCIR_BAR(0),
334 		    sc->vtpci_res);
335 		sc->vtpci_res = NULL;
336 	}
337 
338 	return (0);
339 }
340 
341 static int
342 vtpci_suspend(device_t dev)
343 {
344 
345 	return (bus_generic_suspend(dev));
346 }
347 
348 static int
349 vtpci_resume(device_t dev)
350 {
351 
352 	return (bus_generic_resume(dev));
353 }
354 
355 static int
356 vtpci_shutdown(device_t dev)
357 {
358 
359 	(void) bus_generic_shutdown(dev);
360 	/* Forcibly stop the host device. */
361 	vtpci_stop(dev);
362 
363 	return (0);
364 }
365 
366 static void
367 vtpci_driver_added(device_t dev, driver_t *driver)
368 {
369 	struct vtpci_softc *sc;
370 
371 	sc = device_get_softc(dev);
372 
373 	vtpci_probe_and_attach_child(sc);
374 }
375 
376 static void
377 vtpci_child_detached(device_t dev, device_t child)
378 {
379 	struct vtpci_softc *sc;
380 
381 	sc = device_get_softc(dev);
382 
383 	vtpci_reset(sc);
384 	vtpci_release_child_resources(sc);
385 }
386 
387 static int
388 vtpci_read_ivar(device_t dev, device_t child, int index, uintptr_t *result)
389 {
390 	struct vtpci_softc *sc;
391 
392 	sc = device_get_softc(dev);
393 
394 	if (sc->vtpci_child_dev != child)
395 		return (ENOENT);
396 
397 	switch (index) {
398 	case VIRTIO_IVAR_DEVTYPE:
399 	case VIRTIO_IVAR_SUBDEVICE:
400 		*result = pci_get_subdevice(dev);
401 		break;
402 	case VIRTIO_IVAR_VENDOR:
403 		*result = pci_get_vendor(dev);
404 		break;
405 	case VIRTIO_IVAR_DEVICE:
406 		*result = pci_get_device(dev);
407 		break;
408 	case VIRTIO_IVAR_SUBVENDOR:
409 		*result = pci_get_subdevice(dev);
410 		break;
411 	default:
412 		return (ENOENT);
413 	}
414 
415 	return (0);
416 }
417 
418 static int
419 vtpci_write_ivar(device_t dev, device_t child, int index, uintptr_t value)
420 {
421 	struct vtpci_softc *sc;
422 
423 	sc = device_get_softc(dev);
424 
425 	if (sc->vtpci_child_dev != child)
426 		return (ENOENT);
427 
428 	switch (index) {
429 	case VIRTIO_IVAR_FEATURE_DESC:
430 		sc->vtpci_child_feat_desc = (void *) value;
431 		break;
432 	default:
433 		return (ENOENT);
434 	}
435 
436 	return (0);
437 }
438 
439 static uint64_t
440 vtpci_negotiate_features(device_t dev, uint64_t child_features)
441 {
442 	struct vtpci_softc *sc;
443 	uint64_t host_features, features;
444 
445 	sc = device_get_softc(dev);
446 
447 	host_features = vtpci_read_config_4(sc, VIRTIO_PCI_HOST_FEATURES);
448 	vtpci_describe_features(sc, "host", host_features);
449 
450 	/*
451 	 * Limit negotiated features to what the driver, virtqueue, and
452 	 * host all support.
453 	 */
454 	features = host_features & child_features;
455 	features = virtqueue_filter_features(features);
456 	sc->vtpci_features = features;
457 
458 	vtpci_describe_features(sc, "negotiated", features);
459 	vtpci_write_config_4(sc, VIRTIO_PCI_GUEST_FEATURES, features);
460 
461 	return (features);
462 }
463 
464 static int
465 vtpci_with_feature(device_t dev, uint64_t feature)
466 {
467 	struct vtpci_softc *sc;
468 
469 	sc = device_get_softc(dev);
470 
471 	return ((sc->vtpci_features & feature) != 0);
472 }
473 
474 static int
475 vtpci_alloc_virtqueues(device_t dev, int flags, int nvqs,
476     struct vq_alloc_info *vq_info)
477 {
478 	struct vtpci_softc *sc;
479 	struct virtqueue *vq;
480 	struct vtpci_virtqueue *vqx;
481 	struct vq_alloc_info *info;
482 	int idx, error;
483 	uint16_t size;
484 
485 	sc = device_get_softc(dev);
486 
487 	if (sc->vtpci_nvqs != 0)
488 		return (EALREADY);
489 	if (nvqs <= 0)
490 		return (EINVAL);
491 
492 	sc->vtpci_vqs = malloc(nvqs * sizeof(struct vtpci_virtqueue),
493 	    M_DEVBUF, M_NOWAIT | M_ZERO);
494 	if (sc->vtpci_vqs == NULL)
495 		return (ENOMEM);
496 
497 	for (idx = 0; idx < nvqs; idx++) {
498 		vqx = &sc->vtpci_vqs[idx];
499 		info = &vq_info[idx];
500 
501 		vtpci_select_virtqueue(sc, idx);
502 		size = vtpci_read_config_2(sc, VIRTIO_PCI_QUEUE_NUM);
503 
504 		error = virtqueue_alloc(dev, idx, size, VIRTIO_PCI_VRING_ALIGN,
505 		    0xFFFFFFFFUL, info, &vq);
506 		if (error) {
507 			device_printf(dev,
508 			    "cannot allocate virtqueue %d: %d\n", idx, error);
509 			break;
510 		}
511 
512 		vtpci_write_config_4(sc, VIRTIO_PCI_QUEUE_PFN,
513 		    virtqueue_paddr(vq) >> VIRTIO_PCI_QUEUE_ADDR_SHIFT);
514 
515 		vqx->vtv_vq = *info->vqai_vq = vq;
516 		vqx->vtv_no_intr = info->vqai_intr == NULL;
517 
518 		sc->vtpci_nvqs++;
519 	}
520 
521 	if (error)
522 		vtpci_free_virtqueues(sc);
523 
524 	return (error);
525 }
526 
527 static int
528 vtpci_setup_intr(device_t dev, enum intr_type type)
529 {
530 	struct vtpci_softc *sc;
531 	int attempt, error;
532 
533 	sc = device_get_softc(dev);
534 
535 	for (attempt = 0; attempt < 5; attempt++) {
536 		/*
537 		 * Start with the most desirable interrupt configuration and
538 		 * fallback towards less desirable ones.
539 		 */
540 		switch (attempt) {
541 		case 0:
542 			error = vtpci_alloc_intr_msix_pervq(sc);
543 			break;
544 		case 1:
545 			error = vtpci_alloc_intr_msix_shared(sc);
546 			break;
547 		case 2:
548 			error = vtpci_alloc_intr_msi(sc);
549 			break;
550 		case 3:
551 			error = vtpci_alloc_intr_legacy(sc);
552 			break;
553 		default:
554 			device_printf(dev,
555 			    "exhausted all interrupt allocation attempts\n");
556 			return (ENXIO);
557 		}
558 
559 		if (error == 0 && vtpci_setup_interrupts(sc, type) == 0)
560 			break;
561 
562 		vtpci_cleanup_setup_intr_attempt(sc);
563 	}
564 
565 	if (bootverbose) {
566 		if (sc->vtpci_flags & VTPCI_FLAG_LEGACY)
567 			device_printf(dev, "using legacy interrupt\n");
568 		else if (sc->vtpci_flags & VTPCI_FLAG_MSI)
569 			device_printf(dev, "using MSI interrupt\n");
570 		else if (sc->vtpci_flags & VTPCI_FLAG_SHARED_MSIX)
571 			device_printf(dev, "using shared MSIX interrupts\n");
572 		else
573 			device_printf(dev, "using per VQ MSIX interrupts\n");
574 	}
575 
576 	return (0);
577 }
578 
579 static void
580 vtpci_stop(device_t dev)
581 {
582 
583 	vtpci_reset(device_get_softc(dev));
584 }
585 
586 static int
587 vtpci_reinit(device_t dev, uint64_t features)
588 {
589 	struct vtpci_softc *sc;
590 	int idx, error;
591 
592 	sc = device_get_softc(dev);
593 
594 	/*
595 	 * Redrive the device initialization. This is a bit of an abuse of
596 	 * the specification, but VirtualBox, QEMU/KVM, and BHyVe seem to
597 	 * play nice.
598 	 *
599 	 * We do not allow the host device to change from what was originally
600 	 * negotiated beyond what the guest driver changed. MSIX state should
601 	 * not change, number of virtqueues and their size remain the same, etc.
602 	 * This will need to be rethought when we want to support migration.
603 	 */
604 
605 	if (vtpci_get_status(dev) != VIRTIO_CONFIG_STATUS_RESET)
606 		vtpci_stop(dev);
607 
608 	/*
609 	 * Quickly drive the status through ACK and DRIVER. The device
610 	 * does not become usable again until vtpci_reinit_complete().
611 	 */
612 	vtpci_set_status(dev, VIRTIO_CONFIG_STATUS_ACK);
613 	vtpci_set_status(dev, VIRTIO_CONFIG_STATUS_DRIVER);
614 
615 	vtpci_negotiate_features(dev, features);
616 
617 	for (idx = 0; idx < sc->vtpci_nvqs; idx++) {
618 		error = vtpci_reinit_virtqueue(sc, idx);
619 		if (error)
620 			return (error);
621 	}
622 
623 	if (sc->vtpci_flags & VTPCI_FLAG_MSIX) {
624 		error = vtpci_set_host_msix_vectors(sc);
625 		if (error)
626 			return (error);
627 	}
628 
629 	return (0);
630 }
631 
632 static void
633 vtpci_reinit_complete(device_t dev)
634 {
635 
636 	vtpci_set_status(dev, VIRTIO_CONFIG_STATUS_DRIVER_OK);
637 }
638 
639 static void
640 vtpci_notify_virtqueue(device_t dev, uint16_t queue)
641 {
642 	struct vtpci_softc *sc;
643 
644 	sc = device_get_softc(dev);
645 
646 	vtpci_write_config_2(sc, VIRTIO_PCI_QUEUE_NOTIFY, queue);
647 }
648 
649 static uint8_t
650 vtpci_get_status(device_t dev)
651 {
652 	struct vtpci_softc *sc;
653 
654 	sc = device_get_softc(dev);
655 
656 	return (vtpci_read_config_1(sc, VIRTIO_PCI_STATUS));
657 }
658 
659 static void
660 vtpci_set_status(device_t dev, uint8_t status)
661 {
662 	struct vtpci_softc *sc;
663 
664 	sc = device_get_softc(dev);
665 
666 	if (status != VIRTIO_CONFIG_STATUS_RESET)
667 		status |= vtpci_get_status(dev);
668 
669 	vtpci_write_config_1(sc, VIRTIO_PCI_STATUS, status);
670 }
671 
672 static void
673 vtpci_read_dev_config(device_t dev, bus_size_t offset,
674     void *dst, int length)
675 {
676 	struct vtpci_softc *sc;
677 	bus_size_t off;
678 	uint8_t *d;
679 	int size;
680 
681 	sc = device_get_softc(dev);
682 	off = VIRTIO_PCI_CONFIG(sc) + offset;
683 
684 	for (d = dst; length > 0; d += size, off += size, length -= size) {
685 		if (length >= 4) {
686 			size = 4;
687 			*(uint32_t *)d = vtpci_read_config_4(sc, off);
688 		} else if (length >= 2) {
689 			size = 2;
690 			*(uint16_t *)d = vtpci_read_config_2(sc, off);
691 		} else {
692 			size = 1;
693 			*d = vtpci_read_config_1(sc, off);
694 		}
695 	}
696 }
697 
698 static void
699 vtpci_write_dev_config(device_t dev, bus_size_t offset,
700     void *src, int length)
701 {
702 	struct vtpci_softc *sc;
703 	bus_size_t off;
704 	uint8_t *s;
705 	int size;
706 
707 	sc = device_get_softc(dev);
708 	off = VIRTIO_PCI_CONFIG(sc) + offset;
709 
710 	for (s = src; length > 0; s += size, off += size, length -= size) {
711 		if (length >= 4) {
712 			size = 4;
713 			vtpci_write_config_4(sc, off, *(uint32_t *)s);
714 		} else if (length >= 2) {
715 			size = 2;
716 			vtpci_write_config_2(sc, off, *(uint16_t *)s);
717 		} else {
718 			size = 1;
719 			vtpci_write_config_1(sc, off, *s);
720 		}
721 	}
722 }
723 
724 static void
725 vtpci_describe_features(struct vtpci_softc *sc, const char *msg,
726     uint64_t features)
727 {
728 	device_t dev, child;
729 
730 	dev = sc->vtpci_dev;
731 	child = sc->vtpci_child_dev;
732 
733 	if (device_is_attached(child) || bootverbose == 0)
734 		return;
735 
736 	virtio_describe(dev, msg, features, sc->vtpci_child_feat_desc);
737 }
738 
739 static void
740 vtpci_probe_and_attach_child(struct vtpci_softc *sc)
741 {
742 	device_t dev, child;
743 
744 	dev = sc->vtpci_dev;
745 	child = sc->vtpci_child_dev;
746 
747 	if (child == NULL)
748 		return;
749 
750 	if (device_get_state(child) != DS_NOTPRESENT)
751 		return;
752 
753 	if (device_probe(child) != 0)
754 		return;
755 
756 	vtpci_set_status(dev, VIRTIO_CONFIG_STATUS_DRIVER);
757 	if (device_attach(child) != 0) {
758 		vtpci_set_status(dev, VIRTIO_CONFIG_STATUS_FAILED);
759 		vtpci_reset(sc);
760 		vtpci_release_child_resources(sc);
761 		/* Reset status for future attempt. */
762 		vtpci_set_status(dev, VIRTIO_CONFIG_STATUS_ACK);
763 	} else {
764 		vtpci_set_status(dev, VIRTIO_CONFIG_STATUS_DRIVER_OK);
765 		VIRTIO_ATTACH_COMPLETED(child);
766 	}
767 }
768 
769 static int
770 vtpci_alloc_msix(struct vtpci_softc *sc, int nvectors)
771 {
772 	device_t dev;
773 	int nmsix, cnt, required;
774 
775 	dev = sc->vtpci_dev;
776 
777 	/* Allocate an additional vector for the config changes. */
778 	required = nvectors + 1;
779 
780 	nmsix = pci_msix_count(dev);
781 	if (nmsix < required)
782 		return (1);
783 
784 	cnt = required;
785 	if (pci_alloc_msix(dev, &cnt) == 0 && cnt >= required) {
786 		sc->vtpci_nmsix_resources = required;
787 		return (0);
788 	}
789 
790 	pci_release_msi(dev);
791 
792 	return (1);
793 }
794 
795 static int
796 vtpci_alloc_msi(struct vtpci_softc *sc)
797 {
798 	device_t dev;
799 	int nmsi, cnt, required;
800 
801 	dev = sc->vtpci_dev;
802 	required = 1;
803 
804 	nmsi = pci_msi_count(dev);
805 	if (nmsi < required)
806 		return (1);
807 
808 	cnt = required;
809 	if (pci_alloc_msi(dev, &cnt) == 0 && cnt >= required)
810 		return (0);
811 
812 	pci_release_msi(dev);
813 
814 	return (1);
815 }
816 
817 static int
818 vtpci_alloc_intr_msix_pervq(struct vtpci_softc *sc)
819 {
820 	int i, nvectors, error;
821 
822 	if (vtpci_disable_msix != 0 ||
823 	    sc->vtpci_flags & VTPCI_FLAG_NO_MSIX)
824 		return (ENOTSUP);
825 
826 	for (nvectors = 0, i = 0; i < sc->vtpci_nvqs; i++) {
827 		if (sc->vtpci_vqs[i].vtv_no_intr == 0)
828 			nvectors++;
829 	}
830 
831 	error = vtpci_alloc_msix(sc, nvectors);
832 	if (error)
833 		return (error);
834 
835 	sc->vtpci_flags |= VTPCI_FLAG_MSIX;
836 
837 	return (0);
838 }
839 
840 static int
841 vtpci_alloc_intr_msix_shared(struct vtpci_softc *sc)
842 {
843 	int error;
844 
845 	if (vtpci_disable_msix != 0 ||
846 	    sc->vtpci_flags & VTPCI_FLAG_NO_MSIX)
847 		return (ENOTSUP);
848 
849 	error = vtpci_alloc_msix(sc, 1);
850 	if (error)
851 		return (error);
852 
853 	sc->vtpci_flags |= VTPCI_FLAG_MSIX | VTPCI_FLAG_SHARED_MSIX;
854 
855 	return (0);
856 }
857 
858 static int
859 vtpci_alloc_intr_msi(struct vtpci_softc *sc)
860 {
861 	int error;
862 
863 	/* Only BHyVe supports MSI. */
864 	if (sc->vtpci_flags & VTPCI_FLAG_NO_MSI)
865 		return (ENOTSUP);
866 
867 	error = vtpci_alloc_msi(sc);
868 	if (error)
869 		return (error);
870 
871 	sc->vtpci_flags |= VTPCI_FLAG_MSI;
872 
873 	return (0);
874 }
875 
876 static int
877 vtpci_alloc_intr_legacy(struct vtpci_softc *sc)
878 {
879 
880 	sc->vtpci_flags |= VTPCI_FLAG_LEGACY;
881 
882 	return (0);
883 }
884 
885 static int
886 vtpci_alloc_interrupt(struct vtpci_softc *sc, int rid, int flags,
887     struct vtpci_interrupt *intr)
888 {
889 	struct resource *irq;
890 
891 	irq = bus_alloc_resource_any(sc->vtpci_dev, SYS_RES_IRQ, &rid, flags);
892 	if (irq == NULL)
893 		return (ENXIO);
894 
895 	intr->vti_irq = irq;
896 	intr->vti_rid = rid;
897 
898 	return (0);
899 }
900 
901 static int
902 vtpci_alloc_intr_resources(struct vtpci_softc *sc)
903 {
904 	struct vtpci_interrupt *intr;
905 	int i, rid, flags, nvq_intrs, error;
906 
907 	rid = 0;
908 	flags = RF_ACTIVE;
909 
910 	if (sc->vtpci_flags & VTPCI_FLAG_LEGACY)
911 		flags |= RF_SHAREABLE;
912 	else
913 		rid = 1;
914 
915 	/*
916 	 * For legacy and MSI interrupts, this single resource handles all
917 	 * interrupts. For MSIX, this resource is used for the configuration
918 	 * changed interrupt.
919 	 */
920 	intr = &sc->vtpci_device_interrupt;
921 	error = vtpci_alloc_interrupt(sc, rid, flags, intr);
922 	if (error || sc->vtpci_flags & (VTPCI_FLAG_LEGACY | VTPCI_FLAG_MSI))
923 		return (error);
924 
925 	/* Subtract one for the configuration changed interrupt. */
926 	nvq_intrs = sc->vtpci_nmsix_resources - 1;
927 
928 	intr = sc->vtpci_msix_vq_interrupts = malloc(nvq_intrs *
929 	    sizeof(struct vtpci_interrupt), M_DEVBUF, M_NOWAIT | M_ZERO);
930 	if (sc->vtpci_msix_vq_interrupts == NULL)
931 		return (ENOMEM);
932 
933 	for (i = 0, rid++; i < nvq_intrs; i++, rid++, intr++) {
934 		error = vtpci_alloc_interrupt(sc, rid, flags, intr);
935 		if (error)
936 			return (error);
937 	}
938 
939 	return (0);
940 }
941 
942 static int
943 vtpci_setup_legacy_interrupt(struct vtpci_softc *sc, enum intr_type type)
944 {
945 	struct vtpci_interrupt *intr;
946 	int error;
947 
948 	intr = &sc->vtpci_device_interrupt;
949 	error = bus_setup_intr(sc->vtpci_dev, intr->vti_irq, type, NULL,
950 	    vtpci_legacy_intr, sc, &intr->vti_handler);
951 
952 	return (error);
953 }
954 
955 static int
956 vtpci_setup_pervq_msix_interrupts(struct vtpci_softc *sc, enum intr_type type)
957 {
958 	struct vtpci_virtqueue *vqx;
959 	struct vtpci_interrupt *intr;
960 	int i, error;
961 
962 	intr = sc->vtpci_msix_vq_interrupts;
963 
964 	for (i = 0; i < sc->vtpci_nvqs; i++) {
965 		vqx = &sc->vtpci_vqs[i];
966 
967 		if (vqx->vtv_no_intr)
968 			continue;
969 
970 		error = bus_setup_intr(sc->vtpci_dev, intr->vti_irq, type,
971 		    vtpci_vq_intr_filter, vtpci_vq_intr, vqx->vtv_vq,
972 		    &intr->vti_handler);
973 		if (error)
974 			return (error);
975 
976 		intr++;
977 	}
978 
979 	return (0);
980 }
981 
982 static int
983 vtpci_setup_msix_interrupts(struct vtpci_softc *sc, enum intr_type type)
984 {
985 	device_t dev;
986 	struct vtpci_interrupt *intr;
987 	int error;
988 
989 	dev = sc->vtpci_dev;
990 	intr = &sc->vtpci_device_interrupt;
991 
992 	error = bus_setup_intr(dev, intr->vti_irq, type, NULL,
993 	    vtpci_config_intr, sc, &intr->vti_handler);
994 	if (error)
995 		return (error);
996 
997 	if (sc->vtpci_flags & VTPCI_FLAG_SHARED_MSIX) {
998 		intr = sc->vtpci_msix_vq_interrupts;
999 		error = bus_setup_intr(dev, intr->vti_irq, type,
1000 		    vtpci_vq_shared_intr_filter, vtpci_vq_shared_intr, sc,
1001 		    &intr->vti_handler);
1002 	} else
1003 		error = vtpci_setup_pervq_msix_interrupts(sc, type);
1004 
1005 	return (error ? error : vtpci_set_host_msix_vectors(sc));
1006 }
1007 
1008 static int
1009 vtpci_setup_interrupts(struct vtpci_softc *sc, enum intr_type type)
1010 {
1011 	int error;
1012 
1013 	type |= INTR_MPSAFE;
1014 	KASSERT(sc->vtpci_flags & VTPCI_FLAG_ITYPE_MASK,
1015 	    ("%s: no interrupt type selected %#x", __func__, sc->vtpci_flags));
1016 
1017 	error = vtpci_alloc_intr_resources(sc);
1018 	if (error)
1019 		return (error);
1020 
1021 	if (sc->vtpci_flags & VTPCI_FLAG_LEGACY)
1022 		error = vtpci_setup_legacy_interrupt(sc, type);
1023 	else if (sc->vtpci_flags & VTPCI_FLAG_MSI)
1024 		error = vtpci_setup_msi_interrupt(sc, type);
1025 	else
1026 		error = vtpci_setup_msix_interrupts(sc, type);
1027 
1028 	return (error);
1029 }
1030 
1031 static int
1032 vtpci_register_msix_vector(struct vtpci_softc *sc, int offset,
1033     struct vtpci_interrupt *intr)
1034 {
1035 	device_t dev;
1036 	uint16_t vector;
1037 
1038 	dev = sc->vtpci_dev;
1039 
1040 	if (intr != NULL) {
1041 		/* Map from guest rid to host vector. */
1042 		vector = intr->vti_rid - 1;
1043 	} else
1044 		vector = VIRTIO_MSI_NO_VECTOR;
1045 
1046 	vtpci_write_config_2(sc, offset, vector);
1047 
1048 	/* Read vector to determine if the host had sufficient resources. */
1049 	if (vtpci_read_config_2(sc, offset) != vector) {
1050 		device_printf(dev,
1051 		    "insufficient host resources for MSIX interrupts\n");
1052 		return (ENODEV);
1053 	}
1054 
1055 	return (0);
1056 }
1057 
1058 static int
1059 vtpci_set_host_msix_vectors(struct vtpci_softc *sc)
1060 {
1061 	struct vtpci_interrupt *intr, *tintr;
1062 	int idx, offset, error;
1063 
1064 	intr = &sc->vtpci_device_interrupt;
1065 	offset = VIRTIO_MSI_CONFIG_VECTOR;
1066 
1067 	error = vtpci_register_msix_vector(sc, offset, intr);
1068 	if (error)
1069 		return (error);
1070 
1071 	intr = sc->vtpci_msix_vq_interrupts;
1072 	offset = VIRTIO_MSI_QUEUE_VECTOR;
1073 
1074 	for (idx = 0; idx < sc->vtpci_nvqs; idx++) {
1075 		vtpci_select_virtqueue(sc, idx);
1076 
1077 		if (sc->vtpci_vqs[idx].vtv_no_intr)
1078 			tintr = NULL;
1079 		else
1080 			tintr = intr;
1081 
1082 		error = vtpci_register_msix_vector(sc, offset, tintr);
1083 		if (error)
1084 			break;
1085 
1086 		/*
1087 		 * For shared MSIX, all the virtqueues share the first
1088 		 * interrupt.
1089 		 */
1090 		if (!sc->vtpci_vqs[idx].vtv_no_intr &&
1091 		    (sc->vtpci_flags & VTPCI_FLAG_SHARED_MSIX) == 0)
1092 			intr++;
1093 	}
1094 
1095 	return (error);
1096 }
1097 
1098 static int
1099 vtpci_reinit_virtqueue(struct vtpci_softc *sc, int idx)
1100 {
1101 	struct vtpci_virtqueue *vqx;
1102 	struct virtqueue *vq;
1103 	int error;
1104 	uint16_t size;
1105 
1106 	vqx = &sc->vtpci_vqs[idx];
1107 	vq = vqx->vtv_vq;
1108 
1109 	KASSERT(vq != NULL, ("%s: vq %d not allocated", __func__, idx));
1110 
1111 	vtpci_select_virtqueue(sc, idx);
1112 	size = vtpci_read_config_2(sc, VIRTIO_PCI_QUEUE_NUM);
1113 
1114 	error = virtqueue_reinit(vq, size);
1115 	if (error)
1116 		return (error);
1117 
1118 	vtpci_write_config_4(sc, VIRTIO_PCI_QUEUE_PFN,
1119 	    virtqueue_paddr(vq) >> VIRTIO_PCI_QUEUE_ADDR_SHIFT);
1120 
1121 	return (0);
1122 }
1123 
1124 static void
1125 vtpci_free_interrupt(struct vtpci_softc *sc, struct vtpci_interrupt *intr)
1126 {
1127 	device_t dev;
1128 
1129 	dev = sc->vtpci_dev;
1130 
1131 	if (intr->vti_handler != NULL) {
1132 		bus_teardown_intr(dev, intr->vti_irq, intr->vti_handler);
1133 		intr->vti_handler = NULL;
1134 	}
1135 
1136 	if (intr->vti_irq != NULL) {
1137 		bus_release_resource(dev, SYS_RES_IRQ, intr->vti_rid,
1138 		    intr->vti_irq);
1139 		intr->vti_irq = NULL;
1140 		intr->vti_rid = -1;
1141 	}
1142 }
1143 
1144 static void
1145 vtpci_free_interrupts(struct vtpci_softc *sc)
1146 {
1147 	struct vtpci_interrupt *intr;
1148 	int i, nvq_intrs;
1149 
1150 	vtpci_free_interrupt(sc, &sc->vtpci_device_interrupt);
1151 
1152 	if (sc->vtpci_nmsix_resources != 0) {
1153 		nvq_intrs = sc->vtpci_nmsix_resources - 1;
1154 		sc->vtpci_nmsix_resources = 0;
1155 
1156 		intr = sc->vtpci_msix_vq_interrupts;
1157 		if (intr != NULL) {
1158 			for (i = 0; i < nvq_intrs; i++, intr++)
1159 				vtpci_free_interrupt(sc, intr);
1160 
1161 			free(sc->vtpci_msix_vq_interrupts, M_DEVBUF);
1162 			sc->vtpci_msix_vq_interrupts = NULL;
1163 		}
1164 	}
1165 
1166 	if (sc->vtpci_flags & (VTPCI_FLAG_MSI | VTPCI_FLAG_MSIX))
1167 		pci_release_msi(sc->vtpci_dev);
1168 
1169 	sc->vtpci_flags &= ~VTPCI_FLAG_ITYPE_MASK;
1170 }
1171 
1172 static void
1173 vtpci_free_virtqueues(struct vtpci_softc *sc)
1174 {
1175 	struct vtpci_virtqueue *vqx;
1176 	int idx;
1177 
1178 	for (idx = 0; idx < sc->vtpci_nvqs; idx++) {
1179 		vqx = &sc->vtpci_vqs[idx];
1180 
1181 		vtpci_select_virtqueue(sc, idx);
1182 		vtpci_write_config_4(sc, VIRTIO_PCI_QUEUE_PFN, 0);
1183 
1184 		virtqueue_free(vqx->vtv_vq);
1185 		vqx->vtv_vq = NULL;
1186 	}
1187 
1188 	free(sc->vtpci_vqs, M_DEVBUF);
1189 	sc->vtpci_vqs = NULL;
1190 	sc->vtpci_nvqs = 0;
1191 }
1192 
1193 static void
1194 vtpci_release_child_resources(struct vtpci_softc *sc)
1195 {
1196 
1197 	vtpci_free_interrupts(sc);
1198 	vtpci_free_virtqueues(sc);
1199 }
1200 
1201 static void
1202 vtpci_cleanup_setup_intr_attempt(struct vtpci_softc *sc)
1203 {
1204 	int idx;
1205 
1206 	if (sc->vtpci_flags & VTPCI_FLAG_MSIX) {
1207 		vtpci_write_config_2(sc, VIRTIO_MSI_CONFIG_VECTOR,
1208 		    VIRTIO_MSI_NO_VECTOR);
1209 
1210 		for (idx = 0; idx < sc->vtpci_nvqs; idx++) {
1211 			vtpci_select_virtqueue(sc, idx);
1212 			vtpci_write_config_2(sc, VIRTIO_MSI_QUEUE_VECTOR,
1213 			    VIRTIO_MSI_NO_VECTOR);
1214 		}
1215 	}
1216 
1217 	vtpci_free_interrupts(sc);
1218 }
1219 
1220 static void
1221 vtpci_reset(struct vtpci_softc *sc)
1222 {
1223 
1224 	/*
1225 	 * Setting the status to RESET sets the host device to
1226 	 * the original, uninitialized state.
1227 	 */
1228 	vtpci_set_status(sc->vtpci_dev, VIRTIO_CONFIG_STATUS_RESET);
1229 }
1230 
1231 static void
1232 vtpci_select_virtqueue(struct vtpci_softc *sc, int idx)
1233 {
1234 
1235 	vtpci_write_config_2(sc, VIRTIO_PCI_QUEUE_SEL, idx);
1236 }
1237 
1238 static void
1239 vtpci_legacy_intr(void *xsc)
1240 {
1241 	struct vtpci_softc *sc;
1242 	struct vtpci_virtqueue *vqx;
1243 	int i;
1244 	uint8_t isr;
1245 
1246 	sc = xsc;
1247 	vqx = &sc->vtpci_vqs[0];
1248 
1249 	/* Reading the ISR also clears it. */
1250 	isr = vtpci_read_config_1(sc, VIRTIO_PCI_ISR);
1251 
1252 	if (isr & VIRTIO_PCI_ISR_CONFIG)
1253 		vtpci_config_intr(sc);
1254 
1255 	if (isr & VIRTIO_PCI_ISR_INTR) {
1256 		for (i = 0; i < sc->vtpci_nvqs; i++, vqx++) {
1257 			if (vqx->vtv_no_intr == 0)
1258 				virtqueue_intr(vqx->vtv_vq);
1259 		}
1260 	}
1261 }
1262 
1263 static int
1264 vtpci_vq_shared_intr_filter(void *xsc)
1265 {
1266 	struct vtpci_softc *sc;
1267 	struct vtpci_virtqueue *vqx;
1268 	int i, rc;
1269 
1270 	rc = 0;
1271 	sc = xsc;
1272 	vqx = &sc->vtpci_vqs[0];
1273 
1274 	for (i = 0; i < sc->vtpci_nvqs; i++, vqx++) {
1275 		if (vqx->vtv_no_intr == 0)
1276 			rc |= virtqueue_intr_filter(vqx->vtv_vq);
1277 	}
1278 
1279 	return (rc ? FILTER_SCHEDULE_THREAD : FILTER_STRAY);
1280 }
1281 
1282 static void
1283 vtpci_vq_shared_intr(void *xsc)
1284 {
1285 	struct vtpci_softc *sc;
1286 	struct vtpci_virtqueue *vqx;
1287 	int i;
1288 
1289 	sc = xsc;
1290 	vqx = &sc->vtpci_vqs[0];
1291 
1292 	for (i = 0; i < sc->vtpci_nvqs; i++, vqx++) {
1293 		if (vqx->vtv_no_intr == 0)
1294 			virtqueue_intr(vqx->vtv_vq);
1295 	}
1296 }
1297 
1298 static int
1299 vtpci_vq_intr_filter(void *xvq)
1300 {
1301 	struct virtqueue *vq;
1302 	int rc;
1303 
1304 	vq = xvq;
1305 	rc = virtqueue_intr_filter(vq);
1306 
1307 	return (rc ? FILTER_SCHEDULE_THREAD : FILTER_STRAY);
1308 }
1309 
1310 static void
1311 vtpci_vq_intr(void *xvq)
1312 {
1313 	struct virtqueue *vq;
1314 
1315 	vq = xvq;
1316 	virtqueue_intr(vq);
1317 }
1318 
1319 static void
1320 vtpci_config_intr(void *xsc)
1321 {
1322 	struct vtpci_softc *sc;
1323 	device_t child;
1324 
1325 	sc = xsc;
1326 	child = sc->vtpci_child_dev;
1327 
1328 	if (child != NULL)
1329 		VIRTIO_CONFIG_CHANGE(child);
1330 }
1331