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 VirtIO memory balloon devices. */
28 
29 #include <sys/cdefs.h>
30 __FBSDID("$FreeBSD$");
31 
32 #include <sys/param.h>
33 #include <sys/systm.h>
34 #include <sys/kernel.h>
35 #include <sys/endian.h>
36 #include <sys/kthread.h>
37 #include <sys/malloc.h>
38 #include <sys/module.h>
39 #include <sys/sglist.h>
40 #include <sys/sysctl.h>
41 #include <sys/lock.h>
42 #include <sys/mutex.h>
43 #include <sys/queue.h>
44 
45 #include <vm/vm.h>
46 #include <vm/vm_page.h>
47 
48 #include <machine/bus.h>
49 #include <machine/resource.h>
50 #include <sys/bus.h>
51 #include <sys/rman.h>
52 
53 #include <dev/virtio/virtio.h>
54 #include <dev/virtio/virtqueue.h>
55 #include <dev/virtio/balloon/virtio_balloon.h>
56 
57 #include "virtio_if.h"
58 
59 struct vtballoon_softc {
60 	device_t		 vtballoon_dev;
61 	struct mtx		 vtballoon_mtx;
62 	uint64_t		 vtballoon_features;
63 	uint32_t		 vtballoon_flags;
64 #define VTBALLOON_FLAG_DETACH	 0x01
65 
66 	struct virtqueue	*vtballoon_inflate_vq;
67 	struct virtqueue	*vtballoon_deflate_vq;
68 
69 	uint32_t		 vtballoon_desired_npages;
70 	uint32_t		 vtballoon_current_npages;
71 	TAILQ_HEAD(,vm_page)	 vtballoon_pages;
72 
73 	struct thread		*vtballoon_td;
74 	uint32_t		*vtballoon_page_frames;
75 	int			 vtballoon_timeout;
76 };
77 
78 static struct virtio_feature_desc vtballoon_feature_desc[] = {
79 	{ VIRTIO_BALLOON_F_MUST_TELL_HOST,	"MustTellHost"	},
80 	{ VIRTIO_BALLOON_F_STATS_VQ,		"StatsVq"	},
81 
82 	{ 0, NULL }
83 };
84 
85 static int	vtballoon_probe(device_t);
86 static int	vtballoon_attach(device_t);
87 static int	vtballoon_detach(device_t);
88 static int	vtballoon_config_change(device_t);
89 
90 static void	vtballoon_negotiate_features(struct vtballoon_softc *);
91 static int	vtballoon_alloc_virtqueues(struct vtballoon_softc *);
92 
93 static void	vtballoon_vq_intr(void *);
94 
95 static void	vtballoon_inflate(struct vtballoon_softc *, int);
96 static void	vtballoon_deflate(struct vtballoon_softc *, int);
97 
98 static void	vtballoon_send_page_frames(struct vtballoon_softc *,
99 		    struct virtqueue *, int);
100 
101 static void	vtballoon_pop(struct vtballoon_softc *);
102 static void	vtballoon_stop(struct vtballoon_softc *);
103 
104 static vm_page_t
105 		vtballoon_alloc_page(struct vtballoon_softc *);
106 static void	vtballoon_free_page(struct vtballoon_softc *, vm_page_t);
107 
108 static int	vtballoon_sleep(struct vtballoon_softc *);
109 static void	vtballoon_thread(void *);
110 static void	vtballoon_add_sysctl(struct vtballoon_softc *);
111 
112 /* Features desired/implemented by this driver. */
113 #define VTBALLOON_FEATURES		0
114 
115 /* Timeout between retries when the balloon needs inflating. */
116 #define VTBALLOON_LOWMEM_TIMEOUT	hz
117 
118 /*
119  * Maximum number of pages we'll request to inflate or deflate
120  * the balloon in one virtqueue request. Both Linux and NetBSD
121  * have settled on 256, doing up to 1MB at a time.
122  */
123 #define VTBALLOON_PAGES_PER_REQUEST	256
124 
125 /* Must be able to fix all pages frames in one page (segment). */
126 CTASSERT(VTBALLOON_PAGES_PER_REQUEST * sizeof(uint32_t) <= PAGE_SIZE);
127 
128 #define VTBALLOON_MTX(_sc)		&(_sc)->vtballoon_mtx
129 #define VTBALLOON_LOCK_INIT(_sc, _name)	mtx_init(VTBALLOON_MTX((_sc)), _name, \
130 					    "VirtIO Balloon Lock", MTX_DEF)
131 #define VTBALLOON_LOCK(_sc)		mtx_lock(VTBALLOON_MTX((_sc)))
132 #define VTBALLOON_UNLOCK(_sc)		mtx_unlock(VTBALLOON_MTX((_sc)))
133 #define VTBALLOON_LOCK_DESTROY(_sc)	mtx_destroy(VTBALLOON_MTX((_sc)))
134 
135 static device_method_t vtballoon_methods[] = {
136 	/* Device methods. */
137 	DEVMETHOD(device_probe,		vtballoon_probe),
138 	DEVMETHOD(device_attach,	vtballoon_attach),
139 	DEVMETHOD(device_detach,	vtballoon_detach),
140 
141 	/* VirtIO methods. */
142 	DEVMETHOD(virtio_config_change, vtballoon_config_change),
143 
144 	DEVMETHOD_END
145 };
146 
147 static driver_t vtballoon_driver = {
148 	"vtballoon",
149 	vtballoon_methods,
150 	sizeof(struct vtballoon_softc)
151 };
152 static devclass_t vtballoon_devclass;
153 
154 DRIVER_MODULE(virtio_balloon, virtio_pci, vtballoon_driver,
155     vtballoon_devclass, 0, 0);
156 MODULE_VERSION(virtio_balloon, 1);
157 MODULE_DEPEND(virtio_balloon, virtio, 1, 1, 1);
158 
159 static int
160 vtballoon_probe(device_t dev)
161 {
162 
163 	if (virtio_get_device_type(dev) != VIRTIO_ID_BALLOON)
164 		return (ENXIO);
165 
166 	device_set_desc(dev, "VirtIO Balloon Adapter");
167 
168 	return (BUS_PROBE_DEFAULT);
169 }
170 
171 static int
172 vtballoon_attach(device_t dev)
173 {
174 	struct vtballoon_softc *sc;
175 	int error;
176 
177 	sc = device_get_softc(dev);
178 	sc->vtballoon_dev = dev;
179 
180 	VTBALLOON_LOCK_INIT(sc, device_get_nameunit(dev));
181 	TAILQ_INIT(&sc->vtballoon_pages);
182 
183 	vtballoon_add_sysctl(sc);
184 
185 	virtio_set_feature_desc(dev, vtballoon_feature_desc);
186 	vtballoon_negotiate_features(sc);
187 
188 	sc->vtballoon_page_frames = malloc(VTBALLOON_PAGES_PER_REQUEST *
189 	    sizeof(uint32_t), M_DEVBUF, M_NOWAIT | M_ZERO);
190 	if (sc->vtballoon_page_frames == NULL) {
191 		error = ENOMEM;
192 		device_printf(dev,
193 		    "cannot allocate page frame request array\n");
194 		goto fail;
195 	}
196 
197 	error = vtballoon_alloc_virtqueues(sc);
198 	if (error) {
199 		device_printf(dev, "cannot allocate virtqueues\n");
200 		goto fail;
201 	}
202 
203 	error = virtio_setup_intr(dev, INTR_TYPE_MISC);
204 	if (error) {
205 		device_printf(dev, "cannot setup virtqueue interrupts\n");
206 		goto fail;
207 	}
208 
209 	error = kthread_add(vtballoon_thread, sc, NULL, &sc->vtballoon_td,
210 	    0, 0, "virtio_balloon");
211 	if (error) {
212 		device_printf(dev, "cannot create balloon kthread\n");
213 		goto fail;
214 	}
215 
216 	virtqueue_enable_intr(sc->vtballoon_inflate_vq);
217 	virtqueue_enable_intr(sc->vtballoon_deflate_vq);
218 
219 fail:
220 	if (error)
221 		vtballoon_detach(dev);
222 
223 	return (error);
224 }
225 
226 static int
227 vtballoon_detach(device_t dev)
228 {
229 	struct vtballoon_softc *sc;
230 
231 	sc = device_get_softc(dev);
232 
233 	if (sc->vtballoon_td != NULL) {
234 		VTBALLOON_LOCK(sc);
235 		sc->vtballoon_flags |= VTBALLOON_FLAG_DETACH;
236 		wakeup_one(sc);
237 		msleep(sc->vtballoon_td, VTBALLOON_MTX(sc), 0, "vtbdth", 0);
238 		VTBALLOON_UNLOCK(sc);
239 
240 		sc->vtballoon_td = NULL;
241 	}
242 
243 	if (device_is_attached(dev)) {
244 		vtballoon_pop(sc);
245 		vtballoon_stop(sc);
246 	}
247 
248 	if (sc->vtballoon_page_frames != NULL) {
249 		free(sc->vtballoon_page_frames, M_DEVBUF);
250 		sc->vtballoon_page_frames = NULL;
251 	}
252 
253 	VTBALLOON_LOCK_DESTROY(sc);
254 
255 	return (0);
256 }
257 
258 static int
259 vtballoon_config_change(device_t dev)
260 {
261 	struct vtballoon_softc *sc;
262 
263 	sc = device_get_softc(dev);
264 
265 	VTBALLOON_LOCK(sc);
266 	wakeup_one(sc);
267 	VTBALLOON_UNLOCK(sc);
268 
269 	return (1);
270 }
271 
272 static void
273 vtballoon_negotiate_features(struct vtballoon_softc *sc)
274 {
275 	device_t dev;
276 	uint64_t features;
277 
278 	dev = sc->vtballoon_dev;
279 	features = virtio_negotiate_features(dev, VTBALLOON_FEATURES);
280 	sc->vtballoon_features = features;
281 }
282 
283 static int
284 vtballoon_alloc_virtqueues(struct vtballoon_softc *sc)
285 {
286 	device_t dev;
287 	struct vq_alloc_info vq_info[2];
288 	int nvqs;
289 
290 	dev = sc->vtballoon_dev;
291 	nvqs = 2;
292 
293 	VQ_ALLOC_INFO_INIT(&vq_info[0], 0, vtballoon_vq_intr, sc,
294 	    &sc->vtballoon_inflate_vq, "%s inflate", device_get_nameunit(dev));
295 
296 	VQ_ALLOC_INFO_INIT(&vq_info[1], 0, vtballoon_vq_intr, sc,
297 	    &sc->vtballoon_deflate_vq, "%s deflate", device_get_nameunit(dev));
298 
299 	return (virtio_alloc_virtqueues(dev, 0, nvqs, vq_info));
300 }
301 
302 static void
303 vtballoon_vq_intr(void *xsc)
304 {
305 	struct vtballoon_softc *sc;
306 
307 	sc = xsc;
308 
309 	VTBALLOON_LOCK(sc);
310 	wakeup_one(sc);
311 	VTBALLOON_UNLOCK(sc);
312 }
313 
314 static void
315 vtballoon_inflate(struct vtballoon_softc *sc, int npages)
316 {
317 	struct virtqueue *vq;
318 	vm_page_t m;
319 	int i;
320 
321 	vq = sc->vtballoon_inflate_vq;
322 
323 	if (npages > VTBALLOON_PAGES_PER_REQUEST)
324 		npages = VTBALLOON_PAGES_PER_REQUEST;
325 
326 	for (i = 0; i < npages; i++) {
327 		if ((m = vtballoon_alloc_page(sc)) == NULL) {
328 			sc->vtballoon_timeout = VTBALLOON_LOWMEM_TIMEOUT;
329 			break;
330 		}
331 
332 		sc->vtballoon_page_frames[i] =
333 		    VM_PAGE_TO_PHYS(m) >> VIRTIO_BALLOON_PFN_SHIFT;
334 
335 		KASSERT(m->queue == PQ_NONE,
336 		    ("%s: allocated page %p on queue", __func__, m));
337 		TAILQ_INSERT_TAIL(&sc->vtballoon_pages, m, plinks.q);
338 	}
339 
340 	if (i > 0)
341 		vtballoon_send_page_frames(sc, vq, i);
342 }
343 
344 static void
345 vtballoon_deflate(struct vtballoon_softc *sc, int npages)
346 {
347 	TAILQ_HEAD(, vm_page) free_pages;
348 	struct virtqueue *vq;
349 	vm_page_t m;
350 	int i;
351 
352 	vq = sc->vtballoon_deflate_vq;
353 	TAILQ_INIT(&free_pages);
354 
355 	if (npages > VTBALLOON_PAGES_PER_REQUEST)
356 		npages = VTBALLOON_PAGES_PER_REQUEST;
357 
358 	for (i = 0; i < npages; i++) {
359 		m = TAILQ_FIRST(&sc->vtballoon_pages);
360 		KASSERT(m != NULL, ("%s: no more pages to deflate", __func__));
361 
362 		sc->vtballoon_page_frames[i] =
363 		    VM_PAGE_TO_PHYS(m) >> VIRTIO_BALLOON_PFN_SHIFT;
364 
365 		TAILQ_REMOVE(&sc->vtballoon_pages, m, plinks.q);
366 		TAILQ_INSERT_TAIL(&free_pages, m, plinks.q);
367 	}
368 
369 	if (i > 0) {
370 		/* Always tell host first before freeing the pages. */
371 		vtballoon_send_page_frames(sc, vq, i);
372 
373 		while ((m = TAILQ_FIRST(&free_pages)) != NULL) {
374 			TAILQ_REMOVE(&free_pages, m, plinks.q);
375 			vtballoon_free_page(sc, m);
376 		}
377 	}
378 
379 	KASSERT((TAILQ_EMPTY(&sc->vtballoon_pages) &&
380 	    sc->vtballoon_current_npages == 0) ||
381 	    (!TAILQ_EMPTY(&sc->vtballoon_pages) &&
382 	    sc->vtballoon_current_npages != 0),
383 	    ("%s: bogus page count %d", __func__,
384 	    sc->vtballoon_current_npages));
385 }
386 
387 static void
388 vtballoon_send_page_frames(struct vtballoon_softc *sc, struct virtqueue *vq,
389     int npages)
390 {
391 	struct sglist sg;
392 	struct sglist_seg segs[1];
393 	void *c;
394 	int error;
395 
396 	sglist_init(&sg, 1, segs);
397 
398 	error = sglist_append(&sg, sc->vtballoon_page_frames,
399 	    npages * sizeof(uint32_t));
400 	KASSERT(error == 0, ("error adding page frames to sglist"));
401 
402 	error = virtqueue_enqueue(vq, vq, &sg, 1, 0);
403 	KASSERT(error == 0, ("error enqueuing page frames to virtqueue"));
404 	virtqueue_notify(vq);
405 
406 	/*
407 	 * Inflate and deflate operations are done synchronously. The
408 	 * interrupt handler will wake us up.
409 	 */
410 	VTBALLOON_LOCK(sc);
411 	while ((c = virtqueue_dequeue(vq, NULL)) == NULL)
412 		msleep(sc, VTBALLOON_MTX(sc), 0, "vtbspf", 0);
413 	VTBALLOON_UNLOCK(sc);
414 
415 	KASSERT(c == vq, ("unexpected balloon operation response"));
416 }
417 
418 static void
419 vtballoon_pop(struct vtballoon_softc *sc)
420 {
421 
422 	while (!TAILQ_EMPTY(&sc->vtballoon_pages))
423 		vtballoon_deflate(sc, sc->vtballoon_current_npages);
424 }
425 
426 static void
427 vtballoon_stop(struct vtballoon_softc *sc)
428 {
429 
430 	virtqueue_disable_intr(sc->vtballoon_inflate_vq);
431 	virtqueue_disable_intr(sc->vtballoon_deflate_vq);
432 
433 	virtio_stop(sc->vtballoon_dev);
434 }
435 
436 static vm_page_t
437 vtballoon_alloc_page(struct vtballoon_softc *sc)
438 {
439 	vm_page_t m;
440 
441 	m = vm_page_alloc(NULL, 0, VM_ALLOC_NORMAL | VM_ALLOC_NOOBJ);
442 	if (m != NULL)
443 		sc->vtballoon_current_npages++;
444 
445 	return (m);
446 }
447 
448 static void
449 vtballoon_free_page(struct vtballoon_softc *sc, vm_page_t m)
450 {
451 
452 	vm_page_free(m);
453 	sc->vtballoon_current_npages--;
454 }
455 
456 static uint32_t
457 vtballoon_desired_size(struct vtballoon_softc *sc)
458 {
459 	uint32_t desired;
460 
461 	desired = virtio_read_dev_config_4(sc->vtballoon_dev,
462 	    offsetof(struct virtio_balloon_config, num_pages));
463 
464 	return (le32toh(desired));
465 }
466 
467 static void
468 vtballoon_update_size(struct vtballoon_softc *sc)
469 {
470 
471 	virtio_write_dev_config_4(sc->vtballoon_dev,
472 	    offsetof(struct virtio_balloon_config, actual),
473 	    htole32(sc->vtballoon_current_npages));
474 }
475 
476 static int
477 vtballoon_sleep(struct vtballoon_softc *sc)
478 {
479 	int rc, timeout;
480 	uint32_t current, desired;
481 
482 	rc = 0;
483 	current = sc->vtballoon_current_npages;
484 
485 	VTBALLOON_LOCK(sc);
486 	for (;;) {
487 		if (sc->vtballoon_flags & VTBALLOON_FLAG_DETACH) {
488 			rc = 1;
489 			break;
490 		}
491 
492 		desired = vtballoon_desired_size(sc);
493 		sc->vtballoon_desired_npages = desired;
494 
495 		/*
496 		 * If given, use non-zero timeout on the first time through
497 		 * the loop. On subsequent times, timeout will be zero so
498 		 * we will reevaluate the desired size of the balloon and
499 		 * break out to retry if needed.
500 		 */
501 		timeout = sc->vtballoon_timeout;
502 		sc->vtballoon_timeout = 0;
503 
504 		if (current > desired)
505 			break;
506 		if (current < desired && timeout == 0)
507 			break;
508 
509 		msleep(sc, VTBALLOON_MTX(sc), 0, "vtbslp", timeout);
510 	}
511 	VTBALLOON_UNLOCK(sc);
512 
513 	return (rc);
514 }
515 
516 static void
517 vtballoon_thread(void *xsc)
518 {
519 	struct vtballoon_softc *sc;
520 	uint32_t current, desired;
521 
522 	sc = xsc;
523 
524 	for (;;) {
525 		if (vtballoon_sleep(sc) != 0)
526 			break;
527 
528 		current = sc->vtballoon_current_npages;
529 		desired = sc->vtballoon_desired_npages;
530 
531 		if (desired != current) {
532 			if (desired > current)
533 				vtballoon_inflate(sc, desired - current);
534 			else
535 				vtballoon_deflate(sc, current - desired);
536 
537 			vtballoon_update_size(sc);
538 		}
539 	}
540 
541 	kthread_exit();
542 }
543 
544 static void
545 vtballoon_add_sysctl(struct vtballoon_softc *sc)
546 {
547 	device_t dev;
548 	struct sysctl_ctx_list *ctx;
549 	struct sysctl_oid *tree;
550 	struct sysctl_oid_list *child;
551 
552 	dev = sc->vtballoon_dev;
553 	ctx = device_get_sysctl_ctx(dev);
554 	tree = device_get_sysctl_tree(dev);
555 	child = SYSCTL_CHILDREN(tree);
556 
557 	SYSCTL_ADD_UINT(ctx, child, OID_AUTO, "desired",
558 	    CTLFLAG_RD, &sc->vtballoon_desired_npages, sizeof(uint32_t),
559 	    "Desired balloon size in pages");
560 
561 	SYSCTL_ADD_UINT(ctx, child, OID_AUTO, "current",
562 	    CTLFLAG_RD, &sc->vtballoon_current_npages, sizeof(uint32_t),
563 	    "Current balloon size in pages");
564 }
565