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 VirtIO memory balloon devices. */
30 
31 #include <sys/cdefs.h>
32 __FBSDID("$FreeBSD$");
33 
34 #include <sys/param.h>
35 #include <sys/systm.h>
36 #include <sys/kernel.h>
37 #include <sys/endian.h>
38 #include <sys/kthread.h>
39 #include <sys/malloc.h>
40 #include <sys/module.h>
41 #include <sys/sglist.h>
42 #include <sys/sysctl.h>
43 #include <sys/lock.h>
44 #include <sys/mutex.h>
45 #include <sys/queue.h>
46 
47 #include <vm/vm.h>
48 #include <vm/vm_page.h>
49 
50 #include <machine/bus.h>
51 #include <machine/resource.h>
52 #include <sys/bus.h>
53 #include <sys/rman.h>
54 
55 #include <dev/virtio/virtio.h>
56 #include <dev/virtio/virtqueue.h>
57 #include <dev/virtio/balloon/virtio_balloon.h>
58 
59 #include "virtio_if.h"
60 
61 struct vtballoon_softc {
62 	device_t		 vtballoon_dev;
63 	struct mtx		 vtballoon_mtx;
64 	uint64_t		 vtballoon_features;
65 	uint32_t		 vtballoon_flags;
66 #define VTBALLOON_FLAG_DETACH	 0x01
67 
68 	struct virtqueue	*vtballoon_inflate_vq;
69 	struct virtqueue	*vtballoon_deflate_vq;
70 
71 	uint32_t		 vtballoon_desired_npages;
72 	uint32_t		 vtballoon_current_npages;
73 	TAILQ_HEAD(,vm_page)	 vtballoon_pages;
74 
75 	struct thread		*vtballoon_td;
76 	uint32_t		*vtballoon_page_frames;
77 	int			 vtballoon_timeout;
78 };
79 
80 static struct virtio_feature_desc vtballoon_feature_desc[] = {
81 	{ VIRTIO_BALLOON_F_MUST_TELL_HOST,	"MustTellHost"	},
82 	{ VIRTIO_BALLOON_F_STATS_VQ,		"StatsVq"	},
83 	{ VIRTIO_BALLOON_F_DEFLATE_ON_OOM,	"DeflateOnOOM"	},
84 
85 	{ 0, NULL }
86 };
87 
88 static int	vtballoon_probe(device_t);
89 static int	vtballoon_attach(device_t);
90 static int	vtballoon_detach(device_t);
91 static int	vtballoon_config_change(device_t);
92 
93 static int	vtballoon_negotiate_features(struct vtballoon_softc *);
94 static int	vtballoon_setup_features(struct vtballoon_softc *);
95 static int	vtballoon_alloc_virtqueues(struct vtballoon_softc *);
96 
97 static void	vtballoon_vq_intr(void *);
98 
99 static void	vtballoon_inflate(struct vtballoon_softc *, int);
100 static void	vtballoon_deflate(struct vtballoon_softc *, int);
101 
102 static void	vtballoon_send_page_frames(struct vtballoon_softc *,
103 		    struct virtqueue *, int);
104 
105 static void	vtballoon_pop(struct vtballoon_softc *);
106 static void	vtballoon_stop(struct vtballoon_softc *);
107 
108 static vm_page_t
109 		vtballoon_alloc_page(struct vtballoon_softc *);
110 static void	vtballoon_free_page(struct vtballoon_softc *, vm_page_t);
111 
112 static int	vtballoon_sleep(struct vtballoon_softc *);
113 static void	vtballoon_thread(void *);
114 static void	vtballoon_setup_sysctl(struct vtballoon_softc *);
115 
116 #define vtballoon_modern(_sc) \
117     (((_sc)->vtballoon_features & VIRTIO_F_VERSION_1) != 0)
118 
119 /* Features desired/implemented by this driver. */
120 #define VTBALLOON_FEATURES		VIRTIO_BALLOON_F_MUST_TELL_HOST
121 
122 /* Timeout between retries when the balloon needs inflating. */
123 #define VTBALLOON_LOWMEM_TIMEOUT	hz
124 
125 /*
126  * Maximum number of pages we'll request to inflate or deflate
127  * the balloon in one virtqueue request. Both Linux and NetBSD
128  * have settled on 256, doing up to 1MB at a time.
129  */
130 #define VTBALLOON_PAGES_PER_REQUEST	256
131 
132 /* Must be able to fix all pages frames in one page (segment). */
133 CTASSERT(VTBALLOON_PAGES_PER_REQUEST * sizeof(uint32_t) <= PAGE_SIZE);
134 
135 #define VTBALLOON_MTX(_sc)		&(_sc)->vtballoon_mtx
136 #define VTBALLOON_LOCK_INIT(_sc, _name)	mtx_init(VTBALLOON_MTX((_sc)), _name, \
137 					    "VirtIO Balloon Lock", MTX_DEF)
138 #define VTBALLOON_LOCK(_sc)		mtx_lock(VTBALLOON_MTX((_sc)))
139 #define VTBALLOON_UNLOCK(_sc)		mtx_unlock(VTBALLOON_MTX((_sc)))
140 #define VTBALLOON_LOCK_DESTROY(_sc)	mtx_destroy(VTBALLOON_MTX((_sc)))
141 
142 static device_method_t vtballoon_methods[] = {
143 	/* Device methods. */
144 	DEVMETHOD(device_probe,		vtballoon_probe),
145 	DEVMETHOD(device_attach,	vtballoon_attach),
146 	DEVMETHOD(device_detach,	vtballoon_detach),
147 
148 	/* VirtIO methods. */
149 	DEVMETHOD(virtio_config_change, vtballoon_config_change),
150 
151 	DEVMETHOD_END
152 };
153 
154 static driver_t vtballoon_driver = {
155 	"vtballoon",
156 	vtballoon_methods,
157 	sizeof(struct vtballoon_softc)
158 };
159 static devclass_t vtballoon_devclass;
160 
161 VIRTIO_DRIVER_MODULE(virtio_balloon, vtballoon_driver,
162     vtballoon_devclass, 0, 0);
163 MODULE_VERSION(virtio_balloon, 1);
164 MODULE_DEPEND(virtio_balloon, virtio, 1, 1, 1);
165 
166 VIRTIO_SIMPLE_PNPINFO(virtio_balloon, VIRTIO_ID_BALLOON,
167     "VirtIO Balloon Adapter");
168 
169 static int
170 vtballoon_probe(device_t dev)
171 {
172 	return (VIRTIO_SIMPLE_PROBE(dev, virtio_balloon));
173 }
174 
175 static int
176 vtballoon_attach(device_t dev)
177 {
178 	struct vtballoon_softc *sc;
179 	int error;
180 
181 	sc = device_get_softc(dev);
182 	sc->vtballoon_dev = dev;
183 	virtio_set_feature_desc(dev, vtballoon_feature_desc);
184 
185 	VTBALLOON_LOCK_INIT(sc, device_get_nameunit(dev));
186 	TAILQ_INIT(&sc->vtballoon_pages);
187 
188 	vtballoon_setup_sysctl(sc);
189 
190 	error = vtballoon_setup_features(sc);
191 	if (error) {
192 		device_printf(dev, "cannot setup features\n");
193 		goto fail;
194 	}
195 
196 	sc->vtballoon_page_frames = malloc(VTBALLOON_PAGES_PER_REQUEST *
197 	    sizeof(uint32_t), M_DEVBUF, M_NOWAIT | M_ZERO);
198 	if (sc->vtballoon_page_frames == NULL) {
199 		error = ENOMEM;
200 		device_printf(dev,
201 		    "cannot allocate page frame request array\n");
202 		goto fail;
203 	}
204 
205 	error = vtballoon_alloc_virtqueues(sc);
206 	if (error) {
207 		device_printf(dev, "cannot allocate virtqueues\n");
208 		goto fail;
209 	}
210 
211 	error = virtio_setup_intr(dev, INTR_TYPE_MISC);
212 	if (error) {
213 		device_printf(dev, "cannot setup virtqueue interrupts\n");
214 		goto fail;
215 	}
216 
217 	error = kthread_add(vtballoon_thread, sc, NULL, &sc->vtballoon_td,
218 	    0, 0, "virtio_balloon");
219 	if (error) {
220 		device_printf(dev, "cannot create balloon kthread\n");
221 		goto fail;
222 	}
223 
224 	virtqueue_enable_intr(sc->vtballoon_inflate_vq);
225 	virtqueue_enable_intr(sc->vtballoon_deflate_vq);
226 
227 fail:
228 	if (error)
229 		vtballoon_detach(dev);
230 
231 	return (error);
232 }
233 
234 static int
235 vtballoon_detach(device_t dev)
236 {
237 	struct vtballoon_softc *sc;
238 
239 	sc = device_get_softc(dev);
240 
241 	if (sc->vtballoon_td != NULL) {
242 		VTBALLOON_LOCK(sc);
243 		sc->vtballoon_flags |= VTBALLOON_FLAG_DETACH;
244 		wakeup_one(sc);
245 		msleep(sc->vtballoon_td, VTBALLOON_MTX(sc), 0, "vtbdth", 0);
246 		VTBALLOON_UNLOCK(sc);
247 
248 		sc->vtballoon_td = NULL;
249 	}
250 
251 	if (device_is_attached(dev)) {
252 		vtballoon_pop(sc);
253 		vtballoon_stop(sc);
254 	}
255 
256 	if (sc->vtballoon_page_frames != NULL) {
257 		free(sc->vtballoon_page_frames, M_DEVBUF);
258 		sc->vtballoon_page_frames = NULL;
259 	}
260 
261 	VTBALLOON_LOCK_DESTROY(sc);
262 
263 	return (0);
264 }
265 
266 static int
267 vtballoon_config_change(device_t dev)
268 {
269 	struct vtballoon_softc *sc;
270 
271 	sc = device_get_softc(dev);
272 
273 	VTBALLOON_LOCK(sc);
274 	wakeup_one(sc);
275 	VTBALLOON_UNLOCK(sc);
276 
277 	return (1);
278 }
279 
280 static int
281 vtballoon_negotiate_features(struct vtballoon_softc *sc)
282 {
283 	device_t dev;
284 	uint64_t features;
285 
286 	dev = sc->vtballoon_dev;
287 	features = VTBALLOON_FEATURES;
288 
289 	sc->vtballoon_features = virtio_negotiate_features(dev, features);
290 	return (virtio_finalize_features(dev));
291 }
292 
293 static int
294 vtballoon_setup_features(struct vtballoon_softc *sc)
295 {
296 	int error;
297 
298 	error = vtballoon_negotiate_features(sc);
299 	if (error)
300 		return (error);
301 
302 	return (0);
303 }
304 
305 static int
306 vtballoon_alloc_virtqueues(struct vtballoon_softc *sc)
307 {
308 	device_t dev;
309 	struct vq_alloc_info vq_info[2];
310 	int nvqs;
311 
312 	dev = sc->vtballoon_dev;
313 	nvqs = 2;
314 
315 	VQ_ALLOC_INFO_INIT(&vq_info[0], 0, vtballoon_vq_intr, sc,
316 	    &sc->vtballoon_inflate_vq, "%s inflate", device_get_nameunit(dev));
317 
318 	VQ_ALLOC_INFO_INIT(&vq_info[1], 0, vtballoon_vq_intr, sc,
319 	    &sc->vtballoon_deflate_vq, "%s deflate", device_get_nameunit(dev));
320 
321 	return (virtio_alloc_virtqueues(dev, 0, nvqs, vq_info));
322 }
323 
324 static void
325 vtballoon_vq_intr(void *xsc)
326 {
327 	struct vtballoon_softc *sc;
328 
329 	sc = xsc;
330 
331 	VTBALLOON_LOCK(sc);
332 	wakeup_one(sc);
333 	VTBALLOON_UNLOCK(sc);
334 }
335 
336 static void
337 vtballoon_inflate(struct vtballoon_softc *sc, int npages)
338 {
339 	struct virtqueue *vq;
340 	vm_page_t m;
341 	int i;
342 
343 	vq = sc->vtballoon_inflate_vq;
344 
345 	if (npages > VTBALLOON_PAGES_PER_REQUEST)
346 		npages = VTBALLOON_PAGES_PER_REQUEST;
347 
348 	for (i = 0; i < npages; i++) {
349 		if ((m = vtballoon_alloc_page(sc)) == NULL) {
350 			sc->vtballoon_timeout = VTBALLOON_LOWMEM_TIMEOUT;
351 			break;
352 		}
353 
354 		sc->vtballoon_page_frames[i] =
355 		    VM_PAGE_TO_PHYS(m) >> VIRTIO_BALLOON_PFN_SHIFT;
356 
357 		KASSERT(m->a.queue == PQ_NONE,
358 		    ("%s: allocated page %p on queue", __func__, m));
359 		TAILQ_INSERT_TAIL(&sc->vtballoon_pages, m, plinks.q);
360 	}
361 
362 	if (i > 0)
363 		vtballoon_send_page_frames(sc, vq, i);
364 }
365 
366 static void
367 vtballoon_deflate(struct vtballoon_softc *sc, int npages)
368 {
369 	TAILQ_HEAD(, vm_page) free_pages;
370 	struct virtqueue *vq;
371 	vm_page_t m;
372 	int i;
373 
374 	vq = sc->vtballoon_deflate_vq;
375 	TAILQ_INIT(&free_pages);
376 
377 	if (npages > VTBALLOON_PAGES_PER_REQUEST)
378 		npages = VTBALLOON_PAGES_PER_REQUEST;
379 
380 	for (i = 0; i < npages; i++) {
381 		m = TAILQ_FIRST(&sc->vtballoon_pages);
382 		KASSERT(m != NULL, ("%s: no more pages to deflate", __func__));
383 
384 		sc->vtballoon_page_frames[i] =
385 		    VM_PAGE_TO_PHYS(m) >> VIRTIO_BALLOON_PFN_SHIFT;
386 
387 		TAILQ_REMOVE(&sc->vtballoon_pages, m, plinks.q);
388 		TAILQ_INSERT_TAIL(&free_pages, m, plinks.q);
389 	}
390 
391 	if (i > 0) {
392 		/* Always tell host first before freeing the pages. */
393 		vtballoon_send_page_frames(sc, vq, i);
394 
395 		while ((m = TAILQ_FIRST(&free_pages)) != NULL) {
396 			TAILQ_REMOVE(&free_pages, m, plinks.q);
397 			vtballoon_free_page(sc, m);
398 		}
399 	}
400 
401 	KASSERT((TAILQ_EMPTY(&sc->vtballoon_pages) &&
402 	    sc->vtballoon_current_npages == 0) ||
403 	    (!TAILQ_EMPTY(&sc->vtballoon_pages) &&
404 	    sc->vtballoon_current_npages != 0),
405 	    ("%s: bogus page count %d", __func__,
406 	    sc->vtballoon_current_npages));
407 }
408 
409 static void
410 vtballoon_send_page_frames(struct vtballoon_softc *sc, struct virtqueue *vq,
411     int npages)
412 {
413 	struct sglist sg;
414 	struct sglist_seg segs[1];
415 	void *c;
416 	int error;
417 
418 	sglist_init(&sg, 1, segs);
419 
420 	error = sglist_append(&sg, sc->vtballoon_page_frames,
421 	    npages * sizeof(uint32_t));
422 	KASSERT(error == 0, ("error adding page frames to sglist"));
423 
424 	error = virtqueue_enqueue(vq, vq, &sg, 1, 0);
425 	KASSERT(error == 0, ("error enqueuing page frames to virtqueue"));
426 	virtqueue_notify(vq);
427 
428 	/*
429 	 * Inflate and deflate operations are done synchronously. The
430 	 * interrupt handler will wake us up.
431 	 */
432 	VTBALLOON_LOCK(sc);
433 	while ((c = virtqueue_dequeue(vq, NULL)) == NULL)
434 		msleep(sc, VTBALLOON_MTX(sc), 0, "vtbspf", 0);
435 	VTBALLOON_UNLOCK(sc);
436 
437 	KASSERT(c == vq, ("unexpected balloon operation response"));
438 }
439 
440 static void
441 vtballoon_pop(struct vtballoon_softc *sc)
442 {
443 
444 	while (!TAILQ_EMPTY(&sc->vtballoon_pages))
445 		vtballoon_deflate(sc, sc->vtballoon_current_npages);
446 }
447 
448 static void
449 vtballoon_stop(struct vtballoon_softc *sc)
450 {
451 
452 	virtqueue_disable_intr(sc->vtballoon_inflate_vq);
453 	virtqueue_disable_intr(sc->vtballoon_deflate_vq);
454 
455 	virtio_stop(sc->vtballoon_dev);
456 }
457 
458 static vm_page_t
459 vtballoon_alloc_page(struct vtballoon_softc *sc)
460 {
461 	vm_page_t m;
462 
463 	m = vm_page_alloc_noobj(VM_ALLOC_NODUMP);
464 	if (m != NULL)
465 		sc->vtballoon_current_npages++;
466 
467 	return (m);
468 }
469 
470 static void
471 vtballoon_free_page(struct vtballoon_softc *sc, vm_page_t m)
472 {
473 
474 	vm_page_free(m);
475 	sc->vtballoon_current_npages--;
476 }
477 
478 static uint32_t
479 vtballoon_desired_size(struct vtballoon_softc *sc)
480 {
481 	uint32_t desired;
482 
483 	desired = virtio_read_dev_config_4(sc->vtballoon_dev,
484 	    offsetof(struct virtio_balloon_config, num_pages));
485 
486 	if (vtballoon_modern(sc))
487 		return (desired);
488 	else
489 		return (le32toh(desired));
490 }
491 
492 static void
493 vtballoon_update_size(struct vtballoon_softc *sc)
494 {
495 	uint32_t npages;
496 
497 	npages = sc->vtballoon_current_npages;
498 	if (!vtballoon_modern(sc))
499 		npages = htole32(npages);
500 
501 	virtio_write_dev_config_4(sc->vtballoon_dev,
502 	    offsetof(struct virtio_balloon_config, actual), npages);
503 }
504 
505 static int
506 vtballoon_sleep(struct vtballoon_softc *sc)
507 {
508 	int rc, timeout;
509 	uint32_t current, desired;
510 
511 	rc = 0;
512 	current = sc->vtballoon_current_npages;
513 
514 	VTBALLOON_LOCK(sc);
515 	for (;;) {
516 		if (sc->vtballoon_flags & VTBALLOON_FLAG_DETACH) {
517 			rc = 1;
518 			break;
519 		}
520 
521 		desired = vtballoon_desired_size(sc);
522 		sc->vtballoon_desired_npages = desired;
523 
524 		/*
525 		 * If given, use non-zero timeout on the first time through
526 		 * the loop. On subsequent times, timeout will be zero so
527 		 * we will reevaluate the desired size of the balloon and
528 		 * break out to retry if needed.
529 		 */
530 		timeout = sc->vtballoon_timeout;
531 		sc->vtballoon_timeout = 0;
532 
533 		if (current > desired)
534 			break;
535 		if (current < desired && timeout == 0)
536 			break;
537 
538 		msleep(sc, VTBALLOON_MTX(sc), 0, "vtbslp", timeout);
539 	}
540 	VTBALLOON_UNLOCK(sc);
541 
542 	return (rc);
543 }
544 
545 static void
546 vtballoon_thread(void *xsc)
547 {
548 	struct vtballoon_softc *sc;
549 	uint32_t current, desired;
550 
551 	sc = xsc;
552 
553 	for (;;) {
554 		if (vtballoon_sleep(sc) != 0)
555 			break;
556 
557 		current = sc->vtballoon_current_npages;
558 		desired = sc->vtballoon_desired_npages;
559 
560 		if (desired != current) {
561 			if (desired > current)
562 				vtballoon_inflate(sc, desired - current);
563 			else
564 				vtballoon_deflate(sc, current - desired);
565 
566 			vtballoon_update_size(sc);
567 		}
568 	}
569 
570 	kthread_exit();
571 }
572 
573 static void
574 vtballoon_setup_sysctl(struct vtballoon_softc *sc)
575 {
576 	device_t dev;
577 	struct sysctl_ctx_list *ctx;
578 	struct sysctl_oid *tree;
579 	struct sysctl_oid_list *child;
580 
581 	dev = sc->vtballoon_dev;
582 	ctx = device_get_sysctl_ctx(dev);
583 	tree = device_get_sysctl_tree(dev);
584 	child = SYSCTL_CHILDREN(tree);
585 
586 	SYSCTL_ADD_UINT(ctx, child, OID_AUTO, "desired",
587 	    CTLFLAG_RD, &sc->vtballoon_desired_npages, sizeof(uint32_t),
588 	    "Desired balloon size in pages");
589 
590 	SYSCTL_ADD_UINT(ctx, child, OID_AUTO, "current",
591 	    CTLFLAG_RD, &sc->vtballoon_current_npages, sizeof(uint32_t),
592 	    "Current balloon size in pages");
593 }
594