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