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 
84 	{ 0, NULL }
85 };
86 
87 static int	vtballoon_probe(device_t);
88 static int	vtballoon_attach(device_t);
89 static int	vtballoon_detach(device_t);
90 static int	vtballoon_config_change(device_t);
91 
92 static void	vtballoon_negotiate_features(struct vtballoon_softc *);
93 static int	vtballoon_alloc_virtqueues(struct vtballoon_softc *);
94 
95 static void	vtballoon_vq_intr(void *);
96 
97 static void	vtballoon_inflate(struct vtballoon_softc *, int);
98 static void	vtballoon_deflate(struct vtballoon_softc *, int);
99 
100 static void	vtballoon_send_page_frames(struct vtballoon_softc *,
101 		    struct virtqueue *, int);
102 
103 static void	vtballoon_pop(struct vtballoon_softc *);
104 static void	vtballoon_stop(struct vtballoon_softc *);
105 
106 static vm_page_t
107 		vtballoon_alloc_page(struct vtballoon_softc *);
108 static void	vtballoon_free_page(struct vtballoon_softc *, vm_page_t);
109 
110 static int	vtballoon_sleep(struct vtballoon_softc *);
111 static void	vtballoon_thread(void *);
112 static void	vtballoon_add_sysctl(struct vtballoon_softc *);
113 
114 /* Features desired/implemented by this driver. */
115 #define VTBALLOON_FEATURES		0
116 
117 /* Timeout between retries when the balloon needs inflating. */
118 #define VTBALLOON_LOWMEM_TIMEOUT	hz
119 
120 /*
121  * Maximum number of pages we'll request to inflate or deflate
122  * the balloon in one virtqueue request. Both Linux and NetBSD
123  * have settled on 256, doing up to 1MB at a time.
124  */
125 #define VTBALLOON_PAGES_PER_REQUEST	256
126 
127 /* Must be able to fix all pages frames in one page (segment). */
128 CTASSERT(VTBALLOON_PAGES_PER_REQUEST * sizeof(uint32_t) <= PAGE_SIZE);
129 
130 #define VTBALLOON_MTX(_sc)		&(_sc)->vtballoon_mtx
131 #define VTBALLOON_LOCK_INIT(_sc, _name)	mtx_init(VTBALLOON_MTX((_sc)), _name, \
132 					    "VirtIO Balloon Lock", MTX_DEF)
133 #define VTBALLOON_LOCK(_sc)		mtx_lock(VTBALLOON_MTX((_sc)))
134 #define VTBALLOON_UNLOCK(_sc)		mtx_unlock(VTBALLOON_MTX((_sc)))
135 #define VTBALLOON_LOCK_DESTROY(_sc)	mtx_destroy(VTBALLOON_MTX((_sc)))
136 
137 static device_method_t vtballoon_methods[] = {
138 	/* Device methods. */
139 	DEVMETHOD(device_probe,		vtballoon_probe),
140 	DEVMETHOD(device_attach,	vtballoon_attach),
141 	DEVMETHOD(device_detach,	vtballoon_detach),
142 
143 	/* VirtIO methods. */
144 	DEVMETHOD(virtio_config_change, vtballoon_config_change),
145 
146 	DEVMETHOD_END
147 };
148 
149 static driver_t vtballoon_driver = {
150 	"vtballoon",
151 	vtballoon_methods,
152 	sizeof(struct vtballoon_softc)
153 };
154 static devclass_t vtballoon_devclass;
155 
156 DRIVER_MODULE(virtio_balloon, virtio_mmio, vtballoon_driver,
157     vtballoon_devclass, 0, 0);
158 DRIVER_MODULE(virtio_balloon, virtio_pci, vtballoon_driver,
159     vtballoon_devclass, 0, 0);
160 MODULE_VERSION(virtio_balloon, 1);
161 MODULE_DEPEND(virtio_balloon, virtio, 1, 1, 1);
162 
163 VIRTIO_SIMPLE_PNPTABLE(virtio_balloon, VIRTIO_ID_BALLOON,
164     "VirtIO Balloon Adapter");
165 VIRTIO_SIMPLE_PNPINFO(virtio_mmio, virtio_balloon);
166 VIRTIO_SIMPLE_PNPINFO(virtio_pci, virtio_balloon);
167 
168 static int
169 vtballoon_probe(device_t dev)
170 {
171 	return (VIRTIO_SIMPLE_PROBE(dev, virtio_balloon));
172 }
173 
174 static int
175 vtballoon_attach(device_t dev)
176 {
177 	struct vtballoon_softc *sc;
178 	int error;
179 
180 	sc = device_get_softc(dev);
181 	sc->vtballoon_dev = dev;
182 
183 	VTBALLOON_LOCK_INIT(sc, device_get_nameunit(dev));
184 	TAILQ_INIT(&sc->vtballoon_pages);
185 
186 	vtballoon_add_sysctl(sc);
187 
188 	virtio_set_feature_desc(dev, vtballoon_feature_desc);
189 	vtballoon_negotiate_features(sc);
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 void
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 = virtio_negotiate_features(dev, VTBALLOON_FEATURES);
283 	sc->vtballoon_features = features;
284 }
285 
286 static int
287 vtballoon_alloc_virtqueues(struct vtballoon_softc *sc)
288 {
289 	device_t dev;
290 	struct vq_alloc_info vq_info[2];
291 	int nvqs;
292 
293 	dev = sc->vtballoon_dev;
294 	nvqs = 2;
295 
296 	VQ_ALLOC_INFO_INIT(&vq_info[0], 0, vtballoon_vq_intr, sc,
297 	    &sc->vtballoon_inflate_vq, "%s inflate", device_get_nameunit(dev));
298 
299 	VQ_ALLOC_INFO_INIT(&vq_info[1], 0, vtballoon_vq_intr, sc,
300 	    &sc->vtballoon_deflate_vq, "%s deflate", device_get_nameunit(dev));
301 
302 	return (virtio_alloc_virtqueues(dev, 0, nvqs, vq_info));
303 }
304 
305 static void
306 vtballoon_vq_intr(void *xsc)
307 {
308 	struct vtballoon_softc *sc;
309 
310 	sc = xsc;
311 
312 	VTBALLOON_LOCK(sc);
313 	wakeup_one(sc);
314 	VTBALLOON_UNLOCK(sc);
315 }
316 
317 static void
318 vtballoon_inflate(struct vtballoon_softc *sc, int npages)
319 {
320 	struct virtqueue *vq;
321 	vm_page_t m;
322 	int i;
323 
324 	vq = sc->vtballoon_inflate_vq;
325 
326 	if (npages > VTBALLOON_PAGES_PER_REQUEST)
327 		npages = VTBALLOON_PAGES_PER_REQUEST;
328 
329 	for (i = 0; i < npages; i++) {
330 		if ((m = vtballoon_alloc_page(sc)) == NULL) {
331 			sc->vtballoon_timeout = VTBALLOON_LOWMEM_TIMEOUT;
332 			break;
333 		}
334 
335 		sc->vtballoon_page_frames[i] =
336 		    VM_PAGE_TO_PHYS(m) >> VIRTIO_BALLOON_PFN_SHIFT;
337 
338 		KASSERT(m->a.queue == PQ_NONE,
339 		    ("%s: allocated page %p on queue", __func__, m));
340 		TAILQ_INSERT_TAIL(&sc->vtballoon_pages, m, plinks.q);
341 	}
342 
343 	if (i > 0)
344 		vtballoon_send_page_frames(sc, vq, i);
345 }
346 
347 static void
348 vtballoon_deflate(struct vtballoon_softc *sc, int npages)
349 {
350 	TAILQ_HEAD(, vm_page) free_pages;
351 	struct virtqueue *vq;
352 	vm_page_t m;
353 	int i;
354 
355 	vq = sc->vtballoon_deflate_vq;
356 	TAILQ_INIT(&free_pages);
357 
358 	if (npages > VTBALLOON_PAGES_PER_REQUEST)
359 		npages = VTBALLOON_PAGES_PER_REQUEST;
360 
361 	for (i = 0; i < npages; i++) {
362 		m = TAILQ_FIRST(&sc->vtballoon_pages);
363 		KASSERT(m != NULL, ("%s: no more pages to deflate", __func__));
364 
365 		sc->vtballoon_page_frames[i] =
366 		    VM_PAGE_TO_PHYS(m) >> VIRTIO_BALLOON_PFN_SHIFT;
367 
368 		TAILQ_REMOVE(&sc->vtballoon_pages, m, plinks.q);
369 		TAILQ_INSERT_TAIL(&free_pages, m, plinks.q);
370 	}
371 
372 	if (i > 0) {
373 		/* Always tell host first before freeing the pages. */
374 		vtballoon_send_page_frames(sc, vq, i);
375 
376 		while ((m = TAILQ_FIRST(&free_pages)) != NULL) {
377 			TAILQ_REMOVE(&free_pages, m, plinks.q);
378 			vtballoon_free_page(sc, m);
379 		}
380 	}
381 
382 	KASSERT((TAILQ_EMPTY(&sc->vtballoon_pages) &&
383 	    sc->vtballoon_current_npages == 0) ||
384 	    (!TAILQ_EMPTY(&sc->vtballoon_pages) &&
385 	    sc->vtballoon_current_npages != 0),
386 	    ("%s: bogus page count %d", __func__,
387 	    sc->vtballoon_current_npages));
388 }
389 
390 static void
391 vtballoon_send_page_frames(struct vtballoon_softc *sc, struct virtqueue *vq,
392     int npages)
393 {
394 	struct sglist sg;
395 	struct sglist_seg segs[1];
396 	void *c;
397 	int error;
398 
399 	sglist_init(&sg, 1, segs);
400 
401 	error = sglist_append(&sg, sc->vtballoon_page_frames,
402 	    npages * sizeof(uint32_t));
403 	KASSERT(error == 0, ("error adding page frames to sglist"));
404 
405 	error = virtqueue_enqueue(vq, vq, &sg, 1, 0);
406 	KASSERT(error == 0, ("error enqueuing page frames to virtqueue"));
407 	virtqueue_notify(vq);
408 
409 	/*
410 	 * Inflate and deflate operations are done synchronously. The
411 	 * interrupt handler will wake us up.
412 	 */
413 	VTBALLOON_LOCK(sc);
414 	while ((c = virtqueue_dequeue(vq, NULL)) == NULL)
415 		msleep(sc, VTBALLOON_MTX(sc), 0, "vtbspf", 0);
416 	VTBALLOON_UNLOCK(sc);
417 
418 	KASSERT(c == vq, ("unexpected balloon operation response"));
419 }
420 
421 static void
422 vtballoon_pop(struct vtballoon_softc *sc)
423 {
424 
425 	while (!TAILQ_EMPTY(&sc->vtballoon_pages))
426 		vtballoon_deflate(sc, sc->vtballoon_current_npages);
427 }
428 
429 static void
430 vtballoon_stop(struct vtballoon_softc *sc)
431 {
432 
433 	virtqueue_disable_intr(sc->vtballoon_inflate_vq);
434 	virtqueue_disable_intr(sc->vtballoon_deflate_vq);
435 
436 	virtio_stop(sc->vtballoon_dev);
437 }
438 
439 static vm_page_t
440 vtballoon_alloc_page(struct vtballoon_softc *sc)
441 {
442 	vm_page_t m;
443 
444 	m = vm_page_alloc(NULL, 0, VM_ALLOC_NORMAL | VM_ALLOC_NOOBJ);
445 	if (m != NULL)
446 		sc->vtballoon_current_npages++;
447 
448 	return (m);
449 }
450 
451 static void
452 vtballoon_free_page(struct vtballoon_softc *sc, vm_page_t m)
453 {
454 
455 	vm_page_free(m);
456 	sc->vtballoon_current_npages--;
457 }
458 
459 static uint32_t
460 vtballoon_desired_size(struct vtballoon_softc *sc)
461 {
462 	uint32_t desired;
463 
464 	desired = virtio_read_dev_config_4(sc->vtballoon_dev,
465 	    offsetof(struct virtio_balloon_config, num_pages));
466 
467 	return (le32toh(desired));
468 }
469 
470 static void
471 vtballoon_update_size(struct vtballoon_softc *sc)
472 {
473 
474 	virtio_write_dev_config_4(sc->vtballoon_dev,
475 	    offsetof(struct virtio_balloon_config, actual),
476 	    htole32(sc->vtballoon_current_npages));
477 }
478 
479 static int
480 vtballoon_sleep(struct vtballoon_softc *sc)
481 {
482 	int rc, timeout;
483 	uint32_t current, desired;
484 
485 	rc = 0;
486 	current = sc->vtballoon_current_npages;
487 
488 	VTBALLOON_LOCK(sc);
489 	for (;;) {
490 		if (sc->vtballoon_flags & VTBALLOON_FLAG_DETACH) {
491 			rc = 1;
492 			break;
493 		}
494 
495 		desired = vtballoon_desired_size(sc);
496 		sc->vtballoon_desired_npages = desired;
497 
498 		/*
499 		 * If given, use non-zero timeout on the first time through
500 		 * the loop. On subsequent times, timeout will be zero so
501 		 * we will reevaluate the desired size of the balloon and
502 		 * break out to retry if needed.
503 		 */
504 		timeout = sc->vtballoon_timeout;
505 		sc->vtballoon_timeout = 0;
506 
507 		if (current > desired)
508 			break;
509 		if (current < desired && timeout == 0)
510 			break;
511 
512 		msleep(sc, VTBALLOON_MTX(sc), 0, "vtbslp", timeout);
513 	}
514 	VTBALLOON_UNLOCK(sc);
515 
516 	return (rc);
517 }
518 
519 static void
520 vtballoon_thread(void *xsc)
521 {
522 	struct vtballoon_softc *sc;
523 	uint32_t current, desired;
524 
525 	sc = xsc;
526 
527 	for (;;) {
528 		if (vtballoon_sleep(sc) != 0)
529 			break;
530 
531 		current = sc->vtballoon_current_npages;
532 		desired = sc->vtballoon_desired_npages;
533 
534 		if (desired != current) {
535 			if (desired > current)
536 				vtballoon_inflate(sc, desired - current);
537 			else
538 				vtballoon_deflate(sc, current - desired);
539 
540 			vtballoon_update_size(sc);
541 		}
542 	}
543 
544 	kthread_exit();
545 }
546 
547 static void
548 vtballoon_add_sysctl(struct vtballoon_softc *sc)
549 {
550 	device_t dev;
551 	struct sysctl_ctx_list *ctx;
552 	struct sysctl_oid *tree;
553 	struct sysctl_oid_list *child;
554 
555 	dev = sc->vtballoon_dev;
556 	ctx = device_get_sysctl_ctx(dev);
557 	tree = device_get_sysctl_tree(dev);
558 	child = SYSCTL_CHILDREN(tree);
559 
560 	SYSCTL_ADD_UINT(ctx, child, OID_AUTO, "desired",
561 	    CTLFLAG_RD, &sc->vtballoon_desired_npages, sizeof(uint32_t),
562 	    "Desired balloon size in pages");
563 
564 	SYSCTL_ADD_UINT(ctx, child, OID_AUTO, "current",
565 	    CTLFLAG_RD, &sc->vtballoon_current_npages, sizeof(uint32_t),
566 	    "Current balloon size in pages");
567 }
568