sys/dev/virtio/balloon/virtio_balloon.c

   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_pci, vtballoon_driver,
 157     vtballoon_devclass, 0, 0);
 158 MODULE_VERSION(virtio_balloon, 1);
 159 MODULE_DEPEND(virtio_balloon, virtio, 1, 1, 1);
 160
 161 static int
 162 vtballoon_probe(device_t dev)
 163 {
 164
 165         if (virtio_get_device_type(dev) != VIRTIO_ID_BALLOON)
 166                 return (ENXIO);
 167
 168         device_set_desc(dev, "VirtIO Balloon Adapter");
 169
 170         return (BUS_PROBE_DEFAULT);
 171 }
 172
 173 static int
 174 vtballoon_attach(device_t dev)
 175 {
 176         struct vtballoon_softc *sc;
 177         int error;
 178
 179         sc = device_get_softc(dev);
 180         sc->vtballoon_dev = dev;
 181
 182         VTBALLOON_LOCK_INIT(sc, device_get_nameunit(dev));
 183         TAILQ_INIT(&sc->vtballoon_pages);
 184
 185         vtballoon_add_sysctl(sc);
 186
 187         virtio_set_feature_desc(dev, vtballoon_feature_desc);
 188         vtballoon_negotiate_features(sc);
 189
 190         sc->vtballoon_page_frames = malloc(VTBALLOON_PAGES_PER_REQUEST *
 191             sizeof(uint32_t), M_DEVBUF, M_NOWAIT | M_ZERO);
 192         if (sc->vtballoon_page_frames == NULL) {
 193                 error = ENOMEM;
 194                 device_printf(dev,
 195                     "cannot allocate page frame request array\n");
 196                 goto fail;
 197         }
 198
 199         error = vtballoon_alloc_virtqueues(sc);
 200         if (error) {
 201                 device_printf(dev, "cannot allocate virtqueues\n");
 202                 goto fail;
 203         }
 204
 205         error = virtio_setup_intr(dev, INTR_TYPE_MISC);
 206         if (error) {
 207                 device_printf(dev, "cannot setup virtqueue interrupts\n");
 208                 goto fail;
 209         }
 210
 211         error = kthread_add(vtballoon_thread, sc, NULL, &sc->vtballoon_td,
 212             0, 0, "virtio_balloon");
 213         if (error) {
 214                 device_printf(dev, "cannot create balloon kthread\n");
 215                 goto fail;
 216         }
 217
 218         virtqueue_enable_intr(sc->vtballoon_inflate_vq);
 219         virtqueue_enable_intr(sc->vtballoon_deflate_vq);
 220
 221 fail:
 222         if (error)
 223                 vtballoon_detach(dev);
 224
 225         return (error);
 226 }
 227
 228 static int
 229 vtballoon_detach(device_t dev)
 230 {
 231         struct vtballoon_softc *sc;
 232
 233         sc = device_get_softc(dev);
 234
 235         if (sc->vtballoon_td != NULL) {
 236                 VTBALLOON_LOCK(sc);
 237                 sc->vtballoon_flags |= VTBALLOON_FLAG_DETACH;
 238                 wakeup_one(sc);
 239                 msleep(sc->vtballoon_td, VTBALLOON_MTX(sc), 0, "vtbdth", 0);
 240                 VTBALLOON_UNLOCK(sc);
 241
 242                 sc->vtballoon_td = NULL;
 243         }
 244
 245         if (device_is_attached(dev)) {
 246                 vtballoon_pop(sc);
 247                 vtballoon_stop(sc);
 248         }
 249
 250         if (sc->vtballoon_page_frames != NULL) {
 251                 free(sc->vtballoon_page_frames, M_DEVBUF);
 252                 sc->vtballoon_page_frames = NULL;
 253         }
 254
 255         VTBALLOON_LOCK_DESTROY(sc);
 256
 257         return (0);
 258 }
 259
 260 static int
 261 vtballoon_config_change(device_t dev)
 262 {
 263         struct vtballoon_softc *sc;
 264
 265         sc = device_get_softc(dev);
 266
 267         VTBALLOON_LOCK(sc);
 268         wakeup_one(sc);
 269         VTBALLOON_UNLOCK(sc);
 270
 271         return (1);
 272 }
 273
 274 static void
 275 vtballoon_negotiate_features(struct vtballoon_softc *sc)
 276 {
 277         device_t dev;
 278         uint64_t features;
 279
 280         dev = sc->vtballoon_dev;
 281         features = virtio_negotiate_features(dev, VTBALLOON_FEATURES);
 282         sc->vtballoon_features = features;
 283 }
 284
 285 static int
 286 vtballoon_alloc_virtqueues(struct vtballoon_softc *sc)
 287 {
 288         device_t dev;
 289         struct vq_alloc_info vq_info[2];
 290         int nvqs;
 291
 292         dev = sc->vtballoon_dev;
 293         nvqs = 2;
 294
 295         VQ_ALLOC_INFO_INIT(&vq_info[0], 0, vtballoon_vq_intr, sc,
 296             &sc->vtballoon_inflate_vq, "%s inflate", device_get_nameunit(dev));
 297
 298         VQ_ALLOC_INFO_INIT(&vq_info[1], 0, vtballoon_vq_intr, sc,
 299             &sc->vtballoon_deflate_vq, "%s deflate", device_get_nameunit(dev));
 300
 301         return (virtio_alloc_virtqueues(dev, 0, nvqs, vq_info));
 302 }
 303
 304 static void
 305 vtballoon_vq_intr(void *xsc)
 306 {
 307         struct vtballoon_softc *sc;
 308
 309         sc = xsc;
 310
 311         VTBALLOON_LOCK(sc);
 312         wakeup_one(sc);
 313         VTBALLOON_UNLOCK(sc);
 314 }
 315
 316 static void
 317 vtballoon_inflate(struct vtballoon_softc *sc, int npages)
 318 {
 319         struct virtqueue *vq;
 320         vm_page_t m;
 321         int i;
 322
 323         vq = sc->vtballoon_inflate_vq;
 324
 325         if (npages > VTBALLOON_PAGES_PER_REQUEST)
 326                 npages = VTBALLOON_PAGES_PER_REQUEST;
 327
 328         for (i = 0; i < npages; i++) {
 329                 if ((m = vtballoon_alloc_page(sc)) == NULL) {
 330                         sc->vtballoon_timeout = VTBALLOON_LOWMEM_TIMEOUT;
 331                         break;
 332                 }
 333
 334                 sc->vtballoon_page_frames[i] =
 335                     VM_PAGE_TO_PHYS(m) >> VIRTIO_BALLOON_PFN_SHIFT;
 336
 337                 KASSERT(m->queue == PQ_NONE,
 338                     ("%s: allocated page %p on queue", __func__, m));
 339                 TAILQ_INSERT_TAIL(&sc->vtballoon_pages, m, plinks.q);
 340         }
 341
 342         if (i > 0)
 343                 vtballoon_send_page_frames(sc, vq, i);
 344 }
 345
 346 static void
 347 vtballoon_deflate(struct vtballoon_softc *sc, int npages)
 348 {
 349         TAILQ_HEAD(, vm_page) free_pages;
 350         struct virtqueue *vq;
 351         vm_page_t m;
 352         int i;
 353
 354         vq = sc->vtballoon_deflate_vq;
 355         TAILQ_INIT(&free_pages);
 356
 357         if (npages > VTBALLOON_PAGES_PER_REQUEST)
 358                 npages = VTBALLOON_PAGES_PER_REQUEST;
 359
 360         for (i = 0; i < npages; i++) {
 361                 m = TAILQ_FIRST(&sc->vtballoon_pages);
 362                 KASSERT(m != NULL, ("%s: no more pages to deflate", __func__));
 363
 364                 sc->vtballoon_page_frames[i] =
 365                     VM_PAGE_TO_PHYS(m) >> VIRTIO_BALLOON_PFN_SHIFT;
 366
 367                 TAILQ_REMOVE(&sc->vtballoon_pages, m, plinks.q);
 368                 TAILQ_INSERT_TAIL(&free_pages, m, plinks.q);
 369         }
 370
 371         if (i > 0) {
 372                 /* Always tell host first before freeing the pages. */
 373                 vtballoon_send_page_frames(sc, vq, i);
 374
 375                 while ((m = TAILQ_FIRST(&free_pages)) != NULL) {
 376                         TAILQ_REMOVE(&free_pages, m, plinks.q);
 377                         vtballoon_free_page(sc, m);
 378                 }
 379         }
 380
 381         KASSERT((TAILQ_EMPTY(&sc->vtballoon_pages) &&
 382             sc->vtballoon_current_npages == 0) ||
 383             (!TAILQ_EMPTY(&sc->vtballoon_pages) &&
 384             sc->vtballoon_current_npages != 0),
 385             ("%s: bogus page count %d", __func__,
 386             sc->vtballoon_current_npages));
 387 }
 388
 389 static void
 390 vtballoon_send_page_frames(struct vtballoon_softc *sc, struct virtqueue *vq,
 391     int npages)
 392 {
 393         struct sglist sg;
 394         struct sglist_seg segs[1];
 395         void *c;
 396         int error;
 397
 398         sglist_init(&sg, 1, segs);
 399
 400         error = sglist_append(&sg, sc->vtballoon_page_frames,
 401             npages * sizeof(uint32_t));
 402         KASSERT(error == 0, ("error adding page frames to sglist"));
 403
 404         error = virtqueue_enqueue(vq, vq, &sg, 1, 0);
 405         KASSERT(error == 0, ("error enqueuing page frames to virtqueue"));
 406         virtqueue_notify(vq);
 407
 408         /*
 409          * Inflate and deflate operations are done synchronously. The
 410          * interrupt handler will wake us up.
 411          */
 412         VTBALLOON_LOCK(sc);
 413         while ((c = virtqueue_dequeue(vq, NULL)) == NULL)
 414                 msleep(sc, VTBALLOON_MTX(sc), 0, "vtbspf", 0);
 415         VTBALLOON_UNLOCK(sc);
 416
 417         KASSERT(c == vq, ("unexpected balloon operation response"));
 418 }
 419
 420 static void
 421 vtballoon_pop(struct vtballoon_softc *sc)
 422 {
 423
 424         while (!TAILQ_EMPTY(&sc->vtballoon_pages))
 425                 vtballoon_deflate(sc, sc->vtballoon_current_npages);
 426 }
 427
 428 static void
 429 vtballoon_stop(struct vtballoon_softc *sc)
 430 {
 431
 432         virtqueue_disable_intr(sc->vtballoon_inflate_vq);
 433         virtqueue_disable_intr(sc->vtballoon_deflate_vq);
 434
 435         virtio_stop(sc->vtballoon_dev);
 436 }
 437
 438 static vm_page_t
 439 vtballoon_alloc_page(struct vtballoon_softc *sc)
 440 {
 441         vm_page_t m;
 442
 443         m = vm_page_alloc(NULL, 0, VM_ALLOC_NORMAL | VM_ALLOC_NOOBJ);
 444         if (m != NULL)
 445                 sc->vtballoon_current_npages++;
 446
 447         return (m);
 448 }
 449
 450 static void
 451 vtballoon_free_page(struct vtballoon_softc *sc, vm_page_t m)
 452 {
 453
 454         vm_page_free(m);
 455         sc->vtballoon_current_npages--;
 456 }
 457
 458 static uint32_t
 459 vtballoon_desired_size(struct vtballoon_softc *sc)
 460 {
 461         uint32_t desired;
 462
 463         desired = virtio_read_dev_config_4(sc->vtballoon_dev,
 464             offsetof(struct virtio_balloon_config, num_pages));
 465
 466         return (le32toh(desired));
 467 }
 468
 469 static void
 470 vtballoon_update_size(struct vtballoon_softc *sc)
 471 {
 472
 473         virtio_write_dev_config_4(sc->vtballoon_dev,
 474             offsetof(struct virtio_balloon_config, actual),
 475             htole32(sc->vtballoon_current_npages));
 476 }
 477
 478 static int
 479 vtballoon_sleep(struct vtballoon_softc *sc)
 480 {
 481         int rc, timeout;
 482         uint32_t current, desired;
 483
 484         rc = 0;
 485         current = sc->vtballoon_current_npages;
 486
 487         VTBALLOON_LOCK(sc);
 488         for (;;) {
 489                 if (sc->vtballoon_flags & VTBALLOON_FLAG_DETACH) {
 490                         rc = 1;
 491                         break;
 492                 }
 493
 494                 desired = vtballoon_desired_size(sc);
 495                 sc->vtballoon_desired_npages = desired;
 496
 497                 /*
 498                  * If given, use non-zero timeout on the first time through
 499                  * the loop. On subsequent times, timeout will be zero so
 500                  * we will reevaluate the desired size of the balloon and
 501                  * break out to retry if needed.
 502                  */
 503                 timeout = sc->vtballoon_timeout;
 504                 sc->vtballoon_timeout = 0;
 505
 506                 if (current > desired)
 507                         break;
 508                 if (current < desired && timeout == 0)
 509                         break;
 510
 511                 msleep(sc, VTBALLOON_MTX(sc), 0, "vtbslp", timeout);
 512         }
 513         VTBALLOON_UNLOCK(sc);
 514
 515         return (rc);
 516 }
 517
 518 static void
 519 vtballoon_thread(void *xsc)
 520 {
 521         struct vtballoon_softc *sc;
 522         uint32_t current, desired;
 523
 524         sc = xsc;
 525
 526         for (;;) {
 527                 if (vtballoon_sleep(sc) != 0)
 528                         break;
 529
 530                 current = sc->vtballoon_current_npages;
 531                 desired = sc->vtballoon_desired_npages;
 532
 533                 if (desired != current) {
 534                         if (desired > current)
 535                                 vtballoon_inflate(sc, desired - current);
 536                         else
 537                                 vtballoon_deflate(sc, current - desired);
 538
 539                         vtballoon_update_size(sc);
 540                 }
 541         }
 542
 543         kthread_exit();
 544 }
 545
 546 static void
 547 vtballoon_add_sysctl(struct vtballoon_softc *sc)
 548 {
 549         device_t dev;
 550         struct sysctl_ctx_list *ctx;
 551         struct sysctl_oid *tree;
 552         struct sysctl_oid_list *child;
 553
 554         dev = sc->vtballoon_dev;
 555         ctx = device_get_sysctl_ctx(dev);
 556         tree = device_get_sysctl_tree(dev);
 557         child = SYSCTL_CHILDREN(tree);
 558
 559         SYSCTL_ADD_UINT(ctx, child, OID_AUTO, "desired",
 560             CTLFLAG_RD, &sc->vtballoon_desired_npages, sizeof(uint32_t),
 561             "Desired balloon size in pages");
 562
 563         SYSCTL_ADD_UINT(ctx, child, OID_AUTO, "current",
 564             CTLFLAG_RD, &sc->vtballoon_current_npages, sizeof(uint32_t),
 565             "Current balloon size in pages");
 566 }