tools/virtio/vringh_test.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /* Simple test of virtio code, entirely in userpsace. */
   3 #define _GNU_SOURCE
   4 #include <sched.h>
   5 #include <err.h>
   6 #include <linux/kernel.h>
   7 #include <linux/err.h>
   8 #include <linux/virtio.h>
   9 #include <linux/vringh.h>
  10 #include <linux/virtio_ring.h>
  11 #include <linux/virtio_config.h>
  12 #include <linux/uaccess.h>
  13 #include <sys/types.h>
  14 #include <sys/stat.h>
  15 #include <sys/mman.h>
  16 #include <sys/wait.h>
  17 #include <fcntl.h>
  18
  19 #define USER_MEM (1024*1024)
  20 void *__user_addr_min, *__user_addr_max;
  21 void *__kmalloc_fake, *__kfree_ignore_start, *__kfree_ignore_end;
  22 static u64 user_addr_offset;
  23
  24 #define RINGSIZE 256
  25 #define ALIGN 4096
  26
  27 static bool never_notify_host(struct virtqueue *vq)
  28 {
  29         abort();
  30 }
  31
  32 static void never_callback_guest(struct virtqueue *vq)
  33 {
  34         abort();
  35 }
  36
  37 static bool getrange_iov(struct vringh *vrh, u64 addr, struct vringh_range *r)
  38 {
  39         if (addr < (u64)(unsigned long)__user_addr_min - user_addr_offset)
  40                 return false;
  41         if (addr >= (u64)(unsigned long)__user_addr_max - user_addr_offset)
  42                 return false;
  43
  44         r->start = (u64)(unsigned long)__user_addr_min - user_addr_offset;
  45         r->end_incl = (u64)(unsigned long)__user_addr_max - 1 - user_addr_offset;
  46         r->offset = user_addr_offset;
  47         return true;
  48 }
  49
  50 /* We return single byte ranges. */
  51 static bool getrange_slow(struct vringh *vrh, u64 addr, struct vringh_range *r)
  52 {
  53         if (addr < (u64)(unsigned long)__user_addr_min - user_addr_offset)
  54                 return false;
  55         if (addr >= (u64)(unsigned long)__user_addr_max - user_addr_offset)
  56                 return false;
  57
  58         r->start = addr;
  59         r->end_incl = r->start;
  60         r->offset = user_addr_offset;
  61         return true;
  62 }
  63
  64 struct guest_virtio_device {
  65         struct virtio_device vdev;
  66         int to_host_fd;
  67         unsigned long notifies;
  68 };
  69
  70 static bool parallel_notify_host(struct virtqueue *vq)
  71 {
  72         int rc;
  73         struct guest_virtio_device *gvdev;
  74
  75         gvdev = container_of(vq->vdev, struct guest_virtio_device, vdev);
  76         rc = write(gvdev->to_host_fd, "", 1);
  77         if (rc < 0)
  78                 return false;
  79         gvdev->notifies++;
  80         return true;
  81 }
  82
  83 static bool no_notify_host(struct virtqueue *vq)
  84 {
  85         return true;
  86 }
  87
  88 #define NUM_XFERS (10000000)
  89
  90 /* We aim for two "distant" cpus. */
  91 static void find_cpus(unsigned int *first, unsigned int *last)
  92 {
  93         unsigned int i;
  94
  95         *first = -1U;
  96         *last = 0;
  97         for (i = 0; i < 4096; i++) {
  98                 cpu_set_t set;
  99                 CPU_ZERO(&set);
 100                 CPU_SET(i, &set);
 101                 if (sched_setaffinity(getpid(), sizeof(set), &set) == 0) {
 102                         if (i < *first)
 103                                 *first = i;
 104                         if (i > *last)
 105                                 *last = i;
 106                 }
 107         }
 108 }
 109
 110 /* Opencoded version for fast mode */
 111 static inline int vringh_get_head(struct vringh *vrh, u16 *head)
 112 {
 113         u16 avail_idx, i;
 114         int err;
 115
 116         err = get_user(avail_idx, &vrh->vring.avail->idx);
 117         if (err)
 118                 return err;
 119
 120         if (vrh->last_avail_idx == avail_idx)
 121                 return 0;
 122
 123         /* Only get avail ring entries after they have been exposed by guest. */
 124         virtio_rmb(vrh->weak_barriers);
 125
 126         i = vrh->last_avail_idx & (vrh->vring.num - 1);
 127
 128         err = get_user(*head, &vrh->vring.avail->ring[i]);
 129         if (err)
 130                 return err;
 131
 132         vrh->last_avail_idx++;
 133         return 1;
 134 }
 135
 136 static int parallel_test(u64 features,
 137                          bool (*getrange)(struct vringh *vrh,
 138                                           u64 addr, struct vringh_range *r),
 139                          bool fast_vringh)
 140 {
 141         void *host_map, *guest_map;
 142         int fd, mapsize, to_guest[2], to_host[2];
 143         unsigned long xfers = 0, notifies = 0, receives = 0;
 144         unsigned int first_cpu, last_cpu;
 145         cpu_set_t cpu_set;
 146         char buf[128];
 147
 148         /* Create real file to mmap. */
 149         fd = open("/tmp/vringh_test-file", O_RDWR|O_CREAT|O_TRUNC, 0600);
 150         if (fd < 0)
 151                 err(1, "Opening /tmp/vringh_test-file");
 152
 153         /* Extra room at the end for some data, and indirects */
 154         mapsize = vring_size(RINGSIZE, ALIGN)
 155                 + RINGSIZE * 2 * sizeof(int)
 156                 + RINGSIZE * 6 * sizeof(struct vring_desc);
 157         mapsize = (mapsize + getpagesize() - 1) & ~(getpagesize() - 1);
 158         ftruncate(fd, mapsize);
 159
 160         /* Parent and child use separate addresses, to check our mapping logic! */
 161         host_map = mmap(NULL, mapsize, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0);
 162         guest_map = mmap(NULL, mapsize, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0);
 163
 164         pipe(to_guest);
 165         pipe(to_host);
 166
 167         CPU_ZERO(&cpu_set);
 168         find_cpus(&first_cpu, &last_cpu);
 169         printf("Using CPUS %u and %u\n", first_cpu, last_cpu);
 170         fflush(stdout);
 171
 172         if (fork() != 0) {
 173                 struct vringh vrh;
 174                 int status, err, rlen = 0;
 175                 char rbuf[5];
 176
 177                 /* We are the host: never access guest addresses! */
 178                 munmap(guest_map, mapsize);
 179
 180                 __user_addr_min = host_map;
 181                 __user_addr_max = __user_addr_min + mapsize;
 182                 user_addr_offset = host_map - guest_map;
 183                 assert(user_addr_offset);
 184
 185                 close(to_guest[0]);
 186                 close(to_host[1]);
 187
 188                 vring_init(&vrh.vring, RINGSIZE, host_map, ALIGN);
 189                 vringh_init_user(&vrh, features, RINGSIZE, true,
 190                                  vrh.vring.desc, vrh.vring.avail, vrh.vring.used);
 191                 CPU_SET(first_cpu, &cpu_set);
 192                 if (sched_setaffinity(getpid(), sizeof(cpu_set), &cpu_set))
 193                         errx(1, "Could not set affinity to cpu %u", first_cpu);
 194
 195                 while (xfers < NUM_XFERS) {
 196                         struct iovec host_riov[2], host_wiov[2];
 197                         struct vringh_iov riov, wiov;
 198                         u16 head, written;
 199
 200                         if (fast_vringh) {
 201                                 for (;;) {
 202                                         err = vringh_get_head(&vrh, &head);
 203                                         if (err != 0)
 204                                                 break;
 205                                         err = vringh_need_notify_user(&vrh);
 206                                         if (err < 0)
 207                                                 errx(1, "vringh_need_notify_user: %i",
 208                                                      err);
 209                                         if (err) {
 210                                                 write(to_guest[1], "", 1);
 211                                                 notifies++;
 212                                         }
 213                                 }
 214                                 if (err != 1)
 215                                         errx(1, "vringh_get_head");
 216                                 written = 0;
 217                                 goto complete;
 218                         } else {
 219                                 vringh_iov_init(&riov,
 220                                                 host_riov,
 221                                                 ARRAY_SIZE(host_riov));
 222                                 vringh_iov_init(&wiov,
 223                                                 host_wiov,
 224                                                 ARRAY_SIZE(host_wiov));
 225
 226                                 err = vringh_getdesc_user(&vrh, &riov, &wiov,
 227                                                           getrange, &head);
 228                         }
 229                         if (err == 0) {
 230                                 err = vringh_need_notify_user(&vrh);
 231                                 if (err < 0)
 232                                         errx(1, "vringh_need_notify_user: %i",
 233                                              err);
 234                                 if (err) {
 235                                         write(to_guest[1], "", 1);
 236                                         notifies++;
 237                                 }
 238
 239                                 if (!vringh_notify_enable_user(&vrh))
 240                                         continue;
 241
 242                                 /* Swallow all notifies at once. */
 243                                 if (read(to_host[0], buf, sizeof(buf)) < 1)
 244                                         break;
 245
 246                                 vringh_notify_disable_user(&vrh);
 247                                 receives++;
 248                                 continue;
 249                         }
 250                         if (err != 1)
 251                                 errx(1, "vringh_getdesc_user: %i", err);
 252
 253                         /* We simply copy bytes. */
 254                         if (riov.used) {
 255                                 rlen = vringh_iov_pull_user(&riov, rbuf,
 256                                                             sizeof(rbuf));
 257                                 if (rlen != 4)
 258                                         errx(1, "vringh_iov_pull_user: %i",
 259                                              rlen);
 260                                 assert(riov.i == riov.used);
 261                                 written = 0;
 262                         } else {
 263                                 err = vringh_iov_push_user(&wiov, rbuf, rlen);
 264                                 if (err != rlen)
 265                                         errx(1, "vringh_iov_push_user: %i",
 266                                              err);
 267                                 assert(wiov.i == wiov.used);
 268                                 written = err;
 269                         }
 270                 complete:
 271                         xfers++;
 272
 273                         err = vringh_complete_user(&vrh, head, written);
 274                         if (err != 0)
 275                                 errx(1, "vringh_complete_user: %i", err);
 276                 }
 277
 278                 err = vringh_need_notify_user(&vrh);
 279                 if (err < 0)
 280                         errx(1, "vringh_need_notify_user: %i", err);
 281                 if (err) {
 282                         write(to_guest[1], "", 1);
 283                         notifies++;
 284                 }
 285                 wait(&status);
 286                 if (!WIFEXITED(status))
 287                         errx(1, "Child died with signal %i?", WTERMSIG(status));
 288                 if (WEXITSTATUS(status) != 0)
 289                         errx(1, "Child exited %i?", WEXITSTATUS(status));
 290                 printf("Host: notified %lu, pinged %lu\n", notifies, receives);
 291                 return 0;
 292         } else {
 293                 struct guest_virtio_device gvdev;
 294                 struct virtqueue *vq;
 295                 unsigned int *data;
 296                 struct vring_desc *indirects;
 297                 unsigned int finished = 0;
 298
 299                 /* We pass sg[]s pointing into here, but we need RINGSIZE+1 */
 300                 data = guest_map + vring_size(RINGSIZE, ALIGN);
 301                 indirects = (void *)data + (RINGSIZE + 1) * 2 * sizeof(int);
 302
 303                 /* We are the guest. */
 304                 munmap(host_map, mapsize);
 305
 306                 close(to_guest[1]);
 307                 close(to_host[0]);
 308
 309                 gvdev.vdev.features = features;
 310                 gvdev.to_host_fd = to_host[1];
 311                 gvdev.notifies = 0;
 312
 313                 CPU_SET(first_cpu, &cpu_set);
 314                 if (sched_setaffinity(getpid(), sizeof(cpu_set), &cpu_set))
 315                         err(1, "Could not set affinity to cpu %u", first_cpu);
 316
 317                 vq = vring_new_virtqueue(0, RINGSIZE, ALIGN, &gvdev.vdev, true,
 318                                          false, guest_map,
 319                                          fast_vringh ? no_notify_host
 320                                          : parallel_notify_host,
 321                                          never_callback_guest, "guest vq");
 322
 323                 /* Don't kfree indirects. */
 324                 __kfree_ignore_start = indirects;
 325                 __kfree_ignore_end = indirects + RINGSIZE * 6;
 326
 327                 while (xfers < NUM_XFERS) {
 328                         struct scatterlist sg[4];
 329                         unsigned int num_sg, len;
 330                         int *dbuf, err;
 331                         bool output = !(xfers % 2);
 332
 333                         /* Consume bufs. */
 334                         while ((dbuf = virtqueue_get_buf(vq, &len)) != NULL) {
 335                                 if (len == 4)
 336                                         assert(*dbuf == finished - 1);
 337                                 else if (!fast_vringh)
 338                                         assert(*dbuf == finished);
 339                                 finished++;
 340                         }
 341
 342                         /* Produce a buffer. */
 343                         dbuf = data + (xfers % (RINGSIZE + 1));
 344
 345                         if (output)
 346                                 *dbuf = xfers;
 347                         else
 348                                 *dbuf = -1;
 349
 350                         switch ((xfers / sizeof(*dbuf)) % 4) {
 351                         case 0:
 352                                 /* Nasty three-element sg list. */
 353                                 sg_init_table(sg, num_sg = 3);
 354                                 sg_set_buf(&sg[0], (void *)dbuf, 1);
 355                                 sg_set_buf(&sg[1], (void *)dbuf + 1, 2);
 356                                 sg_set_buf(&sg[2], (void *)dbuf + 3, 1);
 357                                 break;
 358                         case 1:
 359                                 sg_init_table(sg, num_sg = 2);
 360                                 sg_set_buf(&sg[0], (void *)dbuf, 1);
 361                                 sg_set_buf(&sg[1], (void *)dbuf + 1, 3);
 362                                 break;
 363                         case 2:
 364                                 sg_init_table(sg, num_sg = 1);
 365                                 sg_set_buf(&sg[0], (void *)dbuf, 4);
 366                                 break;
 367                         case 3:
 368                                 sg_init_table(sg, num_sg = 4);
 369                                 sg_set_buf(&sg[0], (void *)dbuf, 1);
 370                                 sg_set_buf(&sg[1], (void *)dbuf + 1, 1);
 371                                 sg_set_buf(&sg[2], (void *)dbuf + 2, 1);
 372                                 sg_set_buf(&sg[3], (void *)dbuf + 3, 1);
 373                                 break;
 374                         }
 375
 376                         /* May allocate an indirect, so force it to allocate
 377                          * user addr */
 378                         __kmalloc_fake = indirects + (xfers % RINGSIZE) * 4;
 379                         if (output)
 380                                 err = virtqueue_add_outbuf(vq, sg, num_sg, dbuf,
 381                                                            GFP_KERNEL);
 382                         else
 383                                 err = virtqueue_add_inbuf(vq, sg, num_sg,
 384                                                           dbuf, GFP_KERNEL);
 385
 386                         if (err == -ENOSPC) {
 387                                 if (!virtqueue_enable_cb_delayed(vq))
 388                                         continue;
 389                                 /* Swallow all notifies at once. */
 390                                 if (read(to_guest[0], buf, sizeof(buf)) < 1)
 391                                         break;
 392
 393                                 receives++;
 394                                 virtqueue_disable_cb(vq);
 395                                 continue;
 396                         }
 397
 398                         if (err)
 399                                 errx(1, "virtqueue_add_in/outbuf: %i", err);
 400
 401                         xfers++;
 402                         virtqueue_kick(vq);
 403                 }
 404
 405                 /* Any extra? */
 406                 while (finished != xfers) {
 407                         int *dbuf;
 408                         unsigned int len;
 409
 410                         /* Consume bufs. */
 411                         dbuf = virtqueue_get_buf(vq, &len);
 412                         if (dbuf) {
 413                                 if (len == 4)
 414                                         assert(*dbuf == finished - 1);
 415                                 else
 416                                         assert(len == 0);
 417                                 finished++;
 418                                 continue;
 419                         }
 420
 421                         if (!virtqueue_enable_cb_delayed(vq))
 422                                 continue;
 423                         if (read(to_guest[0], buf, sizeof(buf)) < 1)
 424                                 break;
 425
 426                         receives++;
 427                         virtqueue_disable_cb(vq);
 428                 }
 429
 430                 printf("Guest: notified %lu, pinged %lu\n",
 431                        gvdev.notifies, receives);
 432                 vring_del_virtqueue(vq);
 433                 return 0;
 434         }
 435 }
 436
 437 int main(int argc, char *argv[])
 438 {
 439         struct virtio_device vdev;
 440         struct virtqueue *vq;
 441         struct vringh vrh;
 442         struct scatterlist guest_sg[RINGSIZE], *sgs[2];
 443         struct iovec host_riov[2], host_wiov[2];
 444         struct vringh_iov riov, wiov;
 445         struct vring_used_elem used[RINGSIZE];
 446         char buf[28];
 447         u16 head;
 448         int err;
 449         unsigned i;
 450         void *ret;
 451         bool (*getrange)(struct vringh *vrh, u64 addr, struct vringh_range *r);
 452         bool fast_vringh = false, parallel = false;
 453
 454         getrange = getrange_iov;
 455         vdev.features = 0;
 456
 457         while (argv[1]) {
 458                 if (strcmp(argv[1], "--indirect") == 0)
 459                         __virtio_set_bit(&vdev, VIRTIO_RING_F_INDIRECT_DESC);
 460                 else if (strcmp(argv[1], "--eventidx") == 0)
 461                         __virtio_set_bit(&vdev, VIRTIO_RING_F_EVENT_IDX);
 462                 else if (strcmp(argv[1], "--virtio-1") == 0)
 463                         __virtio_set_bit(&vdev, VIRTIO_F_VERSION_1);
 464                 else if (strcmp(argv[1], "--slow-range") == 0)
 465                         getrange = getrange_slow;
 466                 else if (strcmp(argv[1], "--fast-vringh") == 0)
 467                         fast_vringh = true;
 468                 else if (strcmp(argv[1], "--parallel") == 0)
 469                         parallel = true;
 470                 else
 471                         errx(1, "Unknown arg %s", argv[1]);
 472                 argv++;
 473         }
 474
 475         if (parallel)
 476                 return parallel_test(vdev.features, getrange, fast_vringh);
 477
 478         if (posix_memalign(&__user_addr_min, PAGE_SIZE, USER_MEM) != 0)
 479                 abort();
 480         __user_addr_max = __user_addr_min + USER_MEM;
 481         memset(__user_addr_min, 0, vring_size(RINGSIZE, ALIGN));
 482
 483         /* Set up guest side. */
 484         vq = vring_new_virtqueue(0, RINGSIZE, ALIGN, &vdev, true, false,
 485                                  __user_addr_min,
 486                                  never_notify_host, never_callback_guest,
 487                                  "guest vq");
 488
 489         /* Set up host side. */
 490         vring_init(&vrh.vring, RINGSIZE, __user_addr_min, ALIGN);
 491         vringh_init_user(&vrh, vdev.features, RINGSIZE, true,
 492                          vrh.vring.desc, vrh.vring.avail, vrh.vring.used);
 493
 494         /* No descriptor to get yet... */
 495         err = vringh_getdesc_user(&vrh, &riov, &wiov, getrange, &head);
 496         if (err != 0)
 497                 errx(1, "vringh_getdesc_user: %i", err);
 498
 499         /* Guest puts in a descriptor. */
 500         memcpy(__user_addr_max - 1, "a", 1);
 501         sg_init_table(guest_sg, 1);
 502         sg_set_buf(&guest_sg[0], __user_addr_max - 1, 1);
 503         sg_init_table(guest_sg+1, 1);
 504         sg_set_buf(&guest_sg[1], __user_addr_max - 3, 2);
 505         sgs[0] = &guest_sg[0];
 506         sgs[1] = &guest_sg[1];
 507
 508         /* May allocate an indirect, so force it to allocate user addr */
 509         __kmalloc_fake = __user_addr_min + vring_size(RINGSIZE, ALIGN);
 510         err = virtqueue_add_sgs(vq, sgs, 1, 1, &err, GFP_KERNEL);
 511         if (err)
 512                 errx(1, "virtqueue_add_sgs: %i", err);
 513         __kmalloc_fake = NULL;
 514
 515         /* Host retreives it. */
 516         vringh_iov_init(&riov, host_riov, ARRAY_SIZE(host_riov));
 517         vringh_iov_init(&wiov, host_wiov, ARRAY_SIZE(host_wiov));
 518
 519         err = vringh_getdesc_user(&vrh, &riov, &wiov, getrange, &head);
 520         if (err != 1)
 521                 errx(1, "vringh_getdesc_user: %i", err);
 522
 523         assert(riov.used == 1);
 524         assert(riov.iov[0].iov_base == __user_addr_max - 1);
 525         assert(riov.iov[0].iov_len == 1);
 526         if (getrange != getrange_slow) {
 527                 assert(wiov.used == 1);
 528                 assert(wiov.iov[0].iov_base == __user_addr_max - 3);
 529                 assert(wiov.iov[0].iov_len == 2);
 530         } else {
 531                 assert(wiov.used == 2);
 532                 assert(wiov.iov[0].iov_base == __user_addr_max - 3);
 533                 assert(wiov.iov[0].iov_len == 1);
 534                 assert(wiov.iov[1].iov_base == __user_addr_max - 2);
 535                 assert(wiov.iov[1].iov_len == 1);
 536         }
 537
 538         err = vringh_iov_pull_user(&riov, buf, 5);
 539         if (err != 1)
 540                 errx(1, "vringh_iov_pull_user: %i", err);
 541         assert(buf[0] == 'a');
 542         assert(riov.i == 1);
 543         assert(vringh_iov_pull_user(&riov, buf, 5) == 0);
 544
 545         memcpy(buf, "bcdef", 5);
 546         err = vringh_iov_push_user(&wiov, buf, 5);
 547         if (err != 2)
 548                 errx(1, "vringh_iov_push_user: %i", err);
 549         assert(memcmp(__user_addr_max - 3, "bc", 2) == 0);
 550         assert(wiov.i == wiov.used);
 551         assert(vringh_iov_push_user(&wiov, buf, 5) == 0);
 552
 553         /* Host is done. */
 554         err = vringh_complete_user(&vrh, head, err);
 555         if (err != 0)
 556                 errx(1, "vringh_complete_user: %i", err);
 557
 558         /* Guest should see used token now. */
 559         __kfree_ignore_start = __user_addr_min + vring_size(RINGSIZE, ALIGN);
 560         __kfree_ignore_end = __kfree_ignore_start + 1;
 561         ret = virtqueue_get_buf(vq, &i);
 562         if (ret != &err)
 563                 errx(1, "virtqueue_get_buf: %p", ret);
 564         assert(i == 2);
 565
 566         /* Guest puts in a huge descriptor. */
 567         sg_init_table(guest_sg, RINGSIZE);
 568         for (i = 0; i < RINGSIZE; i++) {
 569                 sg_set_buf(&guest_sg[i],
 570                            __user_addr_max - USER_MEM/4, USER_MEM/4);
 571         }
 572
 573         /* Fill contents with recognisable garbage. */
 574         for (i = 0; i < USER_MEM/4; i++)
 575                 ((char *)__user_addr_max - USER_MEM/4)[i] = i;
 576
 577         /* This will allocate an indirect, so force it to allocate user addr */
 578         __kmalloc_fake = __user_addr_min + vring_size(RINGSIZE, ALIGN);
 579         err = virtqueue_add_outbuf(vq, guest_sg, RINGSIZE, &err, GFP_KERNEL);
 580         if (err)
 581                 errx(1, "virtqueue_add_outbuf (large): %i", err);
 582         __kmalloc_fake = NULL;
 583
 584         /* Host picks it up (allocates new iov). */
 585         vringh_iov_init(&riov, host_riov, ARRAY_SIZE(host_riov));
 586         vringh_iov_init(&wiov, host_wiov, ARRAY_SIZE(host_wiov));
 587
 588         err = vringh_getdesc_user(&vrh, &riov, &wiov, getrange, &head);
 589         if (err != 1)
 590                 errx(1, "vringh_getdesc_user: %i", err);
 591
 592         assert(riov.max_num & VRINGH_IOV_ALLOCATED);
 593         assert(riov.iov != host_riov);
 594         if (getrange != getrange_slow)
 595                 assert(riov.used == RINGSIZE);
 596         else
 597                 assert(riov.used == RINGSIZE * USER_MEM/4);
 598
 599         assert(!(wiov.max_num & VRINGH_IOV_ALLOCATED));
 600         assert(wiov.used == 0);
 601
 602         /* Pull data back out (in odd chunks), should be as expected. */
 603         for (i = 0; i < RINGSIZE * USER_MEM/4; i += 3) {
 604                 err = vringh_iov_pull_user(&riov, buf, 3);
 605                 if (err != 3 && i + err != RINGSIZE * USER_MEM/4)
 606                         errx(1, "vringh_iov_pull_user large: %i", err);
 607                 assert(buf[0] == (char)i);
 608                 assert(err < 2 || buf[1] == (char)(i + 1));
 609                 assert(err < 3 || buf[2] == (char)(i + 2));
 610         }
 611         assert(riov.i == riov.used);
 612         vringh_iov_cleanup(&riov);
 613         vringh_iov_cleanup(&wiov);
 614
 615         /* Complete using multi interface, just because we can. */
 616         used[0].id = head;
 617         used[0].len = 0;
 618         err = vringh_complete_multi_user(&vrh, used, 1);
 619         if (err)
 620                 errx(1, "vringh_complete_multi_user(1): %i", err);
 621
 622         /* Free up those descriptors. */
 623         ret = virtqueue_get_buf(vq, &i);
 624         if (ret != &err)
 625                 errx(1, "virtqueue_get_buf: %p", ret);
 626
 627         /* Add lots of descriptors. */
 628         sg_init_table(guest_sg, 1);
 629         sg_set_buf(&guest_sg[0], __user_addr_max - 1, 1);
 630         for (i = 0; i < RINGSIZE; i++) {
 631                 err = virtqueue_add_outbuf(vq, guest_sg, 1, &err, GFP_KERNEL);
 632                 if (err)
 633                         errx(1, "virtqueue_add_outbuf (multiple): %i", err);
 634         }
 635
 636         /* Now get many, and consume them all at once. */
 637         vringh_iov_init(&riov, host_riov, ARRAY_SIZE(host_riov));
 638         vringh_iov_init(&wiov, host_wiov, ARRAY_SIZE(host_wiov));
 639
 640         for (i = 0; i < RINGSIZE; i++) {
 641                 err = vringh_getdesc_user(&vrh, &riov, &wiov, getrange, &head);
 642                 if (err != 1)
 643                         errx(1, "vringh_getdesc_user: %i", err);
 644                 used[i].id = head;
 645                 used[i].len = 0;
 646         }
 647         /* Make sure it wraps around ring, to test! */
 648         assert(vrh.vring.used->idx % RINGSIZE != 0);
 649         err = vringh_complete_multi_user(&vrh, used, RINGSIZE);
 650         if (err)
 651                 errx(1, "vringh_complete_multi_user: %i", err);
 652
 653         /* Free those buffers. */
 654         for (i = 0; i < RINGSIZE; i++) {
 655                 unsigned len;
 656                 assert(virtqueue_get_buf(vq, &len) != NULL);
 657         }
 658
 659         /* Test weird (but legal!) indirect. */
 660         if (__virtio_test_bit(&vdev, VIRTIO_RING_F_INDIRECT_DESC)) {
 661                 char *data = __user_addr_max - USER_MEM/4;
 662                 struct vring_desc *d = __user_addr_max - USER_MEM/2;
 663                 struct vring vring;
 664
 665                 /* Force creation of direct, which we modify. */
 666                 __virtio_clear_bit(&vdev, VIRTIO_RING_F_INDIRECT_DESC);
 667                 vq = vring_new_virtqueue(0, RINGSIZE, ALIGN, &vdev, true,
 668                                          false, __user_addr_min,
 669                                          never_notify_host,
 670                                          never_callback_guest,
 671                                          "guest vq");
 672
 673                 sg_init_table(guest_sg, 4);
 674                 sg_set_buf(&guest_sg[0], d, sizeof(*d)*2);
 675                 sg_set_buf(&guest_sg[1], d + 2, sizeof(*d)*1);
 676                 sg_set_buf(&guest_sg[2], data + 6, 4);
 677                 sg_set_buf(&guest_sg[3], d + 3, sizeof(*d)*3);
 678
 679                 err = virtqueue_add_outbuf(vq, guest_sg, 4, &err, GFP_KERNEL);
 680                 if (err)
 681                         errx(1, "virtqueue_add_outbuf (indirect): %i", err);
 682
 683                 vring_init(&vring, RINGSIZE, __user_addr_min, ALIGN);
 684
 685                 /* They're used in order, but double-check... */
 686                 assert(vring.desc[0].addr == (unsigned long)d);
 687                 assert(vring.desc[1].addr == (unsigned long)(d+2));
 688                 assert(vring.desc[2].addr == (unsigned long)data + 6);
 689                 assert(vring.desc[3].addr == (unsigned long)(d+3));
 690                 vring.desc[0].flags |= VRING_DESC_F_INDIRECT;
 691                 vring.desc[1].flags |= VRING_DESC_F_INDIRECT;
 692                 vring.desc[3].flags |= VRING_DESC_F_INDIRECT;
 693
 694                 /* First indirect */
 695                 d[0].addr = (unsigned long)data;
 696                 d[0].len = 1;
 697                 d[0].flags = VRING_DESC_F_NEXT;
 698                 d[0].next = 1;
 699                 d[1].addr = (unsigned long)data + 1;
 700                 d[1].len = 2;
 701                 d[1].flags = 0;
 702
 703                 /* Second indirect */
 704                 d[2].addr = (unsigned long)data + 3;
 705                 d[2].len = 3;
 706                 d[2].flags = 0;
 707
 708                 /* Third indirect */
 709                 d[3].addr = (unsigned long)data + 10;
 710                 d[3].len = 5;
 711                 d[3].flags = VRING_DESC_F_NEXT;
 712                 d[3].next = 1;
 713                 d[4].addr = (unsigned long)data + 15;
 714                 d[4].len = 6;
 715                 d[4].flags = VRING_DESC_F_NEXT;
 716                 d[4].next = 2;
 717                 d[5].addr = (unsigned long)data + 21;
 718                 d[5].len = 7;
 719                 d[5].flags = 0;
 720
 721                 /* Host picks it up (allocates new iov). */
 722                 vringh_iov_init(&riov, host_riov, ARRAY_SIZE(host_riov));
 723                 vringh_iov_init(&wiov, host_wiov, ARRAY_SIZE(host_wiov));
 724
 725                 err = vringh_getdesc_user(&vrh, &riov, &wiov, getrange, &head);
 726                 if (err != 1)
 727                         errx(1, "vringh_getdesc_user: %i", err);
 728
 729                 if (head != 0)
 730                         errx(1, "vringh_getdesc_user: head %i not 0", head);
 731
 732                 assert(riov.max_num & VRINGH_IOV_ALLOCATED);
 733                 if (getrange != getrange_slow)
 734                         assert(riov.used == 7);
 735                 else
 736                         assert(riov.used == 28);
 737                 err = vringh_iov_pull_user(&riov, buf, 29);
 738                 assert(err == 28);
 739
 740                 /* Data should be linear. */
 741                 for (i = 0; i < err; i++)
 742                         assert(buf[i] == i);
 743                 vringh_iov_cleanup(&riov);
 744         }
 745
 746         /* Don't leak memory... */
 747         vring_del_virtqueue(vq);
 748         free(__user_addr_min);
 749
 750         return 0;
 751 }