hw/virtio.c

   1 /*
   2  * Virtio Support
   3  *
   4  * Copyright IBM, Corp. 2007
   5  *
   6  * Authors:
   7  *  Anthony Liguori   <aliguori@us.ibm.com>
   8  *
   9  * This work is licensed under the terms of the GNU GPL, version 2.  See
  10  * the COPYING file in the top-level directory.
  11  *
  12  */
  13
  14 #include <inttypes.h>
  15
  16 #include "trace.h"
  17 #include "qemu-error.h"
  18 #include "virtio.h"
  19
  20 /* The alignment to use between consumer and producer parts of vring.
  21  * x86 pagesize again. */
  22 #define VIRTIO_PCI_VRING_ALIGN         4096
  23
  24 /* QEMU doesn't strictly need write barriers since everything runs in
  25  * lock-step.  We'll leave the calls to wmb() in though to make it obvious for
  26  * KVM or if kqemu gets SMP support.
  27  * In any case, we must prevent the compiler from reordering the code.
  28  * TODO: we likely need some rmb()/mb() as well.
  29  */
  30
  31 #define wmb() __asm__ __volatile__("": : :"memory")
  32
  33 typedef struct VRingDesc
  34 {
  35     uint64_t addr;
  36     uint32_t len;
  37     uint16_t flags;
  38     uint16_t next;
  39 } VRingDesc;
  40
  41 typedef struct VRingAvail
  42 {
  43     uint16_t flags;
  44     uint16_t idx;
  45     uint16_t ring[0];
  46 } VRingAvail;
  47
  48 typedef struct VRingUsedElem
  49 {
  50     uint32_t id;
  51     uint32_t len;
  52 } VRingUsedElem;
  53
  54 typedef struct VRingUsed
  55 {
  56     uint16_t flags;
  57     uint16_t idx;
  58     VRingUsedElem ring[0];
  59 } VRingUsed;
  60
  61 typedef struct VRing
  62 {
  63     unsigned int num;
  64     target_phys_addr_t desc;
  65     target_phys_addr_t avail;
  66     target_phys_addr_t used;
  67 } VRing;
  68
  69 struct VirtQueue
  70 {
  71     VRing vring;
  72     target_phys_addr_t pa;
  73     uint16_t last_avail_idx;
  74     /* Last used index value we have signalled on */
  75     uint16_t signalled_used;
  76
  77     /* Last used index value we have signalled on */
  78     bool signalled_used_valid;
  79
  80     /* Notification enabled? */
  81     bool notification;
  82
  83     int inuse;
  84
  85     uint16_t vector;
  86     void (*handle_output)(VirtIODevice *vdev, VirtQueue *vq);
  87     VirtIODevice *vdev;
  88     EventNotifier guest_notifier;
  89     EventNotifier host_notifier;
  90 };
  91
  92 /* virt queue functions */
  93 static void virtqueue_init(VirtQueue *vq)
  94 {
  95     target_phys_addr_t pa = vq->pa;
  96
  97     vq->vring.desc = pa;
  98     vq->vring.avail = pa + vq->vring.num * sizeof(VRingDesc);
  99     vq->vring.used = vring_align(vq->vring.avail +
 100                                  offsetof(VRingAvail, ring[vq->vring.num]),
 101                                  VIRTIO_PCI_VRING_ALIGN);
 102 }
 103
 104 static inline uint64_t vring_desc_addr(target_phys_addr_t desc_pa, int i)
 105 {
 106     target_phys_addr_t pa;
 107     pa = desc_pa + sizeof(VRingDesc) * i + offsetof(VRingDesc, addr);
 108     return ldq_phys(pa);
 109 }
 110
 111 static inline uint32_t vring_desc_len(target_phys_addr_t desc_pa, int i)
 112 {
 113     target_phys_addr_t pa;
 114     pa = desc_pa + sizeof(VRingDesc) * i + offsetof(VRingDesc, len);
 115     return ldl_phys(pa);
 116 }
 117
 118 static inline uint16_t vring_desc_flags(target_phys_addr_t desc_pa, int i)
 119 {
 120     target_phys_addr_t pa;
 121     pa = desc_pa + sizeof(VRingDesc) * i + offsetof(VRingDesc, flags);
 122     return lduw_phys(pa);
 123 }
 124
 125 static inline uint16_t vring_desc_next(target_phys_addr_t desc_pa, int i)
 126 {
 127     target_phys_addr_t pa;
 128     pa = desc_pa + sizeof(VRingDesc) * i + offsetof(VRingDesc, next);
 129     return lduw_phys(pa);
 130 }
 131
 132 static inline uint16_t vring_avail_flags(VirtQueue *vq)
 133 {
 134     target_phys_addr_t pa;
 135     pa = vq->vring.avail + offsetof(VRingAvail, flags);
 136     return lduw_phys(pa);
 137 }
 138
 139 static inline uint16_t vring_avail_idx(VirtQueue *vq)
 140 {
 141     target_phys_addr_t pa;
 142     pa = vq->vring.avail + offsetof(VRingAvail, idx);
 143     return lduw_phys(pa);
 144 }
 145
 146 static inline uint16_t vring_avail_ring(VirtQueue *vq, int i)
 147 {
 148     target_phys_addr_t pa;
 149     pa = vq->vring.avail + offsetof(VRingAvail, ring[i]);
 150     return lduw_phys(pa);
 151 }
 152
 153 static inline uint16_t vring_used_event(VirtQueue *vq)
 154 {
 155     return vring_avail_ring(vq, vq->vring.num);
 156 }
 157
 158 static inline void vring_used_ring_id(VirtQueue *vq, int i, uint32_t val)
 159 {
 160     target_phys_addr_t pa;
 161     pa = vq->vring.used + offsetof(VRingUsed, ring[i].id);
 162     stl_phys(pa, val);
 163 }
 164
 165 static inline void vring_used_ring_len(VirtQueue *vq, int i, uint32_t val)
 166 {
 167     target_phys_addr_t pa;
 168     pa = vq->vring.used + offsetof(VRingUsed, ring[i].len);
 169     stl_phys(pa, val);
 170 }
 171
 172 static uint16_t vring_used_idx(VirtQueue *vq)
 173 {
 174     target_phys_addr_t pa;
 175     pa = vq->vring.used + offsetof(VRingUsed, idx);
 176     return lduw_phys(pa);
 177 }
 178
 179 static inline void vring_used_idx_set(VirtQueue *vq, uint16_t val)
 180 {
 181     target_phys_addr_t pa;
 182     pa = vq->vring.used + offsetof(VRingUsed, idx);
 183     stw_phys(pa, val);
 184 }
 185
 186 static inline void vring_used_flags_set_bit(VirtQueue *vq, int mask)
 187 {
 188     target_phys_addr_t pa;
 189     pa = vq->vring.used + offsetof(VRingUsed, flags);
 190     stw_phys(pa, lduw_phys(pa) | mask);
 191 }
 192
 193 static inline void vring_used_flags_unset_bit(VirtQueue *vq, int mask)
 194 {
 195     target_phys_addr_t pa;
 196     pa = vq->vring.used + offsetof(VRingUsed, flags);
 197     stw_phys(pa, lduw_phys(pa) & ~mask);
 198 }
 199
 200 static inline void vring_avail_event(VirtQueue *vq, uint16_t val)
 201 {
 202     target_phys_addr_t pa;
 203     if (!vq->notification) {
 204         return;
 205     }
 206     pa = vq->vring.used + offsetof(VRingUsed, ring[vq->vring.num]);
 207     stw_phys(pa, val);
 208 }
 209
 210 void virtio_queue_set_notification(VirtQueue *vq, int enable)
 211 {
 212     vq->notification = enable;
 213     if (vq->vdev->guest_features & (1 << VIRTIO_RING_F_EVENT_IDX)) {
 214         vring_avail_event(vq, vring_avail_idx(vq));
 215     } else if (enable) {
 216         vring_used_flags_unset_bit(vq, VRING_USED_F_NO_NOTIFY);
 217     } else {
 218         vring_used_flags_set_bit(vq, VRING_USED_F_NO_NOTIFY);
 219     }
 220 }
 221
 222 int virtio_queue_ready(VirtQueue *vq)
 223 {
 224     return vq->vring.avail != 0;
 225 }
 226
 227 int virtio_queue_empty(VirtQueue *vq)
 228 {
 229     return vring_avail_idx(vq) == vq->last_avail_idx;
 230 }
 231
 232 void virtqueue_fill(VirtQueue *vq, const VirtQueueElement *elem,
 233                     unsigned int len, unsigned int idx)
 234 {
 235     unsigned int offset;
 236     int i;
 237
 238     trace_virtqueue_fill(vq, elem, len, idx);
 239
 240     offset = 0;
 241     for (i = 0; i < elem->in_num; i++) {
 242         size_t size = MIN(len - offset, elem->in_sg[i].iov_len);
 243
 244         cpu_physical_memory_unmap(elem->in_sg[i].iov_base,
 245                                   elem->in_sg[i].iov_len,
 246                                   1, size);
 247
 248         offset += elem->in_sg[i].iov_len;
 249     }
 250
 251     for (i = 0; i < elem->out_num; i++)
 252         cpu_physical_memory_unmap(elem->out_sg[i].iov_base,
 253                                   elem->out_sg[i].iov_len,
 254                                   0, elem->out_sg[i].iov_len);
 255
 256     idx = (idx + vring_used_idx(vq)) % vq->vring.num;
 257
 258     /* Get a pointer to the next entry in the used ring. */
 259     vring_used_ring_id(vq, idx, elem->index);
 260     vring_used_ring_len(vq, idx, len);
 261 }
 262
 263 void virtqueue_flush(VirtQueue *vq, unsigned int count)
 264 {
 265     uint16_t old, new;
 266     /* Make sure buffer is written before we update index. */
 267     wmb();
 268     trace_virtqueue_flush(vq, count);
 269     old = vring_used_idx(vq);
 270     new = old + count;
 271     vring_used_idx_set(vq, new);
 272     vq->inuse -= count;
 273     if (unlikely((int16_t)(new - vq->signalled_used) < (uint16_t)(new - old)))
 274         vq->signalled_used_valid = false;
 275 }
 276
 277 void virtqueue_push(VirtQueue *vq, const VirtQueueElement *elem,
 278                     unsigned int len)
 279 {
 280     virtqueue_fill(vq, elem, len, 0);
 281     virtqueue_flush(vq, 1);
 282 }
 283
 284 static int virtqueue_num_heads(VirtQueue *vq, unsigned int idx)
 285 {
 286     uint16_t num_heads = vring_avail_idx(vq) - idx;
 287
 288     /* Check it isn't doing very strange things with descriptor numbers. */
 289     if (num_heads > vq->vring.num) {
 290         error_report("Guest moved used index from %u to %u",
 291                      idx, vring_avail_idx(vq));
 292         exit(1);
 293     }
 294
 295     return num_heads;
 296 }
 297
 298 static unsigned int virtqueue_get_head(VirtQueue *vq, unsigned int idx)
 299 {
 300     unsigned int head;
 301
 302     /* Grab the next descriptor number they're advertising, and increment
 303      * the index we've seen. */
 304     head = vring_avail_ring(vq, idx % vq->vring.num);
 305
 306     /* If their number is silly, that's a fatal mistake. */
 307     if (head >= vq->vring.num) {
 308         error_report("Guest says index %u is available", head);
 309         exit(1);
 310     }
 311
 312     return head;
 313 }
 314
 315 static unsigned virtqueue_next_desc(target_phys_addr_t desc_pa,
 316                                     unsigned int i, unsigned int max)
 317 {
 318     unsigned int next;
 319
 320     /* If this descriptor says it doesn't chain, we're done. */
 321     if (!(vring_desc_flags(desc_pa, i) & VRING_DESC_F_NEXT))
 322         return max;
 323
 324     /* Check they're not leading us off end of descriptors. */
 325     next = vring_desc_next(desc_pa, i);
 326     /* Make sure compiler knows to grab that: we don't want it changing! */
 327     wmb();
 328
 329     if (next >= max) {
 330         error_report("Desc next is %u", next);
 331         exit(1);
 332     }
 333
 334     return next;
 335 }
 336
 337 int virtqueue_avail_bytes(VirtQueue *vq, int in_bytes, int out_bytes)
 338 {
 339     unsigned int idx;
 340     int total_bufs, in_total, out_total;
 341
 342     idx = vq->last_avail_idx;
 343
 344     total_bufs = in_total = out_total = 0;
 345     while (virtqueue_num_heads(vq, idx)) {
 346         unsigned int max, num_bufs, indirect = 0;
 347         target_phys_addr_t desc_pa;
 348         int i;
 349
 350         max = vq->vring.num;
 351         num_bufs = total_bufs;
 352         i = virtqueue_get_head(vq, idx++);
 353         desc_pa = vq->vring.desc;
 354
 355         if (vring_desc_flags(desc_pa, i) & VRING_DESC_F_INDIRECT) {
 356             if (vring_desc_len(desc_pa, i) % sizeof(VRingDesc)) {
 357                 error_report("Invalid size for indirect buffer table");
 358                 exit(1);
 359             }
 360
 361             /* If we've got too many, that implies a descriptor loop. */
 362             if (num_bufs >= max) {
 363                 error_report("Looped descriptor");
 364                 exit(1);
 365             }
 366
 367             /* loop over the indirect descriptor table */
 368             indirect = 1;
 369             max = vring_desc_len(desc_pa, i) / sizeof(VRingDesc);
 370             num_bufs = i = 0;
 371             desc_pa = vring_desc_addr(desc_pa, i);
 372         }
 373
 374         do {
 375             /* If we've got too many, that implies a descriptor loop. */
 376             if (++num_bufs > max) {
 377                 error_report("Looped descriptor");
 378                 exit(1);
 379             }
 380
 381             if (vring_desc_flags(desc_pa, i) & VRING_DESC_F_WRITE) {
 382                 if (in_bytes > 0 &&
 383                     (in_total += vring_desc_len(desc_pa, i)) >= in_bytes)
 384                     return 1;
 385             } else {
 386                 if (out_bytes > 0 &&
 387                     (out_total += vring_desc_len(desc_pa, i)) >= out_bytes)
 388                     return 1;
 389             }
 390         } while ((i = virtqueue_next_desc(desc_pa, i, max)) != max);
 391
 392         if (!indirect)
 393             total_bufs = num_bufs;
 394         else
 395             total_bufs++;
 396     }
 397
 398     return 0;
 399 }
 400
 401 void virtqueue_map_sg(struct iovec *sg, target_phys_addr_t *addr,
 402     size_t num_sg, int is_write)
 403 {
 404     unsigned int i;
 405     target_phys_addr_t len;
 406
 407     for (i = 0; i < num_sg; i++) {
 408         len = sg[i].iov_len;
 409         sg[i].iov_base = cpu_physical_memory_map(addr[i], &len, is_write);
 410         if (sg[i].iov_base == NULL || len != sg[i].iov_len) {
 411             error_report("virtio: trying to map MMIO memory");
 412             exit(1);
 413         }
 414     }
 415 }
 416
 417 int virtqueue_pop(VirtQueue *vq, VirtQueueElement *elem)
 418 {
 419     unsigned int i, head, max;
 420     target_phys_addr_t desc_pa = vq->vring.desc;
 421
 422     if (!virtqueue_num_heads(vq, vq->last_avail_idx))
 423         return 0;
 424
 425     /* When we start there are none of either input nor output. */
 426     elem->out_num = elem->in_num = 0;
 427
 428     max = vq->vring.num;
 429
 430     i = head = virtqueue_get_head(vq, vq->last_avail_idx++);
 431     if (vq->vdev->guest_features & (1 << VIRTIO_RING_F_EVENT_IDX)) {
 432         vring_avail_event(vq, vring_avail_idx(vq));
 433     }
 434
 435     if (vring_desc_flags(desc_pa, i) & VRING_DESC_F_INDIRECT) {
 436         if (vring_desc_len(desc_pa, i) % sizeof(VRingDesc)) {
 437             error_report("Invalid size for indirect buffer table");
 438             exit(1);
 439         }
 440
 441         /* loop over the indirect descriptor table */
 442         max = vring_desc_len(desc_pa, i) / sizeof(VRingDesc);
 443         desc_pa = vring_desc_addr(desc_pa, i);
 444         i = 0;
 445     }
 446
 447     /* Collect all the descriptors */
 448     do {
 449         struct iovec *sg;
 450
 451         if (vring_desc_flags(desc_pa, i) & VRING_DESC_F_WRITE) {
 452             if (elem->in_num >= ARRAY_SIZE(elem->in_sg)) {
 453                 error_report("Too many write descriptors in indirect table");
 454                 exit(1);
 455             }
 456             elem->in_addr[elem->in_num] = vring_desc_addr(desc_pa, i);
 457             sg = &elem->in_sg[elem->in_num++];
 458         } else {
 459             if (elem->out_num >= ARRAY_SIZE(elem->out_sg)) {
 460                 error_report("Too many read descriptors in indirect table");
 461                 exit(1);
 462             }
 463             elem->out_addr[elem->out_num] = vring_desc_addr(desc_pa, i);
 464             sg = &elem->out_sg[elem->out_num++];
 465         }
 466
 467         sg->iov_len = vring_desc_len(desc_pa, i);
 468
 469         /* If we've got too many, that implies a descriptor loop. */
 470         if ((elem->in_num + elem->out_num) > max) {
 471             error_report("Looped descriptor");
 472             exit(1);
 473         }
 474     } while ((i = virtqueue_next_desc(desc_pa, i, max)) != max);
 475
 476     /* Now map what we have collected */
 477     virtqueue_map_sg(elem->in_sg, elem->in_addr, elem->in_num, 1);
 478     virtqueue_map_sg(elem->out_sg, elem->out_addr, elem->out_num, 0);
 479
 480     elem->index = head;
 481
 482     vq->inuse++;
 483
 484     trace_virtqueue_pop(vq, elem, elem->in_num, elem->out_num);
 485     return elem->in_num + elem->out_num;
 486 }
 487
 488 /* virtio device */
 489 static void virtio_notify_vector(VirtIODevice *vdev, uint16_t vector)
 490 {
 491     if (vdev->binding->notify) {
 492         vdev->binding->notify(vdev->binding_opaque, vector);
 493     }
 494 }
 495
 496 void virtio_update_irq(VirtIODevice *vdev)
 497 {
 498     virtio_notify_vector(vdev, VIRTIO_NO_VECTOR);
 499 }
 500
 501 void virtio_reset(void *opaque)
 502 {
 503     VirtIODevice *vdev = opaque;
 504     int i;
 505
 506     virtio_set_status(vdev, 0);
 507
 508     if (vdev->reset)
 509         vdev->reset(vdev);
 510
 511     vdev->guest_features = 0;
 512     vdev->queue_sel = 0;
 513     vdev->status = 0;
 514     vdev->isr = 0;
 515     vdev->config_vector = VIRTIO_NO_VECTOR;
 516     virtio_notify_vector(vdev, vdev->config_vector);
 517
 518     for(i = 0; i < VIRTIO_PCI_QUEUE_MAX; i++) {
 519         vdev->vq[i].vring.desc = 0;
 520         vdev->vq[i].vring.avail = 0;
 521         vdev->vq[i].vring.used = 0;
 522         vdev->vq[i].last_avail_idx = 0;
 523         vdev->vq[i].pa = 0;
 524         vdev->vq[i].vector = VIRTIO_NO_VECTOR;
 525         vdev->vq[i].signalled_used = 0;
 526         vdev->vq[i].signalled_used_valid = false;
 527         vdev->vq[i].notification = true;
 528     }
 529 }
 530
 531 uint32_t virtio_config_readb(VirtIODevice *vdev, uint32_t addr)
 532 {
 533     uint8_t val;
 534
 535     vdev->get_config(vdev, vdev->config);
 536
 537     if (addr > (vdev->config_len - sizeof(val)))
 538         return (uint32_t)-1;
 539
 540     memcpy(&val, vdev->config + addr, sizeof(val));
 541     return val;
 542 }
 543
 544 uint32_t virtio_config_readw(VirtIODevice *vdev, uint32_t addr)
 545 {
 546     uint16_t val;
 547
 548     vdev->get_config(vdev, vdev->config);
 549
 550     if (addr > (vdev->config_len - sizeof(val)))
 551         return (uint32_t)-1;
 552
 553     memcpy(&val, vdev->config + addr, sizeof(val));
 554     return val;
 555 }
 556
 557 uint32_t virtio_config_readl(VirtIODevice *vdev, uint32_t addr)
 558 {
 559     uint32_t val;
 560
 561     vdev->get_config(vdev, vdev->config);
 562
 563     if (addr > (vdev->config_len - sizeof(val)))
 564         return (uint32_t)-1;
 565
 566     memcpy(&val, vdev->config + addr, sizeof(val));
 567     return val;
 568 }
 569
 570 void virtio_config_writeb(VirtIODevice *vdev, uint32_t addr, uint32_t data)
 571 {
 572     uint8_t val = data;
 573
 574     if (addr > (vdev->config_len - sizeof(val)))
 575         return;
 576
 577     memcpy(vdev->config + addr, &val, sizeof(val));
 578
 579     if (vdev->set_config)
 580         vdev->set_config(vdev, vdev->config);
 581 }
 582
 583 void virtio_config_writew(VirtIODevice *vdev, uint32_t addr, uint32_t data)
 584 {
 585     uint16_t val = data;
 586
 587     if (addr > (vdev->config_len - sizeof(val)))
 588         return;
 589
 590     memcpy(vdev->config + addr, &val, sizeof(val));
 591
 592     if (vdev->set_config)
 593         vdev->set_config(vdev, vdev->config);
 594 }
 595
 596 void virtio_config_writel(VirtIODevice *vdev, uint32_t addr, uint32_t data)
 597 {
 598     uint32_t val = data;
 599
 600     if (addr > (vdev->config_len - sizeof(val)))
 601         return;
 602
 603     memcpy(vdev->config + addr, &val, sizeof(val));
 604
 605     if (vdev->set_config)
 606         vdev->set_config(vdev, vdev->config);
 607 }
 608
 609 void virtio_queue_set_addr(VirtIODevice *vdev, int n, target_phys_addr_t addr)
 610 {
 611     vdev->vq[n].pa = addr;
 612     virtqueue_init(&vdev->vq[n]);
 613 }
 614
 615 target_phys_addr_t virtio_queue_get_addr(VirtIODevice *vdev, int n)
 616 {
 617     return vdev->vq[n].pa;
 618 }
 619
 620 int virtio_queue_get_num(VirtIODevice *vdev, int n)
 621 {
 622     return vdev->vq[n].vring.num;
 623 }
 624
 625 void virtio_queue_notify_vq(VirtQueue *vq)
 626 {
 627     if (vq->vring.desc) {
 628         VirtIODevice *vdev = vq->vdev;
 629         trace_virtio_queue_notify(vdev, vq - vdev->vq, vq);
 630         vq->handle_output(vdev, vq);
 631     }
 632 }
 633
 634 void virtio_queue_notify(VirtIODevice *vdev, int n)
 635 {
 636     virtio_queue_notify_vq(&vdev->vq[n]);
 637 }
 638
 639 uint16_t virtio_queue_vector(VirtIODevice *vdev, int n)
 640 {
 641     return n < VIRTIO_PCI_QUEUE_MAX ? vdev->vq[n].vector :
 642         VIRTIO_NO_VECTOR;
 643 }
 644
 645 void virtio_queue_set_vector(VirtIODevice *vdev, int n, uint16_t vector)
 646 {
 647     if (n < VIRTIO_PCI_QUEUE_MAX)
 648         vdev->vq[n].vector = vector;
 649 }
 650
 651 VirtQueue *virtio_add_queue(VirtIODevice *vdev, int queue_size,
 652                             void (*handle_output)(VirtIODevice *, VirtQueue *))
 653 {
 654     int i;
 655
 656     for (i = 0; i < VIRTIO_PCI_QUEUE_MAX; i++) {
 657         if (vdev->vq[i].vring.num == 0)
 658             break;
 659     }
 660
 661     if (i == VIRTIO_PCI_QUEUE_MAX || queue_size > VIRTQUEUE_MAX_SIZE)
 662         abort();
 663
 664     vdev->vq[i].vring.num = queue_size;
 665     vdev->vq[i].handle_output = handle_output;
 666
 667     return &vdev->vq[i];
 668 }
 669
 670 void virtio_irq(VirtQueue *vq)
 671 {
 672     trace_virtio_irq(vq);
 673     vq->vdev->isr |= 0x01;
 674     virtio_notify_vector(vq->vdev, vq->vector);
 675 }
 676
 677 /* Assuming a given event_idx value from the other size, if
 678  * we have just incremented index from old to new_idx,
 679  * should we trigger an event? */
 680 static inline int vring_need_event(uint16_t event, uint16_t new, uint16_t old)
 681 {
 682         /* Note: Xen has similar logic for notification hold-off
 683          * in include/xen/interface/io/ring.h with req_event and req_prod
 684          * corresponding to event_idx + 1 and new respectively.
 685          * Note also that req_event and req_prod in Xen start at 1,
 686          * event indexes in virtio start at 0. */
 687         return (uint16_t)(new - event - 1) < (uint16_t)(new - old);
 688 }
 689
 690 static bool vring_notify(VirtIODevice *vdev, VirtQueue *vq)
 691 {
 692     uint16_t old, new;
 693     bool v;
 694     /* Always notify when queue is empty (when feature acknowledge) */
 695     if (((vdev->guest_features & (1 << VIRTIO_F_NOTIFY_ON_EMPTY)) &&
 696          !vq->inuse && vring_avail_idx(vq) == vq->last_avail_idx)) {
 697         return true;
 698     }
 699
 700     if (!(vdev->guest_features & (1 << VIRTIO_RING_F_EVENT_IDX))) {
 701         return !(vring_avail_flags(vq) & VRING_AVAIL_F_NO_INTERRUPT);
 702     }
 703
 704     v = vq->signalled_used_valid;
 705     vq->signalled_used_valid = true;
 706     old = vq->signalled_used;
 707     new = vq->signalled_used = vring_used_idx(vq);
 708     return !v || vring_need_event(vring_used_event(vq), new, old);
 709 }
 710
 711 void virtio_notify(VirtIODevice *vdev, VirtQueue *vq)
 712 {
 713     if (!vring_notify(vdev, vq)) {
 714         return;
 715     }
 716
 717     trace_virtio_notify(vdev, vq);
 718     vdev->isr |= 0x01;
 719     virtio_notify_vector(vdev, vq->vector);
 720 }
 721
 722 void virtio_notify_config(VirtIODevice *vdev)
 723 {
 724     if (!(vdev->status & VIRTIO_CONFIG_S_DRIVER_OK))
 725         return;
 726
 727     vdev->isr |= 0x03;
 728     virtio_notify_vector(vdev, vdev->config_vector);
 729 }
 730
 731 void virtio_save(VirtIODevice *vdev, QEMUFile *f)
 732 {
 733     int i;
 734
 735     if (vdev->binding->save_config)
 736         vdev->binding->save_config(vdev->binding_opaque, f);
 737
 738     qemu_put_8s(f, &vdev->status);
 739     qemu_put_8s(f, &vdev->isr);
 740     qemu_put_be16s(f, &vdev->queue_sel);
 741     qemu_put_be32s(f, &vdev->guest_features);
 742     qemu_put_be32(f, vdev->config_len);
 743     qemu_put_buffer(f, vdev->config, vdev->config_len);
 744
 745     for (i = 0; i < VIRTIO_PCI_QUEUE_MAX; i++) {
 746         if (vdev->vq[i].vring.num == 0)
 747             break;
 748     }
 749
 750     qemu_put_be32(f, i);
 751
 752     for (i = 0; i < VIRTIO_PCI_QUEUE_MAX; i++) {
 753         if (vdev->vq[i].vring.num == 0)
 754             break;
 755
 756         qemu_put_be32(f, vdev->vq[i].vring.num);
 757         qemu_put_be64(f, vdev->vq[i].pa);
 758         qemu_put_be16s(f, &vdev->vq[i].last_avail_idx);
 759         if (vdev->binding->save_queue)
 760             vdev->binding->save_queue(vdev->binding_opaque, i, f);
 761     }
 762 }
 763
 764 int virtio_load(VirtIODevice *vdev, QEMUFile *f)
 765 {
 766     int num, i, ret;
 767     uint32_t features;
 768     uint32_t supported_features =
 769         vdev->binding->get_features(vdev->binding_opaque);
 770
 771     if (vdev->binding->load_config) {
 772         ret = vdev->binding->load_config(vdev->binding_opaque, f);
 773         if (ret)
 774             return ret;
 775     }
 776
 777     qemu_get_8s(f, &vdev->status);
 778     qemu_get_8s(f, &vdev->isr);
 779     qemu_get_be16s(f, &vdev->queue_sel);
 780     qemu_get_be32s(f, &features);
 781     if (features & ~supported_features) {
 782         error_report("Features 0x%x unsupported. Allowed features: 0x%x",
 783                      features, supported_features);
 784         return -1;
 785     }
 786     if (vdev->set_features)
 787         vdev->set_features(vdev, features);
 788     vdev->guest_features = features;
 789     vdev->config_len = qemu_get_be32(f);
 790     qemu_get_buffer(f, vdev->config, vdev->config_len);
 791
 792     num = qemu_get_be32(f);
 793
 794     for (i = 0; i < num; i++) {
 795         vdev->vq[i].vring.num = qemu_get_be32(f);
 796         vdev->vq[i].pa = qemu_get_be64(f);
 797         qemu_get_be16s(f, &vdev->vq[i].last_avail_idx);
 798         vdev->vq[i].signalled_used_valid = false;
 799         vdev->vq[i].notification = true;
 800
 801         if (vdev->vq[i].pa) {
 802             uint16_t nheads;
 803             virtqueue_init(&vdev->vq[i]);
 804             nheads = vring_avail_idx(&vdev->vq[i]) - vdev->vq[i].last_avail_idx;
 805             /* Check it isn't doing very strange things with descriptor numbers. */
 806             if (nheads > vdev->vq[i].vring.num) {
 807                 error_report("VQ %d size 0x%x Guest index 0x%x "
 808                              "inconsistent with Host index 0x%x: delta 0x%x",
 809                              i, vdev->vq[i].vring.num,
 810                              vring_avail_idx(&vdev->vq[i]),
 811                              vdev->vq[i].last_avail_idx, nheads);
 812                 return -1;
 813             }
 814         } else if (vdev->vq[i].last_avail_idx) {
 815             error_report("VQ %d address 0x0 "
 816                          "inconsistent with Host index 0x%x",
 817                          i, vdev->vq[i].last_avail_idx);
 818                 return -1;
 819         }
 820         if (vdev->binding->load_queue) {
 821             ret = vdev->binding->load_queue(vdev->binding_opaque, i, f);
 822             if (ret)
 823                 return ret;
 824         }
 825     }
 826
 827     virtio_notify_vector(vdev, VIRTIO_NO_VECTOR);
 828     return 0;
 829 }
 830
 831 void virtio_cleanup(VirtIODevice *vdev)
 832 {
 833     qemu_del_vm_change_state_handler(vdev->vmstate);
 834     if (vdev->config)
 835         qemu_free(vdev->config);
 836     qemu_free(vdev->vq);
 837 }
 838
 839 static void virtio_vmstate_change(void *opaque, int running, int reason)
 840 {
 841     VirtIODevice *vdev = opaque;
 842     bool backend_run = running && (vdev->status & VIRTIO_CONFIG_S_DRIVER_OK);
 843     vdev->vm_running = running;
 844
 845     if (backend_run) {
 846         virtio_set_status(vdev, vdev->status);
 847     }
 848
 849     if (vdev->binding->vmstate_change) {
 850         vdev->binding->vmstate_change(vdev->binding_opaque, backend_run);
 851     }
 852
 853     if (!backend_run) {
 854         virtio_set_status(vdev, vdev->status);
 855     }
 856 }
 857
 858 VirtIODevice *virtio_common_init(const char *name, uint16_t device_id,
 859                                  size_t config_size, size_t struct_size)
 860 {
 861     VirtIODevice *vdev;
 862     int i;
 863
 864     vdev = qemu_mallocz(struct_size);
 865
 866     vdev->device_id = device_id;
 867     vdev->status = 0;
 868     vdev->isr = 0;
 869     vdev->queue_sel = 0;
 870     vdev->config_vector = VIRTIO_NO_VECTOR;
 871     vdev->vq = qemu_mallocz(sizeof(VirtQueue) * VIRTIO_PCI_QUEUE_MAX);
 872     vdev->vm_running = vm_running;
 873     for(i = 0; i < VIRTIO_PCI_QUEUE_MAX; i++) {
 874         vdev->vq[i].vector = VIRTIO_NO_VECTOR;
 875         vdev->vq[i].vdev = vdev;
 876     }
 877
 878     vdev->name = name;
 879     vdev->config_len = config_size;
 880     if (vdev->config_len)
 881         vdev->config = qemu_mallocz(config_size);
 882     else
 883         vdev->config = NULL;
 884
 885     vdev->vmstate = qemu_add_vm_change_state_handler(virtio_vmstate_change, vdev);
 886
 887     return vdev;
 888 }
 889
 890 void virtio_bind_device(VirtIODevice *vdev, const VirtIOBindings *binding,
 891                         void *opaque)
 892 {
 893     vdev->binding = binding;
 894     vdev->binding_opaque = opaque;
 895 }
 896
 897 target_phys_addr_t virtio_queue_get_desc_addr(VirtIODevice *vdev, int n)
 898 {
 899     return vdev->vq[n].vring.desc;
 900 }
 901
 902 target_phys_addr_t virtio_queue_get_avail_addr(VirtIODevice *vdev, int n)
 903 {
 904     return vdev->vq[n].vring.avail;
 905 }
 906
 907 target_phys_addr_t virtio_queue_get_used_addr(VirtIODevice *vdev, int n)
 908 {
 909     return vdev->vq[n].vring.used;
 910 }
 911
 912 target_phys_addr_t virtio_queue_get_ring_addr(VirtIODevice *vdev, int n)
 913 {
 914     return vdev->vq[n].vring.desc;
 915 }
 916
 917 target_phys_addr_t virtio_queue_get_desc_size(VirtIODevice *vdev, int n)
 918 {
 919     return sizeof(VRingDesc) * vdev->vq[n].vring.num;
 920 }
 921
 922 target_phys_addr_t virtio_queue_get_avail_size(VirtIODevice *vdev, int n)
 923 {
 924     return offsetof(VRingAvail, ring) +
 925         sizeof(uint64_t) * vdev->vq[n].vring.num;
 926 }
 927
 928 target_phys_addr_t virtio_queue_get_used_size(VirtIODevice *vdev, int n)
 929 {
 930     return offsetof(VRingUsed, ring) +
 931         sizeof(VRingUsedElem) * vdev->vq[n].vring.num;
 932 }
 933
 934 target_phys_addr_t virtio_queue_get_ring_size(VirtIODevice *vdev, int n)
 935 {
 936     return vdev->vq[n].vring.used - vdev->vq[n].vring.desc +
 937             virtio_queue_get_used_size(vdev, n);
 938 }
 939
 940 uint16_t virtio_queue_get_last_avail_idx(VirtIODevice *vdev, int n)
 941 {
 942     return vdev->vq[n].last_avail_idx;
 943 }
 944
 945 void virtio_queue_set_last_avail_idx(VirtIODevice *vdev, int n, uint16_t idx)
 946 {
 947     vdev->vq[n].last_avail_idx = idx;
 948 }
 949
 950 VirtQueue *virtio_get_queue(VirtIODevice *vdev, int n)
 951 {
 952     return vdev->vq + n;
 953 }
 954
 955 EventNotifier *virtio_queue_get_guest_notifier(VirtQueue *vq)
 956 {
 957     return &vq->guest_notifier;
 958 }
 959 EventNotifier *virtio_queue_get_host_notifier(VirtQueue *vq)
 960 {
 961     return &vq->host_notifier;
 962 }