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 #include "qemu-barrier.h"
  20
  21 /* The alignment to use between consumer and producer parts of vring.
  22  * x86 pagesize again. */
  23 #define VIRTIO_PCI_VRING_ALIGN         4096
  24
  25 typedef struct VRingDesc
  26 {
  27     uint64_t addr;
  28     uint32_t len;
  29     uint16_t flags;
  30     uint16_t next;
  31 } VRingDesc;
  32
  33 typedef struct VRingAvail
  34 {
  35     uint16_t flags;
  36     uint16_t idx;
  37     uint16_t ring[0];
  38 } VRingAvail;
  39
  40 typedef struct VRingUsedElem
  41 {
  42     uint32_t id;
  43     uint32_t len;
  44 } VRingUsedElem;
  45
  46 typedef struct VRingUsed
  47 {
  48     uint16_t flags;
  49     uint16_t idx;
  50     VRingUsedElem ring[0];
  51 } VRingUsed;
  52
  53 typedef struct VRing
  54 {
  55     unsigned int num;
  56     target_phys_addr_t desc;
  57     target_phys_addr_t avail;
  58     target_phys_addr_t used;
  59 } VRing;
  60
  61 struct VirtQueue
  62 {
  63     VRing vring;
  64     target_phys_addr_t pa;
  65     uint16_t last_avail_idx;
  66     /* Last used index value we have signalled on */
  67     uint16_t signalled_used;
  68
  69     /* Last used index value we have signalled on */
  70     bool signalled_used_valid;
  71
  72     /* Notification enabled? */
  73     bool notification;
  74
  75     int inuse;
  76
  77     uint16_t vector;
  78     void (*handle_output)(VirtIODevice *vdev, VirtQueue *vq);
  79     VirtIODevice *vdev;
  80     EventNotifier guest_notifier;
  81     EventNotifier host_notifier;
  82 };
  83
  84 /* virt queue functions */
  85 static void virtqueue_init(VirtQueue *vq)
  86 {
  87     target_phys_addr_t pa = vq->pa;
  88
  89     vq->vring.desc = pa;
  90     vq->vring.avail = pa + vq->vring.num * sizeof(VRingDesc);
  91     vq->vring.used = vring_align(vq->vring.avail +
  92                                  offsetof(VRingAvail, ring[vq->vring.num]),
  93                                  VIRTIO_PCI_VRING_ALIGN);
  94 }
  95
  96 static inline uint64_t vring_desc_addr(target_phys_addr_t desc_pa, int i)
  97 {
  98     target_phys_addr_t pa;
  99     pa = desc_pa + sizeof(VRingDesc) * i + offsetof(VRingDesc, addr);
 100     return ldq_phys(pa);
 101 }
 102
 103 static inline uint32_t vring_desc_len(target_phys_addr_t desc_pa, int i)
 104 {
 105     target_phys_addr_t pa;
 106     pa = desc_pa + sizeof(VRingDesc) * i + offsetof(VRingDesc, len);
 107     return ldl_phys(pa);
 108 }
 109
 110 static inline uint16_t vring_desc_flags(target_phys_addr_t desc_pa, int i)
 111 {
 112     target_phys_addr_t pa;
 113     pa = desc_pa + sizeof(VRingDesc) * i + offsetof(VRingDesc, flags);
 114     return lduw_phys(pa);
 115 }
 116
 117 static inline uint16_t vring_desc_next(target_phys_addr_t desc_pa, int i)
 118 {
 119     target_phys_addr_t pa;
 120     pa = desc_pa + sizeof(VRingDesc) * i + offsetof(VRingDesc, next);
 121     return lduw_phys(pa);
 122 }
 123
 124 static inline uint16_t vring_avail_flags(VirtQueue *vq)
 125 {
 126     target_phys_addr_t pa;
 127     pa = vq->vring.avail + offsetof(VRingAvail, flags);
 128     return lduw_phys(pa);
 129 }
 130
 131 static inline uint16_t vring_avail_idx(VirtQueue *vq)
 132 {
 133     target_phys_addr_t pa;
 134     pa = vq->vring.avail + offsetof(VRingAvail, idx);
 135     return lduw_phys(pa);
 136 }
 137
 138 static inline uint16_t vring_avail_ring(VirtQueue *vq, int i)
 139 {
 140     target_phys_addr_t pa;
 141     pa = vq->vring.avail + offsetof(VRingAvail, ring[i]);
 142     return lduw_phys(pa);
 143 }
 144
 145 static inline uint16_t vring_used_event(VirtQueue *vq)
 146 {
 147     return vring_avail_ring(vq, vq->vring.num);
 148 }
 149
 150 static inline void vring_used_ring_id(VirtQueue *vq, int i, uint32_t val)
 151 {
 152     target_phys_addr_t pa;
 153     pa = vq->vring.used + offsetof(VRingUsed, ring[i].id);
 154     stl_phys(pa, val);
 155 }
 156
 157 static inline void vring_used_ring_len(VirtQueue *vq, int i, uint32_t val)
 158 {
 159     target_phys_addr_t pa;
 160     pa = vq->vring.used + offsetof(VRingUsed, ring[i].len);
 161     stl_phys(pa, val);
 162 }
 163
 164 static uint16_t vring_used_idx(VirtQueue *vq)
 165 {
 166     target_phys_addr_t pa;
 167     pa = vq->vring.used + offsetof(VRingUsed, idx);
 168     return lduw_phys(pa);
 169 }
 170
 171 static inline void vring_used_idx_set(VirtQueue *vq, uint16_t val)
 172 {
 173     target_phys_addr_t pa;
 174     pa = vq->vring.used + offsetof(VRingUsed, idx);
 175     stw_phys(pa, val);
 176 }
 177
 178 static inline void vring_used_flags_set_bit(VirtQueue *vq, int mask)
 179 {
 180     target_phys_addr_t pa;
 181     pa = vq->vring.used + offsetof(VRingUsed, flags);
 182     stw_phys(pa, lduw_phys(pa) | mask);
 183 }
 184
 185 static inline void vring_used_flags_unset_bit(VirtQueue *vq, int mask)
 186 {
 187     target_phys_addr_t pa;
 188     pa = vq->vring.used + offsetof(VRingUsed, flags);
 189     stw_phys(pa, lduw_phys(pa) & ~mask);
 190 }
 191
 192 static inline void vring_avail_event(VirtQueue *vq, uint16_t val)
 193 {
 194     target_phys_addr_t pa;
 195     if (!vq->notification) {
 196         return;
 197     }
 198     pa = vq->vring.used + offsetof(VRingUsed, ring[vq->vring.num]);
 199     stw_phys(pa, val);
 200 }
 201
 202 void virtio_queue_set_notification(VirtQueue *vq, int enable)
 203 {
 204     vq->notification = enable;
 205     if (vq->vdev->guest_features & (1 << VIRTIO_RING_F_EVENT_IDX)) {
 206         vring_avail_event(vq, vring_avail_idx(vq));
 207     } else if (enable) {
 208         vring_used_flags_unset_bit(vq, VRING_USED_F_NO_NOTIFY);
 209     } else {
 210         vring_used_flags_set_bit(vq, VRING_USED_F_NO_NOTIFY);
 211     }
 212     if (enable) {
 213         /* Expose avail event/used flags before caller checks the avail idx. */
 214         smp_mb();
 215     }
 216 }
 217
 218 int virtio_queue_ready(VirtQueue *vq)
 219 {
 220     return vq->vring.avail != 0;
 221 }
 222
 223 int virtio_queue_empty(VirtQueue *vq)
 224 {
 225     return vring_avail_idx(vq) == vq->last_avail_idx;
 226 }
 227
 228 void virtqueue_fill(VirtQueue *vq, const VirtQueueElement *elem,
 229                     unsigned int len, unsigned int idx)
 230 {
 231     unsigned int offset;
 232     int i;
 233
 234     trace_virtqueue_fill(vq, elem, len, idx);
 235
 236     offset = 0;
 237     for (i = 0; i < elem->in_num; i++) {
 238         size_t size = MIN(len - offset, elem->in_sg[i].iov_len);
 239
 240         cpu_physical_memory_unmap(elem->in_sg[i].iov_base,
 241                                   elem->in_sg[i].iov_len,
 242                                   1, size);
 243
 244         offset += elem->in_sg[i].iov_len;
 245     }
 246
 247     for (i = 0; i < elem->out_num; i++)
 248         cpu_physical_memory_unmap(elem->out_sg[i].iov_base,
 249                                   elem->out_sg[i].iov_len,
 250                                   0, elem->out_sg[i].iov_len);
 251
 252     idx = (idx + vring_used_idx(vq)) % vq->vring.num;
 253
 254     /* Get a pointer to the next entry in the used ring. */
 255     vring_used_ring_id(vq, idx, elem->index);
 256     vring_used_ring_len(vq, idx, len);
 257 }
 258
 259 void virtqueue_flush(VirtQueue *vq, unsigned int count)
 260 {
 261     uint16_t old, new;
 262     /* Make sure buffer is written before we update index. */
 263     smp_wmb();
 264     trace_virtqueue_flush(vq, count);
 265     old = vring_used_idx(vq);
 266     new = old + count;
 267     vring_used_idx_set(vq, new);
 268     vq->inuse -= count;
 269     if (unlikely((int16_t)(new - vq->signalled_used) < (uint16_t)(new - old)))
 270         vq->signalled_used_valid = false;
 271 }
 272
 273 void virtqueue_push(VirtQueue *vq, const VirtQueueElement *elem,
 274                     unsigned int len)
 275 {
 276     virtqueue_fill(vq, elem, len, 0);
 277     virtqueue_flush(vq, 1);
 278 }
 279
 280 static int virtqueue_num_heads(VirtQueue *vq, unsigned int idx)
 281 {
 282     uint16_t num_heads = vring_avail_idx(vq) - idx;
 283
 284     /* Check it isn't doing very strange things with descriptor numbers. */
 285     if (num_heads > vq->vring.num) {
 286         error_report("Guest moved used index from %u to %u",
 287                      idx, vring_avail_idx(vq));
 288         exit(1);
 289     }
 290     /* On success, callers read a descriptor at vq->last_avail_idx.
 291      * Make sure descriptor read does not bypass avail index read. */
 292     if (num_heads) {
 293         smp_rmb();
 294     }
 295
 296     return num_heads;
 297 }
 298
 299 static unsigned int virtqueue_get_head(VirtQueue *vq, unsigned int idx)
 300 {
 301     unsigned int head;
 302
 303     /* Grab the next descriptor number they're advertising, and increment
 304      * the index we've seen. */
 305     head = vring_avail_ring(vq, idx % vq->vring.num);
 306
 307     /* If their number is silly, that's a fatal mistake. */
 308     if (head >= vq->vring.num) {
 309         error_report("Guest says index %u is available", head);
 310         exit(1);
 311     }
 312
 313     return head;
 314 }
 315
 316 static unsigned virtqueue_next_desc(target_phys_addr_t desc_pa,
 317                                     unsigned int i, unsigned int max)
 318 {
 319     unsigned int next;
 320
 321     /* If this descriptor says it doesn't chain, we're done. */
 322     if (!(vring_desc_flags(desc_pa, i) & VRING_DESC_F_NEXT))
 323         return max;
 324
 325     /* Check they're not leading us off end of descriptors. */
 326     next = vring_desc_next(desc_pa, i);
 327     /* Make sure compiler knows to grab that: we don't want it changing! */
 328     smp_wmb();
 329
 330     if (next >= max) {
 331         error_report("Desc next is %u", next);
 332         exit(1);
 333     }
 334
 335     return next;
 336 }
 337
 338 int virtqueue_avail_bytes(VirtQueue *vq, int in_bytes, int out_bytes)
 339 {
 340     unsigned int idx;
 341     int total_bufs, in_total, out_total;
 342
 343     idx = vq->last_avail_idx;
 344
 345     total_bufs = in_total = out_total = 0;
 346     while (virtqueue_num_heads(vq, idx)) {
 347         unsigned int max, num_bufs, indirect = 0;
 348         target_phys_addr_t desc_pa;
 349         int i;
 350
 351         max = vq->vring.num;
 352         num_bufs = total_bufs;
 353         i = virtqueue_get_head(vq, idx++);
 354         desc_pa = vq->vring.desc;
 355
 356         if (vring_desc_flags(desc_pa, i) & VRING_DESC_F_INDIRECT) {
 357             if (vring_desc_len(desc_pa, i) % sizeof(VRingDesc)) {
 358                 error_report("Invalid size for indirect buffer table");
 359                 exit(1);
 360             }
 361
 362             /* If we've got too many, that implies a descriptor loop. */
 363             if (num_bufs >= max) {
 364                 error_report("Looped descriptor");
 365                 exit(1);
 366             }
 367
 368             /* loop over the indirect descriptor table */
 369             indirect = 1;
 370             max = vring_desc_len(desc_pa, i) / sizeof(VRingDesc);
 371             num_bufs = i = 0;
 372             desc_pa = vring_desc_addr(desc_pa, i);
 373         }
 374
 375         do {
 376             /* If we've got too many, that implies a descriptor loop. */
 377             if (++num_bufs > max) {
 378                 error_report("Looped descriptor");
 379                 exit(1);
 380             }
 381
 382             if (vring_desc_flags(desc_pa, i) & VRING_DESC_F_WRITE) {
 383                 if (in_bytes > 0 &&
 384                     (in_total += vring_desc_len(desc_pa, i)) >= in_bytes)
 385                     return 1;
 386             } else {
 387                 if (out_bytes > 0 &&
 388                     (out_total += vring_desc_len(desc_pa, i)) >= out_bytes)
 389                     return 1;
 390             }
 391         } while ((i = virtqueue_next_desc(desc_pa, i, max)) != max);
 392
 393         if (!indirect)
 394             total_bufs = num_bufs;
 395         else
 396             total_bufs++;
 397     }
 398
 399     return 0;
 400 }
 401
 402 void virtqueue_map_sg(struct iovec *sg, target_phys_addr_t *addr,
 403     size_t num_sg, int is_write)
 404 {
 405     unsigned int i;
 406     target_phys_addr_t len;
 407
 408     for (i = 0; i < num_sg; i++) {
 409         len = sg[i].iov_len;
 410         sg[i].iov_base = cpu_physical_memory_map(addr[i], &len, is_write);
 411         if (sg[i].iov_base == NULL || len != sg[i].iov_len) {
 412             error_report("virtio: trying to map MMIO memory");
 413             exit(1);
 414         }
 415     }
 416 }
 417
 418 int virtqueue_pop(VirtQueue *vq, VirtQueueElement *elem)
 419 {
 420     unsigned int i, head, max;
 421     target_phys_addr_t desc_pa = vq->vring.desc;
 422
 423     if (!virtqueue_num_heads(vq, vq->last_avail_idx))
 424         return 0;
 425
 426     /* When we start there are none of either input nor output. */
 427     elem->out_num = elem->in_num = 0;
 428
 429     max = vq->vring.num;
 430
 431     i = head = virtqueue_get_head(vq, vq->last_avail_idx++);
 432     if (vq->vdev->guest_features & (1 << VIRTIO_RING_F_EVENT_IDX)) {
 433         vring_avail_event(vq, vring_avail_idx(vq));
 434     }
 435
 436     if (vring_desc_flags(desc_pa, i) & VRING_DESC_F_INDIRECT) {
 437         if (vring_desc_len(desc_pa, i) % sizeof(VRingDesc)) {
 438             error_report("Invalid size for indirect buffer table");
 439             exit(1);
 440         }
 441
 442         /* loop over the indirect descriptor table */
 443         max = vring_desc_len(desc_pa, i) / sizeof(VRingDesc);
 444         desc_pa = vring_desc_addr(desc_pa, i);
 445         i = 0;
 446     }
 447
 448     /* Collect all the descriptors */
 449     do {
 450         struct iovec *sg;
 451
 452         if (vring_desc_flags(desc_pa, i) & VRING_DESC_F_WRITE) {
 453             if (elem->in_num >= ARRAY_SIZE(elem->in_sg)) {
 454                 error_report("Too many write descriptors in indirect table");
 455                 exit(1);
 456             }
 457             elem->in_addr[elem->in_num] = vring_desc_addr(desc_pa, i);
 458             sg = &elem->in_sg[elem->in_num++];
 459         } else {
 460             if (elem->out_num >= ARRAY_SIZE(elem->out_sg)) {
 461                 error_report("Too many read descriptors in indirect table");
 462                 exit(1);
 463             }
 464             elem->out_addr[elem->out_num] = vring_desc_addr(desc_pa, i);
 465             sg = &elem->out_sg[elem->out_num++];
 466         }
 467
 468         sg->iov_len = vring_desc_len(desc_pa, i);
 469
 470         /* If we've got too many, that implies a descriptor loop. */
 471         if ((elem->in_num + elem->out_num) > max) {
 472             error_report("Looped descriptor");
 473             exit(1);
 474         }
 475     } while ((i = virtqueue_next_desc(desc_pa, i, max)) != max);
 476
 477     /* Now map what we have collected */
 478     virtqueue_map_sg(elem->in_sg, elem->in_addr, elem->in_num, 1);
 479     virtqueue_map_sg(elem->out_sg, elem->out_addr, elem->out_num, 0);
 480
 481     elem->index = head;
 482
 483     vq->inuse++;
 484
 485     trace_virtqueue_pop(vq, elem, elem->in_num, elem->out_num);
 486     return elem->in_num + elem->out_num;
 487 }
 488
 489 /* virtio device */
 490 static void virtio_notify_vector(VirtIODevice *vdev, uint16_t vector)
 491 {
 492     if (vdev->binding->notify) {
 493         vdev->binding->notify(vdev->binding_opaque, vector);
 494     }
 495 }
 496
 497 void virtio_update_irq(VirtIODevice *vdev)
 498 {
 499     virtio_notify_vector(vdev, VIRTIO_NO_VECTOR);
 500 }
 501
 502 void virtio_set_status(VirtIODevice *vdev, uint8_t val)
 503 {
 504     trace_virtio_set_status(vdev, val);
 505
 506     if (vdev->set_status) {
 507         vdev->set_status(vdev, val);
 508     }
 509     vdev->status = val;
 510 }
 511
 512 void virtio_reset(void *opaque)
 513 {
 514     VirtIODevice *vdev = opaque;
 515     int i;
 516
 517     virtio_set_status(vdev, 0);
 518
 519     if (vdev->reset)
 520         vdev->reset(vdev);
 521
 522     vdev->guest_features = 0;
 523     vdev->queue_sel = 0;
 524     vdev->status = 0;
 525     vdev->isr = 0;
 526     vdev->config_vector = VIRTIO_NO_VECTOR;
 527     virtio_notify_vector(vdev, vdev->config_vector);
 528
 529     for(i = 0; i < VIRTIO_PCI_QUEUE_MAX; i++) {
 530         vdev->vq[i].vring.desc = 0;
 531         vdev->vq[i].vring.avail = 0;
 532         vdev->vq[i].vring.used = 0;
 533         vdev->vq[i].last_avail_idx = 0;
 534         vdev->vq[i].pa = 0;
 535         vdev->vq[i].vector = VIRTIO_NO_VECTOR;
 536         vdev->vq[i].signalled_used = 0;
 537         vdev->vq[i].signalled_used_valid = false;
 538         vdev->vq[i].notification = true;
 539     }
 540 }
 541
 542 uint32_t virtio_config_readb(VirtIODevice *vdev, uint32_t addr)
 543 {
 544     uint8_t val;
 545
 546     vdev->get_config(vdev, vdev->config);
 547
 548     if (addr > (vdev->config_len - sizeof(val)))
 549         return (uint32_t)-1;
 550
 551     val = ldub_p(vdev->config + addr);
 552     return val;
 553 }
 554
 555 uint32_t virtio_config_readw(VirtIODevice *vdev, uint32_t addr)
 556 {
 557     uint16_t val;
 558
 559     vdev->get_config(vdev, vdev->config);
 560
 561     if (addr > (vdev->config_len - sizeof(val)))
 562         return (uint32_t)-1;
 563
 564     val = lduw_p(vdev->config + addr);
 565     return val;
 566 }
 567
 568 uint32_t virtio_config_readl(VirtIODevice *vdev, uint32_t addr)
 569 {
 570     uint32_t val;
 571
 572     vdev->get_config(vdev, vdev->config);
 573
 574     if (addr > (vdev->config_len - sizeof(val)))
 575         return (uint32_t)-1;
 576
 577     val = ldl_p(vdev->config + addr);
 578     return val;
 579 }
 580
 581 void virtio_config_writeb(VirtIODevice *vdev, uint32_t addr, uint32_t data)
 582 {
 583     uint8_t val = data;
 584
 585     if (addr > (vdev->config_len - sizeof(val)))
 586         return;
 587
 588     stb_p(vdev->config + addr, val);
 589
 590     if (vdev->set_config)
 591         vdev->set_config(vdev, vdev->config);
 592 }
 593
 594 void virtio_config_writew(VirtIODevice *vdev, uint32_t addr, uint32_t data)
 595 {
 596     uint16_t val = data;
 597
 598     if (addr > (vdev->config_len - sizeof(val)))
 599         return;
 600
 601     stw_p(vdev->config + addr, val);
 602
 603     if (vdev->set_config)
 604         vdev->set_config(vdev, vdev->config);
 605 }
 606
 607 void virtio_config_writel(VirtIODevice *vdev, uint32_t addr, uint32_t data)
 608 {
 609     uint32_t val = data;
 610
 611     if (addr > (vdev->config_len - sizeof(val)))
 612         return;
 613
 614     stl_p(vdev->config + addr, val);
 615
 616     if (vdev->set_config)
 617         vdev->set_config(vdev, vdev->config);
 618 }
 619
 620 void virtio_queue_set_addr(VirtIODevice *vdev, int n, target_phys_addr_t addr)
 621 {
 622     vdev->vq[n].pa = addr;
 623     virtqueue_init(&vdev->vq[n]);
 624 }
 625
 626 target_phys_addr_t virtio_queue_get_addr(VirtIODevice *vdev, int n)
 627 {
 628     return vdev->vq[n].pa;
 629 }
 630
 631 int virtio_queue_get_num(VirtIODevice *vdev, int n)
 632 {
 633     return vdev->vq[n].vring.num;
 634 }
 635
 636 int virtio_queue_get_id(VirtQueue *vq)
 637 {
 638     VirtIODevice *vdev = vq->vdev;
 639     assert(vq >= &vdev->vq[0] && vq < &vdev->vq[VIRTIO_PCI_QUEUE_MAX]);
 640     return vq - &vdev->vq[0];
 641 }
 642
 643 void virtio_queue_notify_vq(VirtQueue *vq)
 644 {
 645     if (vq->vring.desc) {
 646         VirtIODevice *vdev = vq->vdev;
 647         trace_virtio_queue_notify(vdev, vq - vdev->vq, vq);
 648         vq->handle_output(vdev, vq);
 649     }
 650 }
 651
 652 void virtio_queue_notify(VirtIODevice *vdev, int n)
 653 {
 654     virtio_queue_notify_vq(&vdev->vq[n]);
 655 }
 656
 657 uint16_t virtio_queue_vector(VirtIODevice *vdev, int n)
 658 {
 659     return n < VIRTIO_PCI_QUEUE_MAX ? vdev->vq[n].vector :
 660         VIRTIO_NO_VECTOR;
 661 }
 662
 663 void virtio_queue_set_vector(VirtIODevice *vdev, int n, uint16_t vector)
 664 {
 665     if (n < VIRTIO_PCI_QUEUE_MAX)
 666         vdev->vq[n].vector = vector;
 667 }
 668
 669 VirtQueue *virtio_add_queue(VirtIODevice *vdev, int queue_size,
 670                             void (*handle_output)(VirtIODevice *, VirtQueue *))
 671 {
 672     int i;
 673
 674     for (i = 0; i < VIRTIO_PCI_QUEUE_MAX; i++) {
 675         if (vdev->vq[i].vring.num == 0)
 676             break;
 677     }
 678
 679     if (i == VIRTIO_PCI_QUEUE_MAX || queue_size > VIRTQUEUE_MAX_SIZE)
 680         abort();
 681
 682     vdev->vq[i].vring.num = queue_size;
 683     vdev->vq[i].handle_output = handle_output;
 684
 685     return &vdev->vq[i];
 686 }
 687
 688 void virtio_irq(VirtQueue *vq)
 689 {
 690     trace_virtio_irq(vq);
 691     vq->vdev->isr |= 0x01;
 692     virtio_notify_vector(vq->vdev, vq->vector);
 693 }
 694
 695 /* Assuming a given event_idx value from the other size, if
 696  * we have just incremented index from old to new_idx,
 697  * should we trigger an event? */
 698 static inline int vring_need_event(uint16_t event, uint16_t new, uint16_t old)
 699 {
 700         /* Note: Xen has similar logic for notification hold-off
 701          * in include/xen/interface/io/ring.h with req_event and req_prod
 702          * corresponding to event_idx + 1 and new respectively.
 703          * Note also that req_event and req_prod in Xen start at 1,
 704          * event indexes in virtio start at 0. */
 705         return (uint16_t)(new - event - 1) < (uint16_t)(new - old);
 706 }
 707
 708 static bool vring_notify(VirtIODevice *vdev, VirtQueue *vq)
 709 {
 710     uint16_t old, new;
 711     bool v;
 712     /* We need to expose used array entries before checking used event. */
 713     smp_mb();
 714     /* Always notify when queue is empty (when feature acknowledge) */
 715     if (((vdev->guest_features & (1 << VIRTIO_F_NOTIFY_ON_EMPTY)) &&
 716          !vq->inuse && vring_avail_idx(vq) == vq->last_avail_idx)) {
 717         return true;
 718     }
 719
 720     if (!(vdev->guest_features & (1 << VIRTIO_RING_F_EVENT_IDX))) {
 721         return !(vring_avail_flags(vq) & VRING_AVAIL_F_NO_INTERRUPT);
 722     }
 723
 724     v = vq->signalled_used_valid;
 725     vq->signalled_used_valid = true;
 726     old = vq->signalled_used;
 727     new = vq->signalled_used = vring_used_idx(vq);
 728     return !v || vring_need_event(vring_used_event(vq), new, old);
 729 }
 730
 731 void virtio_notify(VirtIODevice *vdev, VirtQueue *vq)
 732 {
 733     if (!vring_notify(vdev, vq)) {
 734         return;
 735     }
 736
 737     trace_virtio_notify(vdev, vq);
 738     vdev->isr |= 0x01;
 739     virtio_notify_vector(vdev, vq->vector);
 740 }
 741
 742 void virtio_notify_config(VirtIODevice *vdev)
 743 {
 744     if (!(vdev->status & VIRTIO_CONFIG_S_DRIVER_OK))
 745         return;
 746
 747     vdev->isr |= 0x03;
 748     virtio_notify_vector(vdev, vdev->config_vector);
 749 }
 750
 751 void virtio_save(VirtIODevice *vdev, QEMUFile *f)
 752 {
 753     int i;
 754
 755     if (vdev->binding->save_config)
 756         vdev->binding->save_config(vdev->binding_opaque, f);
 757
 758     qemu_put_8s(f, &vdev->status);
 759     qemu_put_8s(f, &vdev->isr);
 760     qemu_put_be16s(f, &vdev->queue_sel);
 761     qemu_put_be32s(f, &vdev->guest_features);
 762     qemu_put_be32(f, vdev->config_len);
 763     qemu_put_buffer(f, vdev->config, vdev->config_len);
 764
 765     for (i = 0; i < VIRTIO_PCI_QUEUE_MAX; i++) {
 766         if (vdev->vq[i].vring.num == 0)
 767             break;
 768     }
 769
 770     qemu_put_be32(f, i);
 771
 772     for (i = 0; i < VIRTIO_PCI_QUEUE_MAX; i++) {
 773         if (vdev->vq[i].vring.num == 0)
 774             break;
 775
 776         qemu_put_be32(f, vdev->vq[i].vring.num);
 777         qemu_put_be64(f, vdev->vq[i].pa);
 778         qemu_put_be16s(f, &vdev->vq[i].last_avail_idx);
 779         if (vdev->binding->save_queue)
 780             vdev->binding->save_queue(vdev->binding_opaque, i, f);
 781     }
 782 }
 783
 784 int virtio_set_features(VirtIODevice *vdev, uint32_t val)
 785 {
 786     uint32_t supported_features =
 787         vdev->binding->get_features(vdev->binding_opaque);
 788     bool bad = (val & ~supported_features) != 0;
 789
 790     val &= supported_features;
 791     if (vdev->set_features) {
 792         vdev->set_features(vdev, val);
 793     }
 794     vdev->guest_features = val;
 795     return bad ? -1 : 0;
 796 }
 797
 798 int virtio_load(VirtIODevice *vdev, QEMUFile *f)
 799 {
 800     int num, i, ret;
 801     uint32_t features;
 802     uint32_t supported_features;
 803
 804     if (vdev->binding->load_config) {
 805         ret = vdev->binding->load_config(vdev->binding_opaque, f);
 806         if (ret)
 807             return ret;
 808     }
 809
 810     qemu_get_8s(f, &vdev->status);
 811     qemu_get_8s(f, &vdev->isr);
 812     qemu_get_be16s(f, &vdev->queue_sel);
 813     qemu_get_be32s(f, &features);
 814
 815     if (virtio_set_features(vdev, features) < 0) {
 816         supported_features = vdev->binding->get_features(vdev->binding_opaque);
 817         error_report("Features 0x%x unsupported. Allowed features: 0x%x",
 818                      features, supported_features);
 819         return -1;
 820     }
 821     vdev->config_len = qemu_get_be32(f);
 822     qemu_get_buffer(f, vdev->config, vdev->config_len);
 823
 824     num = qemu_get_be32(f);
 825
 826     for (i = 0; i < num; i++) {
 827         vdev->vq[i].vring.num = qemu_get_be32(f);
 828         vdev->vq[i].pa = qemu_get_be64(f);
 829         qemu_get_be16s(f, &vdev->vq[i].last_avail_idx);
 830         vdev->vq[i].signalled_used_valid = false;
 831         vdev->vq[i].notification = true;
 832
 833         if (vdev->vq[i].pa) {
 834             uint16_t nheads;
 835             virtqueue_init(&vdev->vq[i]);
 836             nheads = vring_avail_idx(&vdev->vq[i]) - vdev->vq[i].last_avail_idx;
 837             /* Check it isn't doing very strange things with descriptor numbers. */
 838             if (nheads > vdev->vq[i].vring.num) {
 839                 error_report("VQ %d size 0x%x Guest index 0x%x "
 840                              "inconsistent with Host index 0x%x: delta 0x%x",
 841                              i, vdev->vq[i].vring.num,
 842                              vring_avail_idx(&vdev->vq[i]),
 843                              vdev->vq[i].last_avail_idx, nheads);
 844                 return -1;
 845             }
 846         } else if (vdev->vq[i].last_avail_idx) {
 847             error_report("VQ %d address 0x0 "
 848                          "inconsistent with Host index 0x%x",
 849                          i, vdev->vq[i].last_avail_idx);
 850                 return -1;
 851         }
 852         if (vdev->binding->load_queue) {
 853             ret = vdev->binding->load_queue(vdev->binding_opaque, i, f);
 854             if (ret)
 855                 return ret;
 856         }
 857     }
 858
 859     virtio_notify_vector(vdev, VIRTIO_NO_VECTOR);
 860     return 0;
 861 }
 862
 863 void virtio_cleanup(VirtIODevice *vdev)
 864 {
 865     qemu_del_vm_change_state_handler(vdev->vmstate);
 866     g_free(vdev->config);
 867     g_free(vdev->vq);
 868     g_free(vdev);
 869 }
 870
 871 static void virtio_vmstate_change(void *opaque, int running, RunState state)
 872 {
 873     VirtIODevice *vdev = opaque;
 874     bool backend_run = running && (vdev->status & VIRTIO_CONFIG_S_DRIVER_OK);
 875     vdev->vm_running = running;
 876
 877     if (backend_run) {
 878         virtio_set_status(vdev, vdev->status);
 879     }
 880
 881     if (vdev->binding->vmstate_change) {
 882         vdev->binding->vmstate_change(vdev->binding_opaque, backend_run);
 883     }
 884
 885     if (!backend_run) {
 886         virtio_set_status(vdev, vdev->status);
 887     }
 888 }
 889
 890 VirtIODevice *virtio_common_init(const char *name, uint16_t device_id,
 891                                  size_t config_size, size_t struct_size)
 892 {
 893     VirtIODevice *vdev;
 894     int i;
 895
 896     vdev = g_malloc0(struct_size);
 897
 898     vdev->device_id = device_id;
 899     vdev->status = 0;
 900     vdev->isr = 0;
 901     vdev->queue_sel = 0;
 902     vdev->config_vector = VIRTIO_NO_VECTOR;
 903     vdev->vq = g_malloc0(sizeof(VirtQueue) * VIRTIO_PCI_QUEUE_MAX);
 904     vdev->vm_running = runstate_is_running();
 905     for(i = 0; i < VIRTIO_PCI_QUEUE_MAX; i++) {
 906         vdev->vq[i].vector = VIRTIO_NO_VECTOR;
 907         vdev->vq[i].vdev = vdev;
 908     }
 909
 910     vdev->name = name;
 911     vdev->config_len = config_size;
 912     if (vdev->config_len)
 913         vdev->config = g_malloc0(config_size);
 914     else
 915         vdev->config = NULL;
 916
 917     vdev->vmstate = qemu_add_vm_change_state_handler(virtio_vmstate_change, vdev);
 918
 919     return vdev;
 920 }
 921
 922 void virtio_bind_device(VirtIODevice *vdev, const VirtIOBindings *binding,
 923                         void *opaque)
 924 {
 925     vdev->binding = binding;
 926     vdev->binding_opaque = opaque;
 927 }
 928
 929 target_phys_addr_t virtio_queue_get_desc_addr(VirtIODevice *vdev, int n)
 930 {
 931     return vdev->vq[n].vring.desc;
 932 }
 933
 934 target_phys_addr_t virtio_queue_get_avail_addr(VirtIODevice *vdev, int n)
 935 {
 936     return vdev->vq[n].vring.avail;
 937 }
 938
 939 target_phys_addr_t virtio_queue_get_used_addr(VirtIODevice *vdev, int n)
 940 {
 941     return vdev->vq[n].vring.used;
 942 }
 943
 944 target_phys_addr_t virtio_queue_get_ring_addr(VirtIODevice *vdev, int n)
 945 {
 946     return vdev->vq[n].vring.desc;
 947 }
 948
 949 target_phys_addr_t virtio_queue_get_desc_size(VirtIODevice *vdev, int n)
 950 {
 951     return sizeof(VRingDesc) * vdev->vq[n].vring.num;
 952 }
 953
 954 target_phys_addr_t virtio_queue_get_avail_size(VirtIODevice *vdev, int n)
 955 {
 956     return offsetof(VRingAvail, ring) +
 957         sizeof(uint64_t) * vdev->vq[n].vring.num;
 958 }
 959
 960 target_phys_addr_t virtio_queue_get_used_size(VirtIODevice *vdev, int n)
 961 {
 962     return offsetof(VRingUsed, ring) +
 963         sizeof(VRingUsedElem) * vdev->vq[n].vring.num;
 964 }
 965
 966 target_phys_addr_t virtio_queue_get_ring_size(VirtIODevice *vdev, int n)
 967 {
 968     return vdev->vq[n].vring.used - vdev->vq[n].vring.desc +
 969             virtio_queue_get_used_size(vdev, n);
 970 }
 971
 972 uint16_t virtio_queue_get_last_avail_idx(VirtIODevice *vdev, int n)
 973 {
 974     return vdev->vq[n].last_avail_idx;
 975 }
 976
 977 void virtio_queue_set_last_avail_idx(VirtIODevice *vdev, int n, uint16_t idx)
 978 {
 979     vdev->vq[n].last_avail_idx = idx;
 980 }
 981
 982 VirtQueue *virtio_get_queue(VirtIODevice *vdev, int n)
 983 {
 984     return vdev->vq + n;
 985 }
 986
 987 EventNotifier *virtio_queue_get_guest_notifier(VirtQueue *vq)
 988 {
 989     return &vq->guest_notifier;
 990 }
 991 EventNotifier *virtio_queue_get_host_notifier(VirtQueue *vq)
 992 {
 993     return &vq->host_notifier;
 994 }