drivers/virtio/virtio_ring.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  * Copyright (C) 2018, Tuomas Tynkkynen <tuomas.tynkkynen@iki.fi>
   4  * Copyright (C) 2018, Bin Meng <bmeng.cn@gmail.com>
   5  *
   6  * virtio ring implementation
   7  */
   8
   9 #include <bouncebuf.h>
  10 #include <common.h>
  11 #include <dm.h>
  12 #include <log.h>
  13 #include <malloc.h>
  14 #include <virtio_types.h>
  15 #include <virtio.h>
  16 #include <virtio_ring.h>
  17 #include <linux/bug.h>
  18 #include <linux/compat.h>
  19 #include <linux/kernel.h>
  20
  21 static void *virtio_alloc_pages(struct udevice *vdev, u32 npages)
  22 {
  23         return memalign(PAGE_SIZE, npages * PAGE_SIZE);
  24 }
  25
  26 static void virtio_free_pages(struct udevice *vdev, void *ptr, u32 npages)
  27 {
  28         free(ptr);
  29 }
  30
  31 static int __bb_force_page_align(struct bounce_buffer *state)
  32 {
  33         const ulong align_mask = PAGE_SIZE - 1;
  34
  35         if ((ulong)state->user_buffer & align_mask)
  36                 return 0;
  37
  38         if (state->len != state->len_aligned)
  39                 return 0;
  40
  41         return 1;
  42 }
  43
  44 static unsigned int virtqueue_attach_desc(struct virtqueue *vq, unsigned int i,
  45                                           struct virtio_sg *sg, u16 flags)
  46 {
  47         struct vring_desc_shadow *desc_shadow = &vq->vring_desc_shadow[i];
  48         struct vring_desc *desc = &vq->vring.desc[i];
  49         void *addr;
  50
  51         if (IS_ENABLED(CONFIG_BOUNCE_BUFFER) && vq->vring.bouncebufs) {
  52                 struct bounce_buffer *bb = &vq->vring.bouncebufs[i];
  53                 unsigned int bbflags;
  54                 int ret;
  55
  56                 if (flags & VRING_DESC_F_WRITE)
  57                         bbflags = GEN_BB_WRITE;
  58                 else
  59                         bbflags = GEN_BB_READ;
  60
  61                 ret = bounce_buffer_start_extalign(bb, sg->addr, sg->length,
  62                                                    bbflags, PAGE_SIZE,
  63                                                    __bb_force_page_align);
  64                 if (ret) {
  65                         debug("%s: failed to allocate bounce buffer (length 0x%zx)\n",
  66                               vq->vdev->name, sg->length);
  67                 }
  68
  69                 addr = bb->bounce_buffer;
  70         } else {
  71                 addr = sg->addr;
  72         }
  73
  74         /* Update the shadow descriptor. */
  75         desc_shadow->addr = (u64)(uintptr_t)addr;
  76         desc_shadow->len = sg->length;
  77         desc_shadow->flags = flags;
  78
  79         /* Update the shared descriptor to match the shadow. */
  80         desc->addr = cpu_to_virtio64(vq->vdev, desc_shadow->addr);
  81         desc->len = cpu_to_virtio32(vq->vdev, desc_shadow->len);
  82         desc->flags = cpu_to_virtio16(vq->vdev, desc_shadow->flags);
  83         desc->next = cpu_to_virtio16(vq->vdev, desc_shadow->next);
  84
  85         return desc_shadow->next;
  86 }
  87
  88 static void virtqueue_detach_desc(struct virtqueue *vq, unsigned int idx)
  89 {
  90         struct vring_desc *desc = &vq->vring.desc[idx];
  91         struct bounce_buffer *bb;
  92
  93         if (!IS_ENABLED(CONFIG_BOUNCE_BUFFER) || !vq->vring.bouncebufs)
  94                 return;
  95
  96         bb = &vq->vring.bouncebufs[idx];
  97         bounce_buffer_stop(bb);
  98         desc->addr = cpu_to_virtio64(vq->vdev, (u64)(uintptr_t)bb->user_buffer);
  99 }
 100
 101 int virtqueue_add(struct virtqueue *vq, struct virtio_sg *sgs[],
 102                   unsigned int out_sgs, unsigned int in_sgs)
 103 {
 104         struct vring_desc *desc;
 105         unsigned int descs_used = out_sgs + in_sgs;
 106         unsigned int i, n, avail, uninitialized_var(prev);
 107         int head;
 108
 109         WARN_ON(descs_used == 0);
 110
 111         head = vq->free_head;
 112
 113         desc = vq->vring.desc;
 114         i = head;
 115
 116         if (vq->num_free < descs_used) {
 117                 debug("Can't add buf len %i - avail = %i\n",
 118                       descs_used, vq->num_free);
 119                 /*
 120                  * FIXME: for historical reasons, we force a notify here if
 121                  * there are outgoing parts to the buffer.  Presumably the
 122                  * host should service the ring ASAP.
 123                  */
 124                 if (out_sgs)
 125                         virtio_notify(vq->vdev, vq);
 126                 return -ENOSPC;
 127         }
 128
 129         for (n = 0; n < descs_used; n++) {
 130                 u16 flags = VRING_DESC_F_NEXT;
 131
 132                 if (n >= out_sgs)
 133                         flags |= VRING_DESC_F_WRITE;
 134                 prev = i;
 135                 i = virtqueue_attach_desc(vq, i, sgs[n], flags);
 136         }
 137         /* Last one doesn't continue */
 138         vq->vring_desc_shadow[prev].flags &= ~VRING_DESC_F_NEXT;
 139         desc[prev].flags = cpu_to_virtio16(vq->vdev, vq->vring_desc_shadow[prev].flags);
 140
 141         /* We're using some buffers from the free list. */
 142         vq->num_free -= descs_used;
 143
 144         /* Update free pointer */
 145         vq->free_head = i;
 146
 147         /* Mark the descriptor as the head of a chain. */
 148         vq->vring_desc_shadow[head].chain_head = true;
 149
 150         /*
 151          * Put entry in available array (but don't update avail->idx
 152          * until they do sync).
 153          */
 154         avail = vq->avail_idx_shadow & (vq->vring.num - 1);
 155         vq->vring.avail->ring[avail] = cpu_to_virtio16(vq->vdev, head);
 156
 157         /*
 158          * Descriptors and available array need to be set before we expose the
 159          * new available array entries.
 160          */
 161         virtio_wmb();
 162         vq->avail_idx_shadow++;
 163         vq->vring.avail->idx = cpu_to_virtio16(vq->vdev, vq->avail_idx_shadow);
 164         vq->num_added++;
 165
 166         /*
 167          * This is very unlikely, but theoretically possible.
 168          * Kick just in case.
 169          */
 170         if (unlikely(vq->num_added == (1 << 16) - 1))
 171                 virtqueue_kick(vq);
 172
 173         return 0;
 174 }
 175
 176 static bool virtqueue_kick_prepare(struct virtqueue *vq)
 177 {
 178         u16 new, old;
 179         bool needs_kick;
 180
 181         /*
 182          * We need to expose available array entries before checking
 183          * avail event.
 184          */
 185         virtio_mb();
 186
 187         old = vq->avail_idx_shadow - vq->num_added;
 188         new = vq->avail_idx_shadow;
 189         vq->num_added = 0;
 190
 191         if (vq->event) {
 192                 needs_kick = vring_need_event(virtio16_to_cpu(vq->vdev,
 193                                 vring_avail_event(&vq->vring)), new, old);
 194         } else {
 195                 needs_kick = !(vq->vring.used->flags & cpu_to_virtio16(vq->vdev,
 196                                 VRING_USED_F_NO_NOTIFY));
 197         }
 198
 199         return needs_kick;
 200 }
 201
 202 void virtqueue_kick(struct virtqueue *vq)
 203 {
 204         if (virtqueue_kick_prepare(vq))
 205                 virtio_notify(vq->vdev, vq);
 206 }
 207
 208 static void detach_buf(struct virtqueue *vq, unsigned int head)
 209 {
 210         unsigned int i;
 211
 212         /* Unmark the descriptor as the head of a chain. */
 213         vq->vring_desc_shadow[head].chain_head = false;
 214
 215         /* Put back on free list: unmap first-level descriptors and find end */
 216         i = head;
 217
 218         while (vq->vring_desc_shadow[i].flags & VRING_DESC_F_NEXT) {
 219                 virtqueue_detach_desc(vq, i);
 220                 i = vq->vring_desc_shadow[i].next;
 221                 vq->num_free++;
 222         }
 223
 224         virtqueue_detach_desc(vq, i);
 225         vq->vring_desc_shadow[i].next = vq->free_head;
 226         vq->free_head = head;
 227
 228         /* Plus final descriptor */
 229         vq->num_free++;
 230 }
 231
 232 static inline bool more_used(const struct virtqueue *vq)
 233 {
 234         return vq->last_used_idx != virtio16_to_cpu(vq->vdev,
 235                         vq->vring.used->idx);
 236 }
 237
 238 void *virtqueue_get_buf(struct virtqueue *vq, unsigned int *len)
 239 {
 240         unsigned int i;
 241         u16 last_used;
 242
 243         if (!more_used(vq)) {
 244                 debug("(%s.%d): No more buffers in queue\n",
 245                       vq->vdev->name, vq->index);
 246                 return NULL;
 247         }
 248
 249         /* Only get used array entries after they have been exposed by host */
 250         virtio_rmb();
 251
 252         last_used = (vq->last_used_idx & (vq->vring.num - 1));
 253         i = virtio32_to_cpu(vq->vdev, vq->vring.used->ring[last_used].id);
 254         if (len) {
 255                 *len = virtio32_to_cpu(vq->vdev,
 256                                        vq->vring.used->ring[last_used].len);
 257                 debug("(%s.%d): last used idx %u with len %u\n",
 258                       vq->vdev->name, vq->index, i, *len);
 259         }
 260
 261         if (unlikely(i >= vq->vring.num)) {
 262                 printf("(%s.%d): id %u out of range\n",
 263                        vq->vdev->name, vq->index, i);
 264                 return NULL;
 265         }
 266
 267         if (unlikely(!vq->vring_desc_shadow[i].chain_head)) {
 268                 printf("(%s.%d): id %u is not a head\n",
 269                        vq->vdev->name, vq->index, i);
 270                 return NULL;
 271         }
 272
 273         detach_buf(vq, i);
 274         vq->last_used_idx++;
 275         /*
 276          * If we expect an interrupt for the next entry, tell host
 277          * by writing event index and flush out the write before
 278          * the read in the next get_buf call.
 279          */
 280         if (!(vq->avail_flags_shadow & VRING_AVAIL_F_NO_INTERRUPT))
 281                 virtio_store_mb(&vring_used_event(&vq->vring),
 282                                 cpu_to_virtio16(vq->vdev, vq->last_used_idx));
 283
 284         return (void *)(uintptr_t)vq->vring_desc_shadow[i].addr;
 285 }
 286
 287 static struct virtqueue *__vring_new_virtqueue(unsigned int index,
 288                                                struct vring vring,
 289                                                struct udevice *udev)
 290 {
 291         unsigned int i;
 292         struct virtqueue *vq;
 293         struct vring_desc_shadow *vring_desc_shadow;
 294         struct virtio_dev_priv *uc_priv = dev_get_uclass_priv(udev);
 295         struct udevice *vdev = uc_priv->vdev;
 296
 297         vq = malloc(sizeof(*vq));
 298         if (!vq)
 299                 return NULL;
 300
 301         vring_desc_shadow = calloc(vring.num, sizeof(struct vring_desc_shadow));
 302         if (!vring_desc_shadow) {
 303                 free(vq);
 304                 return NULL;
 305         }
 306
 307         vq->vdev = vdev;
 308         vq->index = index;
 309         vq->num_free = vring.num;
 310         vq->vring = vring;
 311         vq->vring_desc_shadow = vring_desc_shadow;
 312         vq->last_used_idx = 0;
 313         vq->avail_flags_shadow = 0;
 314         vq->avail_idx_shadow = 0;
 315         vq->num_added = 0;
 316         list_add_tail(&vq->list, &uc_priv->vqs);
 317
 318         vq->event = virtio_has_feature(vdev, VIRTIO_RING_F_EVENT_IDX);
 319
 320         /* Tell other side not to bother us */
 321         vq->avail_flags_shadow |= VRING_AVAIL_F_NO_INTERRUPT;
 322         if (!vq->event)
 323                 vq->vring.avail->flags = cpu_to_virtio16(vdev,
 324                                 vq->avail_flags_shadow);
 325
 326         /* Put everything in free lists */
 327         vq->free_head = 0;
 328         for (i = 0; i < vring.num - 1; i++)
 329                 vq->vring_desc_shadow[i].next = i + 1;
 330
 331         return vq;
 332 }
 333
 334 struct virtqueue *vring_create_virtqueue(unsigned int index, unsigned int num,
 335                                          unsigned int vring_align,
 336                                          struct udevice *udev)
 337 {
 338         struct virtio_dev_priv *uc_priv = dev_get_uclass_priv(udev);
 339         struct udevice *vdev = uc_priv->vdev;
 340         struct virtqueue *vq;
 341         void *queue = NULL;
 342         struct bounce_buffer *bbs = NULL;
 343         struct vring vring;
 344
 345         /* We assume num is a power of 2 */
 346         if (num & (num - 1)) {
 347                 printf("Bad virtqueue length %u\n", num);
 348                 return NULL;
 349         }
 350
 351         /* TODO: allocate each queue chunk individually */
 352         for (; num && vring_size(num, vring_align) > PAGE_SIZE; num /= 2) {
 353                 size_t sz = vring_size(num, vring_align);
 354
 355                 queue = virtio_alloc_pages(vdev, DIV_ROUND_UP(sz, PAGE_SIZE));
 356                 if (queue)
 357                         break;
 358         }
 359
 360         if (!num)
 361                 return NULL;
 362
 363         if (!queue) {
 364                 /* Try to get a single page. You are my only hope! */
 365                 queue = virtio_alloc_pages(vdev, 1);
 366         }
 367         if (!queue)
 368                 return NULL;
 369
 370         memset(queue, 0, vring_size(num, vring_align));
 371
 372         if (virtio_has_feature(vdev, VIRTIO_F_IOMMU_PLATFORM)) {
 373                 bbs = calloc(num, sizeof(*bbs));
 374                 if (!bbs)
 375                         goto err_free_queue;
 376         }
 377
 378         vring_init(&vring, num, queue, vring_align, bbs);
 379
 380         vq = __vring_new_virtqueue(index, vring, udev);
 381         if (!vq)
 382                 goto err_free_bbs;
 383
 384         debug("(%s): created vring @ %p for vq @ %p with num %u\n", udev->name,
 385               queue, vq, num);
 386
 387         return vq;
 388
 389 err_free_bbs:
 390         free(bbs);
 391 err_free_queue:
 392         virtio_free_pages(vdev, queue, DIV_ROUND_UP(vring.size, PAGE_SIZE));
 393         return NULL;
 394 }
 395
 396 void vring_del_virtqueue(struct virtqueue *vq)
 397 {
 398         virtio_free_pages(vq->vdev, vq->vring.desc,
 399                           DIV_ROUND_UP(vq->vring.size, PAGE_SIZE));
 400         free(vq->vring_desc_shadow);
 401         list_del(&vq->list);
 402         free(vq->vring.bouncebufs);
 403         free(vq);
 404 }
 405
 406 unsigned int virtqueue_get_vring_size(struct virtqueue *vq)
 407 {
 408         return vq->vring.num;
 409 }
 410
 411 ulong virtqueue_get_desc_addr(struct virtqueue *vq)
 412 {
 413         return (ulong)vq->vring.desc;
 414 }
 415
 416 ulong virtqueue_get_avail_addr(struct virtqueue *vq)
 417 {
 418         return (ulong)vq->vring.desc +
 419                ((char *)vq->vring.avail - (char *)vq->vring.desc);
 420 }
 421
 422 ulong virtqueue_get_used_addr(struct virtqueue *vq)
 423 {
 424         return (ulong)vq->vring.desc +
 425                ((char *)vq->vring.used - (char *)vq->vring.desc);
 426 }
 427
 428 bool virtqueue_poll(struct virtqueue *vq, u16 last_used_idx)
 429 {
 430         virtio_mb();
 431
 432         return last_used_idx != virtio16_to_cpu(vq->vdev, vq->vring.used->idx);
 433 }
 434
 435 void virtqueue_dump(struct virtqueue *vq)
 436 {
 437         unsigned int i;
 438
 439         printf("virtqueue %p for dev %s:\n", vq, vq->vdev->name);
 440         printf("\tindex %u, phys addr %p num %u\n",
 441                vq->index, vq->vring.desc, vq->vring.num);
 442         printf("\tfree_head %u, num_added %u, num_free %u\n",
 443                vq->free_head, vq->num_added, vq->num_free);
 444         printf("\tlast_used_idx %u, avail_flags_shadow %u, avail_idx_shadow %u\n",
 445                vq->last_used_idx, vq->avail_flags_shadow, vq->avail_idx_shadow);
 446
 447         printf("Shadow descriptor dump:\n");
 448         for (i = 0; i < vq->vring.num; i++) {
 449                 struct vring_desc_shadow *desc = &vq->vring_desc_shadow[i];
 450
 451                 printf("\tdesc_shadow[%u] = { 0x%llx, len %u, flags %u, next %u }\n",
 452                        i, desc->addr, desc->len, desc->flags, desc->next);
 453         }
 454
 455         printf("Avail ring dump:\n");
 456         printf("\tflags %u, idx %u\n",
 457                vq->vring.avail->flags, vq->vring.avail->idx);
 458         for (i = 0; i < vq->vring.num; i++) {
 459                 printf("\tavail[%u] = %u\n",
 460                        i, vq->vring.avail->ring[i]);
 461         }
 462
 463         printf("Used ring dump:\n");
 464         printf("\tflags %u, idx %u\n",
 465                vq->vring.used->flags, vq->vring.used->idx);
 466         for (i = 0; i < vq->vring.num; i++) {
 467                 printf("\tused[%u] = { %u, %u }\n", i,
 468                        vq->vring.used->ring[i].id, vq->vring.used->ring[i].len);
 469         }
 470 }