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0a8a69dd RR |
1 | /* Virtio ring implementation. |
2 | * | |
3 | * Copyright 2007 Rusty Russell IBM Corporation | |
4 | * | |
5 | * This program is free software; you can redistribute it and/or modify | |
6 | * it under the terms of the GNU General Public License as published by | |
7 | * the Free Software Foundation; either version 2 of the License, or | |
8 | * (at your option) any later version. | |
9 | * | |
10 | * This program is distributed in the hope that it will be useful, | |
11 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
12 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
13 | * GNU General Public License for more details. | |
14 | * | |
15 | * You should have received a copy of the GNU General Public License | |
16 | * along with this program; if not, write to the Free Software | |
17 | * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA | |
18 | */ | |
19 | #include <linux/virtio.h> | |
20 | #include <linux/virtio_ring.h> | |
e34f8725 | 21 | #include <linux/virtio_config.h> |
0a8a69dd | 22 | #include <linux/device.h> |
5a0e3ad6 | 23 | #include <linux/slab.h> |
b5a2c4f1 | 24 | #include <linux/module.h> |
0a8a69dd | 25 | |
d57ed95d MT |
26 | /* virtio guest is communicating with a virtual "device" that actually runs on |
27 | * a host processor. Memory barriers are used to control SMP effects. */ | |
28 | #ifdef CONFIG_SMP | |
29 | /* Where possible, use SMP barriers which are more lightweight than mandatory | |
30 | * barriers, because mandatory barriers control MMIO effects on accesses | |
31 | * through relaxed memory I/O windows (which virtio does not use). */ | |
32 | #define virtio_mb() smp_mb() | |
33 | #define virtio_rmb() smp_rmb() | |
34 | #define virtio_wmb() smp_wmb() | |
35 | #else | |
36 | /* We must force memory ordering even if guest is UP since host could be | |
37 | * running on another CPU, but SMP barriers are defined to barrier() in that | |
38 | * configuration. So fall back to mandatory barriers instead. */ | |
39 | #define virtio_mb() mb() | |
40 | #define virtio_rmb() rmb() | |
41 | #define virtio_wmb() wmb() | |
42 | #endif | |
43 | ||
0a8a69dd RR |
44 | #ifdef DEBUG |
45 | /* For development, we want to crash whenever the ring is screwed. */ | |
9499f5e7 RR |
46 | #define BAD_RING(_vq, fmt, args...) \ |
47 | do { \ | |
48 | dev_err(&(_vq)->vq.vdev->dev, \ | |
49 | "%s:"fmt, (_vq)->vq.name, ##args); \ | |
50 | BUG(); \ | |
51 | } while (0) | |
c5f841f1 RR |
52 | /* Caller is supposed to guarantee no reentry. */ |
53 | #define START_USE(_vq) \ | |
54 | do { \ | |
55 | if ((_vq)->in_use) \ | |
9499f5e7 RR |
56 | panic("%s:in_use = %i\n", \ |
57 | (_vq)->vq.name, (_vq)->in_use); \ | |
c5f841f1 | 58 | (_vq)->in_use = __LINE__; \ |
9499f5e7 | 59 | } while (0) |
3a35ce7d | 60 | #define END_USE(_vq) \ |
97a545ab | 61 | do { BUG_ON(!(_vq)->in_use); (_vq)->in_use = 0; } while(0) |
0a8a69dd | 62 | #else |
9499f5e7 RR |
63 | #define BAD_RING(_vq, fmt, args...) \ |
64 | do { \ | |
65 | dev_err(&_vq->vq.vdev->dev, \ | |
66 | "%s:"fmt, (_vq)->vq.name, ##args); \ | |
67 | (_vq)->broken = true; \ | |
68 | } while (0) | |
0a8a69dd RR |
69 | #define START_USE(vq) |
70 | #define END_USE(vq) | |
71 | #endif | |
72 | ||
73 | struct vring_virtqueue | |
74 | { | |
75 | struct virtqueue vq; | |
76 | ||
77 | /* Actual memory layout for this queue */ | |
78 | struct vring vring; | |
79 | ||
80 | /* Other side has made a mess, don't try any more. */ | |
81 | bool broken; | |
82 | ||
9fa29b9d MM |
83 | /* Host supports indirect buffers */ |
84 | bool indirect; | |
85 | ||
a5c262c5 MT |
86 | /* Host publishes avail event idx */ |
87 | bool event; | |
88 | ||
0a8a69dd RR |
89 | /* Number of free buffers */ |
90 | unsigned int num_free; | |
91 | /* Head of free buffer list. */ | |
92 | unsigned int free_head; | |
93 | /* Number we've added since last sync. */ | |
94 | unsigned int num_added; | |
95 | ||
96 | /* Last used index we've seen. */ | |
1bc4953e | 97 | u16 last_used_idx; |
0a8a69dd RR |
98 | |
99 | /* How to notify other side. FIXME: commonalize hcalls! */ | |
100 | void (*notify)(struct virtqueue *vq); | |
101 | ||
102 | #ifdef DEBUG | |
103 | /* They're supposed to lock for us. */ | |
104 | unsigned int in_use; | |
105 | #endif | |
106 | ||
107 | /* Tokens for callbacks. */ | |
108 | void *data[]; | |
109 | }; | |
110 | ||
111 | #define to_vvq(_vq) container_of(_vq, struct vring_virtqueue, vq) | |
112 | ||
9fa29b9d MM |
113 | /* Set up an indirect table of descriptors and add it to the queue. */ |
114 | static int vring_add_indirect(struct vring_virtqueue *vq, | |
115 | struct scatterlist sg[], | |
116 | unsigned int out, | |
bbd603ef MT |
117 | unsigned int in, |
118 | gfp_t gfp) | |
9fa29b9d MM |
119 | { |
120 | struct vring_desc *desc; | |
121 | unsigned head; | |
122 | int i; | |
123 | ||
bbd603ef | 124 | desc = kmalloc((out + in) * sizeof(struct vring_desc), gfp); |
9fa29b9d | 125 | if (!desc) |
686d3637 | 126 | return -ENOMEM; |
9fa29b9d MM |
127 | |
128 | /* Transfer entries from the sg list into the indirect page */ | |
129 | for (i = 0; i < out; i++) { | |
130 | desc[i].flags = VRING_DESC_F_NEXT; | |
131 | desc[i].addr = sg_phys(sg); | |
132 | desc[i].len = sg->length; | |
133 | desc[i].next = i+1; | |
134 | sg++; | |
135 | } | |
136 | for (; i < (out + in); i++) { | |
137 | desc[i].flags = VRING_DESC_F_NEXT|VRING_DESC_F_WRITE; | |
138 | desc[i].addr = sg_phys(sg); | |
139 | desc[i].len = sg->length; | |
140 | desc[i].next = i+1; | |
141 | sg++; | |
142 | } | |
143 | ||
144 | /* Last one doesn't continue. */ | |
145 | desc[i-1].flags &= ~VRING_DESC_F_NEXT; | |
146 | desc[i-1].next = 0; | |
147 | ||
148 | /* We're about to use a buffer */ | |
149 | vq->num_free--; | |
150 | ||
151 | /* Use a single buffer which doesn't continue */ | |
152 | head = vq->free_head; | |
153 | vq->vring.desc[head].flags = VRING_DESC_F_INDIRECT; | |
154 | vq->vring.desc[head].addr = virt_to_phys(desc); | |
155 | vq->vring.desc[head].len = i * sizeof(struct vring_desc); | |
156 | ||
157 | /* Update free pointer */ | |
158 | vq->free_head = vq->vring.desc[head].next; | |
159 | ||
160 | return head; | |
161 | } | |
162 | ||
bbd603ef MT |
163 | int virtqueue_add_buf_gfp(struct virtqueue *_vq, |
164 | struct scatterlist sg[], | |
165 | unsigned int out, | |
166 | unsigned int in, | |
167 | void *data, | |
168 | gfp_t gfp) | |
0a8a69dd RR |
169 | { |
170 | struct vring_virtqueue *vq = to_vvq(_vq); | |
1fe9b6fe MT |
171 | unsigned int i, avail, uninitialized_var(prev); |
172 | int head; | |
0a8a69dd | 173 | |
9fa29b9d MM |
174 | START_USE(vq); |
175 | ||
0a8a69dd | 176 | BUG_ON(data == NULL); |
9fa29b9d MM |
177 | |
178 | /* If the host supports indirect descriptor tables, and we have multiple | |
179 | * buffers, then go indirect. FIXME: tune this threshold */ | |
180 | if (vq->indirect && (out + in) > 1 && vq->num_free) { | |
bbd603ef | 181 | head = vring_add_indirect(vq, sg, out, in, gfp); |
1fe9b6fe | 182 | if (likely(head >= 0)) |
9fa29b9d MM |
183 | goto add_head; |
184 | } | |
185 | ||
0a8a69dd RR |
186 | BUG_ON(out + in > vq->vring.num); |
187 | BUG_ON(out + in == 0); | |
188 | ||
0a8a69dd RR |
189 | if (vq->num_free < out + in) { |
190 | pr_debug("Can't add buf len %i - avail = %i\n", | |
191 | out + in, vq->num_free); | |
44653eae RR |
192 | /* FIXME: for historical reasons, we force a notify here if |
193 | * there are outgoing parts to the buffer. Presumably the | |
194 | * host should service the ring ASAP. */ | |
195 | if (out) | |
196 | vq->notify(&vq->vq); | |
0a8a69dd RR |
197 | END_USE(vq); |
198 | return -ENOSPC; | |
199 | } | |
200 | ||
201 | /* We're about to use some buffers from the free list. */ | |
202 | vq->num_free -= out + in; | |
203 | ||
204 | head = vq->free_head; | |
205 | for (i = vq->free_head; out; i = vq->vring.desc[i].next, out--) { | |
206 | vq->vring.desc[i].flags = VRING_DESC_F_NEXT; | |
15f9c890 | 207 | vq->vring.desc[i].addr = sg_phys(sg); |
0a8a69dd RR |
208 | vq->vring.desc[i].len = sg->length; |
209 | prev = i; | |
210 | sg++; | |
211 | } | |
212 | for (; in; i = vq->vring.desc[i].next, in--) { | |
213 | vq->vring.desc[i].flags = VRING_DESC_F_NEXT|VRING_DESC_F_WRITE; | |
15f9c890 | 214 | vq->vring.desc[i].addr = sg_phys(sg); |
0a8a69dd RR |
215 | vq->vring.desc[i].len = sg->length; |
216 | prev = i; | |
217 | sg++; | |
218 | } | |
219 | /* Last one doesn't continue. */ | |
220 | vq->vring.desc[prev].flags &= ~VRING_DESC_F_NEXT; | |
221 | ||
222 | /* Update free pointer */ | |
223 | vq->free_head = i; | |
224 | ||
9fa29b9d | 225 | add_head: |
0a8a69dd RR |
226 | /* Set token. */ |
227 | vq->data[head] = data; | |
228 | ||
229 | /* Put entry in available array (but don't update avail->idx until they | |
230 | * do sync). FIXME: avoid modulus here? */ | |
231 | avail = (vq->vring.avail->idx + vq->num_added++) % vq->vring.num; | |
232 | vq->vring.avail->ring[avail] = head; | |
233 | ||
234 | pr_debug("Added buffer head %i to %p\n", head, vq); | |
235 | END_USE(vq); | |
3c1b27d5 | 236 | |
3c1b27d5 | 237 | return vq->num_free; |
0a8a69dd | 238 | } |
bbd603ef | 239 | EXPORT_SYMBOL_GPL(virtqueue_add_buf_gfp); |
0a8a69dd | 240 | |
7c5e9ed0 | 241 | void virtqueue_kick(struct virtqueue *_vq) |
0a8a69dd RR |
242 | { |
243 | struct vring_virtqueue *vq = to_vvq(_vq); | |
a5c262c5 | 244 | u16 new, old; |
0a8a69dd RR |
245 | START_USE(vq); |
246 | /* Descriptors and available array need to be set before we expose the | |
247 | * new available array entries. */ | |
d57ed95d | 248 | virtio_wmb(); |
0a8a69dd | 249 | |
a5c262c5 MT |
250 | old = vq->vring.avail->idx; |
251 | new = vq->vring.avail->idx = old + vq->num_added; | |
0a8a69dd RR |
252 | vq->num_added = 0; |
253 | ||
254 | /* Need to update avail index before checking if we should notify */ | |
d57ed95d | 255 | virtio_mb(); |
0a8a69dd | 256 | |
a5c262c5 MT |
257 | if (vq->event ? |
258 | vring_need_event(vring_avail_event(&vq->vring), new, old) : | |
259 | !(vq->vring.used->flags & VRING_USED_F_NO_NOTIFY)) | |
0a8a69dd RR |
260 | /* Prod other side to tell it about changes. */ |
261 | vq->notify(&vq->vq); | |
262 | ||
263 | END_USE(vq); | |
264 | } | |
7c5e9ed0 | 265 | EXPORT_SYMBOL_GPL(virtqueue_kick); |
0a8a69dd RR |
266 | |
267 | static void detach_buf(struct vring_virtqueue *vq, unsigned int head) | |
268 | { | |
269 | unsigned int i; | |
270 | ||
271 | /* Clear data ptr. */ | |
272 | vq->data[head] = NULL; | |
273 | ||
274 | /* Put back on free list: find end */ | |
275 | i = head; | |
9fa29b9d MM |
276 | |
277 | /* Free the indirect table */ | |
278 | if (vq->vring.desc[i].flags & VRING_DESC_F_INDIRECT) | |
279 | kfree(phys_to_virt(vq->vring.desc[i].addr)); | |
280 | ||
0a8a69dd RR |
281 | while (vq->vring.desc[i].flags & VRING_DESC_F_NEXT) { |
282 | i = vq->vring.desc[i].next; | |
283 | vq->num_free++; | |
284 | } | |
285 | ||
286 | vq->vring.desc[i].next = vq->free_head; | |
287 | vq->free_head = head; | |
288 | /* Plus final descriptor */ | |
289 | vq->num_free++; | |
290 | } | |
291 | ||
0a8a69dd RR |
292 | static inline bool more_used(const struct vring_virtqueue *vq) |
293 | { | |
294 | return vq->last_used_idx != vq->vring.used->idx; | |
295 | } | |
296 | ||
7c5e9ed0 | 297 | void *virtqueue_get_buf(struct virtqueue *_vq, unsigned int *len) |
0a8a69dd RR |
298 | { |
299 | struct vring_virtqueue *vq = to_vvq(_vq); | |
300 | void *ret; | |
301 | unsigned int i; | |
302 | ||
303 | START_USE(vq); | |
304 | ||
5ef82752 RR |
305 | if (unlikely(vq->broken)) { |
306 | END_USE(vq); | |
307 | return NULL; | |
308 | } | |
309 | ||
0a8a69dd RR |
310 | if (!more_used(vq)) { |
311 | pr_debug("No more buffers in queue\n"); | |
312 | END_USE(vq); | |
313 | return NULL; | |
314 | } | |
315 | ||
2d61ba95 | 316 | /* Only get used array entries after they have been exposed by host. */ |
d57ed95d | 317 | virtio_rmb(); |
2d61ba95 | 318 | |
0a8a69dd RR |
319 | i = vq->vring.used->ring[vq->last_used_idx%vq->vring.num].id; |
320 | *len = vq->vring.used->ring[vq->last_used_idx%vq->vring.num].len; | |
321 | ||
322 | if (unlikely(i >= vq->vring.num)) { | |
323 | BAD_RING(vq, "id %u out of range\n", i); | |
324 | return NULL; | |
325 | } | |
326 | if (unlikely(!vq->data[i])) { | |
327 | BAD_RING(vq, "id %u is not a head!\n", i); | |
328 | return NULL; | |
329 | } | |
330 | ||
331 | /* detach_buf clears data, so grab it now. */ | |
332 | ret = vq->data[i]; | |
333 | detach_buf(vq, i); | |
334 | vq->last_used_idx++; | |
a5c262c5 MT |
335 | /* If we expect an interrupt for the next entry, tell host |
336 | * by writing event index and flush out the write before | |
337 | * the read in the next get_buf call. */ | |
338 | if (!(vq->vring.avail->flags & VRING_AVAIL_F_NO_INTERRUPT)) { | |
339 | vring_used_event(&vq->vring) = vq->last_used_idx; | |
340 | virtio_mb(); | |
341 | } | |
342 | ||
0a8a69dd RR |
343 | END_USE(vq); |
344 | return ret; | |
345 | } | |
7c5e9ed0 | 346 | EXPORT_SYMBOL_GPL(virtqueue_get_buf); |
0a8a69dd | 347 | |
7c5e9ed0 | 348 | void virtqueue_disable_cb(struct virtqueue *_vq) |
18445c4d RR |
349 | { |
350 | struct vring_virtqueue *vq = to_vvq(_vq); | |
351 | ||
18445c4d | 352 | vq->vring.avail->flags |= VRING_AVAIL_F_NO_INTERRUPT; |
18445c4d | 353 | } |
7c5e9ed0 | 354 | EXPORT_SYMBOL_GPL(virtqueue_disable_cb); |
18445c4d | 355 | |
7c5e9ed0 | 356 | bool virtqueue_enable_cb(struct virtqueue *_vq) |
0a8a69dd RR |
357 | { |
358 | struct vring_virtqueue *vq = to_vvq(_vq); | |
359 | ||
360 | START_USE(vq); | |
0a8a69dd RR |
361 | |
362 | /* We optimistically turn back on interrupts, then check if there was | |
363 | * more to do. */ | |
a5c262c5 MT |
364 | /* Depending on the VIRTIO_RING_F_EVENT_IDX feature, we need to |
365 | * either clear the flags bit or point the event index at the next | |
366 | * entry. Always do both to keep code simple. */ | |
0a8a69dd | 367 | vq->vring.avail->flags &= ~VRING_AVAIL_F_NO_INTERRUPT; |
a5c262c5 | 368 | vring_used_event(&vq->vring) = vq->last_used_idx; |
d57ed95d | 369 | virtio_mb(); |
0a8a69dd | 370 | if (unlikely(more_used(vq))) { |
0a8a69dd RR |
371 | END_USE(vq); |
372 | return false; | |
373 | } | |
374 | ||
375 | END_USE(vq); | |
376 | return true; | |
377 | } | |
7c5e9ed0 | 378 | EXPORT_SYMBOL_GPL(virtqueue_enable_cb); |
0a8a69dd | 379 | |
7ab358c2 MT |
380 | bool virtqueue_enable_cb_delayed(struct virtqueue *_vq) |
381 | { | |
382 | struct vring_virtqueue *vq = to_vvq(_vq); | |
383 | u16 bufs; | |
384 | ||
385 | START_USE(vq); | |
386 | ||
387 | /* We optimistically turn back on interrupts, then check if there was | |
388 | * more to do. */ | |
389 | /* Depending on the VIRTIO_RING_F_USED_EVENT_IDX feature, we need to | |
390 | * either clear the flags bit or point the event index at the next | |
391 | * entry. Always do both to keep code simple. */ | |
392 | vq->vring.avail->flags &= ~VRING_AVAIL_F_NO_INTERRUPT; | |
393 | /* TODO: tune this threshold */ | |
394 | bufs = (u16)(vq->vring.avail->idx - vq->last_used_idx) * 3 / 4; | |
395 | vring_used_event(&vq->vring) = vq->last_used_idx + bufs; | |
396 | virtio_mb(); | |
397 | if (unlikely((u16)(vq->vring.used->idx - vq->last_used_idx) > bufs)) { | |
398 | END_USE(vq); | |
399 | return false; | |
400 | } | |
401 | ||
402 | END_USE(vq); | |
403 | return true; | |
404 | } | |
405 | EXPORT_SYMBOL_GPL(virtqueue_enable_cb_delayed); | |
406 | ||
7c5e9ed0 | 407 | void *virtqueue_detach_unused_buf(struct virtqueue *_vq) |
c021eac4 SM |
408 | { |
409 | struct vring_virtqueue *vq = to_vvq(_vq); | |
410 | unsigned int i; | |
411 | void *buf; | |
412 | ||
413 | START_USE(vq); | |
414 | ||
415 | for (i = 0; i < vq->vring.num; i++) { | |
416 | if (!vq->data[i]) | |
417 | continue; | |
418 | /* detach_buf clears data, so grab it now. */ | |
419 | buf = vq->data[i]; | |
420 | detach_buf(vq, i); | |
b3258ff1 | 421 | vq->vring.avail->idx--; |
c021eac4 SM |
422 | END_USE(vq); |
423 | return buf; | |
424 | } | |
425 | /* That should have freed everything. */ | |
426 | BUG_ON(vq->num_free != vq->vring.num); | |
427 | ||
428 | END_USE(vq); | |
429 | return NULL; | |
430 | } | |
7c5e9ed0 | 431 | EXPORT_SYMBOL_GPL(virtqueue_detach_unused_buf); |
c021eac4 | 432 | |
0a8a69dd RR |
433 | irqreturn_t vring_interrupt(int irq, void *_vq) |
434 | { | |
435 | struct vring_virtqueue *vq = to_vvq(_vq); | |
436 | ||
437 | if (!more_used(vq)) { | |
438 | pr_debug("virtqueue interrupt with no work for %p\n", vq); | |
439 | return IRQ_NONE; | |
440 | } | |
441 | ||
442 | if (unlikely(vq->broken)) | |
443 | return IRQ_HANDLED; | |
444 | ||
445 | pr_debug("virtqueue callback for %p (%p)\n", vq, vq->vq.callback); | |
18445c4d RR |
446 | if (vq->vq.callback) |
447 | vq->vq.callback(&vq->vq); | |
0a8a69dd RR |
448 | |
449 | return IRQ_HANDLED; | |
450 | } | |
c6fd4701 | 451 | EXPORT_SYMBOL_GPL(vring_interrupt); |
0a8a69dd | 452 | |
0a8a69dd | 453 | struct virtqueue *vring_new_virtqueue(unsigned int num, |
87c7d57c | 454 | unsigned int vring_align, |
0a8a69dd RR |
455 | struct virtio_device *vdev, |
456 | void *pages, | |
457 | void (*notify)(struct virtqueue *), | |
9499f5e7 RR |
458 | void (*callback)(struct virtqueue *), |
459 | const char *name) | |
0a8a69dd RR |
460 | { |
461 | struct vring_virtqueue *vq; | |
462 | unsigned int i; | |
463 | ||
42b36cc0 RR |
464 | /* We assume num is a power of 2. */ |
465 | if (num & (num - 1)) { | |
466 | dev_warn(&vdev->dev, "Bad virtqueue length %u\n", num); | |
467 | return NULL; | |
468 | } | |
469 | ||
0a8a69dd RR |
470 | vq = kmalloc(sizeof(*vq) + sizeof(void *)*num, GFP_KERNEL); |
471 | if (!vq) | |
472 | return NULL; | |
473 | ||
87c7d57c | 474 | vring_init(&vq->vring, num, pages, vring_align); |
0a8a69dd RR |
475 | vq->vq.callback = callback; |
476 | vq->vq.vdev = vdev; | |
9499f5e7 | 477 | vq->vq.name = name; |
0a8a69dd RR |
478 | vq->notify = notify; |
479 | vq->broken = false; | |
480 | vq->last_used_idx = 0; | |
481 | vq->num_added = 0; | |
9499f5e7 | 482 | list_add_tail(&vq->vq.list, &vdev->vqs); |
0a8a69dd RR |
483 | #ifdef DEBUG |
484 | vq->in_use = false; | |
485 | #endif | |
486 | ||
9fa29b9d | 487 | vq->indirect = virtio_has_feature(vdev, VIRTIO_RING_F_INDIRECT_DESC); |
a5c262c5 | 488 | vq->event = virtio_has_feature(vdev, VIRTIO_RING_F_EVENT_IDX); |
9fa29b9d | 489 | |
0a8a69dd RR |
490 | /* No callback? Tell other side not to bother us. */ |
491 | if (!callback) | |
492 | vq->vring.avail->flags |= VRING_AVAIL_F_NO_INTERRUPT; | |
493 | ||
494 | /* Put everything in free lists. */ | |
495 | vq->num_free = num; | |
496 | vq->free_head = 0; | |
3b870624 | 497 | for (i = 0; i < num-1; i++) { |
0a8a69dd | 498 | vq->vring.desc[i].next = i+1; |
3b870624 AS |
499 | vq->data[i] = NULL; |
500 | } | |
501 | vq->data[i] = NULL; | |
0a8a69dd RR |
502 | |
503 | return &vq->vq; | |
504 | } | |
c6fd4701 | 505 | EXPORT_SYMBOL_GPL(vring_new_virtqueue); |
0a8a69dd RR |
506 | |
507 | void vring_del_virtqueue(struct virtqueue *vq) | |
508 | { | |
9499f5e7 | 509 | list_del(&vq->list); |
0a8a69dd RR |
510 | kfree(to_vvq(vq)); |
511 | } | |
c6fd4701 | 512 | EXPORT_SYMBOL_GPL(vring_del_virtqueue); |
0a8a69dd | 513 | |
e34f8725 RR |
514 | /* Manipulates transport-specific feature bits. */ |
515 | void vring_transport_features(struct virtio_device *vdev) | |
516 | { | |
517 | unsigned int i; | |
518 | ||
519 | for (i = VIRTIO_TRANSPORT_F_START; i < VIRTIO_TRANSPORT_F_END; i++) { | |
520 | switch (i) { | |
9fa29b9d MM |
521 | case VIRTIO_RING_F_INDIRECT_DESC: |
522 | break; | |
a5c262c5 MT |
523 | case VIRTIO_RING_F_EVENT_IDX: |
524 | break; | |
e34f8725 RR |
525 | default: |
526 | /* We don't understand this bit. */ | |
527 | clear_bit(i, vdev->features); | |
528 | } | |
529 | } | |
530 | } | |
531 | EXPORT_SYMBOL_GPL(vring_transport_features); | |
532 | ||
8f9f4668 RJ |
533 | /* return the size of the vring within the virtqueue */ |
534 | unsigned int virtqueue_get_vring_size(struct virtqueue *_vq) | |
535 | { | |
536 | ||
537 | struct vring_virtqueue *vq = to_vvq(_vq); | |
538 | ||
539 | return vq->vring.num; | |
540 | } | |
541 | EXPORT_SYMBOL_GPL(virtqueue_get_vring_size); | |
542 | ||
c6fd4701 | 543 | MODULE_LICENSE("GPL"); |