Commit | Line | Data |
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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 | |
7b21e34f RR |
31 | * through relaxed memory I/O windows (which virtio-pci does not use). */ |
32 | #define virtio_mb(vq) \ | |
33 | do { if ((vq)->weak_barriers) smp_mb(); else mb(); } while(0) | |
34 | #define virtio_rmb(vq) \ | |
35 | do { if ((vq)->weak_barriers) smp_rmb(); else rmb(); } while(0) | |
36 | #define virtio_wmb(vq) \ | |
37 | do { if ((vq)->weak_barriers) smp_rmb(); else rmb(); } while(0) | |
d57ed95d MT |
38 | #else |
39 | /* We must force memory ordering even if guest is UP since host could be | |
40 | * running on another CPU, but SMP barriers are defined to barrier() in that | |
41 | * configuration. So fall back to mandatory barriers instead. */ | |
7b21e34f RR |
42 | #define virtio_mb(vq) mb() |
43 | #define virtio_rmb(vq) rmb() | |
44 | #define virtio_wmb(vq) wmb() | |
d57ed95d MT |
45 | #endif |
46 | ||
0a8a69dd RR |
47 | #ifdef DEBUG |
48 | /* For development, we want to crash whenever the ring is screwed. */ | |
9499f5e7 RR |
49 | #define BAD_RING(_vq, fmt, args...) \ |
50 | do { \ | |
51 | dev_err(&(_vq)->vq.vdev->dev, \ | |
52 | "%s:"fmt, (_vq)->vq.name, ##args); \ | |
53 | BUG(); \ | |
54 | } while (0) | |
c5f841f1 RR |
55 | /* Caller is supposed to guarantee no reentry. */ |
56 | #define START_USE(_vq) \ | |
57 | do { \ | |
58 | if ((_vq)->in_use) \ | |
9499f5e7 RR |
59 | panic("%s:in_use = %i\n", \ |
60 | (_vq)->vq.name, (_vq)->in_use); \ | |
c5f841f1 | 61 | (_vq)->in_use = __LINE__; \ |
9499f5e7 | 62 | } while (0) |
3a35ce7d | 63 | #define END_USE(_vq) \ |
97a545ab | 64 | do { BUG_ON(!(_vq)->in_use); (_vq)->in_use = 0; } while(0) |
0a8a69dd | 65 | #else |
9499f5e7 RR |
66 | #define BAD_RING(_vq, fmt, args...) \ |
67 | do { \ | |
68 | dev_err(&_vq->vq.vdev->dev, \ | |
69 | "%s:"fmt, (_vq)->vq.name, ##args); \ | |
70 | (_vq)->broken = true; \ | |
71 | } while (0) | |
0a8a69dd RR |
72 | #define START_USE(vq) |
73 | #define END_USE(vq) | |
74 | #endif | |
75 | ||
76 | struct vring_virtqueue | |
77 | { | |
78 | struct virtqueue vq; | |
79 | ||
80 | /* Actual memory layout for this queue */ | |
81 | struct vring vring; | |
82 | ||
7b21e34f RR |
83 | /* Can we use weak barriers? */ |
84 | bool weak_barriers; | |
85 | ||
0a8a69dd RR |
86 | /* Other side has made a mess, don't try any more. */ |
87 | bool broken; | |
88 | ||
9fa29b9d MM |
89 | /* Host supports indirect buffers */ |
90 | bool indirect; | |
91 | ||
a5c262c5 MT |
92 | /* Host publishes avail event idx */ |
93 | bool event; | |
94 | ||
0a8a69dd RR |
95 | /* Number of free buffers */ |
96 | unsigned int num_free; | |
97 | /* Head of free buffer list. */ | |
98 | unsigned int free_head; | |
99 | /* Number we've added since last sync. */ | |
100 | unsigned int num_added; | |
101 | ||
102 | /* Last used index we've seen. */ | |
1bc4953e | 103 | u16 last_used_idx; |
0a8a69dd RR |
104 | |
105 | /* How to notify other side. FIXME: commonalize hcalls! */ | |
106 | void (*notify)(struct virtqueue *vq); | |
107 | ||
108 | #ifdef DEBUG | |
109 | /* They're supposed to lock for us. */ | |
110 | unsigned int in_use; | |
111 | #endif | |
112 | ||
113 | /* Tokens for callbacks. */ | |
114 | void *data[]; | |
115 | }; | |
116 | ||
117 | #define to_vvq(_vq) container_of(_vq, struct vring_virtqueue, vq) | |
118 | ||
9fa29b9d MM |
119 | /* Set up an indirect table of descriptors and add it to the queue. */ |
120 | static int vring_add_indirect(struct vring_virtqueue *vq, | |
121 | struct scatterlist sg[], | |
122 | unsigned int out, | |
bbd603ef MT |
123 | unsigned int in, |
124 | gfp_t gfp) | |
9fa29b9d MM |
125 | { |
126 | struct vring_desc *desc; | |
127 | unsigned head; | |
128 | int i; | |
129 | ||
bbd603ef | 130 | desc = kmalloc((out + in) * sizeof(struct vring_desc), gfp); |
9fa29b9d | 131 | if (!desc) |
686d3637 | 132 | return -ENOMEM; |
9fa29b9d MM |
133 | |
134 | /* Transfer entries from the sg list into the indirect page */ | |
135 | for (i = 0; i < out; i++) { | |
136 | desc[i].flags = VRING_DESC_F_NEXT; | |
137 | desc[i].addr = sg_phys(sg); | |
138 | desc[i].len = sg->length; | |
139 | desc[i].next = i+1; | |
140 | sg++; | |
141 | } | |
142 | for (; i < (out + in); i++) { | |
143 | desc[i].flags = VRING_DESC_F_NEXT|VRING_DESC_F_WRITE; | |
144 | desc[i].addr = sg_phys(sg); | |
145 | desc[i].len = sg->length; | |
146 | desc[i].next = i+1; | |
147 | sg++; | |
148 | } | |
149 | ||
150 | /* Last one doesn't continue. */ | |
151 | desc[i-1].flags &= ~VRING_DESC_F_NEXT; | |
152 | desc[i-1].next = 0; | |
153 | ||
154 | /* We're about to use a buffer */ | |
155 | vq->num_free--; | |
156 | ||
157 | /* Use a single buffer which doesn't continue */ | |
158 | head = vq->free_head; | |
159 | vq->vring.desc[head].flags = VRING_DESC_F_INDIRECT; | |
160 | vq->vring.desc[head].addr = virt_to_phys(desc); | |
161 | vq->vring.desc[head].len = i * sizeof(struct vring_desc); | |
162 | ||
163 | /* Update free pointer */ | |
164 | vq->free_head = vq->vring.desc[head].next; | |
165 | ||
166 | return head; | |
167 | } | |
168 | ||
bbd603ef MT |
169 | int virtqueue_add_buf_gfp(struct virtqueue *_vq, |
170 | struct scatterlist sg[], | |
171 | unsigned int out, | |
172 | unsigned int in, | |
173 | void *data, | |
174 | gfp_t gfp) | |
0a8a69dd RR |
175 | { |
176 | struct vring_virtqueue *vq = to_vvq(_vq); | |
1fe9b6fe MT |
177 | unsigned int i, avail, uninitialized_var(prev); |
178 | int head; | |
0a8a69dd | 179 | |
9fa29b9d MM |
180 | START_USE(vq); |
181 | ||
0a8a69dd | 182 | BUG_ON(data == NULL); |
9fa29b9d MM |
183 | |
184 | /* If the host supports indirect descriptor tables, and we have multiple | |
185 | * buffers, then go indirect. FIXME: tune this threshold */ | |
186 | if (vq->indirect && (out + in) > 1 && vq->num_free) { | |
bbd603ef | 187 | head = vring_add_indirect(vq, sg, out, in, gfp); |
1fe9b6fe | 188 | if (likely(head >= 0)) |
9fa29b9d MM |
189 | goto add_head; |
190 | } | |
191 | ||
0a8a69dd RR |
192 | BUG_ON(out + in > vq->vring.num); |
193 | BUG_ON(out + in == 0); | |
194 | ||
0a8a69dd RR |
195 | if (vq->num_free < out + in) { |
196 | pr_debug("Can't add buf len %i - avail = %i\n", | |
197 | out + in, vq->num_free); | |
44653eae RR |
198 | /* FIXME: for historical reasons, we force a notify here if |
199 | * there are outgoing parts to the buffer. Presumably the | |
200 | * host should service the ring ASAP. */ | |
201 | if (out) | |
202 | vq->notify(&vq->vq); | |
0a8a69dd RR |
203 | END_USE(vq); |
204 | return -ENOSPC; | |
205 | } | |
206 | ||
207 | /* We're about to use some buffers from the free list. */ | |
208 | vq->num_free -= out + in; | |
209 | ||
210 | head = vq->free_head; | |
211 | for (i = vq->free_head; out; i = vq->vring.desc[i].next, out--) { | |
212 | vq->vring.desc[i].flags = VRING_DESC_F_NEXT; | |
15f9c890 | 213 | vq->vring.desc[i].addr = sg_phys(sg); |
0a8a69dd RR |
214 | vq->vring.desc[i].len = sg->length; |
215 | prev = i; | |
216 | sg++; | |
217 | } | |
218 | for (; in; i = vq->vring.desc[i].next, in--) { | |
219 | vq->vring.desc[i].flags = VRING_DESC_F_NEXT|VRING_DESC_F_WRITE; | |
15f9c890 | 220 | vq->vring.desc[i].addr = sg_phys(sg); |
0a8a69dd RR |
221 | vq->vring.desc[i].len = sg->length; |
222 | prev = i; | |
223 | sg++; | |
224 | } | |
225 | /* Last one doesn't continue. */ | |
226 | vq->vring.desc[prev].flags &= ~VRING_DESC_F_NEXT; | |
227 | ||
228 | /* Update free pointer */ | |
229 | vq->free_head = i; | |
230 | ||
9fa29b9d | 231 | add_head: |
0a8a69dd RR |
232 | /* Set token. */ |
233 | vq->data[head] = data; | |
234 | ||
235 | /* Put entry in available array (but don't update avail->idx until they | |
236 | * do sync). FIXME: avoid modulus here? */ | |
237 | avail = (vq->vring.avail->idx + vq->num_added++) % vq->vring.num; | |
238 | vq->vring.avail->ring[avail] = head; | |
239 | ||
240 | pr_debug("Added buffer head %i to %p\n", head, vq); | |
241 | END_USE(vq); | |
3c1b27d5 | 242 | |
3c1b27d5 | 243 | return vq->num_free; |
0a8a69dd | 244 | } |
bbd603ef | 245 | EXPORT_SYMBOL_GPL(virtqueue_add_buf_gfp); |
0a8a69dd | 246 | |
7c5e9ed0 | 247 | void virtqueue_kick(struct virtqueue *_vq) |
0a8a69dd RR |
248 | { |
249 | struct vring_virtqueue *vq = to_vvq(_vq); | |
a5c262c5 | 250 | u16 new, old; |
0a8a69dd RR |
251 | START_USE(vq); |
252 | /* Descriptors and available array need to be set before we expose the | |
253 | * new available array entries. */ | |
7b21e34f | 254 | virtio_wmb(vq); |
0a8a69dd | 255 | |
a5c262c5 MT |
256 | old = vq->vring.avail->idx; |
257 | new = vq->vring.avail->idx = old + vq->num_added; | |
0a8a69dd RR |
258 | vq->num_added = 0; |
259 | ||
260 | /* Need to update avail index before checking if we should notify */ | |
7b21e34f | 261 | virtio_mb(vq); |
0a8a69dd | 262 | |
a5c262c5 MT |
263 | if (vq->event ? |
264 | vring_need_event(vring_avail_event(&vq->vring), new, old) : | |
265 | !(vq->vring.used->flags & VRING_USED_F_NO_NOTIFY)) | |
0a8a69dd RR |
266 | /* Prod other side to tell it about changes. */ |
267 | vq->notify(&vq->vq); | |
268 | ||
269 | END_USE(vq); | |
270 | } | |
7c5e9ed0 | 271 | EXPORT_SYMBOL_GPL(virtqueue_kick); |
0a8a69dd RR |
272 | |
273 | static void detach_buf(struct vring_virtqueue *vq, unsigned int head) | |
274 | { | |
275 | unsigned int i; | |
276 | ||
277 | /* Clear data ptr. */ | |
278 | vq->data[head] = NULL; | |
279 | ||
280 | /* Put back on free list: find end */ | |
281 | i = head; | |
9fa29b9d MM |
282 | |
283 | /* Free the indirect table */ | |
284 | if (vq->vring.desc[i].flags & VRING_DESC_F_INDIRECT) | |
285 | kfree(phys_to_virt(vq->vring.desc[i].addr)); | |
286 | ||
0a8a69dd RR |
287 | while (vq->vring.desc[i].flags & VRING_DESC_F_NEXT) { |
288 | i = vq->vring.desc[i].next; | |
289 | vq->num_free++; | |
290 | } | |
291 | ||
292 | vq->vring.desc[i].next = vq->free_head; | |
293 | vq->free_head = head; | |
294 | /* Plus final descriptor */ | |
295 | vq->num_free++; | |
296 | } | |
297 | ||
0a8a69dd RR |
298 | static inline bool more_used(const struct vring_virtqueue *vq) |
299 | { | |
300 | return vq->last_used_idx != vq->vring.used->idx; | |
301 | } | |
302 | ||
7c5e9ed0 | 303 | void *virtqueue_get_buf(struct virtqueue *_vq, unsigned int *len) |
0a8a69dd RR |
304 | { |
305 | struct vring_virtqueue *vq = to_vvq(_vq); | |
306 | void *ret; | |
307 | unsigned int i; | |
308 | ||
309 | START_USE(vq); | |
310 | ||
5ef82752 RR |
311 | if (unlikely(vq->broken)) { |
312 | END_USE(vq); | |
313 | return NULL; | |
314 | } | |
315 | ||
0a8a69dd RR |
316 | if (!more_used(vq)) { |
317 | pr_debug("No more buffers in queue\n"); | |
318 | END_USE(vq); | |
319 | return NULL; | |
320 | } | |
321 | ||
2d61ba95 | 322 | /* Only get used array entries after they have been exposed by host. */ |
7b21e34f | 323 | virtio_rmb(vq); |
2d61ba95 | 324 | |
0a8a69dd RR |
325 | i = vq->vring.used->ring[vq->last_used_idx%vq->vring.num].id; |
326 | *len = vq->vring.used->ring[vq->last_used_idx%vq->vring.num].len; | |
327 | ||
328 | if (unlikely(i >= vq->vring.num)) { | |
329 | BAD_RING(vq, "id %u out of range\n", i); | |
330 | return NULL; | |
331 | } | |
332 | if (unlikely(!vq->data[i])) { | |
333 | BAD_RING(vq, "id %u is not a head!\n", i); | |
334 | return NULL; | |
335 | } | |
336 | ||
337 | /* detach_buf clears data, so grab it now. */ | |
338 | ret = vq->data[i]; | |
339 | detach_buf(vq, i); | |
340 | vq->last_used_idx++; | |
a5c262c5 MT |
341 | /* If we expect an interrupt for the next entry, tell host |
342 | * by writing event index and flush out the write before | |
343 | * the read in the next get_buf call. */ | |
344 | if (!(vq->vring.avail->flags & VRING_AVAIL_F_NO_INTERRUPT)) { | |
345 | vring_used_event(&vq->vring) = vq->last_used_idx; | |
7b21e34f | 346 | virtio_mb(vq); |
a5c262c5 MT |
347 | } |
348 | ||
0a8a69dd RR |
349 | END_USE(vq); |
350 | return ret; | |
351 | } | |
7c5e9ed0 | 352 | EXPORT_SYMBOL_GPL(virtqueue_get_buf); |
0a8a69dd | 353 | |
7c5e9ed0 | 354 | void virtqueue_disable_cb(struct virtqueue *_vq) |
18445c4d RR |
355 | { |
356 | struct vring_virtqueue *vq = to_vvq(_vq); | |
357 | ||
18445c4d | 358 | vq->vring.avail->flags |= VRING_AVAIL_F_NO_INTERRUPT; |
18445c4d | 359 | } |
7c5e9ed0 | 360 | EXPORT_SYMBOL_GPL(virtqueue_disable_cb); |
18445c4d | 361 | |
7c5e9ed0 | 362 | bool virtqueue_enable_cb(struct virtqueue *_vq) |
0a8a69dd RR |
363 | { |
364 | struct vring_virtqueue *vq = to_vvq(_vq); | |
365 | ||
366 | START_USE(vq); | |
0a8a69dd RR |
367 | |
368 | /* We optimistically turn back on interrupts, then check if there was | |
369 | * more to do. */ | |
a5c262c5 MT |
370 | /* Depending on the VIRTIO_RING_F_EVENT_IDX feature, we need to |
371 | * either clear the flags bit or point the event index at the next | |
372 | * entry. Always do both to keep code simple. */ | |
0a8a69dd | 373 | vq->vring.avail->flags &= ~VRING_AVAIL_F_NO_INTERRUPT; |
a5c262c5 | 374 | vring_used_event(&vq->vring) = vq->last_used_idx; |
7b21e34f | 375 | virtio_mb(vq); |
0a8a69dd | 376 | if (unlikely(more_used(vq))) { |
0a8a69dd RR |
377 | END_USE(vq); |
378 | return false; | |
379 | } | |
380 | ||
381 | END_USE(vq); | |
382 | return true; | |
383 | } | |
7c5e9ed0 | 384 | EXPORT_SYMBOL_GPL(virtqueue_enable_cb); |
0a8a69dd | 385 | |
7ab358c2 MT |
386 | bool virtqueue_enable_cb_delayed(struct virtqueue *_vq) |
387 | { | |
388 | struct vring_virtqueue *vq = to_vvq(_vq); | |
389 | u16 bufs; | |
390 | ||
391 | START_USE(vq); | |
392 | ||
393 | /* We optimistically turn back on interrupts, then check if there was | |
394 | * more to do. */ | |
395 | /* Depending on the VIRTIO_RING_F_USED_EVENT_IDX feature, we need to | |
396 | * either clear the flags bit or point the event index at the next | |
397 | * entry. Always do both to keep code simple. */ | |
398 | vq->vring.avail->flags &= ~VRING_AVAIL_F_NO_INTERRUPT; | |
399 | /* TODO: tune this threshold */ | |
400 | bufs = (u16)(vq->vring.avail->idx - vq->last_used_idx) * 3 / 4; | |
401 | vring_used_event(&vq->vring) = vq->last_used_idx + bufs; | |
7b21e34f | 402 | virtio_mb(vq); |
7ab358c2 MT |
403 | if (unlikely((u16)(vq->vring.used->idx - vq->last_used_idx) > bufs)) { |
404 | END_USE(vq); | |
405 | return false; | |
406 | } | |
407 | ||
408 | END_USE(vq); | |
409 | return true; | |
410 | } | |
411 | EXPORT_SYMBOL_GPL(virtqueue_enable_cb_delayed); | |
412 | ||
7c5e9ed0 | 413 | void *virtqueue_detach_unused_buf(struct virtqueue *_vq) |
c021eac4 SM |
414 | { |
415 | struct vring_virtqueue *vq = to_vvq(_vq); | |
416 | unsigned int i; | |
417 | void *buf; | |
418 | ||
419 | START_USE(vq); | |
420 | ||
421 | for (i = 0; i < vq->vring.num; i++) { | |
422 | if (!vq->data[i]) | |
423 | continue; | |
424 | /* detach_buf clears data, so grab it now. */ | |
425 | buf = vq->data[i]; | |
426 | detach_buf(vq, i); | |
b3258ff1 | 427 | vq->vring.avail->idx--; |
c021eac4 SM |
428 | END_USE(vq); |
429 | return buf; | |
430 | } | |
431 | /* That should have freed everything. */ | |
432 | BUG_ON(vq->num_free != vq->vring.num); | |
433 | ||
434 | END_USE(vq); | |
435 | return NULL; | |
436 | } | |
7c5e9ed0 | 437 | EXPORT_SYMBOL_GPL(virtqueue_detach_unused_buf); |
c021eac4 | 438 | |
0a8a69dd RR |
439 | irqreturn_t vring_interrupt(int irq, void *_vq) |
440 | { | |
441 | struct vring_virtqueue *vq = to_vvq(_vq); | |
442 | ||
443 | if (!more_used(vq)) { | |
444 | pr_debug("virtqueue interrupt with no work for %p\n", vq); | |
445 | return IRQ_NONE; | |
446 | } | |
447 | ||
448 | if (unlikely(vq->broken)) | |
449 | return IRQ_HANDLED; | |
450 | ||
451 | pr_debug("virtqueue callback for %p (%p)\n", vq, vq->vq.callback); | |
18445c4d RR |
452 | if (vq->vq.callback) |
453 | vq->vq.callback(&vq->vq); | |
0a8a69dd RR |
454 | |
455 | return IRQ_HANDLED; | |
456 | } | |
c6fd4701 | 457 | EXPORT_SYMBOL_GPL(vring_interrupt); |
0a8a69dd | 458 | |
0a8a69dd | 459 | struct virtqueue *vring_new_virtqueue(unsigned int num, |
87c7d57c | 460 | unsigned int vring_align, |
0a8a69dd | 461 | struct virtio_device *vdev, |
7b21e34f | 462 | bool weak_barriers, |
0a8a69dd RR |
463 | void *pages, |
464 | void (*notify)(struct virtqueue *), | |
9499f5e7 RR |
465 | void (*callback)(struct virtqueue *), |
466 | const char *name) | |
0a8a69dd RR |
467 | { |
468 | struct vring_virtqueue *vq; | |
469 | unsigned int i; | |
470 | ||
42b36cc0 RR |
471 | /* We assume num is a power of 2. */ |
472 | if (num & (num - 1)) { | |
473 | dev_warn(&vdev->dev, "Bad virtqueue length %u\n", num); | |
474 | return NULL; | |
475 | } | |
476 | ||
0a8a69dd RR |
477 | vq = kmalloc(sizeof(*vq) + sizeof(void *)*num, GFP_KERNEL); |
478 | if (!vq) | |
479 | return NULL; | |
480 | ||
87c7d57c | 481 | vring_init(&vq->vring, num, pages, vring_align); |
0a8a69dd RR |
482 | vq->vq.callback = callback; |
483 | vq->vq.vdev = vdev; | |
9499f5e7 | 484 | vq->vq.name = name; |
0a8a69dd | 485 | vq->notify = notify; |
7b21e34f | 486 | vq->weak_barriers = weak_barriers; |
0a8a69dd RR |
487 | vq->broken = false; |
488 | vq->last_used_idx = 0; | |
489 | vq->num_added = 0; | |
9499f5e7 | 490 | list_add_tail(&vq->vq.list, &vdev->vqs); |
0a8a69dd RR |
491 | #ifdef DEBUG |
492 | vq->in_use = false; | |
493 | #endif | |
494 | ||
9fa29b9d | 495 | vq->indirect = virtio_has_feature(vdev, VIRTIO_RING_F_INDIRECT_DESC); |
a5c262c5 | 496 | vq->event = virtio_has_feature(vdev, VIRTIO_RING_F_EVENT_IDX); |
9fa29b9d | 497 | |
0a8a69dd RR |
498 | /* No callback? Tell other side not to bother us. */ |
499 | if (!callback) | |
500 | vq->vring.avail->flags |= VRING_AVAIL_F_NO_INTERRUPT; | |
501 | ||
502 | /* Put everything in free lists. */ | |
503 | vq->num_free = num; | |
504 | vq->free_head = 0; | |
3b870624 | 505 | for (i = 0; i < num-1; i++) { |
0a8a69dd | 506 | vq->vring.desc[i].next = i+1; |
3b870624 AS |
507 | vq->data[i] = NULL; |
508 | } | |
509 | vq->data[i] = NULL; | |
0a8a69dd RR |
510 | |
511 | return &vq->vq; | |
512 | } | |
c6fd4701 | 513 | EXPORT_SYMBOL_GPL(vring_new_virtqueue); |
0a8a69dd RR |
514 | |
515 | void vring_del_virtqueue(struct virtqueue *vq) | |
516 | { | |
9499f5e7 | 517 | list_del(&vq->list); |
0a8a69dd RR |
518 | kfree(to_vvq(vq)); |
519 | } | |
c6fd4701 | 520 | EXPORT_SYMBOL_GPL(vring_del_virtqueue); |
0a8a69dd | 521 | |
e34f8725 RR |
522 | /* Manipulates transport-specific feature bits. */ |
523 | void vring_transport_features(struct virtio_device *vdev) | |
524 | { | |
525 | unsigned int i; | |
526 | ||
527 | for (i = VIRTIO_TRANSPORT_F_START; i < VIRTIO_TRANSPORT_F_END; i++) { | |
528 | switch (i) { | |
9fa29b9d MM |
529 | case VIRTIO_RING_F_INDIRECT_DESC: |
530 | break; | |
a5c262c5 MT |
531 | case VIRTIO_RING_F_EVENT_IDX: |
532 | break; | |
e34f8725 RR |
533 | default: |
534 | /* We don't understand this bit. */ | |
535 | clear_bit(i, vdev->features); | |
536 | } | |
537 | } | |
538 | } | |
539 | EXPORT_SYMBOL_GPL(vring_transport_features); | |
540 | ||
8f9f4668 RJ |
541 | /* return the size of the vring within the virtqueue */ |
542 | unsigned int virtqueue_get_vring_size(struct virtqueue *_vq) | |
543 | { | |
544 | ||
545 | struct vring_virtqueue *vq = to_vvq(_vq); | |
546 | ||
547 | return vq->vring.num; | |
548 | } | |
549 | EXPORT_SYMBOL_GPL(virtqueue_get_vring_size); | |
550 | ||
c6fd4701 | 551 | MODULE_LICENSE("GPL"); |