1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19#include <linux/virtio.h>
20#include <linux/virtio_ring.h>
21#include <linux/virtio_config.h>
22#include <linux/device.h>
23
24#ifdef DEBUG
25
26#define BAD_RING(_vq, fmt, args...) \
27 do { \
28 dev_err(&(_vq)->vq.vdev->dev, \
29 "%s:"fmt, (_vq)->vq.name, ##args); \
30 BUG(); \
31 } while (0)
32
33#define START_USE(_vq) \
34 do { \
35 if ((_vq)->in_use) \
36 panic("%s:in_use = %i\n", \
37 (_vq)->vq.name, (_vq)->in_use); \
38 (_vq)->in_use = __LINE__; \
39 mb(); \
40 } while (0)
41#define END_USE(_vq) \
42 do { BUG_ON(!(_vq)->in_use); (_vq)->in_use = 0; mb(); } while(0)
43#else
44#define BAD_RING(_vq, fmt, args...) \
45 do { \
46 dev_err(&_vq->vq.vdev->dev, \
47 "%s:"fmt, (_vq)->vq.name, ##args); \
48 (_vq)->broken = true; \
49 } while (0)
50#define START_USE(vq)
51#define END_USE(vq)
52#endif
53
54struct vring_virtqueue
55{
56 struct virtqueue vq;
57
58
59 struct vring vring;
60
61
62 bool broken;
63
64
65 bool indirect;
66
67
68 unsigned int num_free;
69
70 unsigned int free_head;
71
72 unsigned int num_added;
73
74
75 u16 last_used_idx;
76
77
78 void (*notify)(struct virtqueue *vq);
79
80#ifdef DEBUG
81
82 unsigned int in_use;
83#endif
84
85
86 void *data[];
87};
88
89#define to_vvq(_vq) container_of(_vq, struct vring_virtqueue, vq)
90
91
92static int vring_add_indirect(struct vring_virtqueue *vq,
93 struct scatterlist sg[],
94 unsigned int out,
95 unsigned int in)
96{
97 struct vring_desc *desc;
98 unsigned head;
99 int i;
100
101 desc = kmalloc((out + in) * sizeof(struct vring_desc), GFP_ATOMIC);
102 if (!desc)
103 return vq->vring.num;
104
105
106 for (i = 0; i < out; i++) {
107 desc[i].flags = VRING_DESC_F_NEXT;
108 desc[i].addr = sg_phys(sg);
109 desc[i].len = sg->length;
110 desc[i].next = i+1;
111 sg++;
112 }
113 for (; i < (out + in); i++) {
114 desc[i].flags = VRING_DESC_F_NEXT|VRING_DESC_F_WRITE;
115 desc[i].addr = sg_phys(sg);
116 desc[i].len = sg->length;
117 desc[i].next = i+1;
118 sg++;
119 }
120
121
122 desc[i-1].flags &= ~VRING_DESC_F_NEXT;
123 desc[i-1].next = 0;
124
125
126 vq->num_free--;
127
128
129 head = vq->free_head;
130 vq->vring.desc[head].flags = VRING_DESC_F_INDIRECT;
131 vq->vring.desc[head].addr = virt_to_phys(desc);
132 vq->vring.desc[head].len = i * sizeof(struct vring_desc);
133
134
135 vq->free_head = vq->vring.desc[head].next;
136
137 return head;
138}
139
140static int vring_add_buf(struct virtqueue *_vq,
141 struct scatterlist sg[],
142 unsigned int out,
143 unsigned int in,
144 void *data)
145{
146 struct vring_virtqueue *vq = to_vvq(_vq);
147 unsigned int i, avail, head, uninitialized_var(prev);
148
149 START_USE(vq);
150
151 BUG_ON(data == NULL);
152
153
154
155 if (vq->indirect && (out + in) > 1 && vq->num_free) {
156 head = vring_add_indirect(vq, sg, out, in);
157 if (head != vq->vring.num)
158 goto add_head;
159 }
160
161 BUG_ON(out + in > vq->vring.num);
162 BUG_ON(out + in == 0);
163
164 if (vq->num_free < out + in) {
165 pr_debug("Can't add buf len %i - avail = %i\n",
166 out + in, vq->num_free);
167
168
169
170 if (out)
171 vq->notify(&vq->vq);
172 END_USE(vq);
173 return -ENOSPC;
174 }
175
176
177 vq->num_free -= out + in;
178
179 head = vq->free_head;
180 for (i = vq->free_head; out; i = vq->vring.desc[i].next, out--) {
181 vq->vring.desc[i].flags = VRING_DESC_F_NEXT;
182 vq->vring.desc[i].addr = sg_phys(sg);
183 vq->vring.desc[i].len = sg->length;
184 prev = i;
185 sg++;
186 }
187 for (; in; i = vq->vring.desc[i].next, in--) {
188 vq->vring.desc[i].flags = VRING_DESC_F_NEXT|VRING_DESC_F_WRITE;
189 vq->vring.desc[i].addr = sg_phys(sg);
190 vq->vring.desc[i].len = sg->length;
191 prev = i;
192 sg++;
193 }
194
195 vq->vring.desc[prev].flags &= ~VRING_DESC_F_NEXT;
196
197
198 vq->free_head = i;
199
200add_head:
201
202 vq->data[head] = data;
203
204
205
206 avail = (vq->vring.avail->idx + vq->num_added++) % vq->vring.num;
207 vq->vring.avail->ring[avail] = head;
208
209 pr_debug("Added buffer head %i to %p\n", head, vq);
210 END_USE(vq);
211
212
213 if (vq->indirect)
214 return vq->num_free ? vq->vring.num : 0;
215 return vq->num_free;
216}
217
218static void vring_kick(struct virtqueue *_vq)
219{
220 struct vring_virtqueue *vq = to_vvq(_vq);
221 START_USE(vq);
222
223
224 wmb();
225
226 vq->vring.avail->idx += vq->num_added;
227 vq->num_added = 0;
228
229
230 mb();
231
232 if (!(vq->vring.used->flags & VRING_USED_F_NO_NOTIFY))
233
234 vq->notify(&vq->vq);
235
236 END_USE(vq);
237}
238
239static void detach_buf(struct vring_virtqueue *vq, unsigned int head)
240{
241 unsigned int i;
242
243
244 vq->data[head] = NULL;
245
246
247 i = head;
248
249
250 if (vq->vring.desc[i].flags & VRING_DESC_F_INDIRECT)
251 kfree(phys_to_virt(vq->vring.desc[i].addr));
252
253 while (vq->vring.desc[i].flags & VRING_DESC_F_NEXT) {
254 i = vq->vring.desc[i].next;
255 vq->num_free++;
256 }
257
258 vq->vring.desc[i].next = vq->free_head;
259 vq->free_head = head;
260
261 vq->num_free++;
262}
263
264static inline bool more_used(const struct vring_virtqueue *vq)
265{
266 return vq->last_used_idx != vq->vring.used->idx;
267}
268
269static void *vring_get_buf(struct virtqueue *_vq, unsigned int *len)
270{
271 struct vring_virtqueue *vq = to_vvq(_vq);
272 void *ret;
273 unsigned int i;
274
275 START_USE(vq);
276
277 if (unlikely(vq->broken)) {
278 END_USE(vq);
279 return NULL;
280 }
281
282 if (!more_used(vq)) {
283 pr_debug("No more buffers in queue\n");
284 END_USE(vq);
285 return NULL;
286 }
287
288
289 rmb();
290
291 i = vq->vring.used->ring[vq->last_used_idx%vq->vring.num].id;
292 *len = vq->vring.used->ring[vq->last_used_idx%vq->vring.num].len;
293
294 if (unlikely(i >= vq->vring.num)) {
295 BAD_RING(vq, "id %u out of range\n", i);
296 return NULL;
297 }
298 if (unlikely(!vq->data[i])) {
299 BAD_RING(vq, "id %u is not a head!\n", i);
300 return NULL;
301 }
302
303
304 ret = vq->data[i];
305 detach_buf(vq, i);
306 vq->last_used_idx++;
307 END_USE(vq);
308 return ret;
309}
310
311static void vring_disable_cb(struct virtqueue *_vq)
312{
313 struct vring_virtqueue *vq = to_vvq(_vq);
314
315 vq->vring.avail->flags |= VRING_AVAIL_F_NO_INTERRUPT;
316}
317
318static bool vring_enable_cb(struct virtqueue *_vq)
319{
320 struct vring_virtqueue *vq = to_vvq(_vq);
321
322 START_USE(vq);
323
324
325
326 vq->vring.avail->flags &= ~VRING_AVAIL_F_NO_INTERRUPT;
327 mb();
328 if (unlikely(more_used(vq))) {
329 END_USE(vq);
330 return false;
331 }
332
333 END_USE(vq);
334 return true;
335}
336
337irqreturn_t vring_interrupt(int irq, void *_vq)
338{
339 struct vring_virtqueue *vq = to_vvq(_vq);
340
341 if (!more_used(vq)) {
342 pr_debug("virtqueue interrupt with no work for %p\n", vq);
343 return IRQ_NONE;
344 }
345
346 if (unlikely(vq->broken))
347 return IRQ_HANDLED;
348
349 pr_debug("virtqueue callback for %p (%p)\n", vq, vq->vq.callback);
350 if (vq->vq.callback)
351 vq->vq.callback(&vq->vq);
352
353 return IRQ_HANDLED;
354}
355EXPORT_SYMBOL_GPL(vring_interrupt);
356
357static struct virtqueue_ops vring_vq_ops = {
358 .add_buf = vring_add_buf,
359 .get_buf = vring_get_buf,
360 .kick = vring_kick,
361 .disable_cb = vring_disable_cb,
362 .enable_cb = vring_enable_cb,
363};
364
365struct virtqueue *vring_new_virtqueue(unsigned int num,
366 unsigned int vring_align,
367 struct virtio_device *vdev,
368 void *pages,
369 void (*notify)(struct virtqueue *),
370 void (*callback)(struct virtqueue *),
371 const char *name)
372{
373 struct vring_virtqueue *vq;
374 unsigned int i;
375
376
377 if (num & (num - 1)) {
378 dev_warn(&vdev->dev, "Bad virtqueue length %u\n", num);
379 return NULL;
380 }
381
382 vq = kmalloc(sizeof(*vq) + sizeof(void *)*num, GFP_KERNEL);
383 if (!vq)
384 return NULL;
385
386 vring_init(&vq->vring, num, pages, vring_align);
387 vq->vq.callback = callback;
388 vq->vq.vdev = vdev;
389 vq->vq.vq_ops = &vring_vq_ops;
390 vq->vq.name = name;
391 vq->notify = notify;
392 vq->broken = false;
393 vq->last_used_idx = 0;
394 vq->num_added = 0;
395 list_add_tail(&vq->vq.list, &vdev->vqs);
396#ifdef DEBUG
397 vq->in_use = false;
398#endif
399
400 vq->indirect = virtio_has_feature(vdev, VIRTIO_RING_F_INDIRECT_DESC);
401
402
403 if (!callback)
404 vq->vring.avail->flags |= VRING_AVAIL_F_NO_INTERRUPT;
405
406
407 vq->num_free = num;
408 vq->free_head = 0;
409 for (i = 0; i < num-1; i++)
410 vq->vring.desc[i].next = i+1;
411
412 return &vq->vq;
413}
414EXPORT_SYMBOL_GPL(vring_new_virtqueue);
415
416void vring_del_virtqueue(struct virtqueue *vq)
417{
418 list_del(&vq->list);
419 kfree(to_vvq(vq));
420}
421EXPORT_SYMBOL_GPL(vring_del_virtqueue);
422
423
424void vring_transport_features(struct virtio_device *vdev)
425{
426 unsigned int i;
427
428 for (i = VIRTIO_TRANSPORT_F_START; i < VIRTIO_TRANSPORT_F_END; i++) {
429 switch (i) {
430 case VIRTIO_RING_F_INDIRECT_DESC:
431 break;
432 default:
433
434 clear_bit(i, vdev->features);
435 }
436 }
437}
438EXPORT_SYMBOL_GPL(vring_transport_features);
439
440MODULE_LICENSE("GPL");
441