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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>
21#include <linux/virtio_config.h>
22#include <linux/device.h>
23#include <linux/slab.h>
24
25/* virtio guest is communicating with a virtual "device" that actually runs on
26 * a host processor. Memory barriers are used to control SMP effects. */
27#ifdef CONFIG_SMP
28/* Where possible, use SMP barriers which are more lightweight than mandatory
29 * barriers, because mandatory barriers control MMIO effects on accesses
30 * through relaxed memory I/O windows (which virtio does not use). */
31#define virtio_mb() smp_mb()
32#define virtio_rmb() smp_rmb()
33#define virtio_wmb() smp_wmb()
34#else
35/* We must force memory ordering even if guest is UP since host could be
36 * running on another CPU, but SMP barriers are defined to barrier() in that
37 * configuration. So fall back to mandatory barriers instead. */
38#define virtio_mb() mb()
39#define virtio_rmb() rmb()
40#define virtio_wmb() wmb()
41#endif
42
43#ifdef DEBUG
44/* For development, we want to crash whenever the ring is screwed. */
45#define BAD_RING(_vq, fmt, args...) \
46 do { \
47 dev_err(&(_vq)->vq.vdev->dev, \
48 "%s:"fmt, (_vq)->vq.name, ##args); \
49 BUG(); \
50 } while (0)
51/* Caller is supposed to guarantee no reentry. */
52#define START_USE(_vq) \
53 do { \
54 if ((_vq)->in_use) \
55 panic("%s:in_use = %i\n", \
56 (_vq)->vq.name, (_vq)->in_use); \
57 (_vq)->in_use = __LINE__; \
58 } while (0)
59#define END_USE(_vq) \
60 do { BUG_ON(!(_vq)->in_use); (_vq)->in_use = 0; } while(0)
61#else
62#define BAD_RING(_vq, fmt, args...) \
63 do { \
64 dev_err(&_vq->vq.vdev->dev, \
65 "%s:"fmt, (_vq)->vq.name, ##args); \
66 (_vq)->broken = true; \
67 } while (0)
68#define START_USE(vq)
69#define END_USE(vq)
70#endif
71
72struct vring_virtqueue
73{
74 struct virtqueue vq;
75
76 /* Actual memory layout for this queue */
77 struct vring vring;
78
79 /* Other side has made a mess, don't try any more. */
80 bool broken;
81
82 /* Host supports indirect buffers */
83 bool indirect;
84
85 /* Host publishes avail event idx */
86 bool event;
87
88 /* Number of free buffers */
89 unsigned int num_free;
90 /* Head of free buffer list. */
91 unsigned int free_head;
92 /* Number we've added since last sync. */
93 unsigned int num_added;
94
95 /* Last used index we've seen. */
96 u16 last_used_idx;
97
98 /* How to notify other side. FIXME: commonalize hcalls! */
99 void (*notify)(struct virtqueue *vq);
100
101#ifdef DEBUG
102 /* They're supposed to lock for us. */
103 unsigned int in_use;
104#endif
105
106 /* Tokens for callbacks. */
107 void *data[];
108};
109
110#define to_vvq(_vq) container_of(_vq, struct vring_virtqueue, vq)
111
112/* Set up an indirect table of descriptors and add it to the queue. */
113static int vring_add_indirect(struct vring_virtqueue *vq,
114 struct scatterlist sg[],
115 unsigned int out,
116 unsigned int in,
117 gfp_t gfp)
118{
119 struct vring_desc *desc;
120 unsigned head;
121 int i;
122
123 desc = kmalloc((out + in) * sizeof(struct vring_desc), gfp);
124 if (!desc)
125 return -ENOMEM;
126
127 /* Transfer entries from the sg list into the indirect page */
128 for (i = 0; i < out; i++) {
129 desc[i].flags = VRING_DESC_F_NEXT;
130 desc[i].addr = sg_phys(sg);
131 desc[i].len = sg->length;
132 desc[i].next = i+1;
133 sg++;
134 }
135 for (; i < (out + in); i++) {
136 desc[i].flags = VRING_DESC_F_NEXT|VRING_DESC_F_WRITE;
137 desc[i].addr = sg_phys(sg);
138 desc[i].len = sg->length;
139 desc[i].next = i+1;
140 sg++;
141 }
142
143 /* Last one doesn't continue. */
144 desc[i-1].flags &= ~VRING_DESC_F_NEXT;
145 desc[i-1].next = 0;
146
147 /* We're about to use a buffer */
148 vq->num_free--;
149
150 /* Use a single buffer which doesn't continue */
151 head = vq->free_head;
152 vq->vring.desc[head].flags = VRING_DESC_F_INDIRECT;
153 vq->vring.desc[head].addr = virt_to_phys(desc);
154 vq->vring.desc[head].len = i * sizeof(struct vring_desc);
155
156 /* Update free pointer */
157 vq->free_head = vq->vring.desc[head].next;
158
159 return head;
160}
161
162int virtqueue_add_buf_gfp(struct virtqueue *_vq,
163 struct scatterlist sg[],
164 unsigned int out,
165 unsigned int in,
166 void *data,
167 gfp_t gfp)
168{
169 struct vring_virtqueue *vq = to_vvq(_vq);
170 unsigned int i, avail, uninitialized_var(prev);
171 int head;
172
173 START_USE(vq);
174
175 BUG_ON(data == NULL);
176
177 /* If the host supports indirect descriptor tables, and we have multiple
178 * buffers, then go indirect. FIXME: tune this threshold */
179 if (vq->indirect && (out + in) > 1 && vq->num_free) {
180 head = vring_add_indirect(vq, sg, out, in, gfp);
181 if (likely(head >= 0))
182 goto add_head;
183 }
184
185 BUG_ON(out + in > vq->vring.num);
186 BUG_ON(out + in == 0);
187
188 if (vq->num_free < out + in) {
189 pr_debug("Can't add buf len %i - avail = %i\n",
190 out + in, vq->num_free);
191 /* FIXME: for historical reasons, we force a notify here if
192 * there are outgoing parts to the buffer. Presumably the
193 * host should service the ring ASAP. */
194 if (out)
195 vq->notify(&vq->vq);
196 END_USE(vq);
197 return -ENOSPC;
198 }
199
200 /* We're about to use some buffers from the free list. */
201 vq->num_free -= out + in;
202
203 head = vq->free_head;
204 for (i = vq->free_head; out; i = vq->vring.desc[i].next, out--) {
205 vq->vring.desc[i].flags = VRING_DESC_F_NEXT;
206 vq->vring.desc[i].addr = sg_phys(sg);
207 vq->vring.desc[i].len = sg->length;
208 prev = i;
209 sg++;
210 }
211 for (; in; i = vq->vring.desc[i].next, in--) {
212 vq->vring.desc[i].flags = VRING_DESC_F_NEXT|VRING_DESC_F_WRITE;
213 vq->vring.desc[i].addr = sg_phys(sg);
214 vq->vring.desc[i].len = sg->length;
215 prev = i;
216 sg++;
217 }
218 /* Last one doesn't continue. */
219 vq->vring.desc[prev].flags &= ~VRING_DESC_F_NEXT;
220
221 /* Update free pointer */
222 vq->free_head = i;
223
224add_head:
225 /* Set token. */
226 vq->data[head] = data;
227
228 /* Put entry in available array (but don't update avail->idx until they
229 * do sync). FIXME: avoid modulus here? */
230 avail = (vq->vring.avail->idx + vq->num_added++) % vq->vring.num;
231 vq->vring.avail->ring[avail] = head;
232
233 pr_debug("Added buffer head %i to %p\n", head, vq);
234 END_USE(vq);
235
236 return vq->num_free;
237}
238EXPORT_SYMBOL_GPL(virtqueue_add_buf_gfp);
239
240void virtqueue_kick(struct virtqueue *_vq)
241{
242 struct vring_virtqueue *vq = to_vvq(_vq);
243 u16 new, old;
244 START_USE(vq);
245 /* Descriptors and available array need to be set before we expose the
246 * new available array entries. */
247 virtio_wmb();
248
249 old = vq->vring.avail->idx;
250 new = vq->vring.avail->idx = old + vq->num_added;
251 vq->num_added = 0;
252
253 /* Need to update avail index before checking if we should notify */
254 virtio_mb();
255
256 if (vq->event ?
257 vring_need_event(vring_avail_event(&vq->vring), new, old) :
258 !(vq->vring.used->flags & VRING_USED_F_NO_NOTIFY))
259 /* Prod other side to tell it about changes. */
260 vq->notify(&vq->vq);
261
262 END_USE(vq);
263}
264EXPORT_SYMBOL_GPL(virtqueue_kick);
265
266static void detach_buf(struct vring_virtqueue *vq, unsigned int head)
267{
268 unsigned int i;
269
270 /* Clear data ptr. */
271 vq->data[head] = NULL;
272
273 /* Put back on free list: find end */
274 i = head;
275
276 /* Free the indirect table */
277 if (vq->vring.desc[i].flags & VRING_DESC_F_INDIRECT)
278 kfree(phys_to_virt(vq->vring.desc[i].addr));
279
280 while (vq->vring.desc[i].flags & VRING_DESC_F_NEXT) {
281 i = vq->vring.desc[i].next;
282 vq->num_free++;
283 }
284
285 vq->vring.desc[i].next = vq->free_head;
286 vq->free_head = head;
287 /* Plus final descriptor */
288 vq->num_free++;
289}
290
291static inline bool more_used(const struct vring_virtqueue *vq)
292{
293 return vq->last_used_idx != vq->vring.used->idx;
294}
295
296void *virtqueue_get_buf(struct virtqueue *_vq, unsigned int *len)
297{
298 struct vring_virtqueue *vq = to_vvq(_vq);
299 void *ret;
300 unsigned int i;
301
302 START_USE(vq);
303
304 if (unlikely(vq->broken)) {
305 END_USE(vq);
306 return NULL;
307 }
308
309 if (!more_used(vq)) {
310 pr_debug("No more buffers in queue\n");
311 END_USE(vq);
312 return NULL;
313 }
314
315 /* Only get used array entries after they have been exposed by host. */
316 virtio_rmb();
317
318 i = vq->vring.used->ring[vq->last_used_idx%vq->vring.num].id;
319 *len = vq->vring.used->ring[vq->last_used_idx%vq->vring.num].len;
320
321 if (unlikely(i >= vq->vring.num)) {
322 BAD_RING(vq, "id %u out of range\n", i);
323 return NULL;
324 }
325 if (unlikely(!vq->data[i])) {
326 BAD_RING(vq, "id %u is not a head!\n", i);
327 return NULL;
328 }
329
330 /* detach_buf clears data, so grab it now. */
331 ret = vq->data[i];
332 detach_buf(vq, i);
333 vq->last_used_idx++;
334 /* If we expect an interrupt for the next entry, tell host
335 * by writing event index and flush out the write before
336 * the read in the next get_buf call. */
337 if (!(vq->vring.avail->flags & VRING_AVAIL_F_NO_INTERRUPT)) {
338 vring_used_event(&vq->vring) = vq->last_used_idx;
339 virtio_mb();
340 }
341
342 END_USE(vq);
343 return ret;
344}
345EXPORT_SYMBOL_GPL(virtqueue_get_buf);
346
347void virtqueue_disable_cb(struct virtqueue *_vq)
348{
349 struct vring_virtqueue *vq = to_vvq(_vq);
350
351 vq->vring.avail->flags |= VRING_AVAIL_F_NO_INTERRUPT;
352}
353EXPORT_SYMBOL_GPL(virtqueue_disable_cb);
354
355bool virtqueue_enable_cb(struct virtqueue *_vq)
356{
357 struct vring_virtqueue *vq = to_vvq(_vq);
358
359 START_USE(vq);
360
361 /* We optimistically turn back on interrupts, then check if there was
362 * more to do. */
363 /* Depending on the VIRTIO_RING_F_EVENT_IDX feature, we need to
364 * either clear the flags bit or point the event index at the next
365 * entry. Always do both to keep code simple. */
366 vq->vring.avail->flags &= ~VRING_AVAIL_F_NO_INTERRUPT;
367 vring_used_event(&vq->vring) = vq->last_used_idx;
368 virtio_mb();
369 if (unlikely(more_used(vq))) {
370 END_USE(vq);
371 return false;
372 }
373
374 END_USE(vq);
375 return true;
376}
377EXPORT_SYMBOL_GPL(virtqueue_enable_cb);
378
379bool virtqueue_enable_cb_delayed(struct virtqueue *_vq)
380{
381 struct vring_virtqueue *vq = to_vvq(_vq);
382 u16 bufs;
383
384 START_USE(vq);
385
386 /* We optimistically turn back on interrupts, then check if there was
387 * more to do. */
388 /* Depending on the VIRTIO_RING_F_USED_EVENT_IDX feature, we need to
389 * either clear the flags bit or point the event index at the next
390 * entry. Always do both to keep code simple. */
391 vq->vring.avail->flags &= ~VRING_AVAIL_F_NO_INTERRUPT;
392 /* TODO: tune this threshold */
393 bufs = (u16)(vq->vring.avail->idx - vq->last_used_idx) * 3 / 4;
394 vring_used_event(&vq->vring) = vq->last_used_idx + bufs;
395 virtio_mb();
396 if (unlikely((u16)(vq->vring.used->idx - vq->last_used_idx) > bufs)) {
397 END_USE(vq);
398 return false;
399 }
400
401 END_USE(vq);
402 return true;
403}
404EXPORT_SYMBOL_GPL(virtqueue_enable_cb_delayed);
405
406void *virtqueue_detach_unused_buf(struct virtqueue *_vq)
407{
408 struct vring_virtqueue *vq = to_vvq(_vq);
409 unsigned int i;
410 void *buf;
411
412 START_USE(vq);
413
414 for (i = 0; i < vq->vring.num; i++) {
415 if (!vq->data[i])
416 continue;
417 /* detach_buf clears data, so grab it now. */
418 buf = vq->data[i];
419 detach_buf(vq, i);
420 vq->vring.avail->idx--;
421 END_USE(vq);
422 return buf;
423 }
424 /* That should have freed everything. */
425 BUG_ON(vq->num_free != vq->vring.num);
426
427 END_USE(vq);
428 return NULL;
429}
430EXPORT_SYMBOL_GPL(virtqueue_detach_unused_buf);
431
432irqreturn_t vring_interrupt(int irq, void *_vq)
433{
434 struct vring_virtqueue *vq = to_vvq(_vq);
435
436 if (!more_used(vq)) {
437 pr_debug("virtqueue interrupt with no work for %p\n", vq);
438 return IRQ_NONE;
439 }
440
441 if (unlikely(vq->broken))
442 return IRQ_HANDLED;
443
444 pr_debug("virtqueue callback for %p (%p)\n", vq, vq->vq.callback);
445 if (vq->vq.callback)
446 vq->vq.callback(&vq->vq);
447
448 return IRQ_HANDLED;
449}
450EXPORT_SYMBOL_GPL(vring_interrupt);
451
452struct virtqueue *vring_new_virtqueue(unsigned int num,
453 unsigned int vring_align,
454 struct virtio_device *vdev,
455 void *pages,
456 void (*notify)(struct virtqueue *),
457 void (*callback)(struct virtqueue *),
458 const char *name)
459{
460 struct vring_virtqueue *vq;
461 unsigned int i;
462
463 /* We assume num is a power of 2. */
464 if (num & (num - 1)) {
465 dev_warn(&vdev->dev, "Bad virtqueue length %u\n", num);
466 return NULL;
467 }
468
469 vq = kmalloc(sizeof(*vq) + sizeof(void *)*num, GFP_KERNEL);
470 if (!vq)
471 return NULL;
472
473 vring_init(&vq->vring, num, pages, vring_align);
474 vq->vq.callback = callback;
475 vq->vq.vdev = vdev;
476 vq->vq.name = name;
477 vq->notify = notify;
478 vq->broken = false;
479 vq->last_used_idx = 0;
480 vq->num_added = 0;
481 list_add_tail(&vq->vq.list, &vdev->vqs);
482#ifdef DEBUG
483 vq->in_use = false;
484#endif
485
486 vq->indirect = virtio_has_feature(vdev, VIRTIO_RING_F_INDIRECT_DESC);
487 vq->event = virtio_has_feature(vdev, VIRTIO_RING_F_EVENT_IDX);
488
489 /* No callback? Tell other side not to bother us. */
490 if (!callback)
491 vq->vring.avail->flags |= VRING_AVAIL_F_NO_INTERRUPT;
492
493 /* Put everything in free lists. */
494 vq->num_free = num;
495 vq->free_head = 0;
496 for (i = 0; i < num-1; i++) {
497 vq->vring.desc[i].next = i+1;
498 vq->data[i] = NULL;
499 }
500 vq->data[i] = NULL;
501
502 return &vq->vq;
503}
504EXPORT_SYMBOL_GPL(vring_new_virtqueue);
505
506void vring_del_virtqueue(struct virtqueue *vq)
507{
508 list_del(&vq->list);
509 kfree(to_vvq(vq));
510}
511EXPORT_SYMBOL_GPL(vring_del_virtqueue);
512
513/* Manipulates transport-specific feature bits. */
514void vring_transport_features(struct virtio_device *vdev)
515{
516 unsigned int i;
517
518 for (i = VIRTIO_TRANSPORT_F_START; i < VIRTIO_TRANSPORT_F_END; i++) {
519 switch (i) {
520 case VIRTIO_RING_F_INDIRECT_DESC:
521 break;
522 case VIRTIO_RING_F_EVENT_IDX:
523 break;
524 default:
525 /* We don't understand this bit. */
526 clear_bit(i, vdev->features);
527 }
528 }
529}
530EXPORT_SYMBOL_GPL(vring_transport_features);
531
532MODULE_LICENSE("GPL");
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>
21#include <linux/virtio_config.h>
22#include <linux/device.h>
23#include <linux/slab.h>
24#include <linux/module.h>
25#include <linux/hrtimer.h>
26#include <linux/kmemleak.h>
27#include <linux/dma-mapping.h>
28#include <xen/xen.h>
29
30#ifdef DEBUG
31/* For development, we want to crash whenever the ring is screwed. */
32#define BAD_RING(_vq, fmt, args...) \
33 do { \
34 dev_err(&(_vq)->vq.vdev->dev, \
35 "%s:"fmt, (_vq)->vq.name, ##args); \
36 BUG(); \
37 } while (0)
38/* Caller is supposed to guarantee no reentry. */
39#define START_USE(_vq) \
40 do { \
41 if ((_vq)->in_use) \
42 panic("%s:in_use = %i\n", \
43 (_vq)->vq.name, (_vq)->in_use); \
44 (_vq)->in_use = __LINE__; \
45 } while (0)
46#define END_USE(_vq) \
47 do { BUG_ON(!(_vq)->in_use); (_vq)->in_use = 0; } while(0)
48#else
49#define BAD_RING(_vq, fmt, args...) \
50 do { \
51 dev_err(&_vq->vq.vdev->dev, \
52 "%s:"fmt, (_vq)->vq.name, ##args); \
53 (_vq)->broken = true; \
54 } while (0)
55#define START_USE(vq)
56#define END_USE(vq)
57#endif
58
59struct vring_desc_state {
60 void *data; /* Data for callback. */
61 struct vring_desc *indir_desc; /* Indirect descriptor, if any. */
62};
63
64struct vring_virtqueue {
65 struct virtqueue vq;
66
67 /* Actual memory layout for this queue */
68 struct vring vring;
69
70 /* Can we use weak barriers? */
71 bool weak_barriers;
72
73 /* Other side has made a mess, don't try any more. */
74 bool broken;
75
76 /* Host supports indirect buffers */
77 bool indirect;
78
79 /* Host publishes avail event idx */
80 bool event;
81
82 /* Head of free buffer list. */
83 unsigned int free_head;
84 /* Number we've added since last sync. */
85 unsigned int num_added;
86
87 /* Last used index we've seen. */
88 u16 last_used_idx;
89
90 /* Last written value to avail->flags */
91 u16 avail_flags_shadow;
92
93 /* Last written value to avail->idx in guest byte order */
94 u16 avail_idx_shadow;
95
96 /* How to notify other side. FIXME: commonalize hcalls! */
97 bool (*notify)(struct virtqueue *vq);
98
99 /* DMA, allocation, and size information */
100 bool we_own_ring;
101 size_t queue_size_in_bytes;
102 dma_addr_t queue_dma_addr;
103
104#ifdef DEBUG
105 /* They're supposed to lock for us. */
106 unsigned int in_use;
107
108 /* Figure out if their kicks are too delayed. */
109 bool last_add_time_valid;
110 ktime_t last_add_time;
111#endif
112
113 /* Per-descriptor state. */
114 struct vring_desc_state desc_state[];
115};
116
117#define to_vvq(_vq) container_of(_vq, struct vring_virtqueue, vq)
118
119/*
120 * The interaction between virtio and a possible IOMMU is a mess.
121 *
122 * On most systems with virtio, physical addresses match bus addresses,
123 * and it doesn't particularly matter whether we use the DMA API.
124 *
125 * On some systems, including Xen and any system with a physical device
126 * that speaks virtio behind a physical IOMMU, we must use the DMA API
127 * for virtio DMA to work at all.
128 *
129 * On other systems, including SPARC and PPC64, virtio-pci devices are
130 * enumerated as though they are behind an IOMMU, but the virtio host
131 * ignores the IOMMU, so we must either pretend that the IOMMU isn't
132 * there or somehow map everything as the identity.
133 *
134 * For the time being, we preserve historic behavior and bypass the DMA
135 * API.
136 */
137
138static bool vring_use_dma_api(struct virtio_device *vdev)
139{
140 /*
141 * In theory, it's possible to have a buggy QEMU-supposed
142 * emulated Q35 IOMMU and Xen enabled at the same time. On
143 * such a configuration, virtio has never worked and will
144 * not work without an even larger kludge. Instead, enable
145 * the DMA API if we're a Xen guest, which at least allows
146 * all of the sensible Xen configurations to work correctly.
147 */
148 if (xen_domain())
149 return true;
150
151 return false;
152}
153
154/*
155 * The DMA ops on various arches are rather gnarly right now, and
156 * making all of the arch DMA ops work on the vring device itself
157 * is a mess. For now, we use the parent device for DMA ops.
158 */
159struct device *vring_dma_dev(const struct vring_virtqueue *vq)
160{
161 return vq->vq.vdev->dev.parent;
162}
163
164/* Map one sg entry. */
165static dma_addr_t vring_map_one_sg(const struct vring_virtqueue *vq,
166 struct scatterlist *sg,
167 enum dma_data_direction direction)
168{
169 if (!vring_use_dma_api(vq->vq.vdev))
170 return (dma_addr_t)sg_phys(sg);
171
172 /*
173 * We can't use dma_map_sg, because we don't use scatterlists in
174 * the way it expects (we don't guarantee that the scatterlist
175 * will exist for the lifetime of the mapping).
176 */
177 return dma_map_page(vring_dma_dev(vq),
178 sg_page(sg), sg->offset, sg->length,
179 direction);
180}
181
182static dma_addr_t vring_map_single(const struct vring_virtqueue *vq,
183 void *cpu_addr, size_t size,
184 enum dma_data_direction direction)
185{
186 if (!vring_use_dma_api(vq->vq.vdev))
187 return (dma_addr_t)virt_to_phys(cpu_addr);
188
189 return dma_map_single(vring_dma_dev(vq),
190 cpu_addr, size, direction);
191}
192
193static void vring_unmap_one(const struct vring_virtqueue *vq,
194 struct vring_desc *desc)
195{
196 u16 flags;
197
198 if (!vring_use_dma_api(vq->vq.vdev))
199 return;
200
201 flags = virtio16_to_cpu(vq->vq.vdev, desc->flags);
202
203 if (flags & VRING_DESC_F_INDIRECT) {
204 dma_unmap_single(vring_dma_dev(vq),
205 virtio64_to_cpu(vq->vq.vdev, desc->addr),
206 virtio32_to_cpu(vq->vq.vdev, desc->len),
207 (flags & VRING_DESC_F_WRITE) ?
208 DMA_FROM_DEVICE : DMA_TO_DEVICE);
209 } else {
210 dma_unmap_page(vring_dma_dev(vq),
211 virtio64_to_cpu(vq->vq.vdev, desc->addr),
212 virtio32_to_cpu(vq->vq.vdev, desc->len),
213 (flags & VRING_DESC_F_WRITE) ?
214 DMA_FROM_DEVICE : DMA_TO_DEVICE);
215 }
216}
217
218static int vring_mapping_error(const struct vring_virtqueue *vq,
219 dma_addr_t addr)
220{
221 if (!vring_use_dma_api(vq->vq.vdev))
222 return 0;
223
224 return dma_mapping_error(vring_dma_dev(vq), addr);
225}
226
227static struct vring_desc *alloc_indirect(struct virtqueue *_vq,
228 unsigned int total_sg, gfp_t gfp)
229{
230 struct vring_desc *desc;
231 unsigned int i;
232
233 /*
234 * We require lowmem mappings for the descriptors because
235 * otherwise virt_to_phys will give us bogus addresses in the
236 * virtqueue.
237 */
238 gfp &= ~__GFP_HIGHMEM;
239
240 desc = kmalloc(total_sg * sizeof(struct vring_desc), gfp);
241 if (!desc)
242 return NULL;
243
244 for (i = 0; i < total_sg; i++)
245 desc[i].next = cpu_to_virtio16(_vq->vdev, i + 1);
246 return desc;
247}
248
249static inline int virtqueue_add(struct virtqueue *_vq,
250 struct scatterlist *sgs[],
251 unsigned int total_sg,
252 unsigned int out_sgs,
253 unsigned int in_sgs,
254 void *data,
255 gfp_t gfp)
256{
257 struct vring_virtqueue *vq = to_vvq(_vq);
258 struct scatterlist *sg;
259 struct vring_desc *desc;
260 unsigned int i, n, avail, descs_used, uninitialized_var(prev), err_idx;
261 int head;
262 bool indirect;
263
264 START_USE(vq);
265
266 BUG_ON(data == NULL);
267
268 if (unlikely(vq->broken)) {
269 END_USE(vq);
270 return -EIO;
271 }
272
273#ifdef DEBUG
274 {
275 ktime_t now = ktime_get();
276
277 /* No kick or get, with .1 second between? Warn. */
278 if (vq->last_add_time_valid)
279 WARN_ON(ktime_to_ms(ktime_sub(now, vq->last_add_time))
280 > 100);
281 vq->last_add_time = now;
282 vq->last_add_time_valid = true;
283 }
284#endif
285
286 BUG_ON(total_sg > vq->vring.num);
287 BUG_ON(total_sg == 0);
288
289 head = vq->free_head;
290
291 /* If the host supports indirect descriptor tables, and we have multiple
292 * buffers, then go indirect. FIXME: tune this threshold */
293 if (vq->indirect && total_sg > 1 && vq->vq.num_free)
294 desc = alloc_indirect(_vq, total_sg, gfp);
295 else
296 desc = NULL;
297
298 if (desc) {
299 /* Use a single buffer which doesn't continue */
300 indirect = true;
301 /* Set up rest to use this indirect table. */
302 i = 0;
303 descs_used = 1;
304 } else {
305 indirect = false;
306 desc = vq->vring.desc;
307 i = head;
308 descs_used = total_sg;
309 }
310
311 if (vq->vq.num_free < descs_used) {
312 pr_debug("Can't add buf len %i - avail = %i\n",
313 descs_used, vq->vq.num_free);
314 /* FIXME: for historical reasons, we force a notify here if
315 * there are outgoing parts to the buffer. Presumably the
316 * host should service the ring ASAP. */
317 if (out_sgs)
318 vq->notify(&vq->vq);
319 END_USE(vq);
320 return -ENOSPC;
321 }
322
323 for (n = 0; n < out_sgs; n++) {
324 for (sg = sgs[n]; sg; sg = sg_next(sg)) {
325 dma_addr_t addr = vring_map_one_sg(vq, sg, DMA_TO_DEVICE);
326 if (vring_mapping_error(vq, addr))
327 goto unmap_release;
328
329 desc[i].flags = cpu_to_virtio16(_vq->vdev, VRING_DESC_F_NEXT);
330 desc[i].addr = cpu_to_virtio64(_vq->vdev, addr);
331 desc[i].len = cpu_to_virtio32(_vq->vdev, sg->length);
332 prev = i;
333 i = virtio16_to_cpu(_vq->vdev, desc[i].next);
334 }
335 }
336 for (; n < (out_sgs + in_sgs); n++) {
337 for (sg = sgs[n]; sg; sg = sg_next(sg)) {
338 dma_addr_t addr = vring_map_one_sg(vq, sg, DMA_FROM_DEVICE);
339 if (vring_mapping_error(vq, addr))
340 goto unmap_release;
341
342 desc[i].flags = cpu_to_virtio16(_vq->vdev, VRING_DESC_F_NEXT | VRING_DESC_F_WRITE);
343 desc[i].addr = cpu_to_virtio64(_vq->vdev, addr);
344 desc[i].len = cpu_to_virtio32(_vq->vdev, sg->length);
345 prev = i;
346 i = virtio16_to_cpu(_vq->vdev, desc[i].next);
347 }
348 }
349 /* Last one doesn't continue. */
350 desc[prev].flags &= cpu_to_virtio16(_vq->vdev, ~VRING_DESC_F_NEXT);
351
352 if (indirect) {
353 /* Now that the indirect table is filled in, map it. */
354 dma_addr_t addr = vring_map_single(
355 vq, desc, total_sg * sizeof(struct vring_desc),
356 DMA_TO_DEVICE);
357 if (vring_mapping_error(vq, addr))
358 goto unmap_release;
359
360 vq->vring.desc[head].flags = cpu_to_virtio16(_vq->vdev, VRING_DESC_F_INDIRECT);
361 vq->vring.desc[head].addr = cpu_to_virtio64(_vq->vdev, addr);
362
363 vq->vring.desc[head].len = cpu_to_virtio32(_vq->vdev, total_sg * sizeof(struct vring_desc));
364 }
365
366 /* We're using some buffers from the free list. */
367 vq->vq.num_free -= descs_used;
368
369 /* Update free pointer */
370 if (indirect)
371 vq->free_head = virtio16_to_cpu(_vq->vdev, vq->vring.desc[head].next);
372 else
373 vq->free_head = i;
374
375 /* Store token and indirect buffer state. */
376 vq->desc_state[head].data = data;
377 if (indirect)
378 vq->desc_state[head].indir_desc = desc;
379
380 /* Put entry in available array (but don't update avail->idx until they
381 * do sync). */
382 avail = vq->avail_idx_shadow & (vq->vring.num - 1);
383 vq->vring.avail->ring[avail] = cpu_to_virtio16(_vq->vdev, head);
384
385 /* Descriptors and available array need to be set before we expose the
386 * new available array entries. */
387 virtio_wmb(vq->weak_barriers);
388 vq->avail_idx_shadow++;
389 vq->vring.avail->idx = cpu_to_virtio16(_vq->vdev, vq->avail_idx_shadow);
390 vq->num_added++;
391
392 pr_debug("Added buffer head %i to %p\n", head, vq);
393 END_USE(vq);
394
395 /* This is very unlikely, but theoretically possible. Kick
396 * just in case. */
397 if (unlikely(vq->num_added == (1 << 16) - 1))
398 virtqueue_kick(_vq);
399
400 return 0;
401
402unmap_release:
403 err_idx = i;
404 i = head;
405
406 for (n = 0; n < total_sg; n++) {
407 if (i == err_idx)
408 break;
409 vring_unmap_one(vq, &desc[i]);
410 i = vq->vring.desc[i].next;
411 }
412
413 vq->vq.num_free += total_sg;
414
415 if (indirect)
416 kfree(desc);
417
418 return -EIO;
419}
420
421/**
422 * virtqueue_add_sgs - expose buffers to other end
423 * @vq: the struct virtqueue we're talking about.
424 * @sgs: array of terminated scatterlists.
425 * @out_num: the number of scatterlists readable by other side
426 * @in_num: the number of scatterlists which are writable (after readable ones)
427 * @data: the token identifying the buffer.
428 * @gfp: how to do memory allocations (if necessary).
429 *
430 * Caller must ensure we don't call this with other virtqueue operations
431 * at the same time (except where noted).
432 *
433 * Returns zero or a negative error (ie. ENOSPC, ENOMEM, EIO).
434 */
435int virtqueue_add_sgs(struct virtqueue *_vq,
436 struct scatterlist *sgs[],
437 unsigned int out_sgs,
438 unsigned int in_sgs,
439 void *data,
440 gfp_t gfp)
441{
442 unsigned int i, total_sg = 0;
443
444 /* Count them first. */
445 for (i = 0; i < out_sgs + in_sgs; i++) {
446 struct scatterlist *sg;
447 for (sg = sgs[i]; sg; sg = sg_next(sg))
448 total_sg++;
449 }
450 return virtqueue_add(_vq, sgs, total_sg, out_sgs, in_sgs, data, gfp);
451}
452EXPORT_SYMBOL_GPL(virtqueue_add_sgs);
453
454/**
455 * virtqueue_add_outbuf - expose output buffers to other end
456 * @vq: the struct virtqueue we're talking about.
457 * @sg: scatterlist (must be well-formed and terminated!)
458 * @num: the number of entries in @sg readable by other side
459 * @data: the token identifying the buffer.
460 * @gfp: how to do memory allocations (if necessary).
461 *
462 * Caller must ensure we don't call this with other virtqueue operations
463 * at the same time (except where noted).
464 *
465 * Returns zero or a negative error (ie. ENOSPC, ENOMEM, EIO).
466 */
467int virtqueue_add_outbuf(struct virtqueue *vq,
468 struct scatterlist *sg, unsigned int num,
469 void *data,
470 gfp_t gfp)
471{
472 return virtqueue_add(vq, &sg, num, 1, 0, data, gfp);
473}
474EXPORT_SYMBOL_GPL(virtqueue_add_outbuf);
475
476/**
477 * virtqueue_add_inbuf - expose input buffers to other end
478 * @vq: the struct virtqueue we're talking about.
479 * @sg: scatterlist (must be well-formed and terminated!)
480 * @num: the number of entries in @sg writable by other side
481 * @data: the token identifying the buffer.
482 * @gfp: how to do memory allocations (if necessary).
483 *
484 * Caller must ensure we don't call this with other virtqueue operations
485 * at the same time (except where noted).
486 *
487 * Returns zero or a negative error (ie. ENOSPC, ENOMEM, EIO).
488 */
489int virtqueue_add_inbuf(struct virtqueue *vq,
490 struct scatterlist *sg, unsigned int num,
491 void *data,
492 gfp_t gfp)
493{
494 return virtqueue_add(vq, &sg, num, 0, 1, data, gfp);
495}
496EXPORT_SYMBOL_GPL(virtqueue_add_inbuf);
497
498/**
499 * virtqueue_kick_prepare - first half of split virtqueue_kick call.
500 * @vq: the struct virtqueue
501 *
502 * Instead of virtqueue_kick(), you can do:
503 * if (virtqueue_kick_prepare(vq))
504 * virtqueue_notify(vq);
505 *
506 * This is sometimes useful because the virtqueue_kick_prepare() needs
507 * to be serialized, but the actual virtqueue_notify() call does not.
508 */
509bool virtqueue_kick_prepare(struct virtqueue *_vq)
510{
511 struct vring_virtqueue *vq = to_vvq(_vq);
512 u16 new, old;
513 bool needs_kick;
514
515 START_USE(vq);
516 /* We need to expose available array entries before checking avail
517 * event. */
518 virtio_mb(vq->weak_barriers);
519
520 old = vq->avail_idx_shadow - vq->num_added;
521 new = vq->avail_idx_shadow;
522 vq->num_added = 0;
523
524#ifdef DEBUG
525 if (vq->last_add_time_valid) {
526 WARN_ON(ktime_to_ms(ktime_sub(ktime_get(),
527 vq->last_add_time)) > 100);
528 }
529 vq->last_add_time_valid = false;
530#endif
531
532 if (vq->event) {
533 needs_kick = vring_need_event(virtio16_to_cpu(_vq->vdev, vring_avail_event(&vq->vring)),
534 new, old);
535 } else {
536 needs_kick = !(vq->vring.used->flags & cpu_to_virtio16(_vq->vdev, VRING_USED_F_NO_NOTIFY));
537 }
538 END_USE(vq);
539 return needs_kick;
540}
541EXPORT_SYMBOL_GPL(virtqueue_kick_prepare);
542
543/**
544 * virtqueue_notify - second half of split virtqueue_kick call.
545 * @vq: the struct virtqueue
546 *
547 * This does not need to be serialized.
548 *
549 * Returns false if host notify failed or queue is broken, otherwise true.
550 */
551bool virtqueue_notify(struct virtqueue *_vq)
552{
553 struct vring_virtqueue *vq = to_vvq(_vq);
554
555 if (unlikely(vq->broken))
556 return false;
557
558 /* Prod other side to tell it about changes. */
559 if (!vq->notify(_vq)) {
560 vq->broken = true;
561 return false;
562 }
563 return true;
564}
565EXPORT_SYMBOL_GPL(virtqueue_notify);
566
567/**
568 * virtqueue_kick - update after add_buf
569 * @vq: the struct virtqueue
570 *
571 * After one or more virtqueue_add_* calls, invoke this to kick
572 * the other side.
573 *
574 * Caller must ensure we don't call this with other virtqueue
575 * operations at the same time (except where noted).
576 *
577 * Returns false if kick failed, otherwise true.
578 */
579bool virtqueue_kick(struct virtqueue *vq)
580{
581 if (virtqueue_kick_prepare(vq))
582 return virtqueue_notify(vq);
583 return true;
584}
585EXPORT_SYMBOL_GPL(virtqueue_kick);
586
587static void detach_buf(struct vring_virtqueue *vq, unsigned int head)
588{
589 unsigned int i, j;
590 u16 nextflag = cpu_to_virtio16(vq->vq.vdev, VRING_DESC_F_NEXT);
591
592 /* Clear data ptr. */
593 vq->desc_state[head].data = NULL;
594
595 /* Put back on free list: unmap first-level descriptors and find end */
596 i = head;
597
598 while (vq->vring.desc[i].flags & nextflag) {
599 vring_unmap_one(vq, &vq->vring.desc[i]);
600 i = virtio16_to_cpu(vq->vq.vdev, vq->vring.desc[i].next);
601 vq->vq.num_free++;
602 }
603
604 vring_unmap_one(vq, &vq->vring.desc[i]);
605 vq->vring.desc[i].next = cpu_to_virtio16(vq->vq.vdev, vq->free_head);
606 vq->free_head = head;
607
608 /* Plus final descriptor */
609 vq->vq.num_free++;
610
611 /* Free the indirect table, if any, now that it's unmapped. */
612 if (vq->desc_state[head].indir_desc) {
613 struct vring_desc *indir_desc = vq->desc_state[head].indir_desc;
614 u32 len = virtio32_to_cpu(vq->vq.vdev, vq->vring.desc[head].len);
615
616 BUG_ON(!(vq->vring.desc[head].flags &
617 cpu_to_virtio16(vq->vq.vdev, VRING_DESC_F_INDIRECT)));
618 BUG_ON(len == 0 || len % sizeof(struct vring_desc));
619
620 for (j = 0; j < len / sizeof(struct vring_desc); j++)
621 vring_unmap_one(vq, &indir_desc[j]);
622
623 kfree(vq->desc_state[head].indir_desc);
624 vq->desc_state[head].indir_desc = NULL;
625 }
626}
627
628static inline bool more_used(const struct vring_virtqueue *vq)
629{
630 return vq->last_used_idx != virtio16_to_cpu(vq->vq.vdev, vq->vring.used->idx);
631}
632
633/**
634 * virtqueue_get_buf - get the next used buffer
635 * @vq: the struct virtqueue we're talking about.
636 * @len: the length written into the buffer
637 *
638 * If the driver wrote data into the buffer, @len will be set to the
639 * amount written. This means you don't need to clear the buffer
640 * beforehand to ensure there's no data leakage in the case of short
641 * writes.
642 *
643 * Caller must ensure we don't call this with other virtqueue
644 * operations at the same time (except where noted).
645 *
646 * Returns NULL if there are no used buffers, or the "data" token
647 * handed to virtqueue_add_*().
648 */
649void *virtqueue_get_buf(struct virtqueue *_vq, unsigned int *len)
650{
651 struct vring_virtqueue *vq = to_vvq(_vq);
652 void *ret;
653 unsigned int i;
654 u16 last_used;
655
656 START_USE(vq);
657
658 if (unlikely(vq->broken)) {
659 END_USE(vq);
660 return NULL;
661 }
662
663 if (!more_used(vq)) {
664 pr_debug("No more buffers in queue\n");
665 END_USE(vq);
666 return NULL;
667 }
668
669 /* Only get used array entries after they have been exposed by host. */
670 virtio_rmb(vq->weak_barriers);
671
672 last_used = (vq->last_used_idx & (vq->vring.num - 1));
673 i = virtio32_to_cpu(_vq->vdev, vq->vring.used->ring[last_used].id);
674 *len = virtio32_to_cpu(_vq->vdev, vq->vring.used->ring[last_used].len);
675
676 if (unlikely(i >= vq->vring.num)) {
677 BAD_RING(vq, "id %u out of range\n", i);
678 return NULL;
679 }
680 if (unlikely(!vq->desc_state[i].data)) {
681 BAD_RING(vq, "id %u is not a head!\n", i);
682 return NULL;
683 }
684
685 /* detach_buf clears data, so grab it now. */
686 ret = vq->desc_state[i].data;
687 detach_buf(vq, i);
688 vq->last_used_idx++;
689 /* If we expect an interrupt for the next entry, tell host
690 * by writing event index and flush out the write before
691 * the read in the next get_buf call. */
692 if (!(vq->avail_flags_shadow & VRING_AVAIL_F_NO_INTERRUPT))
693 virtio_store_mb(vq->weak_barriers,
694 &vring_used_event(&vq->vring),
695 cpu_to_virtio16(_vq->vdev, vq->last_used_idx));
696
697#ifdef DEBUG
698 vq->last_add_time_valid = false;
699#endif
700
701 END_USE(vq);
702 return ret;
703}
704EXPORT_SYMBOL_GPL(virtqueue_get_buf);
705
706/**
707 * virtqueue_disable_cb - disable callbacks
708 * @vq: the struct virtqueue we're talking about.
709 *
710 * Note that this is not necessarily synchronous, hence unreliable and only
711 * useful as an optimization.
712 *
713 * Unlike other operations, this need not be serialized.
714 */
715void virtqueue_disable_cb(struct virtqueue *_vq)
716{
717 struct vring_virtqueue *vq = to_vvq(_vq);
718
719 if (!(vq->avail_flags_shadow & VRING_AVAIL_F_NO_INTERRUPT)) {
720 vq->avail_flags_shadow |= VRING_AVAIL_F_NO_INTERRUPT;
721 vq->vring.avail->flags = cpu_to_virtio16(_vq->vdev, vq->avail_flags_shadow);
722 }
723
724}
725EXPORT_SYMBOL_GPL(virtqueue_disable_cb);
726
727/**
728 * virtqueue_enable_cb_prepare - restart callbacks after disable_cb
729 * @vq: the struct virtqueue we're talking about.
730 *
731 * This re-enables callbacks; it returns current queue state
732 * in an opaque unsigned value. This value should be later tested by
733 * virtqueue_poll, to detect a possible race between the driver checking for
734 * more work, and enabling callbacks.
735 *
736 * Caller must ensure we don't call this with other virtqueue
737 * operations at the same time (except where noted).
738 */
739unsigned virtqueue_enable_cb_prepare(struct virtqueue *_vq)
740{
741 struct vring_virtqueue *vq = to_vvq(_vq);
742 u16 last_used_idx;
743
744 START_USE(vq);
745
746 /* We optimistically turn back on interrupts, then check if there was
747 * more to do. */
748 /* Depending on the VIRTIO_RING_F_EVENT_IDX feature, we need to
749 * either clear the flags bit or point the event index at the next
750 * entry. Always do both to keep code simple. */
751 if (vq->avail_flags_shadow & VRING_AVAIL_F_NO_INTERRUPT) {
752 vq->avail_flags_shadow &= ~VRING_AVAIL_F_NO_INTERRUPT;
753 vq->vring.avail->flags = cpu_to_virtio16(_vq->vdev, vq->avail_flags_shadow);
754 }
755 vring_used_event(&vq->vring) = cpu_to_virtio16(_vq->vdev, last_used_idx = vq->last_used_idx);
756 END_USE(vq);
757 return last_used_idx;
758}
759EXPORT_SYMBOL_GPL(virtqueue_enable_cb_prepare);
760
761/**
762 * virtqueue_poll - query pending used buffers
763 * @vq: the struct virtqueue we're talking about.
764 * @last_used_idx: virtqueue state (from call to virtqueue_enable_cb_prepare).
765 *
766 * Returns "true" if there are pending used buffers in the queue.
767 *
768 * This does not need to be serialized.
769 */
770bool virtqueue_poll(struct virtqueue *_vq, unsigned last_used_idx)
771{
772 struct vring_virtqueue *vq = to_vvq(_vq);
773
774 virtio_mb(vq->weak_barriers);
775 return (u16)last_used_idx != virtio16_to_cpu(_vq->vdev, vq->vring.used->idx);
776}
777EXPORT_SYMBOL_GPL(virtqueue_poll);
778
779/**
780 * virtqueue_enable_cb - restart callbacks after disable_cb.
781 * @vq: the struct virtqueue we're talking about.
782 *
783 * This re-enables callbacks; it returns "false" if there are pending
784 * buffers in the queue, to detect a possible race between the driver
785 * checking for more work, and enabling callbacks.
786 *
787 * Caller must ensure we don't call this with other virtqueue
788 * operations at the same time (except where noted).
789 */
790bool virtqueue_enable_cb(struct virtqueue *_vq)
791{
792 unsigned last_used_idx = virtqueue_enable_cb_prepare(_vq);
793 return !virtqueue_poll(_vq, last_used_idx);
794}
795EXPORT_SYMBOL_GPL(virtqueue_enable_cb);
796
797/**
798 * virtqueue_enable_cb_delayed - restart callbacks after disable_cb.
799 * @vq: the struct virtqueue we're talking about.
800 *
801 * This re-enables callbacks but hints to the other side to delay
802 * interrupts until most of the available buffers have been processed;
803 * it returns "false" if there are many pending buffers in the queue,
804 * to detect a possible race between the driver checking for more work,
805 * and enabling callbacks.
806 *
807 * Caller must ensure we don't call this with other virtqueue
808 * operations at the same time (except where noted).
809 */
810bool virtqueue_enable_cb_delayed(struct virtqueue *_vq)
811{
812 struct vring_virtqueue *vq = to_vvq(_vq);
813 u16 bufs;
814
815 START_USE(vq);
816
817 /* We optimistically turn back on interrupts, then check if there was
818 * more to do. */
819 /* Depending on the VIRTIO_RING_F_USED_EVENT_IDX feature, we need to
820 * either clear the flags bit or point the event index at the next
821 * entry. Always do both to keep code simple. */
822 if (vq->avail_flags_shadow & VRING_AVAIL_F_NO_INTERRUPT) {
823 vq->avail_flags_shadow &= ~VRING_AVAIL_F_NO_INTERRUPT;
824 vq->vring.avail->flags = cpu_to_virtio16(_vq->vdev, vq->avail_flags_shadow);
825 }
826 /* TODO: tune this threshold */
827 bufs = (u16)(vq->avail_idx_shadow - vq->last_used_idx) * 3 / 4;
828
829 virtio_store_mb(vq->weak_barriers,
830 &vring_used_event(&vq->vring),
831 cpu_to_virtio16(_vq->vdev, vq->last_used_idx + bufs));
832
833 if (unlikely((u16)(virtio16_to_cpu(_vq->vdev, vq->vring.used->idx) - vq->last_used_idx) > bufs)) {
834 END_USE(vq);
835 return false;
836 }
837
838 END_USE(vq);
839 return true;
840}
841EXPORT_SYMBOL_GPL(virtqueue_enable_cb_delayed);
842
843/**
844 * virtqueue_detach_unused_buf - detach first unused buffer
845 * @vq: the struct virtqueue we're talking about.
846 *
847 * Returns NULL or the "data" token handed to virtqueue_add_*().
848 * This is not valid on an active queue; it is useful only for device
849 * shutdown.
850 */
851void *virtqueue_detach_unused_buf(struct virtqueue *_vq)
852{
853 struct vring_virtqueue *vq = to_vvq(_vq);
854 unsigned int i;
855 void *buf;
856
857 START_USE(vq);
858
859 for (i = 0; i < vq->vring.num; i++) {
860 if (!vq->desc_state[i].data)
861 continue;
862 /* detach_buf clears data, so grab it now. */
863 buf = vq->desc_state[i].data;
864 detach_buf(vq, i);
865 vq->avail_idx_shadow--;
866 vq->vring.avail->idx = cpu_to_virtio16(_vq->vdev, vq->avail_idx_shadow);
867 END_USE(vq);
868 return buf;
869 }
870 /* That should have freed everything. */
871 BUG_ON(vq->vq.num_free != vq->vring.num);
872
873 END_USE(vq);
874 return NULL;
875}
876EXPORT_SYMBOL_GPL(virtqueue_detach_unused_buf);
877
878irqreturn_t vring_interrupt(int irq, void *_vq)
879{
880 struct vring_virtqueue *vq = to_vvq(_vq);
881
882 if (!more_used(vq)) {
883 pr_debug("virtqueue interrupt with no work for %p\n", vq);
884 return IRQ_NONE;
885 }
886
887 if (unlikely(vq->broken))
888 return IRQ_HANDLED;
889
890 pr_debug("virtqueue callback for %p (%p)\n", vq, vq->vq.callback);
891 if (vq->vq.callback)
892 vq->vq.callback(&vq->vq);
893
894 return IRQ_HANDLED;
895}
896EXPORT_SYMBOL_GPL(vring_interrupt);
897
898struct virtqueue *__vring_new_virtqueue(unsigned int index,
899 struct vring vring,
900 struct virtio_device *vdev,
901 bool weak_barriers,
902 bool (*notify)(struct virtqueue *),
903 void (*callback)(struct virtqueue *),
904 const char *name)
905{
906 unsigned int i;
907 struct vring_virtqueue *vq;
908
909 vq = kmalloc(sizeof(*vq) + vring.num * sizeof(struct vring_desc_state),
910 GFP_KERNEL);
911 if (!vq)
912 return NULL;
913
914 vq->vring = vring;
915 vq->vq.callback = callback;
916 vq->vq.vdev = vdev;
917 vq->vq.name = name;
918 vq->vq.num_free = vring.num;
919 vq->vq.index = index;
920 vq->we_own_ring = false;
921 vq->queue_dma_addr = 0;
922 vq->queue_size_in_bytes = 0;
923 vq->notify = notify;
924 vq->weak_barriers = weak_barriers;
925 vq->broken = false;
926 vq->last_used_idx = 0;
927 vq->avail_flags_shadow = 0;
928 vq->avail_idx_shadow = 0;
929 vq->num_added = 0;
930 list_add_tail(&vq->vq.list, &vdev->vqs);
931#ifdef DEBUG
932 vq->in_use = false;
933 vq->last_add_time_valid = false;
934#endif
935
936 vq->indirect = virtio_has_feature(vdev, VIRTIO_RING_F_INDIRECT_DESC);
937 vq->event = virtio_has_feature(vdev, VIRTIO_RING_F_EVENT_IDX);
938
939 /* No callback? Tell other side not to bother us. */
940 if (!callback) {
941 vq->avail_flags_shadow |= VRING_AVAIL_F_NO_INTERRUPT;
942 vq->vring.avail->flags = cpu_to_virtio16(vdev, vq->avail_flags_shadow);
943 }
944
945 /* Put everything in free lists. */
946 vq->free_head = 0;
947 for (i = 0; i < vring.num-1; i++)
948 vq->vring.desc[i].next = cpu_to_virtio16(vdev, i + 1);
949 memset(vq->desc_state, 0, vring.num * sizeof(struct vring_desc_state));
950
951 return &vq->vq;
952}
953EXPORT_SYMBOL_GPL(__vring_new_virtqueue);
954
955static void *vring_alloc_queue(struct virtio_device *vdev, size_t size,
956 dma_addr_t *dma_handle, gfp_t flag)
957{
958 if (vring_use_dma_api(vdev)) {
959 return dma_alloc_coherent(vdev->dev.parent, size,
960 dma_handle, flag);
961 } else {
962 void *queue = alloc_pages_exact(PAGE_ALIGN(size), flag);
963 if (queue) {
964 phys_addr_t phys_addr = virt_to_phys(queue);
965 *dma_handle = (dma_addr_t)phys_addr;
966
967 /*
968 * Sanity check: make sure we dind't truncate
969 * the address. The only arches I can find that
970 * have 64-bit phys_addr_t but 32-bit dma_addr_t
971 * are certain non-highmem MIPS and x86
972 * configurations, but these configurations
973 * should never allocate physical pages above 32
974 * bits, so this is fine. Just in case, throw a
975 * warning and abort if we end up with an
976 * unrepresentable address.
977 */
978 if (WARN_ON_ONCE(*dma_handle != phys_addr)) {
979 free_pages_exact(queue, PAGE_ALIGN(size));
980 return NULL;
981 }
982 }
983 return queue;
984 }
985}
986
987static void vring_free_queue(struct virtio_device *vdev, size_t size,
988 void *queue, dma_addr_t dma_handle)
989{
990 if (vring_use_dma_api(vdev)) {
991 dma_free_coherent(vdev->dev.parent, size, queue, dma_handle);
992 } else {
993 free_pages_exact(queue, PAGE_ALIGN(size));
994 }
995}
996
997struct virtqueue *vring_create_virtqueue(
998 unsigned int index,
999 unsigned int num,
1000 unsigned int vring_align,
1001 struct virtio_device *vdev,
1002 bool weak_barriers,
1003 bool may_reduce_num,
1004 bool (*notify)(struct virtqueue *),
1005 void (*callback)(struct virtqueue *),
1006 const char *name)
1007{
1008 struct virtqueue *vq;
1009 void *queue = NULL;
1010 dma_addr_t dma_addr;
1011 size_t queue_size_in_bytes;
1012 struct vring vring;
1013
1014 /* We assume num is a power of 2. */
1015 if (num & (num - 1)) {
1016 dev_warn(&vdev->dev, "Bad virtqueue length %u\n", num);
1017 return NULL;
1018 }
1019
1020 /* TODO: allocate each queue chunk individually */
1021 for (; num && vring_size(num, vring_align) > PAGE_SIZE; num /= 2) {
1022 queue = vring_alloc_queue(vdev, vring_size(num, vring_align),
1023 &dma_addr,
1024 GFP_KERNEL|__GFP_NOWARN|__GFP_ZERO);
1025 if (queue)
1026 break;
1027 }
1028
1029 if (!num)
1030 return NULL;
1031
1032 if (!queue) {
1033 /* Try to get a single page. You are my only hope! */
1034 queue = vring_alloc_queue(vdev, vring_size(num, vring_align),
1035 &dma_addr, GFP_KERNEL|__GFP_ZERO);
1036 }
1037 if (!queue)
1038 return NULL;
1039
1040 queue_size_in_bytes = vring_size(num, vring_align);
1041 vring_init(&vring, num, queue, vring_align);
1042
1043 vq = __vring_new_virtqueue(index, vring, vdev, weak_barriers,
1044 notify, callback, name);
1045 if (!vq) {
1046 vring_free_queue(vdev, queue_size_in_bytes, queue,
1047 dma_addr);
1048 return NULL;
1049 }
1050
1051 to_vvq(vq)->queue_dma_addr = dma_addr;
1052 to_vvq(vq)->queue_size_in_bytes = queue_size_in_bytes;
1053 to_vvq(vq)->we_own_ring = true;
1054
1055 return vq;
1056}
1057EXPORT_SYMBOL_GPL(vring_create_virtqueue);
1058
1059struct virtqueue *vring_new_virtqueue(unsigned int index,
1060 unsigned int num,
1061 unsigned int vring_align,
1062 struct virtio_device *vdev,
1063 bool weak_barriers,
1064 void *pages,
1065 bool (*notify)(struct virtqueue *vq),
1066 void (*callback)(struct virtqueue *vq),
1067 const char *name)
1068{
1069 struct vring vring;
1070 vring_init(&vring, num, pages, vring_align);
1071 return __vring_new_virtqueue(index, vring, vdev, weak_barriers,
1072 notify, callback, name);
1073}
1074EXPORT_SYMBOL_GPL(vring_new_virtqueue);
1075
1076void vring_del_virtqueue(struct virtqueue *_vq)
1077{
1078 struct vring_virtqueue *vq = to_vvq(_vq);
1079
1080 if (vq->we_own_ring) {
1081 vring_free_queue(vq->vq.vdev, vq->queue_size_in_bytes,
1082 vq->vring.desc, vq->queue_dma_addr);
1083 }
1084 list_del(&_vq->list);
1085 kfree(vq);
1086}
1087EXPORT_SYMBOL_GPL(vring_del_virtqueue);
1088
1089/* Manipulates transport-specific feature bits. */
1090void vring_transport_features(struct virtio_device *vdev)
1091{
1092 unsigned int i;
1093
1094 for (i = VIRTIO_TRANSPORT_F_START; i < VIRTIO_TRANSPORT_F_END; i++) {
1095 switch (i) {
1096 case VIRTIO_RING_F_INDIRECT_DESC:
1097 break;
1098 case VIRTIO_RING_F_EVENT_IDX:
1099 break;
1100 case VIRTIO_F_VERSION_1:
1101 break;
1102 default:
1103 /* We don't understand this bit. */
1104 __virtio_clear_bit(vdev, i);
1105 }
1106 }
1107}
1108EXPORT_SYMBOL_GPL(vring_transport_features);
1109
1110/**
1111 * virtqueue_get_vring_size - return the size of the virtqueue's vring
1112 * @vq: the struct virtqueue containing the vring of interest.
1113 *
1114 * Returns the size of the vring. This is mainly used for boasting to
1115 * userspace. Unlike other operations, this need not be serialized.
1116 */
1117unsigned int virtqueue_get_vring_size(struct virtqueue *_vq)
1118{
1119
1120 struct vring_virtqueue *vq = to_vvq(_vq);
1121
1122 return vq->vring.num;
1123}
1124EXPORT_SYMBOL_GPL(virtqueue_get_vring_size);
1125
1126bool virtqueue_is_broken(struct virtqueue *_vq)
1127{
1128 struct vring_virtqueue *vq = to_vvq(_vq);
1129
1130 return vq->broken;
1131}
1132EXPORT_SYMBOL_GPL(virtqueue_is_broken);
1133
1134/*
1135 * This should prevent the device from being used, allowing drivers to
1136 * recover. You may need to grab appropriate locks to flush.
1137 */
1138void virtio_break_device(struct virtio_device *dev)
1139{
1140 struct virtqueue *_vq;
1141
1142 list_for_each_entry(_vq, &dev->vqs, list) {
1143 struct vring_virtqueue *vq = to_vvq(_vq);
1144 vq->broken = true;
1145 }
1146}
1147EXPORT_SYMBOL_GPL(virtio_break_device);
1148
1149dma_addr_t virtqueue_get_desc_addr(struct virtqueue *_vq)
1150{
1151 struct vring_virtqueue *vq = to_vvq(_vq);
1152
1153 BUG_ON(!vq->we_own_ring);
1154
1155 return vq->queue_dma_addr;
1156}
1157EXPORT_SYMBOL_GPL(virtqueue_get_desc_addr);
1158
1159dma_addr_t virtqueue_get_avail_addr(struct virtqueue *_vq)
1160{
1161 struct vring_virtqueue *vq = to_vvq(_vq);
1162
1163 BUG_ON(!vq->we_own_ring);
1164
1165 return vq->queue_dma_addr +
1166 ((char *)vq->vring.avail - (char *)vq->vring.desc);
1167}
1168EXPORT_SYMBOL_GPL(virtqueue_get_avail_addr);
1169
1170dma_addr_t virtqueue_get_used_addr(struct virtqueue *_vq)
1171{
1172 struct vring_virtqueue *vq = to_vvq(_vq);
1173
1174 BUG_ON(!vq->we_own_ring);
1175
1176 return vq->queue_dma_addr +
1177 ((char *)vq->vring.used - (char *)vq->vring.desc);
1178}
1179EXPORT_SYMBOL_GPL(virtqueue_get_used_addr);
1180
1181const struct vring *virtqueue_get_vring(struct virtqueue *vq)
1182{
1183 return &to_vvq(vq)->vring;
1184}
1185EXPORT_SYMBOL_GPL(virtqueue_get_vring);
1186
1187MODULE_LICENSE("GPL");