1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3 * Copyright (C) 2018, Tuomas Tynkkynen <tuomas.tynkkynen@iki.fi>
4 * Copyright (C) 2018, Bin Meng <bmeng.cn@gmail.com>
5 *
6 * virtio ring implementation
7 */
8
9 #include <common.h>
10 #include <dm.h>
11 #include <log.h>
12 #include <malloc.h>
13 #include <virtio_types.h>
14 #include <virtio.h>
15 #include <virtio_ring.h>
16 #include <linux/bug.h>
17 #include <linux/compat.h>
18
virtqueue_add(struct virtqueue * vq,struct virtio_sg * sgs[],unsigned int out_sgs,unsigned int in_sgs)19 int virtqueue_add(struct virtqueue *vq, struct virtio_sg *sgs[],
20 unsigned int out_sgs, unsigned int in_sgs)
21 {
22 struct vring_desc *desc;
23 unsigned int total_sg = out_sgs + in_sgs;
24 unsigned int i, n, avail, descs_used, uninitialized_var(prev);
25 int head;
26
27 WARN_ON(total_sg == 0);
28
29 head = vq->free_head;
30
31 desc = vq->vring.desc;
32 i = head;
33 descs_used = total_sg;
34
35 if (vq->num_free < descs_used) {
36 debug("Can't add buf len %i - avail = %i\n",
37 descs_used, vq->num_free);
38 /*
39 * FIXME: for historical reasons, we force a notify here if
40 * there are outgoing parts to the buffer. Presumably the
41 * host should service the ring ASAP.
42 */
43 if (out_sgs)
44 virtio_notify(vq->vdev, vq);
45 return -ENOSPC;
46 }
47
48 for (n = 0; n < out_sgs; n++) {
49 struct virtio_sg *sg = sgs[n];
50
51 desc[i].flags = cpu_to_virtio16(vq->vdev, VRING_DESC_F_NEXT);
52 desc[i].addr = cpu_to_virtio64(vq->vdev, (u64)(size_t)sg->addr);
53 desc[i].len = cpu_to_virtio32(vq->vdev, sg->length);
54
55 prev = i;
56 i = virtio16_to_cpu(vq->vdev, desc[i].next);
57 }
58 for (; n < (out_sgs + in_sgs); n++) {
59 struct virtio_sg *sg = sgs[n];
60
61 desc[i].flags = cpu_to_virtio16(vq->vdev, VRING_DESC_F_NEXT |
62 VRING_DESC_F_WRITE);
63 desc[i].addr = cpu_to_virtio64(vq->vdev,
64 (u64)(uintptr_t)sg->addr);
65 desc[i].len = cpu_to_virtio32(vq->vdev, sg->length);
66
67 prev = i;
68 i = virtio16_to_cpu(vq->vdev, desc[i].next);
69 }
70 /* Last one doesn't continue */
71 desc[prev].flags &= cpu_to_virtio16(vq->vdev, ~VRING_DESC_F_NEXT);
72
73 /* We're using some buffers from the free list. */
74 vq->num_free -= descs_used;
75
76 /* Update free pointer */
77 vq->free_head = i;
78
79 /*
80 * Put entry in available array (but don't update avail->idx
81 * until they do sync).
82 */
83 avail = vq->avail_idx_shadow & (vq->vring.num - 1);
84 vq->vring.avail->ring[avail] = cpu_to_virtio16(vq->vdev, head);
85
86 /*
87 * Descriptors and available array need to be set before we expose the
88 * new available array entries.
89 */
90 virtio_wmb();
91 vq->avail_idx_shadow++;
92 vq->vring.avail->idx = cpu_to_virtio16(vq->vdev, vq->avail_idx_shadow);
93 vq->num_added++;
94
95 /*
96 * This is very unlikely, but theoretically possible.
97 * Kick just in case.
98 */
99 if (unlikely(vq->num_added == (1 << 16) - 1))
100 virtqueue_kick(vq);
101
102 return 0;
103 }
104
virtqueue_kick_prepare(struct virtqueue * vq)105 static bool virtqueue_kick_prepare(struct virtqueue *vq)
106 {
107 u16 new, old;
108 bool needs_kick;
109
110 /*
111 * We need to expose available array entries before checking
112 * avail event.
113 */
114 virtio_mb();
115
116 old = vq->avail_idx_shadow - vq->num_added;
117 new = vq->avail_idx_shadow;
118 vq->num_added = 0;
119
120 if (vq->event) {
121 needs_kick = vring_need_event(virtio16_to_cpu(vq->vdev,
122 vring_avail_event(&vq->vring)), new, old);
123 } else {
124 needs_kick = !(vq->vring.used->flags & cpu_to_virtio16(vq->vdev,
125 VRING_USED_F_NO_NOTIFY));
126 }
127
128 return needs_kick;
129 }
130
virtqueue_kick(struct virtqueue * vq)131 void virtqueue_kick(struct virtqueue *vq)
132 {
133 if (virtqueue_kick_prepare(vq))
134 virtio_notify(vq->vdev, vq);
135 }
136
detach_buf(struct virtqueue * vq,unsigned int head)137 static void detach_buf(struct virtqueue *vq, unsigned int head)
138 {
139 unsigned int i;
140 __virtio16 nextflag = cpu_to_virtio16(vq->vdev, VRING_DESC_F_NEXT);
141
142 /* Put back on free list: unmap first-level descriptors and find end */
143 i = head;
144
145 while (vq->vring.desc[i].flags & nextflag) {
146 i = virtio16_to_cpu(vq->vdev, vq->vring.desc[i].next);
147 vq->num_free++;
148 }
149
150 vq->vring.desc[i].next = cpu_to_virtio16(vq->vdev, vq->free_head);
151 vq->free_head = head;
152
153 /* Plus final descriptor */
154 vq->num_free++;
155 }
156
more_used(const struct virtqueue * vq)157 static inline bool more_used(const struct virtqueue *vq)
158 {
159 return vq->last_used_idx != virtio16_to_cpu(vq->vdev,
160 vq->vring.used->idx);
161 }
162
virtqueue_get_buf(struct virtqueue * vq,unsigned int * len)163 void *virtqueue_get_buf(struct virtqueue *vq, unsigned int *len)
164 {
165 unsigned int i;
166 u16 last_used;
167
168 if (!more_used(vq)) {
169 debug("(%s.%d): No more buffers in queue\n",
170 vq->vdev->name, vq->index);
171 return NULL;
172 }
173
174 /* Only get used array entries after they have been exposed by host */
175 virtio_rmb();
176
177 last_used = (vq->last_used_idx & (vq->vring.num - 1));
178 i = virtio32_to_cpu(vq->vdev, vq->vring.used->ring[last_used].id);
179 if (len) {
180 *len = virtio32_to_cpu(vq->vdev,
181 vq->vring.used->ring[last_used].len);
182 debug("(%s.%d): last used idx %u with len %u\n",
183 vq->vdev->name, vq->index, i, *len);
184 }
185
186 if (unlikely(i >= vq->vring.num)) {
187 printf("(%s.%d): id %u out of range\n",
188 vq->vdev->name, vq->index, i);
189 return NULL;
190 }
191
192 detach_buf(vq, i);
193 vq->last_used_idx++;
194 /*
195 * If we expect an interrupt for the next entry, tell host
196 * by writing event index and flush out the write before
197 * the read in the next get_buf call.
198 */
199 if (!(vq->avail_flags_shadow & VRING_AVAIL_F_NO_INTERRUPT))
200 virtio_store_mb(&vring_used_event(&vq->vring),
201 cpu_to_virtio16(vq->vdev, vq->last_used_idx));
202
203 return (void *)(uintptr_t)virtio64_to_cpu(vq->vdev,
204 vq->vring.desc[i].addr);
205 }
206
__vring_new_virtqueue(unsigned int index,struct vring vring,struct udevice * udev)207 static struct virtqueue *__vring_new_virtqueue(unsigned int index,
208 struct vring vring,
209 struct udevice *udev)
210 {
211 unsigned int i;
212 struct virtqueue *vq;
213 struct virtio_dev_priv *uc_priv = dev_get_uclass_priv(udev);
214 struct udevice *vdev = uc_priv->vdev;
215
216 vq = malloc(sizeof(*vq));
217 if (!vq)
218 return NULL;
219
220 vq->vdev = vdev;
221 vq->index = index;
222 vq->num_free = vring.num;
223 vq->vring = vring;
224 vq->last_used_idx = 0;
225 vq->avail_flags_shadow = 0;
226 vq->avail_idx_shadow = 0;
227 vq->num_added = 0;
228 list_add_tail(&vq->list, &uc_priv->vqs);
229
230 vq->event = virtio_has_feature(vdev, VIRTIO_RING_F_EVENT_IDX);
231
232 /* Tell other side not to bother us */
233 vq->avail_flags_shadow |= VRING_AVAIL_F_NO_INTERRUPT;
234 if (!vq->event)
235 vq->vring.avail->flags = cpu_to_virtio16(vdev,
236 vq->avail_flags_shadow);
237
238 /* Put everything in free lists */
239 vq->free_head = 0;
240 for (i = 0; i < vring.num - 1; i++)
241 vq->vring.desc[i].next = cpu_to_virtio16(vdev, i + 1);
242
243 return vq;
244 }
245
vring_create_virtqueue(unsigned int index,unsigned int num,unsigned int vring_align,struct udevice * udev)246 struct virtqueue *vring_create_virtqueue(unsigned int index, unsigned int num,
247 unsigned int vring_align,
248 struct udevice *udev)
249 {
250 struct virtqueue *vq;
251 void *queue = NULL;
252 struct vring vring;
253
254 /* We assume num is a power of 2 */
255 if (num & (num - 1)) {
256 printf("Bad virtqueue length %u\n", num);
257 return NULL;
258 }
259
260 /* TODO: allocate each queue chunk individually */
261 for (; num && vring_size(num, vring_align) > PAGE_SIZE; num /= 2) {
262 queue = memalign(PAGE_SIZE, vring_size(num, vring_align));
263 if (queue)
264 break;
265 }
266
267 if (!num)
268 return NULL;
269
270 if (!queue) {
271 /* Try to get a single page. You are my only hope! */
272 queue = memalign(PAGE_SIZE, vring_size(num, vring_align));
273 }
274 if (!queue)
275 return NULL;
276
277 memset(queue, 0, vring_size(num, vring_align));
278 vring_init(&vring, num, queue, vring_align);
279
280 vq = __vring_new_virtqueue(index, vring, udev);
281 if (!vq) {
282 free(queue);
283 return NULL;
284 }
285 debug("(%s): created vring @ %p for vq @ %p with num %u\n", udev->name,
286 queue, vq, num);
287
288 return vq;
289 }
290
vring_del_virtqueue(struct virtqueue * vq)291 void vring_del_virtqueue(struct virtqueue *vq)
292 {
293 free(vq->vring.desc);
294 list_del(&vq->list);
295 free(vq);
296 }
297
virtqueue_get_vring_size(struct virtqueue * vq)298 unsigned int virtqueue_get_vring_size(struct virtqueue *vq)
299 {
300 return vq->vring.num;
301 }
302
virtqueue_get_desc_addr(struct virtqueue * vq)303 ulong virtqueue_get_desc_addr(struct virtqueue *vq)
304 {
305 return (ulong)vq->vring.desc;
306 }
307
virtqueue_get_avail_addr(struct virtqueue * vq)308 ulong virtqueue_get_avail_addr(struct virtqueue *vq)
309 {
310 return (ulong)vq->vring.desc +
311 ((char *)vq->vring.avail - (char *)vq->vring.desc);
312 }
313
virtqueue_get_used_addr(struct virtqueue * vq)314 ulong virtqueue_get_used_addr(struct virtqueue *vq)
315 {
316 return (ulong)vq->vring.desc +
317 ((char *)vq->vring.used - (char *)vq->vring.desc);
318 }
319
virtqueue_poll(struct virtqueue * vq,u16 last_used_idx)320 bool virtqueue_poll(struct virtqueue *vq, u16 last_used_idx)
321 {
322 virtio_mb();
323
324 return last_used_idx != virtio16_to_cpu(vq->vdev, vq->vring.used->idx);
325 }
326
virtqueue_dump(struct virtqueue * vq)327 void virtqueue_dump(struct virtqueue *vq)
328 {
329 unsigned int i;
330
331 printf("virtqueue %p for dev %s:\n", vq, vq->vdev->name);
332 printf("\tindex %u, phys addr %p num %u\n",
333 vq->index, vq->vring.desc, vq->vring.num);
334 printf("\tfree_head %u, num_added %u, num_free %u\n",
335 vq->free_head, vq->num_added, vq->num_free);
336 printf("\tlast_used_idx %u, avail_flags_shadow %u, avail_idx_shadow %u\n",
337 vq->last_used_idx, vq->avail_flags_shadow, vq->avail_idx_shadow);
338
339 printf("Descriptor dump:\n");
340 for (i = 0; i < vq->vring.num; i++) {
341 printf("\tdesc[%u] = { 0x%llx, len %u, flags %u, next %u }\n",
342 i, vq->vring.desc[i].addr, vq->vring.desc[i].len,
343 vq->vring.desc[i].flags, vq->vring.desc[i].next);
344 }
345
346 printf("Avail ring dump:\n");
347 printf("\tflags %u, idx %u\n",
348 vq->vring.avail->flags, vq->vring.avail->idx);
349 for (i = 0; i < vq->vring.num; i++) {
350 printf("\tavail[%u] = %u\n",
351 i, vq->vring.avail->ring[i]);
352 }
353
354 printf("Used ring dump:\n");
355 printf("\tflags %u, idx %u\n",
356 vq->vring.used->flags, vq->vring.used->idx);
357 for (i = 0; i < vq->vring.num; i++) {
358 printf("\tused[%u] = { %u, %u }\n", i,
359 vq->vring.used->ring[i].id, vq->vring.used->ring[i].len);
360 }
361 }
362