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3e7ee490 HJ |
1 | /* |
2 | * | |
3 | * Copyright (c) 2009, Microsoft Corporation. | |
4 | * | |
5 | * This program is free software; you can redistribute it and/or modify it | |
6 | * under the terms and conditions of the GNU General Public License, | |
7 | * version 2, as published by the Free Software Foundation. | |
8 | * | |
9 | * This program is distributed in the hope it will be useful, but WITHOUT | |
10 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
11 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for | |
12 | * more details. | |
13 | * | |
14 | * You should have received a copy of the GNU General Public License along with | |
15 | * this program; if not, write to the Free Software Foundation, Inc., 59 Temple | |
16 | * Place - Suite 330, Boston, MA 02111-1307 USA. | |
17 | * | |
18 | * Authors: | |
19 | * Haiyang Zhang <haiyangz@microsoft.com> | |
20 | * Hank Janssen <hjanssen@microsoft.com> | |
b2a5a585 | 21 | * K. Y. Srinivasan <kys@microsoft.com> |
3e7ee490 HJ |
22 | * |
23 | */ | |
0a46618d | 24 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
3e7ee490 | 25 | |
a0086dc5 GKH |
26 | #include <linux/kernel.h> |
27 | #include <linux/mm.h> | |
46a97191 | 28 | #include <linux/hyperv.h> |
3f335ea2 | 29 | |
0f2a6619 | 30 | #include "hyperv_vmbus.h" |
3e7ee490 | 31 | |
6fdf3b21 S |
32 | void hv_begin_read(struct hv_ring_buffer_info *rbi) |
33 | { | |
34 | rbi->ring_buffer->interrupt_mask = 1; | |
35 | smp_mb(); | |
36 | } | |
37 | ||
38 | u32 hv_end_read(struct hv_ring_buffer_info *rbi) | |
39 | { | |
40 | u32 read; | |
41 | u32 write; | |
42 | ||
43 | rbi->ring_buffer->interrupt_mask = 0; | |
44 | smp_mb(); | |
45 | ||
46 | /* | |
47 | * Now check to see if the ring buffer is still empty. | |
48 | * If it is not, we raced and we need to process new | |
49 | * incoming messages. | |
50 | */ | |
51 | hv_get_ringbuffer_availbytes(rbi, &read, &write); | |
52 | ||
53 | return read; | |
54 | } | |
55 | ||
98fa8cf4 S |
56 | /* |
57 | * When we write to the ring buffer, check if the host needs to | |
58 | * be signaled. Here is the details of this protocol: | |
59 | * | |
60 | * 1. The host guarantees that while it is draining the | |
61 | * ring buffer, it will set the interrupt_mask to | |
62 | * indicate it does not need to be interrupted when | |
63 | * new data is placed. | |
64 | * | |
65 | * 2. The host guarantees that it will completely drain | |
66 | * the ring buffer before exiting the read loop. Further, | |
67 | * once the ring buffer is empty, it will clear the | |
68 | * interrupt_mask and re-check to see if new data has | |
69 | * arrived. | |
70 | */ | |
71 | ||
72 | static bool hv_need_to_signal(u32 old_write, struct hv_ring_buffer_info *rbi) | |
73 | { | |
74 | if (rbi->ring_buffer->interrupt_mask) | |
75 | return false; | |
76 | ||
77 | /* | |
78 | * This is the only case we need to signal when the | |
79 | * ring transitions from being empty to non-empty. | |
80 | */ | |
81 | if (old_write == rbi->ring_buffer->read_index) | |
82 | return true; | |
83 | ||
84 | return false; | |
85 | } | |
86 | ||
3e7ee490 | 87 | |
b2a5a585 S |
88 | /* |
89 | * hv_get_next_write_location() | |
90 | * | |
91 | * Get the next write location for the specified ring buffer | |
92 | * | |
93 | */ | |
4d643114 | 94 | static inline u32 |
2b8a912e | 95 | hv_get_next_write_location(struct hv_ring_buffer_info *ring_info) |
3e7ee490 | 96 | { |
fc8c72eb | 97 | u32 next = ring_info->ring_buffer->write_index; |
3e7ee490 | 98 | |
3e7ee490 HJ |
99 | return next; |
100 | } | |
101 | ||
b2a5a585 S |
102 | /* |
103 | * hv_set_next_write_location() | |
104 | * | |
105 | * Set the next write location for the specified ring buffer | |
106 | * | |
107 | */ | |
3e7ee490 | 108 | static inline void |
2b8a912e | 109 | hv_set_next_write_location(struct hv_ring_buffer_info *ring_info, |
fc8c72eb | 110 | u32 next_write_location) |
3e7ee490 | 111 | { |
fc8c72eb | 112 | ring_info->ring_buffer->write_index = next_write_location; |
3e7ee490 HJ |
113 | } |
114 | ||
b2a5a585 S |
115 | /* |
116 | * hv_get_next_read_location() | |
117 | * | |
118 | * Get the next read location for the specified ring buffer | |
119 | */ | |
4d643114 | 120 | static inline u32 |
2b8a912e | 121 | hv_get_next_read_location(struct hv_ring_buffer_info *ring_info) |
3e7ee490 | 122 | { |
fc8c72eb | 123 | u32 next = ring_info->ring_buffer->read_index; |
3e7ee490 | 124 | |
3e7ee490 HJ |
125 | return next; |
126 | } | |
127 | ||
b2a5a585 S |
128 | /* |
129 | * hv_get_next_readlocation_withoffset() | |
130 | * | |
131 | * Get the next read location + offset for the specified ring buffer. | |
132 | * This allows the caller to skip | |
133 | */ | |
4d643114 | 134 | static inline u32 |
2b8a912e | 135 | hv_get_next_readlocation_withoffset(struct hv_ring_buffer_info *ring_info, |
1ac58644 | 136 | u32 offset) |
3e7ee490 | 137 | { |
fc8c72eb | 138 | u32 next = ring_info->ring_buffer->read_index; |
3e7ee490 | 139 | |
fc8c72eb HZ |
140 | next += offset; |
141 | next %= ring_info->ring_datasize; | |
3e7ee490 HJ |
142 | |
143 | return next; | |
144 | } | |
145 | ||
b2a5a585 S |
146 | /* |
147 | * | |
148 | * hv_set_next_read_location() | |
149 | * | |
150 | * Set the next read location for the specified ring buffer | |
151 | * | |
152 | */ | |
3e7ee490 | 153 | static inline void |
2b8a912e | 154 | hv_set_next_read_location(struct hv_ring_buffer_info *ring_info, |
fc8c72eb | 155 | u32 next_read_location) |
3e7ee490 | 156 | { |
fc8c72eb | 157 | ring_info->ring_buffer->read_index = next_read_location; |
3e7ee490 HJ |
158 | } |
159 | ||
160 | ||
b2a5a585 S |
161 | /* |
162 | * | |
163 | * hv_get_ring_buffer() | |
164 | * | |
165 | * Get the start of the ring buffer | |
166 | */ | |
8282c400 | 167 | static inline void * |
2b8a912e | 168 | hv_get_ring_buffer(struct hv_ring_buffer_info *ring_info) |
3e7ee490 | 169 | { |
fc8c72eb | 170 | return (void *)ring_info->ring_buffer->buffer; |
3e7ee490 HJ |
171 | } |
172 | ||
173 | ||
b2a5a585 S |
174 | /* |
175 | * | |
176 | * hv_get_ring_buffersize() | |
177 | * | |
178 | * Get the size of the ring buffer | |
179 | */ | |
4d643114 | 180 | static inline u32 |
2b8a912e | 181 | hv_get_ring_buffersize(struct hv_ring_buffer_info *ring_info) |
3e7ee490 | 182 | { |
fc8c72eb | 183 | return ring_info->ring_datasize; |
3e7ee490 HJ |
184 | } |
185 | ||
b2a5a585 S |
186 | /* |
187 | * | |
188 | * hv_get_ring_bufferindices() | |
189 | * | |
190 | * Get the read and write indices as u64 of the specified ring buffer | |
191 | * | |
192 | */ | |
59471438 | 193 | static inline u64 |
2b8a912e | 194 | hv_get_ring_bufferindices(struct hv_ring_buffer_info *ring_info) |
3e7ee490 | 195 | { |
fc8c72eb | 196 | return (u64)ring_info->ring_buffer->write_index << 32; |
3e7ee490 HJ |
197 | } |
198 | ||
8f1136ae S |
199 | /* |
200 | * | |
201 | * hv_copyfrom_ringbuffer() | |
202 | * | |
203 | * Helper routine to copy to source from ring buffer. | |
204 | * Assume there is enough room. Handles wrap-around in src case only!! | |
205 | * | |
206 | */ | |
207 | static u32 hv_copyfrom_ringbuffer( | |
208 | struct hv_ring_buffer_info *ring_info, | |
209 | void *dest, | |
210 | u32 destlen, | |
211 | u32 start_read_offset) | |
212 | { | |
213 | void *ring_buffer = hv_get_ring_buffer(ring_info); | |
214 | u32 ring_buffer_size = hv_get_ring_buffersize(ring_info); | |
215 | ||
216 | u32 frag_len; | |
217 | ||
218 | /* wrap-around detected at the src */ | |
219 | if (destlen > ring_buffer_size - start_read_offset) { | |
220 | frag_len = ring_buffer_size - start_read_offset; | |
221 | ||
222 | memcpy(dest, ring_buffer + start_read_offset, frag_len); | |
223 | memcpy(dest + frag_len, ring_buffer, destlen - frag_len); | |
224 | } else | |
225 | ||
226 | memcpy(dest, ring_buffer + start_read_offset, destlen); | |
227 | ||
228 | ||
229 | start_read_offset += destlen; | |
230 | start_read_offset %= ring_buffer_size; | |
231 | ||
232 | return start_read_offset; | |
233 | } | |
234 | ||
235 | ||
7581578d S |
236 | /* |
237 | * | |
238 | * hv_copyto_ringbuffer() | |
239 | * | |
240 | * Helper routine to copy from source to ring buffer. | |
241 | * Assume there is enough room. Handles wrap-around in dest case only!! | |
242 | * | |
243 | */ | |
244 | static u32 hv_copyto_ringbuffer( | |
fc8c72eb HZ |
245 | struct hv_ring_buffer_info *ring_info, |
246 | u32 start_write_offset, | |
247 | void *src, | |
7581578d S |
248 | u32 srclen) |
249 | { | |
250 | void *ring_buffer = hv_get_ring_buffer(ring_info); | |
251 | u32 ring_buffer_size = hv_get_ring_buffersize(ring_info); | |
252 | u32 frag_len; | |
253 | ||
254 | /* wrap-around detected! */ | |
255 | if (srclen > ring_buffer_size - start_write_offset) { | |
256 | frag_len = ring_buffer_size - start_write_offset; | |
257 | memcpy(ring_buffer + start_write_offset, src, frag_len); | |
258 | memcpy(ring_buffer, src + frag_len, srclen - frag_len); | |
259 | } else | |
260 | memcpy(ring_buffer + start_write_offset, src, srclen); | |
3e7ee490 | 261 | |
7581578d S |
262 | start_write_offset += srclen; |
263 | start_write_offset %= ring_buffer_size; | |
264 | ||
265 | return start_write_offset; | |
266 | } | |
3e7ee490 | 267 | |
b2a5a585 S |
268 | /* |
269 | * | |
270 | * hv_ringbuffer_get_debuginfo() | |
271 | * | |
272 | * Get various debug metrics for the specified ring buffer | |
273 | * | |
274 | */ | |
a75b61d5 | 275 | void hv_ringbuffer_get_debuginfo(struct hv_ring_buffer_info *ring_info, |
80682b7a | 276 | struct hv_ring_buffer_debug_info *debug_info) |
3e7ee490 | 277 | { |
fc8c72eb HZ |
278 | u32 bytes_avail_towrite; |
279 | u32 bytes_avail_toread; | |
3e7ee490 | 280 | |
fc8c72eb | 281 | if (ring_info->ring_buffer) { |
2b8a912e | 282 | hv_get_ringbuffer_availbytes(ring_info, |
fc8c72eb HZ |
283 | &bytes_avail_toread, |
284 | &bytes_avail_towrite); | |
3e7ee490 | 285 | |
fc8c72eb HZ |
286 | debug_info->bytes_avail_toread = bytes_avail_toread; |
287 | debug_info->bytes_avail_towrite = bytes_avail_towrite; | |
82f8bd40 | 288 | debug_info->current_read_index = |
fc8c72eb | 289 | ring_info->ring_buffer->read_index; |
82f8bd40 | 290 | debug_info->current_write_index = |
fc8c72eb | 291 | ring_info->ring_buffer->write_index; |
82f8bd40 | 292 | debug_info->current_interrupt_mask = |
fc8c72eb | 293 | ring_info->ring_buffer->interrupt_mask; |
3e7ee490 HJ |
294 | } |
295 | } | |
296 | ||
b2a5a585 S |
297 | /* |
298 | * | |
299 | * hv_ringbuffer_init() | |
300 | * | |
301 | *Initialize the ring buffer | |
302 | * | |
303 | */ | |
72a95cbc | 304 | int hv_ringbuffer_init(struct hv_ring_buffer_info *ring_info, |
fc8c72eb | 305 | void *buffer, u32 buflen) |
3e7ee490 | 306 | { |
4a1b3acc | 307 | if (sizeof(struct hv_ring_buffer) != PAGE_SIZE) |
3324fb40 | 308 | return -EINVAL; |
3e7ee490 | 309 | |
fc8c72eb | 310 | memset(ring_info, 0, sizeof(struct hv_ring_buffer_info)); |
3e7ee490 | 311 | |
fc8c72eb HZ |
312 | ring_info->ring_buffer = (struct hv_ring_buffer *)buffer; |
313 | ring_info->ring_buffer->read_index = | |
314 | ring_info->ring_buffer->write_index = 0; | |
3e7ee490 | 315 | |
fc8c72eb HZ |
316 | ring_info->ring_size = buflen; |
317 | ring_info->ring_datasize = buflen - sizeof(struct hv_ring_buffer); | |
3e7ee490 | 318 | |
fc8c72eb | 319 | spin_lock_init(&ring_info->ring_lock); |
3e7ee490 HJ |
320 | |
321 | return 0; | |
322 | } | |
323 | ||
b2a5a585 S |
324 | /* |
325 | * | |
326 | * hv_ringbuffer_cleanup() | |
327 | * | |
328 | * Cleanup the ring buffer | |
329 | * | |
330 | */ | |
2dba688b | 331 | void hv_ringbuffer_cleanup(struct hv_ring_buffer_info *ring_info) |
3e7ee490 | 332 | { |
3e7ee490 HJ |
333 | } |
334 | ||
b2a5a585 S |
335 | /* |
336 | * | |
337 | * hv_ringbuffer_write() | |
338 | * | |
339 | * Write to the ring buffer | |
340 | * | |
341 | */ | |
633c4dce | 342 | int hv_ringbuffer_write(struct hv_ring_buffer_info *outring_info, |
98fa8cf4 | 343 | struct scatterlist *sglist, u32 sgcount, bool *signal) |
3e7ee490 | 344 | { |
4408f531 | 345 | int i = 0; |
fc8c72eb HZ |
346 | u32 bytes_avail_towrite; |
347 | u32 bytes_avail_toread; | |
348 | u32 totalbytes_towrite = 0; | |
3e7ee490 | 349 | |
b219b3f7 | 350 | struct scatterlist *sg; |
66a60543 | 351 | u32 next_write_location; |
98fa8cf4 | 352 | u32 old_write; |
fc8c72eb | 353 | u64 prev_indices = 0; |
a98f96ee | 354 | unsigned long flags; |
3e7ee490 | 355 | |
b219b3f7 | 356 | for_each_sg(sglist, sg, sgcount, i) |
3e7ee490 | 357 | { |
fc8c72eb | 358 | totalbytes_towrite += sg->length; |
3e7ee490 HJ |
359 | } |
360 | ||
fc8c72eb | 361 | totalbytes_towrite += sizeof(u64); |
3e7ee490 | 362 | |
fc8c72eb | 363 | spin_lock_irqsave(&outring_info->ring_lock, flags); |
3e7ee490 | 364 | |
2b8a912e | 365 | hv_get_ringbuffer_availbytes(outring_info, |
fc8c72eb HZ |
366 | &bytes_avail_toread, |
367 | &bytes_avail_towrite); | |
3e7ee490 | 368 | |
3e7ee490 | 369 | |
4408f531 B |
370 | /* If there is only room for the packet, assume it is full. */ |
371 | /* Otherwise, the next time around, we think the ring buffer */ | |
454f18a9 | 372 | /* is empty since the read index == write index */ |
fc8c72eb | 373 | if (bytes_avail_towrite <= totalbytes_towrite) { |
fc8c72eb | 374 | spin_unlock_irqrestore(&outring_info->ring_lock, flags); |
d2598f01 | 375 | return -EAGAIN; |
3e7ee490 HJ |
376 | } |
377 | ||
454f18a9 | 378 | /* Write to the ring buffer */ |
2b8a912e | 379 | next_write_location = hv_get_next_write_location(outring_info); |
3e7ee490 | 380 | |
98fa8cf4 S |
381 | old_write = next_write_location; |
382 | ||
b219b3f7 | 383 | for_each_sg(sglist, sg, sgcount, i) |
3e7ee490 | 384 | { |
2b8a912e | 385 | next_write_location = hv_copyto_ringbuffer(outring_info, |
fc8c72eb | 386 | next_write_location, |
b219b3f7 NP |
387 | sg_virt(sg), |
388 | sg->length); | |
3e7ee490 HJ |
389 | } |
390 | ||
454f18a9 | 391 | /* Set previous packet start */ |
2b8a912e | 392 | prev_indices = hv_get_ring_bufferindices(outring_info); |
3e7ee490 | 393 | |
2b8a912e | 394 | next_write_location = hv_copyto_ringbuffer(outring_info, |
fc8c72eb HZ |
395 | next_write_location, |
396 | &prev_indices, | |
b219b3f7 | 397 | sizeof(u64)); |
3e7ee490 | 398 | |
98fa8cf4 S |
399 | /* Issue a full memory barrier before updating the write index */ |
400 | smp_mb(); | |
3e7ee490 | 401 | |
454f18a9 | 402 | /* Now, update the write location */ |
2b8a912e | 403 | hv_set_next_write_location(outring_info, next_write_location); |
3e7ee490 | 404 | |
3e7ee490 | 405 | |
fc8c72eb | 406 | spin_unlock_irqrestore(&outring_info->ring_lock, flags); |
98fa8cf4 S |
407 | |
408 | *signal = hv_need_to_signal(old_write, outring_info); | |
3e7ee490 HJ |
409 | return 0; |
410 | } | |
411 | ||
412 | ||
b2a5a585 S |
413 | /* |
414 | * | |
415 | * hv_ringbuffer_peek() | |
416 | * | |
417 | * Read without advancing the read index | |
418 | * | |
419 | */ | |
a89186c2 | 420 | int hv_ringbuffer_peek(struct hv_ring_buffer_info *Inring_info, |
fc8c72eb | 421 | void *Buffer, u32 buflen) |
3e7ee490 | 422 | { |
fc8c72eb HZ |
423 | u32 bytes_avail_towrite; |
424 | u32 bytes_avail_toread; | |
425 | u32 next_read_location = 0; | |
a98f96ee | 426 | unsigned long flags; |
3e7ee490 | 427 | |
fc8c72eb | 428 | spin_lock_irqsave(&Inring_info->ring_lock, flags); |
3e7ee490 | 429 | |
2b8a912e | 430 | hv_get_ringbuffer_availbytes(Inring_info, |
fc8c72eb HZ |
431 | &bytes_avail_toread, |
432 | &bytes_avail_towrite); | |
3e7ee490 | 433 | |
454f18a9 | 434 | /* Make sure there is something to read */ |
fc8c72eb | 435 | if (bytes_avail_toread < buflen) { |
3e7ee490 | 436 | |
fc8c72eb | 437 | spin_unlock_irqrestore(&Inring_info->ring_lock, flags); |
3e7ee490 | 438 | |
d2598f01 | 439 | return -EAGAIN; |
3e7ee490 HJ |
440 | } |
441 | ||
454f18a9 | 442 | /* Convert to byte offset */ |
2b8a912e | 443 | next_read_location = hv_get_next_read_location(Inring_info); |
3e7ee490 | 444 | |
2b8a912e | 445 | next_read_location = hv_copyfrom_ringbuffer(Inring_info, |
4408f531 | 446 | Buffer, |
fc8c72eb HZ |
447 | buflen, |
448 | next_read_location); | |
3e7ee490 | 449 | |
fc8c72eb | 450 | spin_unlock_irqrestore(&Inring_info->ring_lock, flags); |
3e7ee490 HJ |
451 | |
452 | return 0; | |
453 | } | |
454 | ||
455 | ||
b2a5a585 S |
456 | /* |
457 | * | |
458 | * hv_ringbuffer_read() | |
459 | * | |
460 | * Read and advance the read index | |
461 | * | |
462 | */ | |
38397c8a | 463 | int hv_ringbuffer_read(struct hv_ring_buffer_info *inring_info, void *buffer, |
fc8c72eb | 464 | u32 buflen, u32 offset) |
3e7ee490 | 465 | { |
fc8c72eb HZ |
466 | u32 bytes_avail_towrite; |
467 | u32 bytes_avail_toread; | |
468 | u32 next_read_location = 0; | |
469 | u64 prev_indices = 0; | |
a98f96ee | 470 | unsigned long flags; |
3e7ee490 | 471 | |
fc8c72eb | 472 | if (buflen <= 0) |
a16e1485 | 473 | return -EINVAL; |
3e7ee490 | 474 | |
fc8c72eb | 475 | spin_lock_irqsave(&inring_info->ring_lock, flags); |
3e7ee490 | 476 | |
2b8a912e | 477 | hv_get_ringbuffer_availbytes(inring_info, |
fc8c72eb HZ |
478 | &bytes_avail_toread, |
479 | &bytes_avail_towrite); | |
3e7ee490 | 480 | |
454f18a9 | 481 | /* Make sure there is something to read */ |
fc8c72eb | 482 | if (bytes_avail_toread < buflen) { |
fc8c72eb | 483 | spin_unlock_irqrestore(&inring_info->ring_lock, flags); |
3e7ee490 | 484 | |
d2598f01 | 485 | return -EAGAIN; |
3e7ee490 HJ |
486 | } |
487 | ||
1ac58644 | 488 | next_read_location = |
2b8a912e | 489 | hv_get_next_readlocation_withoffset(inring_info, offset); |
3e7ee490 | 490 | |
2b8a912e | 491 | next_read_location = hv_copyfrom_ringbuffer(inring_info, |
fc8c72eb HZ |
492 | buffer, |
493 | buflen, | |
494 | next_read_location); | |
3e7ee490 | 495 | |
2b8a912e | 496 | next_read_location = hv_copyfrom_ringbuffer(inring_info, |
fc8c72eb | 497 | &prev_indices, |
4408f531 | 498 | sizeof(u64), |
fc8c72eb | 499 | next_read_location); |
3e7ee490 | 500 | |
454f18a9 | 501 | /* Make sure all reads are done before we update the read index since */ |
4408f531 B |
502 | /* the writer may start writing to the read area once the read index */ |
503 | /*is updated */ | |
ef0d5b23 | 504 | smp_mb(); |
3e7ee490 | 505 | |
454f18a9 | 506 | /* Update the read index */ |
2b8a912e | 507 | hv_set_next_read_location(inring_info, next_read_location); |
3e7ee490 | 508 | |
fc8c72eb | 509 | spin_unlock_irqrestore(&inring_info->ring_lock, flags); |
3e7ee490 HJ |
510 | |
511 | return 0; | |
512 | } |