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Commit | Line | Data |
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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> |
011a7c3c | 29 | #include <linux/uio.h> |
3f335ea2 | 30 | |
0f2a6619 | 31 | #include "hyperv_vmbus.h" |
3e7ee490 | 32 | |
6fdf3b21 S |
33 | void hv_begin_read(struct hv_ring_buffer_info *rbi) |
34 | { | |
35 | rbi->ring_buffer->interrupt_mask = 1; | |
35848f68 | 36 | mb(); |
6fdf3b21 S |
37 | } |
38 | ||
39 | u32 hv_end_read(struct hv_ring_buffer_info *rbi) | |
40 | { | |
41 | u32 read; | |
42 | u32 write; | |
43 | ||
44 | rbi->ring_buffer->interrupt_mask = 0; | |
35848f68 | 45 | mb(); |
6fdf3b21 S |
46 | |
47 | /* | |
48 | * Now check to see if the ring buffer is still empty. | |
49 | * If it is not, we raced and we need to process new | |
50 | * incoming messages. | |
51 | */ | |
52 | hv_get_ringbuffer_availbytes(rbi, &read, &write); | |
53 | ||
54 | return read; | |
55 | } | |
56 | ||
98fa8cf4 S |
57 | /* |
58 | * When we write to the ring buffer, check if the host needs to | |
59 | * be signaled. Here is the details of this protocol: | |
60 | * | |
61 | * 1. The host guarantees that while it is draining the | |
62 | * ring buffer, it will set the interrupt_mask to | |
63 | * indicate it does not need to be interrupted when | |
64 | * new data is placed. | |
65 | * | |
66 | * 2. The host guarantees that it will completely drain | |
67 | * the ring buffer before exiting the read loop. Further, | |
68 | * once the ring buffer is empty, it will clear the | |
69 | * interrupt_mask and re-check to see if new data has | |
70 | * arrived. | |
71 | */ | |
72 | ||
73 | static bool hv_need_to_signal(u32 old_write, struct hv_ring_buffer_info *rbi) | |
74 | { | |
35848f68 | 75 | mb(); |
98fa8cf4 S |
76 | if (rbi->ring_buffer->interrupt_mask) |
77 | return false; | |
78 | ||
e91e84fa JW |
79 | /* check interrupt_mask before read_index */ |
80 | rmb(); | |
98fa8cf4 S |
81 | /* |
82 | * This is the only case we need to signal when the | |
83 | * ring transitions from being empty to non-empty. | |
84 | */ | |
85 | if (old_write == rbi->ring_buffer->read_index) | |
86 | return true; | |
87 | ||
88 | return false; | |
89 | } | |
90 | ||
c2b8e520 S |
91 | /* |
92 | * To optimize the flow management on the send-side, | |
93 | * when the sender is blocked because of lack of | |
94 | * sufficient space in the ring buffer, potential the | |
95 | * consumer of the ring buffer can signal the producer. | |
96 | * This is controlled by the following parameters: | |
97 | * | |
98 | * 1. pending_send_sz: This is the size in bytes that the | |
99 | * producer is trying to send. | |
100 | * 2. The feature bit feat_pending_send_sz set to indicate if | |
101 | * the consumer of the ring will signal when the ring | |
102 | * state transitions from being full to a state where | |
103 | * there is room for the producer to send the pending packet. | |
104 | */ | |
105 | ||
a5cca686 CO |
106 | static bool hv_need_to_signal_on_read(u32 prev_write_sz, |
107 | struct hv_ring_buffer_info *rbi) | |
c2b8e520 | 108 | { |
c2b8e520 S |
109 | u32 cur_write_sz; |
110 | u32 r_size; | |
111 | u32 write_loc = rbi->ring_buffer->write_index; | |
112 | u32 read_loc = rbi->ring_buffer->read_index; | |
113 | u32 pending_sz = rbi->ring_buffer->pending_send_sz; | |
114 | ||
822f18d4 | 115 | /* If the other end is not blocked on write don't bother. */ |
c2b8e520 S |
116 | if (pending_sz == 0) |
117 | return false; | |
118 | ||
119 | r_size = rbi->ring_datasize; | |
120 | cur_write_sz = write_loc >= read_loc ? r_size - (write_loc - read_loc) : | |
121 | read_loc - write_loc; | |
122 | ||
c2b8e520 S |
123 | if ((prev_write_sz < pending_sz) && (cur_write_sz >= pending_sz)) |
124 | return true; | |
125 | ||
126 | return false; | |
127 | } | |
3e7ee490 | 128 | |
822f18d4 | 129 | /* Get the next write location for the specified ring buffer. */ |
4d643114 | 130 | static inline u32 |
2b8a912e | 131 | hv_get_next_write_location(struct hv_ring_buffer_info *ring_info) |
3e7ee490 | 132 | { |
fc8c72eb | 133 | u32 next = ring_info->ring_buffer->write_index; |
3e7ee490 | 134 | |
3e7ee490 HJ |
135 | return next; |
136 | } | |
137 | ||
822f18d4 | 138 | /* Set the next write location for the specified ring buffer. */ |
3e7ee490 | 139 | static inline void |
2b8a912e | 140 | hv_set_next_write_location(struct hv_ring_buffer_info *ring_info, |
fc8c72eb | 141 | u32 next_write_location) |
3e7ee490 | 142 | { |
fc8c72eb | 143 | ring_info->ring_buffer->write_index = next_write_location; |
3e7ee490 HJ |
144 | } |
145 | ||
822f18d4 | 146 | /* Get the next read location for the specified ring buffer. */ |
4d643114 | 147 | static inline u32 |
2b8a912e | 148 | hv_get_next_read_location(struct hv_ring_buffer_info *ring_info) |
3e7ee490 | 149 | { |
fc8c72eb | 150 | u32 next = ring_info->ring_buffer->read_index; |
3e7ee490 | 151 | |
3e7ee490 HJ |
152 | return next; |
153 | } | |
154 | ||
b2a5a585 | 155 | /* |
b2a5a585 | 156 | * Get the next read location + offset for the specified ring buffer. |
822f18d4 | 157 | * This allows the caller to skip. |
b2a5a585 | 158 | */ |
4d643114 | 159 | static inline u32 |
2b8a912e | 160 | hv_get_next_readlocation_withoffset(struct hv_ring_buffer_info *ring_info, |
1ac58644 | 161 | u32 offset) |
3e7ee490 | 162 | { |
fc8c72eb | 163 | u32 next = ring_info->ring_buffer->read_index; |
3e7ee490 | 164 | |
fc8c72eb HZ |
165 | next += offset; |
166 | next %= ring_info->ring_datasize; | |
3e7ee490 HJ |
167 | |
168 | return next; | |
169 | } | |
170 | ||
822f18d4 | 171 | /* Set the next read location for the specified ring buffer. */ |
3e7ee490 | 172 | static inline void |
2b8a912e | 173 | hv_set_next_read_location(struct hv_ring_buffer_info *ring_info, |
fc8c72eb | 174 | u32 next_read_location) |
3e7ee490 | 175 | { |
fc8c72eb | 176 | ring_info->ring_buffer->read_index = next_read_location; |
3e7ee490 HJ |
177 | } |
178 | ||
179 | ||
822f18d4 | 180 | /* Get the start of the ring buffer. */ |
8282c400 | 181 | static inline void * |
2b8a912e | 182 | hv_get_ring_buffer(struct hv_ring_buffer_info *ring_info) |
3e7ee490 | 183 | { |
fc8c72eb | 184 | return (void *)ring_info->ring_buffer->buffer; |
3e7ee490 HJ |
185 | } |
186 | ||
187 | ||
822f18d4 | 188 | /* Get the size of the ring buffer. */ |
4d643114 | 189 | static inline u32 |
2b8a912e | 190 | hv_get_ring_buffersize(struct hv_ring_buffer_info *ring_info) |
3e7ee490 | 191 | { |
fc8c72eb | 192 | return ring_info->ring_datasize; |
3e7ee490 HJ |
193 | } |
194 | ||
822f18d4 | 195 | /* Get the read and write indices as u64 of the specified ring buffer. */ |
59471438 | 196 | static inline u64 |
2b8a912e | 197 | hv_get_ring_bufferindices(struct hv_ring_buffer_info *ring_info) |
3e7ee490 | 198 | { |
fc8c72eb | 199 | return (u64)ring_info->ring_buffer->write_index << 32; |
3e7ee490 HJ |
200 | } |
201 | ||
8f1136ae | 202 | /* |
8f1136ae S |
203 | * Helper routine to copy to source from ring buffer. |
204 | * Assume there is enough room. Handles wrap-around in src case only!! | |
8f1136ae S |
205 | */ |
206 | static u32 hv_copyfrom_ringbuffer( | |
207 | struct hv_ring_buffer_info *ring_info, | |
208 | void *dest, | |
209 | u32 destlen, | |
210 | u32 start_read_offset) | |
211 | { | |
212 | void *ring_buffer = hv_get_ring_buffer(ring_info); | |
213 | u32 ring_buffer_size = hv_get_ring_buffersize(ring_info); | |
214 | ||
215 | u32 frag_len; | |
216 | ||
217 | /* wrap-around detected at the src */ | |
218 | if (destlen > ring_buffer_size - start_read_offset) { | |
219 | frag_len = ring_buffer_size - start_read_offset; | |
220 | ||
221 | memcpy(dest, ring_buffer + start_read_offset, frag_len); | |
222 | memcpy(dest + frag_len, ring_buffer, destlen - frag_len); | |
223 | } else | |
224 | ||
225 | memcpy(dest, ring_buffer + start_read_offset, destlen); | |
226 | ||
227 | ||
228 | start_read_offset += destlen; | |
229 | start_read_offset %= ring_buffer_size; | |
230 | ||
231 | return start_read_offset; | |
232 | } | |
233 | ||
234 | ||
7581578d | 235 | /* |
7581578d S |
236 | * Helper routine to copy from source to ring buffer. |
237 | * Assume there is enough room. Handles wrap-around in dest case only!! | |
7581578d S |
238 | */ |
239 | static u32 hv_copyto_ringbuffer( | |
fc8c72eb HZ |
240 | struct hv_ring_buffer_info *ring_info, |
241 | u32 start_write_offset, | |
242 | void *src, | |
7581578d S |
243 | u32 srclen) |
244 | { | |
245 | void *ring_buffer = hv_get_ring_buffer(ring_info); | |
246 | u32 ring_buffer_size = hv_get_ring_buffersize(ring_info); | |
247 | u32 frag_len; | |
248 | ||
249 | /* wrap-around detected! */ | |
250 | if (srclen > ring_buffer_size - start_write_offset) { | |
251 | frag_len = ring_buffer_size - start_write_offset; | |
252 | memcpy(ring_buffer + start_write_offset, src, frag_len); | |
253 | memcpy(ring_buffer, src + frag_len, srclen - frag_len); | |
254 | } else | |
255 | memcpy(ring_buffer + start_write_offset, src, srclen); | |
3e7ee490 | 256 | |
7581578d S |
257 | start_write_offset += srclen; |
258 | start_write_offset %= ring_buffer_size; | |
259 | ||
260 | return start_write_offset; | |
261 | } | |
3e7ee490 | 262 | |
822f18d4 | 263 | /* Get various debug metrics for the specified ring buffer. */ |
a75b61d5 | 264 | void hv_ringbuffer_get_debuginfo(struct hv_ring_buffer_info *ring_info, |
80682b7a | 265 | struct hv_ring_buffer_debug_info *debug_info) |
3e7ee490 | 266 | { |
fc8c72eb HZ |
267 | u32 bytes_avail_towrite; |
268 | u32 bytes_avail_toread; | |
3e7ee490 | 269 | |
fc8c72eb | 270 | if (ring_info->ring_buffer) { |
2b8a912e | 271 | hv_get_ringbuffer_availbytes(ring_info, |
fc8c72eb HZ |
272 | &bytes_avail_toread, |
273 | &bytes_avail_towrite); | |
3e7ee490 | 274 | |
fc8c72eb HZ |
275 | debug_info->bytes_avail_toread = bytes_avail_toread; |
276 | debug_info->bytes_avail_towrite = bytes_avail_towrite; | |
82f8bd40 | 277 | debug_info->current_read_index = |
fc8c72eb | 278 | ring_info->ring_buffer->read_index; |
82f8bd40 | 279 | debug_info->current_write_index = |
fc8c72eb | 280 | ring_info->ring_buffer->write_index; |
82f8bd40 | 281 | debug_info->current_interrupt_mask = |
fc8c72eb | 282 | ring_info->ring_buffer->interrupt_mask; |
3e7ee490 HJ |
283 | } |
284 | } | |
285 | ||
822f18d4 | 286 | /* Initialize the ring buffer. */ |
72a95cbc | 287 | int hv_ringbuffer_init(struct hv_ring_buffer_info *ring_info, |
fc8c72eb | 288 | void *buffer, u32 buflen) |
3e7ee490 | 289 | { |
4a1b3acc | 290 | if (sizeof(struct hv_ring_buffer) != PAGE_SIZE) |
3324fb40 | 291 | return -EINVAL; |
3e7ee490 | 292 | |
fc8c72eb | 293 | memset(ring_info, 0, sizeof(struct hv_ring_buffer_info)); |
3e7ee490 | 294 | |
fc8c72eb HZ |
295 | ring_info->ring_buffer = (struct hv_ring_buffer *)buffer; |
296 | ring_info->ring_buffer->read_index = | |
297 | ring_info->ring_buffer->write_index = 0; | |
3e7ee490 | 298 | |
822f18d4 | 299 | /* Set the feature bit for enabling flow control. */ |
046c7911 S |
300 | ring_info->ring_buffer->feature_bits.value = 1; |
301 | ||
fc8c72eb HZ |
302 | ring_info->ring_size = buflen; |
303 | ring_info->ring_datasize = buflen - sizeof(struct hv_ring_buffer); | |
3e7ee490 | 304 | |
fc8c72eb | 305 | spin_lock_init(&ring_info->ring_lock); |
3e7ee490 HJ |
306 | |
307 | return 0; | |
308 | } | |
309 | ||
822f18d4 | 310 | /* Cleanup the ring buffer. */ |
2dba688b | 311 | void hv_ringbuffer_cleanup(struct hv_ring_buffer_info *ring_info) |
3e7ee490 | 312 | { |
3e7ee490 HJ |
313 | } |
314 | ||
822f18d4 | 315 | /* Write to the ring buffer. */ |
633c4dce | 316 | int hv_ringbuffer_write(struct hv_ring_buffer_info *outring_info, |
011a7c3c | 317 | struct kvec *kv_list, u32 kv_count, bool *signal) |
3e7ee490 | 318 | { |
4408f531 | 319 | int i = 0; |
fc8c72eb HZ |
320 | u32 bytes_avail_towrite; |
321 | u32 bytes_avail_toread; | |
322 | u32 totalbytes_towrite = 0; | |
3e7ee490 | 323 | |
66a60543 | 324 | u32 next_write_location; |
98fa8cf4 | 325 | u32 old_write; |
fc8c72eb | 326 | u64 prev_indices = 0; |
a98f96ee | 327 | unsigned long flags; |
3e7ee490 | 328 | |
011a7c3c S |
329 | for (i = 0; i < kv_count; i++) |
330 | totalbytes_towrite += kv_list[i].iov_len; | |
3e7ee490 | 331 | |
fc8c72eb | 332 | totalbytes_towrite += sizeof(u64); |
3e7ee490 | 333 | |
fc8c72eb | 334 | spin_lock_irqsave(&outring_info->ring_lock, flags); |
3e7ee490 | 335 | |
2b8a912e | 336 | hv_get_ringbuffer_availbytes(outring_info, |
fc8c72eb HZ |
337 | &bytes_avail_toread, |
338 | &bytes_avail_towrite); | |
3e7ee490 | 339 | |
822f18d4 VK |
340 | /* |
341 | * If there is only room for the packet, assume it is full. | |
342 | * Otherwise, the next time around, we think the ring buffer | |
343 | * is empty since the read index == write index. | |
344 | */ | |
fc8c72eb | 345 | if (bytes_avail_towrite <= totalbytes_towrite) { |
fc8c72eb | 346 | spin_unlock_irqrestore(&outring_info->ring_lock, flags); |
d2598f01 | 347 | return -EAGAIN; |
3e7ee490 HJ |
348 | } |
349 | ||
454f18a9 | 350 | /* Write to the ring buffer */ |
2b8a912e | 351 | next_write_location = hv_get_next_write_location(outring_info); |
3e7ee490 | 352 | |
98fa8cf4 S |
353 | old_write = next_write_location; |
354 | ||
011a7c3c | 355 | for (i = 0; i < kv_count; i++) { |
2b8a912e | 356 | next_write_location = hv_copyto_ringbuffer(outring_info, |
fc8c72eb | 357 | next_write_location, |
011a7c3c S |
358 | kv_list[i].iov_base, |
359 | kv_list[i].iov_len); | |
3e7ee490 HJ |
360 | } |
361 | ||
454f18a9 | 362 | /* Set previous packet start */ |
2b8a912e | 363 | prev_indices = hv_get_ring_bufferindices(outring_info); |
3e7ee490 | 364 | |
2b8a912e | 365 | next_write_location = hv_copyto_ringbuffer(outring_info, |
fc8c72eb HZ |
366 | next_write_location, |
367 | &prev_indices, | |
b219b3f7 | 368 | sizeof(u64)); |
3e7ee490 | 369 | |
98fa8cf4 | 370 | /* Issue a full memory barrier before updating the write index */ |
35848f68 | 371 | mb(); |
3e7ee490 | 372 | |
454f18a9 | 373 | /* Now, update the write location */ |
2b8a912e | 374 | hv_set_next_write_location(outring_info, next_write_location); |
3e7ee490 | 375 | |
3e7ee490 | 376 | |
fc8c72eb | 377 | spin_unlock_irqrestore(&outring_info->ring_lock, flags); |
98fa8cf4 S |
378 | |
379 | *signal = hv_need_to_signal(old_write, outring_info); | |
3e7ee490 HJ |
380 | return 0; |
381 | } | |
382 | ||
940b68e2 VK |
383 | int hv_ringbuffer_read(struct hv_ring_buffer_info *inring_info, |
384 | void *buffer, u32 buflen, u32 *buffer_actual_len, | |
385 | u64 *requestid, bool *signal, bool raw) | |
3e7ee490 | 386 | { |
fc8c72eb HZ |
387 | u32 bytes_avail_towrite; |
388 | u32 bytes_avail_toread; | |
389 | u32 next_read_location = 0; | |
390 | u64 prev_indices = 0; | |
a98f96ee | 391 | unsigned long flags; |
940b68e2 VK |
392 | struct vmpacket_descriptor desc; |
393 | u32 offset; | |
394 | u32 packetlen; | |
395 | int ret = 0; | |
3e7ee490 | 396 | |
fc8c72eb | 397 | if (buflen <= 0) |
a16e1485 | 398 | return -EINVAL; |
3e7ee490 | 399 | |
fc8c72eb | 400 | spin_lock_irqsave(&inring_info->ring_lock, flags); |
3e7ee490 | 401 | |
940b68e2 VK |
402 | *buffer_actual_len = 0; |
403 | *requestid = 0; | |
404 | ||
2b8a912e | 405 | hv_get_ringbuffer_availbytes(inring_info, |
fc8c72eb HZ |
406 | &bytes_avail_toread, |
407 | &bytes_avail_towrite); | |
3e7ee490 | 408 | |
454f18a9 | 409 | /* Make sure there is something to read */ |
940b68e2 VK |
410 | if (bytes_avail_toread < sizeof(desc)) { |
411 | /* | |
412 | * No error is set when there is even no header, drivers are | |
413 | * supposed to analyze buffer_actual_len. | |
414 | */ | |
415 | goto out_unlock; | |
416 | } | |
3e7ee490 | 417 | |
940b68e2 VK |
418 | next_read_location = hv_get_next_read_location(inring_info); |
419 | next_read_location = hv_copyfrom_ringbuffer(inring_info, &desc, | |
420 | sizeof(desc), | |
421 | next_read_location); | |
422 | ||
423 | offset = raw ? 0 : (desc.offset8 << 3); | |
424 | packetlen = (desc.len8 << 3) - offset; | |
425 | *buffer_actual_len = packetlen; | |
426 | *requestid = desc.trans_id; | |
427 | ||
428 | if (bytes_avail_toread < packetlen + offset) { | |
429 | ret = -EAGAIN; | |
430 | goto out_unlock; | |
431 | } | |
432 | ||
433 | if (packetlen > buflen) { | |
434 | ret = -ENOBUFS; | |
435 | goto out_unlock; | |
3e7ee490 HJ |
436 | } |
437 | ||
1ac58644 | 438 | next_read_location = |
2b8a912e | 439 | hv_get_next_readlocation_withoffset(inring_info, offset); |
3e7ee490 | 440 | |
2b8a912e | 441 | next_read_location = hv_copyfrom_ringbuffer(inring_info, |
fc8c72eb | 442 | buffer, |
940b68e2 | 443 | packetlen, |
fc8c72eb | 444 | next_read_location); |
3e7ee490 | 445 | |
2b8a912e | 446 | next_read_location = hv_copyfrom_ringbuffer(inring_info, |
fc8c72eb | 447 | &prev_indices, |
4408f531 | 448 | sizeof(u64), |
fc8c72eb | 449 | next_read_location); |
3e7ee490 | 450 | |
822f18d4 VK |
451 | /* |
452 | * Make sure all reads are done before we update the read index since | |
453 | * the writer may start writing to the read area once the read index | |
454 | * is updated. | |
455 | */ | |
35848f68 | 456 | mb(); |
3e7ee490 | 457 | |
454f18a9 | 458 | /* Update the read index */ |
2b8a912e | 459 | hv_set_next_read_location(inring_info, next_read_location); |
3e7ee490 | 460 | |
a5cca686 | 461 | *signal = hv_need_to_signal_on_read(bytes_avail_towrite, inring_info); |
c2b8e520 | 462 | |
b5f53dde VK |
463 | out_unlock: |
464 | spin_unlock_irqrestore(&inring_info->ring_lock, flags); | |
940b68e2 | 465 | return ret; |
b5f53dde | 466 | } |