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; | |
dcd0eeca | 36 | virt_mb(); |
6fdf3b21 S |
37 | } |
38 | ||
39 | u32 hv_end_read(struct hv_ring_buffer_info *rbi) | |
40 | { | |
6fdf3b21 S |
41 | |
42 | rbi->ring_buffer->interrupt_mask = 0; | |
dcd0eeca | 43 | virt_mb(); |
6fdf3b21 S |
44 | |
45 | /* | |
46 | * Now check to see if the ring buffer is still empty. | |
47 | * If it is not, we raced and we need to process new | |
48 | * incoming messages. | |
49 | */ | |
a6341f00 | 50 | return hv_get_bytes_to_read(rbi); |
6fdf3b21 S |
51 | } |
52 | ||
98fa8cf4 S |
53 | /* |
54 | * When we write to the ring buffer, check if the host needs to | |
55 | * be signaled. Here is the details of this protocol: | |
56 | * | |
57 | * 1. The host guarantees that while it is draining the | |
58 | * ring buffer, it will set the interrupt_mask to | |
59 | * indicate it does not need to be interrupted when | |
60 | * new data is placed. | |
61 | * | |
62 | * 2. The host guarantees that it will completely drain | |
63 | * the ring buffer before exiting the read loop. Further, | |
64 | * once the ring buffer is empty, it will clear the | |
65 | * interrupt_mask and re-check to see if new data has | |
66 | * arrived. | |
67 | */ | |
68 | ||
69 | static bool hv_need_to_signal(u32 old_write, struct hv_ring_buffer_info *rbi) | |
70 | { | |
dcd0eeca | 71 | virt_mb(); |
d45faaee | 72 | if (READ_ONCE(rbi->ring_buffer->interrupt_mask)) |
98fa8cf4 S |
73 | return false; |
74 | ||
e91e84fa | 75 | /* check interrupt_mask before read_index */ |
dcd0eeca | 76 | virt_rmb(); |
98fa8cf4 S |
77 | /* |
78 | * This is the only case we need to signal when the | |
79 | * ring transitions from being empty to non-empty. | |
80 | */ | |
d45faaee | 81 | if (old_write == READ_ONCE(rbi->ring_buffer->read_index)) |
98fa8cf4 S |
82 | return true; |
83 | ||
84 | return false; | |
85 | } | |
86 | ||
822f18d4 | 87 | /* Get the next write location for the specified ring buffer. */ |
4d643114 | 88 | static inline u32 |
2b8a912e | 89 | hv_get_next_write_location(struct hv_ring_buffer_info *ring_info) |
3e7ee490 | 90 | { |
fc8c72eb | 91 | u32 next = ring_info->ring_buffer->write_index; |
3e7ee490 | 92 | |
3e7ee490 HJ |
93 | return next; |
94 | } | |
95 | ||
822f18d4 | 96 | /* Set the next write location for the specified ring buffer. */ |
3e7ee490 | 97 | static inline void |
2b8a912e | 98 | hv_set_next_write_location(struct hv_ring_buffer_info *ring_info, |
fc8c72eb | 99 | u32 next_write_location) |
3e7ee490 | 100 | { |
fc8c72eb | 101 | ring_info->ring_buffer->write_index = next_write_location; |
3e7ee490 HJ |
102 | } |
103 | ||
822f18d4 | 104 | /* Get the next read location for the specified ring buffer. */ |
4d643114 | 105 | static inline u32 |
2b8a912e | 106 | hv_get_next_read_location(struct hv_ring_buffer_info *ring_info) |
3e7ee490 | 107 | { |
fc8c72eb | 108 | u32 next = ring_info->ring_buffer->read_index; |
3e7ee490 | 109 | |
3e7ee490 HJ |
110 | return next; |
111 | } | |
112 | ||
b2a5a585 | 113 | /* |
b2a5a585 | 114 | * Get the next read location + offset for the specified ring buffer. |
822f18d4 | 115 | * This allows the caller to skip. |
b2a5a585 | 116 | */ |
4d643114 | 117 | static inline u32 |
2b8a912e | 118 | hv_get_next_readlocation_withoffset(struct hv_ring_buffer_info *ring_info, |
1ac58644 | 119 | u32 offset) |
3e7ee490 | 120 | { |
fc8c72eb | 121 | u32 next = ring_info->ring_buffer->read_index; |
3e7ee490 | 122 | |
fc8c72eb HZ |
123 | next += offset; |
124 | next %= ring_info->ring_datasize; | |
3e7ee490 HJ |
125 | |
126 | return next; | |
127 | } | |
128 | ||
822f18d4 | 129 | /* Set the next read location for the specified ring buffer. */ |
3e7ee490 | 130 | static inline void |
2b8a912e | 131 | hv_set_next_read_location(struct hv_ring_buffer_info *ring_info, |
fc8c72eb | 132 | u32 next_read_location) |
3e7ee490 | 133 | { |
fc8c72eb | 134 | ring_info->ring_buffer->read_index = next_read_location; |
ab028db4 | 135 | ring_info->priv_read_index = next_read_location; |
3e7ee490 HJ |
136 | } |
137 | ||
822f18d4 | 138 | /* Get the size of the ring buffer. */ |
4d643114 | 139 | static inline u32 |
2b8a912e | 140 | hv_get_ring_buffersize(struct hv_ring_buffer_info *ring_info) |
3e7ee490 | 141 | { |
fc8c72eb | 142 | return ring_info->ring_datasize; |
3e7ee490 HJ |
143 | } |
144 | ||
822f18d4 | 145 | /* Get the read and write indices as u64 of the specified ring buffer. */ |
59471438 | 146 | static inline u64 |
2b8a912e | 147 | hv_get_ring_bufferindices(struct hv_ring_buffer_info *ring_info) |
3e7ee490 | 148 | { |
fc8c72eb | 149 | return (u64)ring_info->ring_buffer->write_index << 32; |
3e7ee490 HJ |
150 | } |
151 | ||
8f1136ae | 152 | /* |
8f1136ae S |
153 | * Helper routine to copy to source from ring buffer. |
154 | * Assume there is enough room. Handles wrap-around in src case only!! | |
8f1136ae S |
155 | */ |
156 | static u32 hv_copyfrom_ringbuffer( | |
157 | struct hv_ring_buffer_info *ring_info, | |
158 | void *dest, | |
159 | u32 destlen, | |
160 | u32 start_read_offset) | |
161 | { | |
162 | void *ring_buffer = hv_get_ring_buffer(ring_info); | |
163 | u32 ring_buffer_size = hv_get_ring_buffersize(ring_info); | |
164 | ||
165 | u32 frag_len; | |
166 | ||
167 | /* wrap-around detected at the src */ | |
168 | if (destlen > ring_buffer_size - start_read_offset) { | |
169 | frag_len = ring_buffer_size - start_read_offset; | |
170 | ||
171 | memcpy(dest, ring_buffer + start_read_offset, frag_len); | |
172 | memcpy(dest + frag_len, ring_buffer, destlen - frag_len); | |
173 | } else | |
174 | ||
175 | memcpy(dest, ring_buffer + start_read_offset, destlen); | |
176 | ||
177 | ||
178 | start_read_offset += destlen; | |
179 | start_read_offset %= ring_buffer_size; | |
180 | ||
181 | return start_read_offset; | |
182 | } | |
183 | ||
184 | ||
7581578d | 185 | /* |
7581578d S |
186 | * Helper routine to copy from source to ring buffer. |
187 | * Assume there is enough room. Handles wrap-around in dest case only!! | |
7581578d S |
188 | */ |
189 | static u32 hv_copyto_ringbuffer( | |
fc8c72eb HZ |
190 | struct hv_ring_buffer_info *ring_info, |
191 | u32 start_write_offset, | |
192 | void *src, | |
7581578d S |
193 | u32 srclen) |
194 | { | |
195 | void *ring_buffer = hv_get_ring_buffer(ring_info); | |
196 | u32 ring_buffer_size = hv_get_ring_buffersize(ring_info); | |
197 | u32 frag_len; | |
198 | ||
199 | /* wrap-around detected! */ | |
200 | if (srclen > ring_buffer_size - start_write_offset) { | |
201 | frag_len = ring_buffer_size - start_write_offset; | |
202 | memcpy(ring_buffer + start_write_offset, src, frag_len); | |
203 | memcpy(ring_buffer, src + frag_len, srclen - frag_len); | |
204 | } else | |
205 | memcpy(ring_buffer + start_write_offset, src, srclen); | |
3e7ee490 | 206 | |
7581578d S |
207 | start_write_offset += srclen; |
208 | start_write_offset %= ring_buffer_size; | |
209 | ||
210 | return start_write_offset; | |
211 | } | |
3e7ee490 | 212 | |
822f18d4 | 213 | /* Get various debug metrics for the specified ring buffer. */ |
a75b61d5 | 214 | void hv_ringbuffer_get_debuginfo(struct hv_ring_buffer_info *ring_info, |
80682b7a | 215 | struct hv_ring_buffer_debug_info *debug_info) |
3e7ee490 | 216 | { |
fc8c72eb HZ |
217 | u32 bytes_avail_towrite; |
218 | u32 bytes_avail_toread; | |
3e7ee490 | 219 | |
fc8c72eb | 220 | if (ring_info->ring_buffer) { |
2b8a912e | 221 | hv_get_ringbuffer_availbytes(ring_info, |
fc8c72eb HZ |
222 | &bytes_avail_toread, |
223 | &bytes_avail_towrite); | |
3e7ee490 | 224 | |
fc8c72eb HZ |
225 | debug_info->bytes_avail_toread = bytes_avail_toread; |
226 | debug_info->bytes_avail_towrite = bytes_avail_towrite; | |
82f8bd40 | 227 | debug_info->current_read_index = |
fc8c72eb | 228 | ring_info->ring_buffer->read_index; |
82f8bd40 | 229 | debug_info->current_write_index = |
fc8c72eb | 230 | ring_info->ring_buffer->write_index; |
82f8bd40 | 231 | debug_info->current_interrupt_mask = |
fc8c72eb | 232 | ring_info->ring_buffer->interrupt_mask; |
3e7ee490 HJ |
233 | } |
234 | } | |
235 | ||
822f18d4 | 236 | /* Initialize the ring buffer. */ |
72a95cbc | 237 | int hv_ringbuffer_init(struct hv_ring_buffer_info *ring_info, |
fc8c72eb | 238 | void *buffer, u32 buflen) |
3e7ee490 | 239 | { |
4a1b3acc | 240 | if (sizeof(struct hv_ring_buffer) != PAGE_SIZE) |
3324fb40 | 241 | return -EINVAL; |
3e7ee490 | 242 | |
fc8c72eb | 243 | memset(ring_info, 0, sizeof(struct hv_ring_buffer_info)); |
3e7ee490 | 244 | |
fc8c72eb HZ |
245 | ring_info->ring_buffer = (struct hv_ring_buffer *)buffer; |
246 | ring_info->ring_buffer->read_index = | |
247 | ring_info->ring_buffer->write_index = 0; | |
3e7ee490 | 248 | |
822f18d4 | 249 | /* Set the feature bit for enabling flow control. */ |
046c7911 S |
250 | ring_info->ring_buffer->feature_bits.value = 1; |
251 | ||
fc8c72eb HZ |
252 | ring_info->ring_size = buflen; |
253 | ring_info->ring_datasize = buflen - sizeof(struct hv_ring_buffer); | |
3e7ee490 | 254 | |
fc8c72eb | 255 | spin_lock_init(&ring_info->ring_lock); |
3e7ee490 HJ |
256 | |
257 | return 0; | |
258 | } | |
259 | ||
822f18d4 | 260 | /* Cleanup the ring buffer. */ |
2dba688b | 261 | void hv_ringbuffer_cleanup(struct hv_ring_buffer_info *ring_info) |
3e7ee490 | 262 | { |
3e7ee490 HJ |
263 | } |
264 | ||
822f18d4 | 265 | /* Write to the ring buffer. */ |
633c4dce | 266 | int hv_ringbuffer_write(struct hv_ring_buffer_info *outring_info, |
fe760e4d | 267 | struct kvec *kv_list, u32 kv_count, bool *signal, bool lock) |
3e7ee490 | 268 | { |
4408f531 | 269 | int i = 0; |
fc8c72eb | 270 | u32 bytes_avail_towrite; |
fc8c72eb | 271 | u32 totalbytes_towrite = 0; |
3e7ee490 | 272 | |
66a60543 | 273 | u32 next_write_location; |
98fa8cf4 | 274 | u32 old_write; |
fc8c72eb | 275 | u64 prev_indices = 0; |
fe760e4d | 276 | unsigned long flags = 0; |
3e7ee490 | 277 | |
011a7c3c S |
278 | for (i = 0; i < kv_count; i++) |
279 | totalbytes_towrite += kv_list[i].iov_len; | |
3e7ee490 | 280 | |
fc8c72eb | 281 | totalbytes_towrite += sizeof(u64); |
3e7ee490 | 282 | |
fe760e4d S |
283 | if (lock) |
284 | spin_lock_irqsave(&outring_info->ring_lock, flags); | |
3e7ee490 | 285 | |
a6341f00 | 286 | bytes_avail_towrite = hv_get_bytes_to_write(outring_info); |
3e7ee490 | 287 | |
822f18d4 VK |
288 | /* |
289 | * If there is only room for the packet, assume it is full. | |
290 | * Otherwise, the next time around, we think the ring buffer | |
291 | * is empty since the read index == write index. | |
292 | */ | |
fc8c72eb | 293 | if (bytes_avail_towrite <= totalbytes_towrite) { |
fe760e4d S |
294 | if (lock) |
295 | spin_unlock_irqrestore(&outring_info->ring_lock, flags); | |
d2598f01 | 296 | return -EAGAIN; |
3e7ee490 HJ |
297 | } |
298 | ||
454f18a9 | 299 | /* Write to the ring buffer */ |
2b8a912e | 300 | next_write_location = hv_get_next_write_location(outring_info); |
3e7ee490 | 301 | |
98fa8cf4 S |
302 | old_write = next_write_location; |
303 | ||
011a7c3c | 304 | for (i = 0; i < kv_count; i++) { |
2b8a912e | 305 | next_write_location = hv_copyto_ringbuffer(outring_info, |
fc8c72eb | 306 | next_write_location, |
011a7c3c S |
307 | kv_list[i].iov_base, |
308 | kv_list[i].iov_len); | |
3e7ee490 HJ |
309 | } |
310 | ||
454f18a9 | 311 | /* Set previous packet start */ |
2b8a912e | 312 | prev_indices = hv_get_ring_bufferindices(outring_info); |
3e7ee490 | 313 | |
2b8a912e | 314 | next_write_location = hv_copyto_ringbuffer(outring_info, |
fc8c72eb HZ |
315 | next_write_location, |
316 | &prev_indices, | |
b219b3f7 | 317 | sizeof(u64)); |
3e7ee490 | 318 | |
98fa8cf4 | 319 | /* Issue a full memory barrier before updating the write index */ |
dcd0eeca | 320 | virt_mb(); |
3e7ee490 | 321 | |
454f18a9 | 322 | /* Now, update the write location */ |
2b8a912e | 323 | hv_set_next_write_location(outring_info, next_write_location); |
3e7ee490 | 324 | |
3e7ee490 | 325 | |
fe760e4d S |
326 | if (lock) |
327 | spin_unlock_irqrestore(&outring_info->ring_lock, flags); | |
98fa8cf4 S |
328 | |
329 | *signal = hv_need_to_signal(old_write, outring_info); | |
3e7ee490 HJ |
330 | return 0; |
331 | } | |
332 | ||
940b68e2 VK |
333 | int hv_ringbuffer_read(struct hv_ring_buffer_info *inring_info, |
334 | void *buffer, u32 buflen, u32 *buffer_actual_len, | |
335 | u64 *requestid, bool *signal, bool raw) | |
3e7ee490 | 336 | { |
fc8c72eb HZ |
337 | u32 bytes_avail_toread; |
338 | u32 next_read_location = 0; | |
339 | u64 prev_indices = 0; | |
940b68e2 VK |
340 | struct vmpacket_descriptor desc; |
341 | u32 offset; | |
342 | u32 packetlen; | |
343 | int ret = 0; | |
3e7ee490 | 344 | |
fc8c72eb | 345 | if (buflen <= 0) |
a16e1485 | 346 | return -EINVAL; |
3e7ee490 | 347 | |
3e7ee490 | 348 | |
940b68e2 VK |
349 | *buffer_actual_len = 0; |
350 | *requestid = 0; | |
351 | ||
a6341f00 | 352 | bytes_avail_toread = hv_get_bytes_to_read(inring_info); |
454f18a9 | 353 | /* Make sure there is something to read */ |
940b68e2 VK |
354 | if (bytes_avail_toread < sizeof(desc)) { |
355 | /* | |
356 | * No error is set when there is even no header, drivers are | |
357 | * supposed to analyze buffer_actual_len. | |
358 | */ | |
3eba9a77 | 359 | return ret; |
940b68e2 | 360 | } |
3e7ee490 | 361 | |
940b68e2 VK |
362 | next_read_location = hv_get_next_read_location(inring_info); |
363 | next_read_location = hv_copyfrom_ringbuffer(inring_info, &desc, | |
364 | sizeof(desc), | |
365 | next_read_location); | |
366 | ||
367 | offset = raw ? 0 : (desc.offset8 << 3); | |
368 | packetlen = (desc.len8 << 3) - offset; | |
369 | *buffer_actual_len = packetlen; | |
370 | *requestid = desc.trans_id; | |
371 | ||
3eba9a77 S |
372 | if (bytes_avail_toread < packetlen + offset) |
373 | return -EAGAIN; | |
940b68e2 | 374 | |
3eba9a77 S |
375 | if (packetlen > buflen) |
376 | return -ENOBUFS; | |
3e7ee490 | 377 | |
1ac58644 | 378 | next_read_location = |
2b8a912e | 379 | hv_get_next_readlocation_withoffset(inring_info, offset); |
3e7ee490 | 380 | |
2b8a912e | 381 | next_read_location = hv_copyfrom_ringbuffer(inring_info, |
fc8c72eb | 382 | buffer, |
940b68e2 | 383 | packetlen, |
fc8c72eb | 384 | next_read_location); |
3e7ee490 | 385 | |
2b8a912e | 386 | next_read_location = hv_copyfrom_ringbuffer(inring_info, |
fc8c72eb | 387 | &prev_indices, |
4408f531 | 388 | sizeof(u64), |
fc8c72eb | 389 | next_read_location); |
3e7ee490 | 390 | |
822f18d4 VK |
391 | /* |
392 | * Make sure all reads are done before we update the read index since | |
393 | * the writer may start writing to the read area once the read index | |
394 | * is updated. | |
395 | */ | |
dcd0eeca | 396 | virt_mb(); |
3e7ee490 | 397 | |
454f18a9 | 398 | /* Update the read index */ |
2b8a912e | 399 | hv_set_next_read_location(inring_info, next_read_location); |
3e7ee490 | 400 | |
a389fcfd | 401 | *signal = hv_need_to_signal_on_read(inring_info); |
c2b8e520 | 402 | |
940b68e2 | 403 | return ret; |
b5f53dde | 404 | } |