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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> |
9988ce68 VK |
30 | #include <linux/vmalloc.h> |
31 | #include <linux/slab.h> | |
3f335ea2 | 32 | |
0f2a6619 | 33 | #include "hyperv_vmbus.h" |
3e7ee490 | 34 | |
6fdf3b21 S |
35 | void hv_begin_read(struct hv_ring_buffer_info *rbi) |
36 | { | |
37 | rbi->ring_buffer->interrupt_mask = 1; | |
dcd0eeca | 38 | virt_mb(); |
6fdf3b21 S |
39 | } |
40 | ||
41 | u32 hv_end_read(struct hv_ring_buffer_info *rbi) | |
42 | { | |
6fdf3b21 S |
43 | |
44 | rbi->ring_buffer->interrupt_mask = 0; | |
dcd0eeca | 45 | virt_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 | */ | |
a6341f00 | 52 | return hv_get_bytes_to_read(rbi); |
6fdf3b21 S |
53 | } |
54 | ||
98fa8cf4 S |
55 | /* |
56 | * When we write to the ring buffer, check if the host needs to | |
57 | * be signaled. Here is the details of this protocol: | |
58 | * | |
59 | * 1. The host guarantees that while it is draining the | |
60 | * ring buffer, it will set the interrupt_mask to | |
61 | * indicate it does not need to be interrupted when | |
62 | * new data is placed. | |
63 | * | |
64 | * 2. The host guarantees that it will completely drain | |
65 | * the ring buffer before exiting the read loop. Further, | |
66 | * once the ring buffer is empty, it will clear the | |
67 | * interrupt_mask and re-check to see if new data has | |
68 | * arrived. | |
69 | */ | |
70 | ||
ccef9bcc S |
71 | static bool hv_need_to_signal(u32 old_write, struct hv_ring_buffer_info *rbi, |
72 | enum hv_signal_policy policy) | |
98fa8cf4 | 73 | { |
dcd0eeca | 74 | virt_mb(); |
d45faaee | 75 | if (READ_ONCE(rbi->ring_buffer->interrupt_mask)) |
98fa8cf4 S |
76 | return false; |
77 | ||
e91e84fa | 78 | /* check interrupt_mask before read_index */ |
dcd0eeca | 79 | virt_rmb(); |
98fa8cf4 S |
80 | /* |
81 | * This is the only case we need to signal when the | |
82 | * ring transitions from being empty to non-empty. | |
83 | */ | |
d45faaee | 84 | if (old_write == READ_ONCE(rbi->ring_buffer->read_index)) |
98fa8cf4 S |
85 | return true; |
86 | ||
87 | return false; | |
88 | } | |
89 | ||
822f18d4 | 90 | /* Get the next write location for the specified ring buffer. */ |
4d643114 | 91 | static inline u32 |
2b8a912e | 92 | hv_get_next_write_location(struct hv_ring_buffer_info *ring_info) |
3e7ee490 | 93 | { |
fc8c72eb | 94 | u32 next = ring_info->ring_buffer->write_index; |
3e7ee490 | 95 | |
3e7ee490 HJ |
96 | return next; |
97 | } | |
98 | ||
822f18d4 | 99 | /* Set the next write location for the specified ring buffer. */ |
3e7ee490 | 100 | static inline void |
2b8a912e | 101 | hv_set_next_write_location(struct hv_ring_buffer_info *ring_info, |
fc8c72eb | 102 | u32 next_write_location) |
3e7ee490 | 103 | { |
fc8c72eb | 104 | ring_info->ring_buffer->write_index = next_write_location; |
3e7ee490 HJ |
105 | } |
106 | ||
822f18d4 | 107 | /* Get the next read location for the specified ring buffer. */ |
4d643114 | 108 | static inline u32 |
2b8a912e | 109 | hv_get_next_read_location(struct hv_ring_buffer_info *ring_info) |
3e7ee490 | 110 | { |
fc8c72eb | 111 | u32 next = ring_info->ring_buffer->read_index; |
3e7ee490 | 112 | |
3e7ee490 HJ |
113 | return next; |
114 | } | |
115 | ||
b2a5a585 | 116 | /* |
b2a5a585 | 117 | * Get the next read location + offset for the specified ring buffer. |
822f18d4 | 118 | * This allows the caller to skip. |
b2a5a585 | 119 | */ |
4d643114 | 120 | static inline u32 |
2b8a912e | 121 | hv_get_next_readlocation_withoffset(struct hv_ring_buffer_info *ring_info, |
1ac58644 | 122 | u32 offset) |
3e7ee490 | 123 | { |
fc8c72eb | 124 | u32 next = ring_info->ring_buffer->read_index; |
3e7ee490 | 125 | |
fc8c72eb HZ |
126 | next += offset; |
127 | next %= ring_info->ring_datasize; | |
3e7ee490 HJ |
128 | |
129 | return next; | |
130 | } | |
131 | ||
822f18d4 | 132 | /* Set the next read location for the specified ring buffer. */ |
3e7ee490 | 133 | static inline void |
2b8a912e | 134 | hv_set_next_read_location(struct hv_ring_buffer_info *ring_info, |
fc8c72eb | 135 | u32 next_read_location) |
3e7ee490 | 136 | { |
fc8c72eb | 137 | ring_info->ring_buffer->read_index = next_read_location; |
ab028db4 | 138 | ring_info->priv_read_index = next_read_location; |
3e7ee490 HJ |
139 | } |
140 | ||
822f18d4 | 141 | /* Get the size of the ring buffer. */ |
4d643114 | 142 | static inline u32 |
2b8a912e | 143 | hv_get_ring_buffersize(struct hv_ring_buffer_info *ring_info) |
3e7ee490 | 144 | { |
fc8c72eb | 145 | return ring_info->ring_datasize; |
3e7ee490 HJ |
146 | } |
147 | ||
822f18d4 | 148 | /* Get the read and write indices as u64 of the specified ring buffer. */ |
59471438 | 149 | static inline u64 |
2b8a912e | 150 | hv_get_ring_bufferindices(struct hv_ring_buffer_info *ring_info) |
3e7ee490 | 151 | { |
fc8c72eb | 152 | return (u64)ring_info->ring_buffer->write_index << 32; |
3e7ee490 HJ |
153 | } |
154 | ||
8f1136ae | 155 | /* |
8f1136ae S |
156 | * Helper routine to copy to source from ring buffer. |
157 | * Assume there is enough room. Handles wrap-around in src case only!! | |
8f1136ae S |
158 | */ |
159 | static u32 hv_copyfrom_ringbuffer( | |
160 | struct hv_ring_buffer_info *ring_info, | |
161 | void *dest, | |
162 | u32 destlen, | |
163 | u32 start_read_offset) | |
164 | { | |
165 | void *ring_buffer = hv_get_ring_buffer(ring_info); | |
166 | u32 ring_buffer_size = hv_get_ring_buffersize(ring_info); | |
167 | ||
f24f0b49 | 168 | memcpy(dest, ring_buffer + start_read_offset, destlen); |
8f1136ae S |
169 | |
170 | start_read_offset += destlen; | |
171 | start_read_offset %= ring_buffer_size; | |
172 | ||
173 | return start_read_offset; | |
174 | } | |
175 | ||
176 | ||
7581578d | 177 | /* |
7581578d S |
178 | * Helper routine to copy from source to ring buffer. |
179 | * Assume there is enough room. Handles wrap-around in dest case only!! | |
7581578d S |
180 | */ |
181 | static u32 hv_copyto_ringbuffer( | |
fc8c72eb HZ |
182 | struct hv_ring_buffer_info *ring_info, |
183 | u32 start_write_offset, | |
184 | void *src, | |
7581578d S |
185 | u32 srclen) |
186 | { | |
187 | void *ring_buffer = hv_get_ring_buffer(ring_info); | |
188 | u32 ring_buffer_size = hv_get_ring_buffersize(ring_info); | |
f24f0b49 VK |
189 | |
190 | memcpy(ring_buffer + start_write_offset, src, srclen); | |
3e7ee490 | 191 | |
7581578d S |
192 | start_write_offset += srclen; |
193 | start_write_offset %= ring_buffer_size; | |
194 | ||
195 | return start_write_offset; | |
196 | } | |
3e7ee490 | 197 | |
822f18d4 | 198 | /* Get various debug metrics for the specified ring buffer. */ |
a75b61d5 | 199 | void hv_ringbuffer_get_debuginfo(struct hv_ring_buffer_info *ring_info, |
80682b7a | 200 | struct hv_ring_buffer_debug_info *debug_info) |
3e7ee490 | 201 | { |
fc8c72eb HZ |
202 | u32 bytes_avail_towrite; |
203 | u32 bytes_avail_toread; | |
3e7ee490 | 204 | |
fc8c72eb | 205 | if (ring_info->ring_buffer) { |
2b8a912e | 206 | hv_get_ringbuffer_availbytes(ring_info, |
fc8c72eb HZ |
207 | &bytes_avail_toread, |
208 | &bytes_avail_towrite); | |
3e7ee490 | 209 | |
fc8c72eb HZ |
210 | debug_info->bytes_avail_toread = bytes_avail_toread; |
211 | debug_info->bytes_avail_towrite = bytes_avail_towrite; | |
82f8bd40 | 212 | debug_info->current_read_index = |
fc8c72eb | 213 | ring_info->ring_buffer->read_index; |
82f8bd40 | 214 | debug_info->current_write_index = |
fc8c72eb | 215 | ring_info->ring_buffer->write_index; |
82f8bd40 | 216 | debug_info->current_interrupt_mask = |
fc8c72eb | 217 | ring_info->ring_buffer->interrupt_mask; |
3e7ee490 HJ |
218 | } |
219 | } | |
220 | ||
822f18d4 | 221 | /* Initialize the ring buffer. */ |
72a95cbc | 222 | int hv_ringbuffer_init(struct hv_ring_buffer_info *ring_info, |
9988ce68 | 223 | struct page *pages, u32 page_cnt) |
3e7ee490 | 224 | { |
9988ce68 VK |
225 | int i; |
226 | struct page **pages_wraparound; | |
227 | ||
228 | BUILD_BUG_ON((sizeof(struct hv_ring_buffer) != PAGE_SIZE)); | |
3e7ee490 | 229 | |
fc8c72eb | 230 | memset(ring_info, 0, sizeof(struct hv_ring_buffer_info)); |
3e7ee490 | 231 | |
9988ce68 VK |
232 | /* |
233 | * First page holds struct hv_ring_buffer, do wraparound mapping for | |
234 | * the rest. | |
235 | */ | |
236 | pages_wraparound = kzalloc(sizeof(struct page *) * (page_cnt * 2 - 1), | |
237 | GFP_KERNEL); | |
238 | if (!pages_wraparound) | |
239 | return -ENOMEM; | |
240 | ||
241 | pages_wraparound[0] = pages; | |
242 | for (i = 0; i < 2 * (page_cnt - 1); i++) | |
243 | pages_wraparound[i + 1] = &pages[i % (page_cnt - 1) + 1]; | |
244 | ||
245 | ring_info->ring_buffer = (struct hv_ring_buffer *) | |
246 | vmap(pages_wraparound, page_cnt * 2 - 1, VM_MAP, PAGE_KERNEL); | |
247 | ||
248 | kfree(pages_wraparound); | |
249 | ||
250 | ||
251 | if (!ring_info->ring_buffer) | |
252 | return -ENOMEM; | |
253 | ||
fc8c72eb HZ |
254 | ring_info->ring_buffer->read_index = |
255 | ring_info->ring_buffer->write_index = 0; | |
3e7ee490 | 256 | |
822f18d4 | 257 | /* Set the feature bit for enabling flow control. */ |
046c7911 S |
258 | ring_info->ring_buffer->feature_bits.value = 1; |
259 | ||
9988ce68 VK |
260 | ring_info->ring_size = page_cnt << PAGE_SHIFT; |
261 | ring_info->ring_datasize = ring_info->ring_size - | |
262 | sizeof(struct hv_ring_buffer); | |
3e7ee490 | 263 | |
fc8c72eb | 264 | spin_lock_init(&ring_info->ring_lock); |
3e7ee490 HJ |
265 | |
266 | return 0; | |
267 | } | |
268 | ||
822f18d4 | 269 | /* Cleanup the ring buffer. */ |
2dba688b | 270 | void hv_ringbuffer_cleanup(struct hv_ring_buffer_info *ring_info) |
3e7ee490 | 271 | { |
9988ce68 | 272 | vunmap(ring_info->ring_buffer); |
3e7ee490 HJ |
273 | } |
274 | ||
822f18d4 | 275 | /* Write to the ring buffer. */ |
633c4dce | 276 | int hv_ringbuffer_write(struct hv_ring_buffer_info *outring_info, |
ccef9bcc S |
277 | struct kvec *kv_list, u32 kv_count, bool *signal, bool lock, |
278 | enum hv_signal_policy policy) | |
3e7ee490 | 279 | { |
4408f531 | 280 | int i = 0; |
fc8c72eb | 281 | u32 bytes_avail_towrite; |
fc8c72eb | 282 | u32 totalbytes_towrite = 0; |
3e7ee490 | 283 | |
66a60543 | 284 | u32 next_write_location; |
98fa8cf4 | 285 | u32 old_write; |
fc8c72eb | 286 | u64 prev_indices = 0; |
fe760e4d | 287 | unsigned long flags = 0; |
3e7ee490 | 288 | |
011a7c3c S |
289 | for (i = 0; i < kv_count; i++) |
290 | totalbytes_towrite += kv_list[i].iov_len; | |
3e7ee490 | 291 | |
fc8c72eb | 292 | totalbytes_towrite += sizeof(u64); |
3e7ee490 | 293 | |
fe760e4d S |
294 | if (lock) |
295 | spin_lock_irqsave(&outring_info->ring_lock, flags); | |
3e7ee490 | 296 | |
a6341f00 | 297 | bytes_avail_towrite = hv_get_bytes_to_write(outring_info); |
3e7ee490 | 298 | |
822f18d4 VK |
299 | /* |
300 | * If there is only room for the packet, assume it is full. | |
301 | * Otherwise, the next time around, we think the ring buffer | |
302 | * is empty since the read index == write index. | |
303 | */ | |
fc8c72eb | 304 | if (bytes_avail_towrite <= totalbytes_towrite) { |
fe760e4d S |
305 | if (lock) |
306 | spin_unlock_irqrestore(&outring_info->ring_lock, flags); | |
d2598f01 | 307 | return -EAGAIN; |
3e7ee490 HJ |
308 | } |
309 | ||
454f18a9 | 310 | /* Write to the ring buffer */ |
2b8a912e | 311 | next_write_location = hv_get_next_write_location(outring_info); |
3e7ee490 | 312 | |
98fa8cf4 S |
313 | old_write = next_write_location; |
314 | ||
011a7c3c | 315 | for (i = 0; i < kv_count; i++) { |
2b8a912e | 316 | next_write_location = hv_copyto_ringbuffer(outring_info, |
fc8c72eb | 317 | next_write_location, |
011a7c3c S |
318 | kv_list[i].iov_base, |
319 | kv_list[i].iov_len); | |
3e7ee490 HJ |
320 | } |
321 | ||
454f18a9 | 322 | /* Set previous packet start */ |
2b8a912e | 323 | prev_indices = hv_get_ring_bufferindices(outring_info); |
3e7ee490 | 324 | |
2b8a912e | 325 | next_write_location = hv_copyto_ringbuffer(outring_info, |
fc8c72eb HZ |
326 | next_write_location, |
327 | &prev_indices, | |
b219b3f7 | 328 | sizeof(u64)); |
3e7ee490 | 329 | |
98fa8cf4 | 330 | /* Issue a full memory barrier before updating the write index */ |
dcd0eeca | 331 | virt_mb(); |
3e7ee490 | 332 | |
454f18a9 | 333 | /* Now, update the write location */ |
2b8a912e | 334 | hv_set_next_write_location(outring_info, next_write_location); |
3e7ee490 | 335 | |
3e7ee490 | 336 | |
fe760e4d S |
337 | if (lock) |
338 | spin_unlock_irqrestore(&outring_info->ring_lock, flags); | |
98fa8cf4 | 339 | |
ccef9bcc | 340 | *signal = hv_need_to_signal(old_write, outring_info, policy); |
3e7ee490 HJ |
341 | return 0; |
342 | } | |
343 | ||
940b68e2 VK |
344 | int hv_ringbuffer_read(struct hv_ring_buffer_info *inring_info, |
345 | void *buffer, u32 buflen, u32 *buffer_actual_len, | |
346 | u64 *requestid, bool *signal, bool raw) | |
3e7ee490 | 347 | { |
fc8c72eb HZ |
348 | u32 bytes_avail_toread; |
349 | u32 next_read_location = 0; | |
350 | u64 prev_indices = 0; | |
940b68e2 VK |
351 | struct vmpacket_descriptor desc; |
352 | u32 offset; | |
353 | u32 packetlen; | |
354 | int ret = 0; | |
3e7ee490 | 355 | |
fc8c72eb | 356 | if (buflen <= 0) |
a16e1485 | 357 | return -EINVAL; |
3e7ee490 | 358 | |
3e7ee490 | 359 | |
940b68e2 VK |
360 | *buffer_actual_len = 0; |
361 | *requestid = 0; | |
362 | ||
a6341f00 | 363 | bytes_avail_toread = hv_get_bytes_to_read(inring_info); |
454f18a9 | 364 | /* Make sure there is something to read */ |
940b68e2 VK |
365 | if (bytes_avail_toread < sizeof(desc)) { |
366 | /* | |
367 | * No error is set when there is even no header, drivers are | |
368 | * supposed to analyze buffer_actual_len. | |
369 | */ | |
3eba9a77 | 370 | return ret; |
940b68e2 | 371 | } |
3e7ee490 | 372 | |
940b68e2 VK |
373 | next_read_location = hv_get_next_read_location(inring_info); |
374 | next_read_location = hv_copyfrom_ringbuffer(inring_info, &desc, | |
375 | sizeof(desc), | |
376 | next_read_location); | |
377 | ||
378 | offset = raw ? 0 : (desc.offset8 << 3); | |
379 | packetlen = (desc.len8 << 3) - offset; | |
380 | *buffer_actual_len = packetlen; | |
381 | *requestid = desc.trans_id; | |
382 | ||
3eba9a77 S |
383 | if (bytes_avail_toread < packetlen + offset) |
384 | return -EAGAIN; | |
940b68e2 | 385 | |
3eba9a77 S |
386 | if (packetlen > buflen) |
387 | return -ENOBUFS; | |
3e7ee490 | 388 | |
1ac58644 | 389 | next_read_location = |
2b8a912e | 390 | hv_get_next_readlocation_withoffset(inring_info, offset); |
3e7ee490 | 391 | |
2b8a912e | 392 | next_read_location = hv_copyfrom_ringbuffer(inring_info, |
fc8c72eb | 393 | buffer, |
940b68e2 | 394 | packetlen, |
fc8c72eb | 395 | next_read_location); |
3e7ee490 | 396 | |
2b8a912e | 397 | next_read_location = hv_copyfrom_ringbuffer(inring_info, |
fc8c72eb | 398 | &prev_indices, |
4408f531 | 399 | sizeof(u64), |
fc8c72eb | 400 | next_read_location); |
3e7ee490 | 401 | |
822f18d4 VK |
402 | /* |
403 | * Make sure all reads are done before we update the read index since | |
404 | * the writer may start writing to the read area once the read index | |
405 | * is updated. | |
406 | */ | |
dcd0eeca | 407 | virt_mb(); |
3e7ee490 | 408 | |
454f18a9 | 409 | /* Update the read index */ |
2b8a912e | 410 | hv_set_next_read_location(inring_info, next_read_location); |
3e7ee490 | 411 | |
a389fcfd | 412 | *signal = hv_need_to_signal_on_read(inring_info); |
c2b8e520 | 413 | |
940b68e2 | 414 | return ret; |
b5f53dde | 415 | } |