Commit | Line | Data |
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1fe56551 DV |
1 | /* |
2 | * Xen event channels (FIFO-based ABI) | |
3 | * | |
4 | * Copyright (C) 2013 Citrix Systems R&D ltd. | |
5 | * | |
6 | * This source code is free software; you can redistribute it and/or | |
7 | * modify it under the terms of the GNU General Public License as | |
8 | * published by the Free Software Foundation; either version 2 of the | |
9 | * License, or (at your option) any later version. | |
10 | * | |
11 | * Or, when distributed separately from the Linux kernel or | |
12 | * incorporated into other software packages, subject to the following | |
13 | * license: | |
14 | * | |
15 | * Permission is hereby granted, free of charge, to any person obtaining a copy | |
16 | * of this source file (the "Software"), to deal in the Software without | |
17 | * restriction, including without limitation the rights to use, copy, modify, | |
18 | * merge, publish, distribute, sublicense, and/or sell copies of the Software, | |
19 | * and to permit persons to whom the Software is furnished to do so, subject to | |
20 | * the following conditions: | |
21 | * | |
22 | * The above copyright notice and this permission notice shall be included in | |
23 | * all copies or substantial portions of the Software. | |
24 | * | |
25 | * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR | |
26 | * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, | |
27 | * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE | |
28 | * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER | |
29 | * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING | |
30 | * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS | |
31 | * IN THE SOFTWARE. | |
32 | */ | |
33 | ||
34 | #define pr_fmt(fmt) "xen:" KBUILD_MODNAME ": " fmt | |
35 | ||
36 | #include <linux/linkage.h> | |
37 | #include <linux/interrupt.h> | |
38 | #include <linux/irq.h> | |
39 | #include <linux/module.h> | |
40 | #include <linux/smp.h> | |
41 | #include <linux/percpu.h> | |
42 | #include <linux/cpu.h> | |
43 | ||
44 | #include <asm/sync_bitops.h> | |
45 | #include <asm/xen/hypercall.h> | |
46 | #include <asm/xen/hypervisor.h> | |
1fe56551 DV |
47 | |
48 | #include <xen/xen.h> | |
49 | #include <xen/xen-ops.h> | |
50 | #include <xen/events.h> | |
51 | #include <xen/interface/xen.h> | |
52 | #include <xen/interface/event_channel.h> | |
a9fd60e2 | 53 | #include <xen/page.h> |
1fe56551 DV |
54 | |
55 | #include "events_internal.h" | |
56 | ||
57 | #define EVENT_WORDS_PER_PAGE (PAGE_SIZE / sizeof(event_word_t)) | |
58 | #define MAX_EVENT_ARRAY_PAGES (EVTCHN_FIFO_NR_CHANNELS / EVENT_WORDS_PER_PAGE) | |
59 | ||
60 | struct evtchn_fifo_queue { | |
61 | uint32_t head[EVTCHN_FIFO_MAX_QUEUES]; | |
62 | }; | |
63 | ||
64 | static DEFINE_PER_CPU(struct evtchn_fifo_control_block *, cpu_control_block); | |
65 | static DEFINE_PER_CPU(struct evtchn_fifo_queue, cpu_queue); | |
66 | static event_word_t *event_array[MAX_EVENT_ARRAY_PAGES] __read_mostly; | |
67 | static unsigned event_array_pages __read_mostly; | |
68 | ||
05a812ac | 69 | /* |
dcecb8fd | 70 | * sync_set_bit() and friends must be unsigned long aligned. |
05a812ac | 71 | */ |
dcecb8fd | 72 | #if BITS_PER_LONG > 32 |
05a812ac VM |
73 | |
74 | #define BM(w) (unsigned long *)((unsigned long)w & ~0x7UL) | |
75 | #define EVTCHN_FIFO_BIT(b, w) \ | |
76 | (((unsigned long)w & 0x4UL) ? (EVTCHN_FIFO_ ##b + 32) : EVTCHN_FIFO_ ##b) | |
77 | ||
78 | #else | |
79 | ||
1fe56551 | 80 | #define BM(w) ((unsigned long *)(w)) |
05a812ac VM |
81 | #define EVTCHN_FIFO_BIT(b, w) EVTCHN_FIFO_ ##b |
82 | ||
83 | #endif | |
1fe56551 DV |
84 | |
85 | static inline event_word_t *event_word_from_port(unsigned port) | |
86 | { | |
87 | unsigned i = port / EVENT_WORDS_PER_PAGE; | |
88 | ||
89 | return event_array[i] + port % EVENT_WORDS_PER_PAGE; | |
90 | } | |
91 | ||
92 | static unsigned evtchn_fifo_max_channels(void) | |
93 | { | |
94 | return EVTCHN_FIFO_NR_CHANNELS; | |
95 | } | |
96 | ||
97 | static unsigned evtchn_fifo_nr_channels(void) | |
98 | { | |
99 | return event_array_pages * EVENT_WORDS_PER_PAGE; | |
100 | } | |
101 | ||
c12784c3 DV |
102 | static int init_control_block(int cpu, |
103 | struct evtchn_fifo_control_block *control_block) | |
104 | { | |
105 | struct evtchn_fifo_queue *q = &per_cpu(cpu_queue, cpu); | |
106 | struct evtchn_init_control init_control; | |
107 | unsigned int i; | |
108 | ||
109 | /* Reset the control block and the local HEADs. */ | |
110 | clear_page(control_block); | |
111 | for (i = 0; i < EVTCHN_FIFO_MAX_QUEUES; i++) | |
112 | q->head[i] = 0; | |
113 | ||
114 | init_control.control_gfn = virt_to_mfn(control_block); | |
115 | init_control.offset = 0; | |
116 | init_control.vcpu = cpu; | |
117 | ||
118 | return HYPERVISOR_event_channel_op(EVTCHNOP_init_control, &init_control); | |
119 | } | |
120 | ||
1fe56551 DV |
121 | static void free_unused_array_pages(void) |
122 | { | |
123 | unsigned i; | |
124 | ||
125 | for (i = event_array_pages; i < MAX_EVENT_ARRAY_PAGES; i++) { | |
126 | if (!event_array[i]) | |
127 | break; | |
128 | free_page((unsigned long)event_array[i]); | |
129 | event_array[i] = NULL; | |
130 | } | |
131 | } | |
132 | ||
133 | static void init_array_page(event_word_t *array_page) | |
134 | { | |
135 | unsigned i; | |
136 | ||
137 | for (i = 0; i < EVENT_WORDS_PER_PAGE; i++) | |
138 | array_page[i] = 1 << EVTCHN_FIFO_MASKED; | |
139 | } | |
140 | ||
141 | static int evtchn_fifo_setup(struct irq_info *info) | |
142 | { | |
143 | unsigned port = info->evtchn; | |
144 | unsigned new_array_pages; | |
be1403b9 | 145 | int ret; |
1fe56551 DV |
146 | |
147 | new_array_pages = port / EVENT_WORDS_PER_PAGE + 1; | |
148 | ||
149 | if (new_array_pages > MAX_EVENT_ARRAY_PAGES) | |
150 | return -EINVAL; | |
151 | ||
152 | while (event_array_pages < new_array_pages) { | |
153 | void *array_page; | |
154 | struct evtchn_expand_array expand_array; | |
155 | ||
156 | /* Might already have a page if we've resumed. */ | |
157 | array_page = event_array[event_array_pages]; | |
158 | if (!array_page) { | |
159 | array_page = (void *)__get_free_page(GFP_KERNEL); | |
be1403b9 WY |
160 | if (array_page == NULL) { |
161 | ret = -ENOMEM; | |
1fe56551 | 162 | goto error; |
be1403b9 | 163 | } |
1fe56551 DV |
164 | event_array[event_array_pages] = array_page; |
165 | } | |
166 | ||
167 | /* Mask all events in this page before adding it. */ | |
168 | init_array_page(array_page); | |
169 | ||
170 | expand_array.array_gfn = virt_to_mfn(array_page); | |
171 | ||
172 | ret = HYPERVISOR_event_channel_op(EVTCHNOP_expand_array, &expand_array); | |
173 | if (ret < 0) | |
174 | goto error; | |
175 | ||
176 | event_array_pages++; | |
177 | } | |
178 | return 0; | |
179 | ||
180 | error: | |
181 | if (event_array_pages == 0) | |
182 | panic("xen: unable to expand event array with initial page (%d)\n", ret); | |
183 | else | |
184 | pr_err("unable to expand event array (%d)\n", ret); | |
185 | free_unused_array_pages(); | |
186 | return ret; | |
187 | } | |
188 | ||
189 | static void evtchn_fifo_bind_to_cpu(struct irq_info *info, unsigned cpu) | |
190 | { | |
191 | /* no-op */ | |
192 | } | |
193 | ||
194 | static void evtchn_fifo_clear_pending(unsigned port) | |
195 | { | |
196 | event_word_t *word = event_word_from_port(port); | |
05a812ac | 197 | sync_clear_bit(EVTCHN_FIFO_BIT(PENDING, word), BM(word)); |
1fe56551 DV |
198 | } |
199 | ||
200 | static void evtchn_fifo_set_pending(unsigned port) | |
201 | { | |
202 | event_word_t *word = event_word_from_port(port); | |
05a812ac | 203 | sync_set_bit(EVTCHN_FIFO_BIT(PENDING, word), BM(word)); |
1fe56551 DV |
204 | } |
205 | ||
206 | static bool evtchn_fifo_is_pending(unsigned port) | |
207 | { | |
208 | event_word_t *word = event_word_from_port(port); | |
05a812ac | 209 | return sync_test_bit(EVTCHN_FIFO_BIT(PENDING, word), BM(word)); |
1fe56551 DV |
210 | } |
211 | ||
212 | static bool evtchn_fifo_test_and_set_mask(unsigned port) | |
213 | { | |
214 | event_word_t *word = event_word_from_port(port); | |
05a812ac | 215 | return sync_test_and_set_bit(EVTCHN_FIFO_BIT(MASKED, word), BM(word)); |
1fe56551 DV |
216 | } |
217 | ||
218 | static void evtchn_fifo_mask(unsigned port) | |
219 | { | |
220 | event_word_t *word = event_word_from_port(port); | |
05a812ac | 221 | sync_set_bit(EVTCHN_FIFO_BIT(MASKED, word), BM(word)); |
1fe56551 DV |
222 | } |
223 | ||
05a812ac VM |
224 | static bool evtchn_fifo_is_masked(unsigned port) |
225 | { | |
226 | event_word_t *word = event_word_from_port(port); | |
227 | return sync_test_bit(EVTCHN_FIFO_BIT(MASKED, word), BM(word)); | |
228 | } | |
1fe56551 DV |
229 | /* |
230 | * Clear MASKED, spinning if BUSY is set. | |
231 | */ | |
232 | static void clear_masked(volatile event_word_t *word) | |
233 | { | |
234 | event_word_t new, old, w; | |
235 | ||
236 | w = *word; | |
237 | ||
238 | do { | |
239 | old = w & ~(1 << EVTCHN_FIFO_BUSY); | |
240 | new = old & ~(1 << EVTCHN_FIFO_MASKED); | |
241 | w = sync_cmpxchg(word, old, new); | |
242 | } while (w != old); | |
243 | } | |
244 | ||
245 | static void evtchn_fifo_unmask(unsigned port) | |
246 | { | |
247 | event_word_t *word = event_word_from_port(port); | |
248 | ||
249 | BUG_ON(!irqs_disabled()); | |
250 | ||
251 | clear_masked(word); | |
05a812ac | 252 | if (evtchn_fifo_is_pending(port)) { |
1fe56551 DV |
253 | struct evtchn_unmask unmask = { .port = port }; |
254 | (void)HYPERVISOR_event_channel_op(EVTCHNOP_unmask, &unmask); | |
255 | } | |
256 | } | |
257 | ||
258 | static uint32_t clear_linked(volatile event_word_t *word) | |
259 | { | |
260 | event_word_t new, old, w; | |
261 | ||
262 | w = *word; | |
263 | ||
264 | do { | |
265 | old = w; | |
266 | new = (w & ~((1 << EVTCHN_FIFO_LINKED) | |
267 | | EVTCHN_FIFO_LINK_MASK)); | |
268 | } while ((w = sync_cmpxchg(word, old, new)) != old); | |
269 | ||
270 | return w & EVTCHN_FIFO_LINK_MASK; | |
271 | } | |
272 | ||
273 | static void handle_irq_for_port(unsigned port) | |
274 | { | |
275 | int irq; | |
1fe56551 DV |
276 | |
277 | irq = get_evtchn_to_irq(port); | |
589d03e9 TG |
278 | if (irq != -1) |
279 | generic_handle_irq(irq); | |
1fe56551 DV |
280 | } |
281 | ||
282 | static void consume_one_event(unsigned cpu, | |
283 | struct evtchn_fifo_control_block *control_block, | |
ad6cd7ba | 284 | unsigned priority, unsigned long *ready) |
1fe56551 DV |
285 | { |
286 | struct evtchn_fifo_queue *q = &per_cpu(cpu_queue, cpu); | |
287 | uint32_t head; | |
288 | unsigned port; | |
289 | event_word_t *word; | |
290 | ||
291 | head = q->head[priority]; | |
292 | ||
293 | /* | |
294 | * Reached the tail last time? Read the new HEAD from the | |
295 | * control block. | |
296 | */ | |
297 | if (head == 0) { | |
298 | rmb(); /* Ensure word is up-to-date before reading head. */ | |
299 | head = control_block->head[priority]; | |
300 | } | |
301 | ||
302 | port = head; | |
303 | word = event_word_from_port(port); | |
304 | head = clear_linked(word); | |
305 | ||
306 | /* | |
307 | * If the link is non-zero, there are more events in the | |
308 | * queue, otherwise the queue is empty. | |
309 | * | |
310 | * If the queue is empty, clear this priority from our local | |
311 | * copy of the ready word. | |
312 | */ | |
313 | if (head == 0) | |
05a812ac | 314 | clear_bit(priority, ready); |
1fe56551 | 315 | |
ad6cd7ba DV |
316 | if (evtchn_fifo_is_pending(port) && !evtchn_fifo_is_masked(port)) |
317 | handle_irq_for_port(port); | |
1fe56551 DV |
318 | |
319 | q->head[priority] = head; | |
320 | } | |
321 | ||
ad6cd7ba | 322 | static void evtchn_fifo_handle_events(unsigned cpu) |
1fe56551 DV |
323 | { |
324 | struct evtchn_fifo_control_block *control_block; | |
05a812ac | 325 | unsigned long ready; |
1fe56551 DV |
326 | unsigned q; |
327 | ||
328 | control_block = per_cpu(cpu_control_block, cpu); | |
329 | ||
330 | ready = xchg(&control_block->ready, 0); | |
331 | ||
332 | while (ready) { | |
e4a74312 | 333 | q = find_first_bit(&ready, EVTCHN_FIFO_MAX_QUEUES); |
ad6cd7ba | 334 | consume_one_event(cpu, control_block, q, &ready); |
1fe56551 DV |
335 | ready |= xchg(&control_block->ready, 0); |
336 | } | |
337 | } | |
338 | ||
339 | static void evtchn_fifo_resume(void) | |
340 | { | |
341 | unsigned cpu; | |
342 | ||
343 | for_each_possible_cpu(cpu) { | |
344 | void *control_block = per_cpu(cpu_control_block, cpu); | |
1fe56551 DV |
345 | int ret; |
346 | ||
347 | if (!control_block) | |
348 | continue; | |
349 | ||
350 | /* | |
351 | * If this CPU is offline, take the opportunity to | |
352 | * free the control block while it is not being | |
353 | * used. | |
354 | */ | |
355 | if (!cpu_online(cpu)) { | |
356 | free_page((unsigned long)control_block); | |
357 | per_cpu(cpu_control_block, cpu) = NULL; | |
358 | continue; | |
359 | } | |
360 | ||
c12784c3 | 361 | ret = init_control_block(cpu, control_block); |
1fe56551 DV |
362 | if (ret < 0) |
363 | BUG(); | |
364 | } | |
365 | ||
366 | /* | |
367 | * The event array starts out as empty again and is extended | |
368 | * as normal when events are bound. The existing pages will | |
369 | * be reused. | |
370 | */ | |
371 | event_array_pages = 0; | |
372 | } | |
373 | ||
374 | static const struct evtchn_ops evtchn_ops_fifo = { | |
375 | .max_channels = evtchn_fifo_max_channels, | |
376 | .nr_channels = evtchn_fifo_nr_channels, | |
377 | .setup = evtchn_fifo_setup, | |
378 | .bind_to_cpu = evtchn_fifo_bind_to_cpu, | |
379 | .clear_pending = evtchn_fifo_clear_pending, | |
380 | .set_pending = evtchn_fifo_set_pending, | |
381 | .is_pending = evtchn_fifo_is_pending, | |
382 | .test_and_set_mask = evtchn_fifo_test_and_set_mask, | |
383 | .mask = evtchn_fifo_mask, | |
384 | .unmask = evtchn_fifo_unmask, | |
385 | .handle_events = evtchn_fifo_handle_events, | |
386 | .resume = evtchn_fifo_resume, | |
387 | }; | |
388 | ||
c12784c3 | 389 | static int evtchn_fifo_alloc_control_block(unsigned cpu) |
1fe56551 | 390 | { |
c12784c3 | 391 | void *control_block = NULL; |
1fe56551 DV |
392 | int ret = -ENOMEM; |
393 | ||
c12784c3 | 394 | control_block = (void *)__get_free_page(GFP_KERNEL); |
1fe56551 DV |
395 | if (control_block == NULL) |
396 | goto error; | |
397 | ||
c12784c3 | 398 | ret = init_control_block(cpu, control_block); |
1fe56551 DV |
399 | if (ret < 0) |
400 | goto error; | |
401 | ||
c12784c3 | 402 | per_cpu(cpu_control_block, cpu) = control_block; |
1fe56551 DV |
403 | |
404 | return 0; | |
405 | ||
406 | error: | |
c12784c3 | 407 | free_page((unsigned long)control_block); |
1fe56551 DV |
408 | return ret; |
409 | } | |
410 | ||
0db6991d | 411 | static int evtchn_fifo_cpu_notification(struct notifier_block *self, |
1fe56551 DV |
412 | unsigned long action, |
413 | void *hcpu) | |
414 | { | |
415 | int cpu = (long)hcpu; | |
416 | int ret = 0; | |
417 | ||
418 | switch (action) { | |
419 | case CPU_UP_PREPARE: | |
420 | if (!per_cpu(cpu_control_block, cpu)) | |
c12784c3 | 421 | ret = evtchn_fifo_alloc_control_block(cpu); |
1fe56551 DV |
422 | break; |
423 | default: | |
424 | break; | |
425 | } | |
426 | return ret < 0 ? NOTIFY_BAD : NOTIFY_OK; | |
427 | } | |
428 | ||
0db6991d | 429 | static struct notifier_block evtchn_fifo_cpu_notifier = { |
1fe56551 DV |
430 | .notifier_call = evtchn_fifo_cpu_notification, |
431 | }; | |
432 | ||
433 | int __init xen_evtchn_fifo_init(void) | |
434 | { | |
435 | int cpu = get_cpu(); | |
436 | int ret; | |
437 | ||
c12784c3 | 438 | ret = evtchn_fifo_alloc_control_block(cpu); |
1fe56551 DV |
439 | if (ret < 0) |
440 | goto out; | |
441 | ||
442 | pr_info("Using FIFO-based ABI\n"); | |
443 | ||
444 | evtchn_ops = &evtchn_ops_fifo; | |
445 | ||
446 | register_cpu_notifier(&evtchn_fifo_cpu_notifier); | |
447 | out: | |
448 | put_cpu(); | |
449 | return ret; | |
450 | } |