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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> | |
1fe56551 DV |
39 | #include <linux/smp.h> |
40 | #include <linux/percpu.h> | |
41 | #include <linux/cpu.h> | |
42 | ||
23492754 | 43 | #include <asm/barrier.h> |
1fe56551 DV |
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 | ||
a001c9d9 | 57 | #define EVENT_WORDS_PER_PAGE (XEN_PAGE_SIZE / sizeof(event_word_t)) |
1fe56551 DV |
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 | ||
0df4f266 | 114 | init_control.control_gfn = virt_to_gfn(control_block); |
c12784c3 | 115 | init_control.offset = 0; |
be78da1c | 116 | init_control.vcpu = xen_vcpu_nr(cpu); |
c12784c3 DV |
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 | ||
0df4f266 | 170 | expand_array.array_gfn = virt_to_gfn(array_page); |
1fe56551 DV |
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 | 229 | /* |
3b258673 JG |
230 | * Clear MASKED if not PENDING, spinning if BUSY is set. |
231 | * Return true if mask was cleared. | |
1fe56551 | 232 | */ |
3b258673 | 233 | static bool clear_masked_cond(volatile event_word_t *word) |
1fe56551 DV |
234 | { |
235 | event_word_t new, old, w; | |
236 | ||
237 | w = *word; | |
238 | ||
239 | do { | |
3b258673 JG |
240 | if (w & (1 << EVTCHN_FIFO_PENDING)) |
241 | return false; | |
242 | ||
1fe56551 DV |
243 | old = w & ~(1 << EVTCHN_FIFO_BUSY); |
244 | new = old & ~(1 << EVTCHN_FIFO_MASKED); | |
245 | w = sync_cmpxchg(word, old, new); | |
246 | } while (w != old); | |
3b258673 JG |
247 | |
248 | return true; | |
1fe56551 DV |
249 | } |
250 | ||
251 | static void evtchn_fifo_unmask(unsigned port) | |
252 | { | |
253 | event_word_t *word = event_word_from_port(port); | |
254 | ||
255 | BUG_ON(!irqs_disabled()); | |
256 | ||
3b258673 | 257 | if (!clear_masked_cond(word)) { |
1fe56551 DV |
258 | struct evtchn_unmask unmask = { .port = port }; |
259 | (void)HYPERVISOR_event_channel_op(EVTCHNOP_unmask, &unmask); | |
260 | } | |
261 | } | |
262 | ||
263 | static uint32_t clear_linked(volatile event_word_t *word) | |
264 | { | |
265 | event_word_t new, old, w; | |
266 | ||
267 | w = *word; | |
268 | ||
269 | do { | |
270 | old = w; | |
271 | new = (w & ~((1 << EVTCHN_FIFO_LINKED) | |
272 | | EVTCHN_FIFO_LINK_MASK)); | |
273 | } while ((w = sync_cmpxchg(word, old, new)) != old); | |
274 | ||
275 | return w & EVTCHN_FIFO_LINK_MASK; | |
276 | } | |
277 | ||
278 | static void handle_irq_for_port(unsigned port) | |
279 | { | |
280 | int irq; | |
1fe56551 DV |
281 | |
282 | irq = get_evtchn_to_irq(port); | |
589d03e9 TG |
283 | if (irq != -1) |
284 | generic_handle_irq(irq); | |
1fe56551 DV |
285 | } |
286 | ||
287 | static void consume_one_event(unsigned cpu, | |
288 | struct evtchn_fifo_control_block *control_block, | |
3de88d62 RL |
289 | unsigned priority, unsigned long *ready, |
290 | bool drop) | |
1fe56551 DV |
291 | { |
292 | struct evtchn_fifo_queue *q = &per_cpu(cpu_queue, cpu); | |
293 | uint32_t head; | |
294 | unsigned port; | |
295 | event_word_t *word; | |
296 | ||
297 | head = q->head[priority]; | |
298 | ||
299 | /* | |
300 | * Reached the tail last time? Read the new HEAD from the | |
301 | * control block. | |
302 | */ | |
303 | if (head == 0) { | |
23492754 | 304 | virt_rmb(); /* Ensure word is up-to-date before reading head. */ |
1fe56551 DV |
305 | head = control_block->head[priority]; |
306 | } | |
307 | ||
308 | port = head; | |
309 | word = event_word_from_port(port); | |
310 | head = clear_linked(word); | |
311 | ||
312 | /* | |
313 | * If the link is non-zero, there are more events in the | |
314 | * queue, otherwise the queue is empty. | |
315 | * | |
316 | * If the queue is empty, clear this priority from our local | |
317 | * copy of the ready word. | |
318 | */ | |
319 | if (head == 0) | |
05a812ac | 320 | clear_bit(priority, ready); |
1fe56551 | 321 | |
3de88d62 RL |
322 | if (evtchn_fifo_is_pending(port) && !evtchn_fifo_is_masked(port)) { |
323 | if (unlikely(drop)) | |
324 | pr_warn("Dropping pending event for port %u\n", port); | |
325 | else | |
326 | handle_irq_for_port(port); | |
327 | } | |
1fe56551 DV |
328 | |
329 | q->head[priority] = head; | |
330 | } | |
331 | ||
3de88d62 | 332 | static void __evtchn_fifo_handle_events(unsigned cpu, bool drop) |
1fe56551 DV |
333 | { |
334 | struct evtchn_fifo_control_block *control_block; | |
05a812ac | 335 | unsigned long ready; |
1fe56551 DV |
336 | unsigned q; |
337 | ||
338 | control_block = per_cpu(cpu_control_block, cpu); | |
339 | ||
340 | ready = xchg(&control_block->ready, 0); | |
341 | ||
342 | while (ready) { | |
e4a74312 | 343 | q = find_first_bit(&ready, EVTCHN_FIFO_MAX_QUEUES); |
3de88d62 | 344 | consume_one_event(cpu, control_block, q, &ready, drop); |
1fe56551 DV |
345 | ready |= xchg(&control_block->ready, 0); |
346 | } | |
347 | } | |
348 | ||
3de88d62 RL |
349 | static void evtchn_fifo_handle_events(unsigned cpu) |
350 | { | |
351 | __evtchn_fifo_handle_events(cpu, false); | |
352 | } | |
353 | ||
1fe56551 DV |
354 | static void evtchn_fifo_resume(void) |
355 | { | |
356 | unsigned cpu; | |
357 | ||
358 | for_each_possible_cpu(cpu) { | |
359 | void *control_block = per_cpu(cpu_control_block, cpu); | |
1fe56551 DV |
360 | int ret; |
361 | ||
362 | if (!control_block) | |
363 | continue; | |
364 | ||
365 | /* | |
366 | * If this CPU is offline, take the opportunity to | |
367 | * free the control block while it is not being | |
368 | * used. | |
369 | */ | |
370 | if (!cpu_online(cpu)) { | |
371 | free_page((unsigned long)control_block); | |
372 | per_cpu(cpu_control_block, cpu) = NULL; | |
373 | continue; | |
374 | } | |
375 | ||
c12784c3 | 376 | ret = init_control_block(cpu, control_block); |
f9751a60 | 377 | BUG_ON(ret < 0); |
1fe56551 DV |
378 | } |
379 | ||
380 | /* | |
381 | * The event array starts out as empty again and is extended | |
382 | * as normal when events are bound. The existing pages will | |
383 | * be reused. | |
384 | */ | |
385 | event_array_pages = 0; | |
386 | } | |
387 | ||
c12784c3 | 388 | static int evtchn_fifo_alloc_control_block(unsigned cpu) |
1fe56551 | 389 | { |
c12784c3 | 390 | void *control_block = NULL; |
1fe56551 DV |
391 | int ret = -ENOMEM; |
392 | ||
c12784c3 | 393 | control_block = (void *)__get_free_page(GFP_KERNEL); |
1fe56551 DV |
394 | if (control_block == NULL) |
395 | goto error; | |
396 | ||
c12784c3 | 397 | ret = init_control_block(cpu, control_block); |
1fe56551 DV |
398 | if (ret < 0) |
399 | goto error; | |
400 | ||
c12784c3 | 401 | per_cpu(cpu_control_block, cpu) = control_block; |
1fe56551 DV |
402 | |
403 | return 0; | |
404 | ||
405 | error: | |
c12784c3 | 406 | free_page((unsigned long)control_block); |
1fe56551 DV |
407 | return ret; |
408 | } | |
409 | ||
2c6ab3f4 | 410 | static int evtchn_fifo_percpu_init(unsigned int cpu) |
1fe56551 | 411 | { |
c8761e20 SAS |
412 | if (!per_cpu(cpu_control_block, cpu)) |
413 | return evtchn_fifo_alloc_control_block(cpu); | |
414 | return 0; | |
1fe56551 DV |
415 | } |
416 | ||
2c6ab3f4 | 417 | static int evtchn_fifo_percpu_deinit(unsigned int cpu) |
c8761e20 SAS |
418 | { |
419 | __evtchn_fifo_handle_events(cpu, true); | |
420 | return 0; | |
421 | } | |
1fe56551 | 422 | |
2c6ab3f4 JG |
423 | static const struct evtchn_ops evtchn_ops_fifo = { |
424 | .max_channels = evtchn_fifo_max_channels, | |
425 | .nr_channels = evtchn_fifo_nr_channels, | |
426 | .setup = evtchn_fifo_setup, | |
427 | .bind_to_cpu = evtchn_fifo_bind_to_cpu, | |
428 | .clear_pending = evtchn_fifo_clear_pending, | |
429 | .set_pending = evtchn_fifo_set_pending, | |
430 | .is_pending = evtchn_fifo_is_pending, | |
431 | .test_and_set_mask = evtchn_fifo_test_and_set_mask, | |
432 | .mask = evtchn_fifo_mask, | |
433 | .unmask = evtchn_fifo_unmask, | |
434 | .handle_events = evtchn_fifo_handle_events, | |
435 | .resume = evtchn_fifo_resume, | |
436 | .percpu_init = evtchn_fifo_percpu_init, | |
437 | .percpu_deinit = evtchn_fifo_percpu_deinit, | |
438 | }; | |
439 | ||
1fe56551 DV |
440 | int __init xen_evtchn_fifo_init(void) |
441 | { | |
22f12f0d | 442 | int cpu = smp_processor_id(); |
1fe56551 DV |
443 | int ret; |
444 | ||
c12784c3 | 445 | ret = evtchn_fifo_alloc_control_block(cpu); |
1fe56551 | 446 | if (ret < 0) |
22f12f0d | 447 | return ret; |
1fe56551 DV |
448 | |
449 | pr_info("Using FIFO-based ABI\n"); | |
450 | ||
451 | evtchn_ops = &evtchn_ops_fifo; | |
452 | ||
1fe56551 DV |
453 | return ret; |
454 | } |