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b2441318 | 1 | // SPDX-License-Identifier: GPL-2.0 |
9a489f45 DV |
2 | /* |
3 | * Xen event channels (2-level ABI) | |
4 | * | |
5 | * Jeremy Fitzhardinge <jeremy@xensource.com>, XenSource Inc, 2007 | |
6 | */ | |
7 | ||
8 | #define pr_fmt(fmt) "xen:" KBUILD_MODNAME ": " fmt | |
9 | ||
10 | #include <linux/linkage.h> | |
11 | #include <linux/interrupt.h> | |
12 | #include <linux/irq.h> | |
9a489f45 DV |
13 | |
14 | #include <asm/sync_bitops.h> | |
15 | #include <asm/xen/hypercall.h> | |
16 | #include <asm/xen/hypervisor.h> | |
17 | ||
18 | #include <xen/xen.h> | |
19 | #include <xen/xen-ops.h> | |
20 | #include <xen/events.h> | |
21 | #include <xen/interface/xen.h> | |
22 | #include <xen/interface/event_channel.h> | |
23 | ||
24 | #include "events_internal.h" | |
25 | ||
26 | /* | |
27 | * Note sizeof(xen_ulong_t) can be more than sizeof(unsigned long). Be | |
28 | * careful to only use bitops which allow for this (e.g | |
29 | * test_bit/find_first_bit and friends but not __ffs) and to pass | |
30 | * BITS_PER_EVTCHN_WORD as the bitmask length. | |
31 | */ | |
32 | #define BITS_PER_EVTCHN_WORD (sizeof(xen_ulong_t)*8) | |
33 | /* | |
34 | * Make a bitmask (i.e. unsigned long *) of a xen_ulong_t | |
35 | * array. Primarily to avoid long lines (hence the terse name). | |
36 | */ | |
37 | #define BM(x) (unsigned long *)(x) | |
38 | /* Find the first set bit in a evtchn mask */ | |
39 | #define EVTCHN_FIRST_BIT(w) find_first_bit(BM(&(w)), BITS_PER_EVTCHN_WORD) | |
40 | ||
25528213 PZ |
41 | #define EVTCHN_MASK_SIZE (EVTCHN_2L_NR_CHANNELS/BITS_PER_EVTCHN_WORD) |
42 | ||
43 | static DEFINE_PER_CPU(xen_ulong_t [EVTCHN_MASK_SIZE], cpu_evtchn_mask); | |
9a489f45 | 44 | |
d0b075ff DV |
45 | static unsigned evtchn_2l_max_channels(void) |
46 | { | |
bf2bbe07 | 47 | return EVTCHN_2L_NR_CHANNELS; |
d0b075ff DV |
48 | } |
49 | ||
9e77d96b JG |
50 | static void evtchn_2l_remove(evtchn_port_t evtchn, unsigned int cpu) |
51 | { | |
52 | clear_bit(evtchn, BM(per_cpu(cpu_evtchn_mask, cpu))); | |
53 | } | |
54 | ||
7e14cde1 JG |
55 | static void evtchn_2l_bind_to_cpu(evtchn_port_t evtchn, unsigned int cpu, |
56 | unsigned int old_cpu) | |
9a489f45 | 57 | { |
7e14cde1 JG |
58 | clear_bit(evtchn, BM(per_cpu(cpu_evtchn_mask, old_cpu))); |
59 | set_bit(evtchn, BM(per_cpu(cpu_evtchn_mask, cpu))); | |
9a489f45 DV |
60 | } |
61 | ||
0102e4ef | 62 | static void evtchn_2l_clear_pending(evtchn_port_t port) |
9a489f45 DV |
63 | { |
64 | struct shared_info *s = HYPERVISOR_shared_info; | |
65 | sync_clear_bit(port, BM(&s->evtchn_pending[0])); | |
66 | } | |
67 | ||
0102e4ef | 68 | static void evtchn_2l_set_pending(evtchn_port_t port) |
9a489f45 DV |
69 | { |
70 | struct shared_info *s = HYPERVISOR_shared_info; | |
71 | sync_set_bit(port, BM(&s->evtchn_pending[0])); | |
72 | } | |
73 | ||
0102e4ef | 74 | static bool evtchn_2l_is_pending(evtchn_port_t port) |
9a489f45 DV |
75 | { |
76 | struct shared_info *s = HYPERVISOR_shared_info; | |
77 | return sync_test_bit(port, BM(&s->evtchn_pending[0])); | |
78 | } | |
79 | ||
0102e4ef | 80 | static void evtchn_2l_mask(evtchn_port_t port) |
9a489f45 DV |
81 | { |
82 | struct shared_info *s = HYPERVISOR_shared_info; | |
83 | sync_set_bit(port, BM(&s->evtchn_mask[0])); | |
84 | } | |
85 | ||
0102e4ef | 86 | static void evtchn_2l_unmask(evtchn_port_t port) |
9a489f45 DV |
87 | { |
88 | struct shared_info *s = HYPERVISOR_shared_info; | |
89 | unsigned int cpu = get_cpu(); | |
90 | int do_hypercall = 0, evtchn_pending = 0; | |
91 | ||
92 | BUG_ON(!irqs_disabled()); | |
93 | ||
4d3fe31b JG |
94 | smp_wmb(); /* All writes before unmask must be visible. */ |
95 | ||
9a489f45 DV |
96 | if (unlikely((cpu != cpu_from_evtchn(port)))) |
97 | do_hypercall = 1; | |
98 | else { | |
99 | /* | |
100 | * Need to clear the mask before checking pending to | |
101 | * avoid a race with an event becoming pending. | |
102 | * | |
103 | * EVTCHNOP_unmask will only trigger an upcall if the | |
104 | * mask bit was set, so if a hypercall is needed | |
105 | * remask the event. | |
106 | */ | |
107 | sync_clear_bit(port, BM(&s->evtchn_mask[0])); | |
108 | evtchn_pending = sync_test_bit(port, BM(&s->evtchn_pending[0])); | |
109 | ||
110 | if (unlikely(evtchn_pending && xen_hvm_domain())) { | |
111 | sync_set_bit(port, BM(&s->evtchn_mask[0])); | |
112 | do_hypercall = 1; | |
113 | } | |
114 | } | |
115 | ||
116 | /* Slow path (hypercall) if this is a non-local port or if this is | |
117 | * an hvm domain and an event is pending (hvm domains don't have | |
118 | * their own implementation of irq_enable). */ | |
119 | if (do_hypercall) { | |
120 | struct evtchn_unmask unmask = { .port = port }; | |
121 | (void)HYPERVISOR_event_channel_op(EVTCHNOP_unmask, &unmask); | |
122 | } else { | |
123 | struct vcpu_info *vcpu_info = __this_cpu_read(xen_vcpu); | |
124 | ||
125 | /* | |
126 | * The following is basically the equivalent of | |
127 | * 'hw_resend_irq'. Just like a real IO-APIC we 'lose | |
128 | * the interrupt edge' if the channel is masked. | |
129 | */ | |
130 | if (evtchn_pending && | |
131 | !sync_test_and_set_bit(port / BITS_PER_EVTCHN_WORD, | |
132 | BM(&vcpu_info->evtchn_pending_sel))) | |
133 | vcpu_info->evtchn_upcall_pending = 1; | |
134 | } | |
135 | ||
136 | put_cpu(); | |
137 | } | |
138 | ||
139 | static DEFINE_PER_CPU(unsigned int, current_word_idx); | |
140 | static DEFINE_PER_CPU(unsigned int, current_bit_idx); | |
141 | ||
142 | /* | |
143 | * Mask out the i least significant bits of w | |
144 | */ | |
145 | #define MASK_LSBS(w, i) (w & ((~((xen_ulong_t)0UL)) << i)) | |
146 | ||
147 | static inline xen_ulong_t active_evtchns(unsigned int cpu, | |
148 | struct shared_info *sh, | |
149 | unsigned int idx) | |
150 | { | |
151 | return sh->evtchn_pending[idx] & | |
152 | per_cpu(cpu_evtchn_mask, cpu)[idx] & | |
153 | ~sh->evtchn_mask[idx]; | |
154 | } | |
155 | ||
156 | /* | |
157 | * Search the CPU's pending events bitmasks. For each one found, map | |
158 | * the event number to an irq, and feed it into do_IRQ() for handling. | |
159 | * | |
160 | * Xen uses a two-level bitmap to speed searching. The first level is | |
161 | * a bitset of words which contain pending event bits. The second | |
162 | * level is a bitset of pending events themselves. | |
163 | */ | |
e99502f7 | 164 | static void evtchn_2l_handle_events(unsigned cpu, struct evtchn_loop_ctrl *ctrl) |
9a489f45 DV |
165 | { |
166 | int irq; | |
167 | xen_ulong_t pending_words; | |
168 | xen_ulong_t pending_bits; | |
169 | int start_word_idx, start_bit_idx; | |
170 | int word_idx, bit_idx; | |
171 | int i; | |
9a489f45 DV |
172 | struct shared_info *s = HYPERVISOR_shared_info; |
173 | struct vcpu_info *vcpu_info = __this_cpu_read(xen_vcpu); | |
68646451 | 174 | evtchn_port_t evtchn; |
9a489f45 DV |
175 | |
176 | /* Timer interrupt has highest priority. */ | |
68646451 | 177 | irq = irq_evtchn_from_virq(cpu, VIRQ_TIMER, &evtchn); |
9a489f45 | 178 | if (irq != -1) { |
9a489f45 DV |
179 | word_idx = evtchn / BITS_PER_LONG; |
180 | bit_idx = evtchn % BITS_PER_LONG; | |
589d03e9 TG |
181 | if (active_evtchns(cpu, s, word_idx) & (1ULL << bit_idx)) |
182 | generic_handle_irq(irq); | |
9a489f45 DV |
183 | } |
184 | ||
185 | /* | |
186 | * Master flag must be cleared /before/ clearing | |
187 | * selector flag. xchg_xen_ulong must contain an | |
188 | * appropriate barrier. | |
189 | */ | |
190 | pending_words = xchg_xen_ulong(&vcpu_info->evtchn_pending_sel, 0); | |
191 | ||
192 | start_word_idx = __this_cpu_read(current_word_idx); | |
193 | start_bit_idx = __this_cpu_read(current_bit_idx); | |
194 | ||
195 | word_idx = start_word_idx; | |
196 | ||
197 | for (i = 0; pending_words != 0; i++) { | |
198 | xen_ulong_t words; | |
199 | ||
200 | words = MASK_LSBS(pending_words, word_idx); | |
201 | ||
202 | /* | |
203 | * If we masked out all events, wrap to beginning. | |
204 | */ | |
205 | if (words == 0) { | |
206 | word_idx = 0; | |
207 | bit_idx = 0; | |
208 | continue; | |
209 | } | |
210 | word_idx = EVTCHN_FIRST_BIT(words); | |
211 | ||
212 | pending_bits = active_evtchns(cpu, s, word_idx); | |
213 | bit_idx = 0; /* usually scan entire word from start */ | |
214 | /* | |
215 | * We scan the starting word in two parts. | |
216 | * | |
217 | * 1st time: start in the middle, scanning the | |
218 | * upper bits. | |
219 | * | |
220 | * 2nd time: scan the whole word (not just the | |
221 | * parts skipped in the first pass) -- if an | |
222 | * event in the previously scanned bits is | |
223 | * pending again it would just be scanned on | |
224 | * the next loop anyway. | |
225 | */ | |
226 | if (word_idx == start_word_idx) { | |
227 | if (i == 0) | |
228 | bit_idx = start_bit_idx; | |
229 | } | |
230 | ||
231 | do { | |
232 | xen_ulong_t bits; | |
0102e4ef | 233 | evtchn_port_t port; |
9a489f45 DV |
234 | |
235 | bits = MASK_LSBS(pending_bits, bit_idx); | |
236 | ||
237 | /* If we masked out all events, move on. */ | |
238 | if (bits == 0) | |
239 | break; | |
240 | ||
241 | bit_idx = EVTCHN_FIRST_BIT(bits); | |
242 | ||
243 | /* Process port. */ | |
244 | port = (word_idx * BITS_PER_EVTCHN_WORD) + bit_idx; | |
e99502f7 | 245 | handle_irq_for_port(port, ctrl); |
9a489f45 DV |
246 | |
247 | bit_idx = (bit_idx + 1) % BITS_PER_EVTCHN_WORD; | |
248 | ||
249 | /* Next caller starts at last processed + 1 */ | |
250 | __this_cpu_write(current_word_idx, | |
251 | bit_idx ? word_idx : | |
252 | (word_idx+1) % BITS_PER_EVTCHN_WORD); | |
253 | __this_cpu_write(current_bit_idx, bit_idx); | |
254 | } while (bit_idx != 0); | |
255 | ||
256 | /* Scan start_l1i twice; all others once. */ | |
257 | if ((word_idx != start_word_idx) || (i != 0)) | |
258 | pending_words &= ~(1UL << word_idx); | |
259 | ||
260 | word_idx = (word_idx + 1) % BITS_PER_EVTCHN_WORD; | |
261 | } | |
262 | } | |
263 | ||
264 | irqreturn_t xen_debug_interrupt(int irq, void *dev_id) | |
265 | { | |
266 | struct shared_info *sh = HYPERVISOR_shared_info; | |
267 | int cpu = smp_processor_id(); | |
268 | xen_ulong_t *cpu_evtchn = per_cpu(cpu_evtchn_mask, cpu); | |
269 | int i; | |
270 | unsigned long flags; | |
271 | static DEFINE_SPINLOCK(debug_lock); | |
272 | struct vcpu_info *v; | |
273 | ||
274 | spin_lock_irqsave(&debug_lock, flags); | |
275 | ||
276 | printk("\nvcpu %d\n ", cpu); | |
277 | ||
278 | for_each_online_cpu(i) { | |
279 | int pending; | |
280 | v = per_cpu(xen_vcpu, i); | |
281 | pending = (get_irq_regs() && i == cpu) | |
282 | ? xen_irqs_disabled(get_irq_regs()) | |
283 | : v->evtchn_upcall_mask; | |
284 | printk("%d: masked=%d pending=%d event_sel %0*"PRI_xen_ulong"\n ", i, | |
285 | pending, v->evtchn_upcall_pending, | |
286 | (int)(sizeof(v->evtchn_pending_sel)*2), | |
287 | v->evtchn_pending_sel); | |
288 | } | |
289 | v = per_cpu(xen_vcpu, cpu); | |
290 | ||
291 | printk("\npending:\n "); | |
292 | for (i = ARRAY_SIZE(sh->evtchn_pending)-1; i >= 0; i--) | |
293 | printk("%0*"PRI_xen_ulong"%s", | |
294 | (int)sizeof(sh->evtchn_pending[0])*2, | |
295 | sh->evtchn_pending[i], | |
296 | i % 8 == 0 ? "\n " : " "); | |
297 | printk("\nglobal mask:\n "); | |
298 | for (i = ARRAY_SIZE(sh->evtchn_mask)-1; i >= 0; i--) | |
299 | printk("%0*"PRI_xen_ulong"%s", | |
300 | (int)(sizeof(sh->evtchn_mask[0])*2), | |
301 | sh->evtchn_mask[i], | |
302 | i % 8 == 0 ? "\n " : " "); | |
303 | ||
304 | printk("\nglobally unmasked:\n "); | |
305 | for (i = ARRAY_SIZE(sh->evtchn_mask)-1; i >= 0; i--) | |
306 | printk("%0*"PRI_xen_ulong"%s", | |
307 | (int)(sizeof(sh->evtchn_mask[0])*2), | |
308 | sh->evtchn_pending[i] & ~sh->evtchn_mask[i], | |
309 | i % 8 == 0 ? "\n " : " "); | |
310 | ||
311 | printk("\nlocal cpu%d mask:\n ", cpu); | |
bf2bbe07 | 312 | for (i = (EVTCHN_2L_NR_CHANNELS/BITS_PER_EVTCHN_WORD)-1; i >= 0; i--) |
9a489f45 DV |
313 | printk("%0*"PRI_xen_ulong"%s", (int)(sizeof(cpu_evtchn[0])*2), |
314 | cpu_evtchn[i], | |
315 | i % 8 == 0 ? "\n " : " "); | |
316 | ||
317 | printk("\nlocally unmasked:\n "); | |
318 | for (i = ARRAY_SIZE(sh->evtchn_mask)-1; i >= 0; i--) { | |
319 | xen_ulong_t pending = sh->evtchn_pending[i] | |
320 | & ~sh->evtchn_mask[i] | |
321 | & cpu_evtchn[i]; | |
322 | printk("%0*"PRI_xen_ulong"%s", | |
323 | (int)(sizeof(sh->evtchn_mask[0])*2), | |
324 | pending, i % 8 == 0 ? "\n " : " "); | |
325 | } | |
326 | ||
327 | printk("\npending list:\n"); | |
bf2bbe07 | 328 | for (i = 0; i < EVTCHN_2L_NR_CHANNELS; i++) { |
9a489f45 DV |
329 | if (sync_test_bit(i, BM(sh->evtchn_pending))) { |
330 | int word_idx = i / BITS_PER_EVTCHN_WORD; | |
68646451 | 331 | printk(" %d: event %d -> irq %u%s%s%s\n", |
9a489f45 | 332 | cpu_from_evtchn(i), i, |
68646451 | 333 | irq_from_evtchn(i), |
9a489f45 DV |
334 | sync_test_bit(word_idx, BM(&v->evtchn_pending_sel)) |
335 | ? "" : " l2-clear", | |
336 | !sync_test_bit(i, BM(sh->evtchn_mask)) | |
337 | ? "" : " globally-masked", | |
338 | sync_test_bit(i, BM(cpu_evtchn)) | |
339 | ? "" : " locally-masked"); | |
340 | } | |
341 | } | |
342 | ||
343 | spin_unlock_irqrestore(&debug_lock, flags); | |
344 | ||
345 | return IRQ_HANDLED; | |
346 | } | |
ab9a1cca | 347 | |
5cec9883 BO |
348 | static void evtchn_2l_resume(void) |
349 | { | |
350 | int i; | |
351 | ||
352 | for_each_online_cpu(i) | |
353 | memset(per_cpu(cpu_evtchn_mask, i), 0, sizeof(xen_ulong_t) * | |
354 | EVTCHN_2L_NR_CHANNELS/BITS_PER_EVTCHN_WORD); | |
355 | } | |
356 | ||
9e77d96b JG |
357 | static int evtchn_2l_percpu_deinit(unsigned int cpu) |
358 | { | |
359 | memset(per_cpu(cpu_evtchn_mask, cpu), 0, sizeof(xen_ulong_t) * | |
360 | EVTCHN_2L_NR_CHANNELS/BITS_PER_EVTCHN_WORD); | |
361 | ||
362 | return 0; | |
363 | } | |
364 | ||
ab9a1cca | 365 | static const struct evtchn_ops evtchn_ops_2l = { |
d0b075ff DV |
366 | .max_channels = evtchn_2l_max_channels, |
367 | .nr_channels = evtchn_2l_max_channels, | |
9e77d96b | 368 | .remove = evtchn_2l_remove, |
ab9a1cca DV |
369 | .bind_to_cpu = evtchn_2l_bind_to_cpu, |
370 | .clear_pending = evtchn_2l_clear_pending, | |
371 | .set_pending = evtchn_2l_set_pending, | |
372 | .is_pending = evtchn_2l_is_pending, | |
ab9a1cca DV |
373 | .mask = evtchn_2l_mask, |
374 | .unmask = evtchn_2l_unmask, | |
375 | .handle_events = evtchn_2l_handle_events, | |
5cec9883 | 376 | .resume = evtchn_2l_resume, |
9e77d96b | 377 | .percpu_deinit = evtchn_2l_percpu_deinit, |
ab9a1cca DV |
378 | }; |
379 | ||
380 | void __init xen_evtchn_2l_init(void) | |
381 | { | |
382 | pr_info("Using 2-level ABI\n"); | |
383 | evtchn_ops = &evtchn_ops_2l; | |
384 | } |