Commit | Line | Data |
---|---|---|
15c84731 JF |
1 | /* |
2 | * Xen time implementation. | |
3 | * | |
4 | * This is implemented in terms of a clocksource driver which uses | |
5 | * the hypervisor clock as a nanosecond timebase, and a clockevent | |
6 | * driver which uses the hypervisor's timer mechanism. | |
7 | * | |
8 | * Jeremy Fitzhardinge <jeremy@xensource.com>, XenSource Inc, 2007 | |
9 | */ | |
10 | #include <linux/kernel.h> | |
11 | #include <linux/interrupt.h> | |
12 | #include <linux/clocksource.h> | |
13 | #include <linux/clockchips.h> | |
f91a8b44 | 14 | #include <linux/kernel_stat.h> |
f595ec96 | 15 | #include <linux/math64.h> |
5a0e3ad6 | 16 | #include <linux/gfp.h> |
15c84731 | 17 | |
1c7b67f7 | 18 | #include <asm/pvclock.h> |
15c84731 JF |
19 | #include <asm/xen/hypervisor.h> |
20 | #include <asm/xen/hypercall.h> | |
21 | ||
22 | #include <xen/events.h> | |
409771d2 | 23 | #include <xen/features.h> |
15c84731 JF |
24 | #include <xen/interface/xen.h> |
25 | #include <xen/interface/vcpu.h> | |
26 | ||
27 | #include "xen-ops.h" | |
28 | ||
29 | #define XEN_SHIFT 22 | |
30 | ||
31 | /* Xen may fire a timer up to this many ns early */ | |
32 | #define TIMER_SLOP 100000 | |
f91a8b44 | 33 | #define NS_PER_TICK (1000000000LL / HZ) |
15c84731 | 34 | |
f91a8b44 | 35 | /* runstate info updated by Xen */ |
c6e22f9e | 36 | static DEFINE_PER_CPU(struct vcpu_runstate_info, xen_runstate); |
f91a8b44 JF |
37 | |
38 | /* snapshots of runstate info */ | |
c6e22f9e | 39 | static DEFINE_PER_CPU(struct vcpu_runstate_info, xen_runstate_snapshot); |
f91a8b44 JF |
40 | |
41 | /* unused ns of stolen and blocked time */ | |
c6e22f9e TH |
42 | static DEFINE_PER_CPU(u64, xen_residual_stolen); |
43 | static DEFINE_PER_CPU(u64, xen_residual_blocked); | |
f91a8b44 JF |
44 | |
45 | /* return an consistent snapshot of 64-bit time/counter value */ | |
46 | static u64 get64(const u64 *p) | |
47 | { | |
48 | u64 ret; | |
49 | ||
50 | if (BITS_PER_LONG < 64) { | |
51 | u32 *p32 = (u32 *)p; | |
52 | u32 h, l; | |
53 | ||
54 | /* | |
55 | * Read high then low, and then make sure high is | |
56 | * still the same; this will only loop if low wraps | |
57 | * and carries into high. | |
58 | * XXX some clean way to make this endian-proof? | |
59 | */ | |
60 | do { | |
61 | h = p32[1]; | |
62 | barrier(); | |
63 | l = p32[0]; | |
64 | barrier(); | |
65 | } while (p32[1] != h); | |
66 | ||
67 | ret = (((u64)h) << 32) | l; | |
68 | } else | |
69 | ret = *p; | |
70 | ||
71 | return ret; | |
72 | } | |
73 | ||
74 | /* | |
75 | * Runstate accounting | |
76 | */ | |
77 | static void get_runstate_snapshot(struct vcpu_runstate_info *res) | |
78 | { | |
79 | u64 state_time; | |
80 | struct vcpu_runstate_info *state; | |
81 | ||
f120f13e | 82 | BUG_ON(preemptible()); |
f91a8b44 | 83 | |
c6e22f9e | 84 | state = &__get_cpu_var(xen_runstate); |
f91a8b44 JF |
85 | |
86 | /* | |
87 | * The runstate info is always updated by the hypervisor on | |
88 | * the current CPU, so there's no need to use anything | |
89 | * stronger than a compiler barrier when fetching it. | |
90 | */ | |
91 | do { | |
92 | state_time = get64(&state->state_entry_time); | |
93 | barrier(); | |
94 | *res = *state; | |
95 | barrier(); | |
96 | } while (get64(&state->state_entry_time) != state_time); | |
f91a8b44 JF |
97 | } |
98 | ||
f0d73394 JF |
99 | /* return true when a vcpu could run but has no real cpu to run on */ |
100 | bool xen_vcpu_stolen(int vcpu) | |
101 | { | |
c6e22f9e | 102 | return per_cpu(xen_runstate, vcpu).state == RUNSTATE_runnable; |
f0d73394 JF |
103 | } |
104 | ||
be012920 | 105 | void xen_setup_runstate_info(int cpu) |
f91a8b44 JF |
106 | { |
107 | struct vcpu_register_runstate_memory_area area; | |
108 | ||
c6e22f9e | 109 | area.addr.v = &per_cpu(xen_runstate, cpu); |
f91a8b44 JF |
110 | |
111 | if (HYPERVISOR_vcpu_op(VCPUOP_register_runstate_memory_area, | |
112 | cpu, &area)) | |
113 | BUG(); | |
114 | } | |
115 | ||
116 | static void do_stolen_accounting(void) | |
117 | { | |
118 | struct vcpu_runstate_info state; | |
119 | struct vcpu_runstate_info *snap; | |
120 | s64 blocked, runnable, offline, stolen; | |
121 | cputime_t ticks; | |
122 | ||
123 | get_runstate_snapshot(&state); | |
124 | ||
125 | WARN_ON(state.state != RUNSTATE_running); | |
126 | ||
c6e22f9e | 127 | snap = &__get_cpu_var(xen_runstate_snapshot); |
f91a8b44 JF |
128 | |
129 | /* work out how much time the VCPU has not been runn*ing* */ | |
130 | blocked = state.time[RUNSTATE_blocked] - snap->time[RUNSTATE_blocked]; | |
131 | runnable = state.time[RUNSTATE_runnable] - snap->time[RUNSTATE_runnable]; | |
132 | offline = state.time[RUNSTATE_offline] - snap->time[RUNSTATE_offline]; | |
133 | ||
134 | *snap = state; | |
135 | ||
136 | /* Add the appropriate number of ticks of stolen time, | |
79741dd3 | 137 | including any left-overs from last time. */ |
c6e22f9e | 138 | stolen = runnable + offline + __get_cpu_var(xen_residual_stolen); |
f91a8b44 JF |
139 | |
140 | if (stolen < 0) | |
141 | stolen = 0; | |
142 | ||
f595ec96 | 143 | ticks = iter_div_u64_rem(stolen, NS_PER_TICK, &stolen); |
c6e22f9e | 144 | __get_cpu_var(xen_residual_stolen) = stolen; |
79741dd3 | 145 | account_steal_ticks(ticks); |
f91a8b44 JF |
146 | |
147 | /* Add the appropriate number of ticks of blocked time, | |
79741dd3 | 148 | including any left-overs from last time. */ |
c6e22f9e | 149 | blocked += __get_cpu_var(xen_residual_blocked); |
f91a8b44 JF |
150 | |
151 | if (blocked < 0) | |
152 | blocked = 0; | |
153 | ||
f595ec96 | 154 | ticks = iter_div_u64_rem(blocked, NS_PER_TICK, &blocked); |
c6e22f9e | 155 | __get_cpu_var(xen_residual_blocked) = blocked; |
79741dd3 | 156 | account_idle_ticks(ticks); |
f91a8b44 JF |
157 | } |
158 | ||
e93ef949 | 159 | /* Get the TSC speed from Xen */ |
409771d2 | 160 | static unsigned long xen_tsc_khz(void) |
15c84731 | 161 | { |
3807f345 | 162 | struct pvclock_vcpu_time_info *info = |
15c84731 JF |
163 | &HYPERVISOR_shared_info->vcpu_info[0].time; |
164 | ||
3807f345 | 165 | return pvclock_tsc_khz(info); |
15c84731 JF |
166 | } |
167 | ||
ee7686bc | 168 | cycle_t xen_clocksource_read(void) |
15c84731 | 169 | { |
1c7b67f7 | 170 | struct pvclock_vcpu_time_info *src; |
15c84731 | 171 | cycle_t ret; |
15c84731 | 172 | |
1c7b67f7 GH |
173 | src = &get_cpu_var(xen_vcpu)->time; |
174 | ret = pvclock_clocksource_read(src); | |
175 | put_cpu_var(xen_vcpu); | |
15c84731 JF |
176 | return ret; |
177 | } | |
178 | ||
8e19608e MD |
179 | static cycle_t xen_clocksource_get_cycles(struct clocksource *cs) |
180 | { | |
181 | return xen_clocksource_read(); | |
182 | } | |
183 | ||
15c84731 JF |
184 | static void xen_read_wallclock(struct timespec *ts) |
185 | { | |
1c7b67f7 GH |
186 | struct shared_info *s = HYPERVISOR_shared_info; |
187 | struct pvclock_wall_clock *wall_clock = &(s->wc); | |
188 | struct pvclock_vcpu_time_info *vcpu_time; | |
15c84731 | 189 | |
1c7b67f7 GH |
190 | vcpu_time = &get_cpu_var(xen_vcpu)->time; |
191 | pvclock_read_wallclock(wall_clock, vcpu_time, ts); | |
192 | put_cpu_var(xen_vcpu); | |
15c84731 JF |
193 | } |
194 | ||
409771d2 | 195 | static unsigned long xen_get_wallclock(void) |
15c84731 JF |
196 | { |
197 | struct timespec ts; | |
198 | ||
199 | xen_read_wallclock(&ts); | |
15c84731 JF |
200 | return ts.tv_sec; |
201 | } | |
202 | ||
409771d2 | 203 | static int xen_set_wallclock(unsigned long now) |
15c84731 JF |
204 | { |
205 | /* do nothing for domU */ | |
206 | return -1; | |
207 | } | |
208 | ||
209 | static struct clocksource xen_clocksource __read_mostly = { | |
210 | .name = "xen", | |
211 | .rating = 400, | |
8e19608e | 212 | .read = xen_clocksource_get_cycles, |
15c84731 JF |
213 | .mask = ~0, |
214 | .mult = 1<<XEN_SHIFT, /* time directly in nanoseconds */ | |
215 | .shift = XEN_SHIFT, | |
216 | .flags = CLOCK_SOURCE_IS_CONTINUOUS, | |
217 | }; | |
218 | ||
219 | /* | |
220 | Xen clockevent implementation | |
221 | ||
222 | Xen has two clockevent implementations: | |
223 | ||
224 | The old timer_op one works with all released versions of Xen prior | |
225 | to version 3.0.4. This version of the hypervisor provides a | |
226 | single-shot timer with nanosecond resolution. However, sharing the | |
227 | same event channel is a 100Hz tick which is delivered while the | |
228 | vcpu is running. We don't care about or use this tick, but it will | |
229 | cause the core time code to think the timer fired too soon, and | |
230 | will end up resetting it each time. It could be filtered, but | |
231 | doing so has complications when the ktime clocksource is not yet | |
232 | the xen clocksource (ie, at boot time). | |
233 | ||
234 | The new vcpu_op-based timer interface allows the tick timer period | |
235 | to be changed or turned off. The tick timer is not useful as a | |
236 | periodic timer because events are only delivered to running vcpus. | |
237 | The one-shot timer can report when a timeout is in the past, so | |
238 | set_next_event is capable of returning -ETIME when appropriate. | |
239 | This interface is used when available. | |
240 | */ | |
241 | ||
242 | ||
243 | /* | |
244 | Get a hypervisor absolute time. In theory we could maintain an | |
245 | offset between the kernel's time and the hypervisor's time, and | |
246 | apply that to a kernel's absolute timeout. Unfortunately the | |
247 | hypervisor and kernel times can drift even if the kernel is using | |
248 | the Xen clocksource, because ntp can warp the kernel's clocksource. | |
249 | */ | |
250 | static s64 get_abs_timeout(unsigned long delta) | |
251 | { | |
252 | return xen_clocksource_read() + delta; | |
253 | } | |
254 | ||
255 | static void xen_timerop_set_mode(enum clock_event_mode mode, | |
256 | struct clock_event_device *evt) | |
257 | { | |
258 | switch (mode) { | |
259 | case CLOCK_EVT_MODE_PERIODIC: | |
260 | /* unsupported */ | |
261 | WARN_ON(1); | |
262 | break; | |
263 | ||
264 | case CLOCK_EVT_MODE_ONESHOT: | |
18de5bc4 | 265 | case CLOCK_EVT_MODE_RESUME: |
15c84731 JF |
266 | break; |
267 | ||
268 | case CLOCK_EVT_MODE_UNUSED: | |
269 | case CLOCK_EVT_MODE_SHUTDOWN: | |
270 | HYPERVISOR_set_timer_op(0); /* cancel timeout */ | |
271 | break; | |
272 | } | |
273 | } | |
274 | ||
275 | static int xen_timerop_set_next_event(unsigned long delta, | |
276 | struct clock_event_device *evt) | |
277 | { | |
278 | WARN_ON(evt->mode != CLOCK_EVT_MODE_ONESHOT); | |
279 | ||
280 | if (HYPERVISOR_set_timer_op(get_abs_timeout(delta)) < 0) | |
281 | BUG(); | |
282 | ||
283 | /* We may have missed the deadline, but there's no real way of | |
284 | knowing for sure. If the event was in the past, then we'll | |
285 | get an immediate interrupt. */ | |
286 | ||
287 | return 0; | |
288 | } | |
289 | ||
290 | static const struct clock_event_device xen_timerop_clockevent = { | |
291 | .name = "xen", | |
292 | .features = CLOCK_EVT_FEAT_ONESHOT, | |
293 | ||
294 | .max_delta_ns = 0xffffffff, | |
295 | .min_delta_ns = TIMER_SLOP, | |
296 | ||
297 | .mult = 1, | |
298 | .shift = 0, | |
299 | .rating = 500, | |
300 | ||
301 | .set_mode = xen_timerop_set_mode, | |
302 | .set_next_event = xen_timerop_set_next_event, | |
303 | }; | |
304 | ||
305 | ||
306 | ||
307 | static void xen_vcpuop_set_mode(enum clock_event_mode mode, | |
308 | struct clock_event_device *evt) | |
309 | { | |
310 | int cpu = smp_processor_id(); | |
311 | ||
312 | switch (mode) { | |
313 | case CLOCK_EVT_MODE_PERIODIC: | |
314 | WARN_ON(1); /* unsupported */ | |
315 | break; | |
316 | ||
317 | case CLOCK_EVT_MODE_ONESHOT: | |
318 | if (HYPERVISOR_vcpu_op(VCPUOP_stop_periodic_timer, cpu, NULL)) | |
319 | BUG(); | |
320 | break; | |
321 | ||
322 | case CLOCK_EVT_MODE_UNUSED: | |
323 | case CLOCK_EVT_MODE_SHUTDOWN: | |
324 | if (HYPERVISOR_vcpu_op(VCPUOP_stop_singleshot_timer, cpu, NULL) || | |
325 | HYPERVISOR_vcpu_op(VCPUOP_stop_periodic_timer, cpu, NULL)) | |
326 | BUG(); | |
327 | break; | |
18de5bc4 TG |
328 | case CLOCK_EVT_MODE_RESUME: |
329 | break; | |
15c84731 JF |
330 | } |
331 | } | |
332 | ||
333 | static int xen_vcpuop_set_next_event(unsigned long delta, | |
334 | struct clock_event_device *evt) | |
335 | { | |
336 | int cpu = smp_processor_id(); | |
337 | struct vcpu_set_singleshot_timer single; | |
338 | int ret; | |
339 | ||
340 | WARN_ON(evt->mode != CLOCK_EVT_MODE_ONESHOT); | |
341 | ||
342 | single.timeout_abs_ns = get_abs_timeout(delta); | |
343 | single.flags = VCPU_SSHOTTMR_future; | |
344 | ||
345 | ret = HYPERVISOR_vcpu_op(VCPUOP_set_singleshot_timer, cpu, &single); | |
346 | ||
347 | BUG_ON(ret != 0 && ret != -ETIME); | |
348 | ||
349 | return ret; | |
350 | } | |
351 | ||
352 | static const struct clock_event_device xen_vcpuop_clockevent = { | |
353 | .name = "xen", | |
354 | .features = CLOCK_EVT_FEAT_ONESHOT, | |
355 | ||
356 | .max_delta_ns = 0xffffffff, | |
357 | .min_delta_ns = TIMER_SLOP, | |
358 | ||
359 | .mult = 1, | |
360 | .shift = 0, | |
361 | .rating = 500, | |
362 | ||
363 | .set_mode = xen_vcpuop_set_mode, | |
364 | .set_next_event = xen_vcpuop_set_next_event, | |
365 | }; | |
366 | ||
367 | static const struct clock_event_device *xen_clockevent = | |
368 | &xen_timerop_clockevent; | |
369 | static DEFINE_PER_CPU(struct clock_event_device, xen_clock_events); | |
370 | ||
371 | static irqreturn_t xen_timer_interrupt(int irq, void *dev_id) | |
372 | { | |
373 | struct clock_event_device *evt = &__get_cpu_var(xen_clock_events); | |
374 | irqreturn_t ret; | |
375 | ||
376 | ret = IRQ_NONE; | |
377 | if (evt->event_handler) { | |
378 | evt->event_handler(evt); | |
379 | ret = IRQ_HANDLED; | |
380 | } | |
381 | ||
f91a8b44 JF |
382 | do_stolen_accounting(); |
383 | ||
15c84731 JF |
384 | return ret; |
385 | } | |
386 | ||
f87e4cac | 387 | void xen_setup_timer(int cpu) |
15c84731 JF |
388 | { |
389 | const char *name; | |
390 | struct clock_event_device *evt; | |
391 | int irq; | |
392 | ||
393 | printk(KERN_INFO "installing Xen timer for CPU %d\n", cpu); | |
394 | ||
395 | name = kasprintf(GFP_KERNEL, "timer%d", cpu); | |
396 | if (!name) | |
397 | name = "<timer kasprintf failed>"; | |
398 | ||
399 | irq = bind_virq_to_irqhandler(VIRQ_TIMER, cpu, xen_timer_interrupt, | |
f350c792 | 400 | IRQF_DISABLED|IRQF_PERCPU|IRQF_NOBALANCING|IRQF_TIMER, |
15c84731 JF |
401 | name, NULL); |
402 | ||
f87e4cac | 403 | evt = &per_cpu(xen_clock_events, cpu); |
15c84731 JF |
404 | memcpy(evt, xen_clockevent, sizeof(*evt)); |
405 | ||
320ab2b0 | 406 | evt->cpumask = cpumask_of(cpu); |
15c84731 | 407 | evt->irq = irq; |
f87e4cac JF |
408 | } |
409 | ||
d68d82af AN |
410 | void xen_teardown_timer(int cpu) |
411 | { | |
412 | struct clock_event_device *evt; | |
413 | BUG_ON(cpu == 0); | |
414 | evt = &per_cpu(xen_clock_events, cpu); | |
415 | unbind_from_irqhandler(evt->irq, NULL); | |
416 | } | |
417 | ||
f87e4cac JF |
418 | void xen_setup_cpu_clockevents(void) |
419 | { | |
420 | BUG_ON(preemptible()); | |
f91a8b44 | 421 | |
f87e4cac | 422 | clockevents_register_device(&__get_cpu_var(xen_clock_events)); |
15c84731 JF |
423 | } |
424 | ||
d07af1f0 JF |
425 | void xen_timer_resume(void) |
426 | { | |
427 | int cpu; | |
428 | ||
429 | if (xen_clockevent != &xen_vcpuop_clockevent) | |
430 | return; | |
431 | ||
432 | for_each_online_cpu(cpu) { | |
433 | if (HYPERVISOR_vcpu_op(VCPUOP_stop_periodic_timer, cpu, NULL)) | |
434 | BUG(); | |
435 | } | |
436 | } | |
437 | ||
409771d2 | 438 | static const struct pv_time_ops xen_time_ops __initdata = { |
ca50a5f3 | 439 | .sched_clock = xen_clocksource_read, |
409771d2 SS |
440 | }; |
441 | ||
442 | static __init void xen_time_init(void) | |
15c84731 JF |
443 | { |
444 | int cpu = smp_processor_id(); | |
c4507257 | 445 | struct timespec tp; |
15c84731 | 446 | |
15c84731 JF |
447 | clocksource_register(&xen_clocksource); |
448 | ||
449 | if (HYPERVISOR_vcpu_op(VCPUOP_stop_periodic_timer, cpu, NULL) == 0) { | |
f91a8b44 | 450 | /* Successfully turned off 100Hz tick, so we have the |
15c84731 JF |
451 | vcpuop-based timer interface */ |
452 | printk(KERN_DEBUG "Xen: using vcpuop timer interface\n"); | |
453 | xen_clockevent = &xen_vcpuop_clockevent; | |
454 | } | |
455 | ||
456 | /* Set initial system time with full resolution */ | |
c4507257 JS |
457 | xen_read_wallclock(&tp); |
458 | do_settimeofday(&tp); | |
15c84731 | 459 | |
404ee5b1 | 460 | setup_force_cpu_cap(X86_FEATURE_TSC); |
15c84731 | 461 | |
be012920 | 462 | xen_setup_runstate_info(cpu); |
15c84731 | 463 | xen_setup_timer(cpu); |
f87e4cac | 464 | xen_setup_cpu_clockevents(); |
15c84731 | 465 | } |
409771d2 SS |
466 | |
467 | __init void xen_init_time_ops(void) | |
468 | { | |
469 | pv_time_ops = xen_time_ops; | |
470 | ||
471 | x86_init.timers.timer_init = xen_time_init; | |
472 | x86_init.timers.setup_percpu_clockev = x86_init_noop; | |
473 | x86_cpuinit.setup_percpu_clockev = x86_init_noop; | |
474 | ||
475 | x86_platform.calibrate_tsc = xen_tsc_khz; | |
476 | x86_platform.get_wallclock = xen_get_wallclock; | |
477 | x86_platform.set_wallclock = xen_set_wallclock; | |
478 | } | |
479 | ||
ca65f9fc | 480 | #ifdef CONFIG_XEN_PVHVM |
409771d2 SS |
481 | static void xen_hvm_setup_cpu_clockevents(void) |
482 | { | |
483 | int cpu = smp_processor_id(); | |
484 | xen_setup_runstate_info(cpu); | |
485 | xen_setup_timer(cpu); | |
486 | xen_setup_cpu_clockevents(); | |
487 | } | |
488 | ||
489 | __init void xen_hvm_init_time_ops(void) | |
490 | { | |
491 | /* vector callback is needed otherwise we cannot receive interrupts | |
492 | * on cpu > 0 */ | |
493 | if (!xen_have_vector_callback && num_present_cpus() > 1) | |
494 | return; | |
495 | if (!xen_feature(XENFEAT_hvm_safe_pvclock)) { | |
496 | printk(KERN_INFO "Xen doesn't support pvclock on HVM," | |
497 | "disable pv timer\n"); | |
498 | return; | |
499 | } | |
500 | ||
501 | pv_time_ops = xen_time_ops; | |
502 | x86_init.timers.setup_percpu_clockev = xen_time_init; | |
503 | x86_cpuinit.setup_percpu_clockev = xen_hvm_setup_cpu_clockevents; | |
504 | ||
505 | x86_platform.calibrate_tsc = xen_tsc_khz; | |
506 | x86_platform.get_wallclock = xen_get_wallclock; | |
507 | x86_platform.set_wallclock = xen_set_wallclock; | |
508 | } | |
ca65f9fc | 509 | #endif |