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