summaryrefslogtreecommitdiffstats
path: root/virt/kvm/arm/arch_timer.c
blob: 32095fbb5d7ce2b367017955ace3ed1573fde395 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
/*
 * Copyright (C) 2012 ARM Ltd.
 * Author: Marc Zyngier <marc.zyngier@arm.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */

#include <linux/cpu.h>
#include <linux/of_irq.h>
#include <linux/kvm.h>
#include <linux/kvm_host.h>
#include <linux/interrupt.h>

#include <clocksource/arm_arch_timer.h>
#include <asm/arch_timer.h>

#include <kvm/arm_vgic.h>
#include <kvm/arm_arch_timer.h>

static struct timecounter *timecounter;
static struct workqueue_struct *wqueue;
static unsigned int host_vtimer_irq;

static cycle_t kvm_phys_timer_read(void)
{
	return timecounter->cc->read(timecounter->cc);
}

static bool timer_is_armed(struct arch_timer_cpu *timer)
{
	return timer->armed;
}

/* timer_arm: as in "arm the timer", not as in ARM the company */
static void timer_arm(struct arch_timer_cpu *timer, u64 ns)
{
	timer->armed = true;
	hrtimer_start(&timer->timer, ktime_add_ns(ktime_get(), ns),
		      HRTIMER_MODE_ABS);
}

static void timer_disarm(struct arch_timer_cpu *timer)
{
	if (timer_is_armed(timer)) {
		hrtimer_cancel(&timer->timer);
		cancel_work_sync(&timer->expired);
		timer->armed = false;
	}
}

static void kvm_timer_inject_irq(struct kvm_vcpu *vcpu)
{
	int ret;
	struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;

	kvm_vgic_set_phys_irq_active(timer->map, true);
	ret = kvm_vgic_inject_mapped_irq(vcpu->kvm, vcpu->vcpu_id,
					 timer->map,
					 timer->irq->level);
	WARN_ON(ret);
}

static irqreturn_t kvm_arch_timer_handler(int irq, void *dev_id)
{
	struct kvm_vcpu *vcpu = *(struct kvm_vcpu **)dev_id;

	/*
	 * We disable the timer in the world switch and let it be
	 * handled by kvm_timer_sync_hwstate(). Getting a timer
	 * interrupt at this point is a sure sign of some major
	 * breakage.
	 */
	pr_warn("Unexpected interrupt %d on vcpu %p\n", irq, vcpu);
	return IRQ_HANDLED;
}

/*
 * Work function for handling the backup timer that we schedule when a vcpu is
 * no longer running, but had a timer programmed to fire in the future.
 */
static void kvm_timer_inject_irq_work(struct work_struct *work)
{
	struct kvm_vcpu *vcpu;

	vcpu = container_of(work, struct kvm_vcpu, arch.timer_cpu.expired);
	vcpu->arch.timer_cpu.armed = false;

	/*
	 * If the vcpu is blocked we want to wake it up so that it will see
	 * the timer has expired when entering the guest.
	 */
	kvm_vcpu_kick(vcpu);
}

static enum hrtimer_restart kvm_timer_expire(struct hrtimer *hrt)
{
	struct arch_timer_cpu *timer;
	timer = container_of(hrt, struct arch_timer_cpu, timer);
	queue_work(wqueue, &timer->expired);
	return HRTIMER_NORESTART;
}

static bool kvm_timer_irq_can_fire(struct kvm_vcpu *vcpu)
{
	struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;

	return !(timer->cntv_ctl & ARCH_TIMER_CTRL_IT_MASK) &&
		(timer->cntv_ctl & ARCH_TIMER_CTRL_ENABLE) &&
		!kvm_vgic_get_phys_irq_active(timer->map);
}

bool kvm_timer_should_fire(struct kvm_vcpu *vcpu)
{
	struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
	cycle_t cval, now;

	if (!kvm_timer_irq_can_fire(vcpu))
		return false;

	cval = timer->cntv_cval;
	now = kvm_phys_timer_read() - vcpu->kvm->arch.timer.cntvoff;

	return cval <= now;
}

/*
 * Schedule the background timer before calling kvm_vcpu_block, so that this
 * thread is removed from its waitqueue and made runnable when there's a timer
 * interrupt to handle.
 */
void kvm_timer_schedule(struct kvm_vcpu *vcpu)
{
	struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
	u64 ns;
	cycle_t cval, now;

	BUG_ON(timer_is_armed(timer));

	/*
	 * No need to schedule a background timer if the guest timer has
	 * already expired, because kvm_vcpu_block will return before putting
	 * the thread to sleep.
	 */
	if (kvm_timer_should_fire(vcpu))
		return;

	/*
	 * If the timer is not capable of raising interrupts (disabled or
	 * masked), then there's no more work for us to do.
	 */
	if (!kvm_timer_irq_can_fire(vcpu))
		return;

	/*  The timer has not yet expired, schedule a background timer */
	cval = timer->cntv_cval;
	now = kvm_phys_timer_read() - vcpu->kvm->arch.timer.cntvoff;

	ns = cyclecounter_cyc2ns(timecounter->cc,
				 cval - now,
				 timecounter->mask,
				 &timecounter->frac);
	timer_arm(timer, ns);
}

void kvm_timer_unschedule(struct kvm_vcpu *vcpu)
{
	struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
	timer_disarm(timer);
}

/**
 * kvm_timer_flush_hwstate - prepare to move the virt timer to the cpu
 * @vcpu: The vcpu pointer
 *
 * Check if the virtual timer has expired while we were running in the host,
 * and inject an interrupt if that was the case.
 */
void kvm_timer_flush_hwstate(struct kvm_vcpu *vcpu)
{
	struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
	bool phys_active;
	int ret;

	if (kvm_timer_should_fire(vcpu))
		kvm_timer_inject_irq(vcpu);

	/*
	 * We keep track of whether the edge-triggered interrupt has been
	 * signalled to the vgic/guest, and if so, we mask the interrupt and
	 * the physical distributor to prevent the timer from raising a
	 * physical interrupt whenever we run a guest, preventing forward
	 * VCPU progress.
	 */
	if (kvm_vgic_get_phys_irq_active(timer->map))
		phys_active = true;
	else
		phys_active = false;

	ret = irq_set_irqchip_state(timer->map->irq,
				    IRQCHIP_STATE_ACTIVE,
				    phys_active);
	WARN_ON(ret);
}

/**
 * kvm_timer_sync_hwstate - sync timer state from cpu
 * @vcpu: The vcpu pointer
 *
 * Check if the virtual timer has expired while we were running in the guest,
 * and inject an interrupt if that was the case.
 */
void kvm_timer_sync_hwstate(struct kvm_vcpu *vcpu)
{
	struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;

	BUG_ON(timer_is_armed(timer));

	if (kvm_timer_should_fire(vcpu))
		kvm_timer_inject_irq(vcpu);
}

int kvm_timer_vcpu_reset(struct kvm_vcpu *vcpu,
			 const struct kvm_irq_level *irq)
{
	struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
	struct irq_phys_map *map;

	/*
	 * The vcpu timer irq number cannot be determined in
	 * kvm_timer_vcpu_init() because it is called much before
	 * kvm_vcpu_set_target(). To handle this, we determine
	 * vcpu timer irq number when the vcpu is reset.
	 */
	timer->irq = irq;

	/*
	 * The bits in CNTV_CTL are architecturally reset to UNKNOWN for ARMv8
	 * and to 0 for ARMv7.  We provide an implementation that always
	 * resets the timer to be disabled and unmasked and is compliant with
	 * the ARMv7 architecture.
	 */
	timer->cntv_ctl = 0;

	/*
	 * Tell the VGIC that the virtual interrupt is tied to a
	 * physical interrupt. We do that once per VCPU.
	 */
	map = kvm_vgic_map_phys_irq(vcpu, irq->irq, host_vtimer_irq);
	if (WARN_ON(IS_ERR(map)))
		return PTR_ERR(map);

	timer->map = map;
	return 0;
}

void kvm_timer_vcpu_init(struct kvm_vcpu *vcpu)
{
	struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;

	INIT_WORK(&timer->expired, kvm_timer_inject_irq_work);
	hrtimer_init(&timer->timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS);
	timer->timer.function = kvm_timer_expire;
}

static void kvm_timer_init_interrupt(void *info)
{
	enable_percpu_irq(host_vtimer_irq, 0);
}

int kvm_arm_timer_set_reg(struct kvm_vcpu *vcpu, u64 regid, u64 value)
{
	struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;

	switch (regid) {
	case KVM_REG_ARM_TIMER_CTL:
		timer->cntv_ctl = value;
		break;
	case KVM_REG_ARM_TIMER_CNT:
		vcpu->kvm->arch.timer.cntvoff = kvm_phys_timer_read() - value;
		break;
	case KVM_REG_ARM_TIMER_CVAL:
		timer->cntv_cval = value;
		break;
	default:
		return -1;
	}
	return 0;
}

u64 kvm_arm_timer_get_reg(struct kvm_vcpu *vcpu, u64 regid)
{
	struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;

	switch (regid) {
	case KVM_REG_ARM_TIMER_CTL:
		return timer->cntv_ctl;
	case KVM_REG_ARM_TIMER_CNT:
		return kvm_phys_timer_read() - vcpu->kvm->arch.timer.cntvoff;
	case KVM_REG_ARM_TIMER_CVAL:
		return timer->cntv_cval;
	}
	return (u64)-1;
}

static int kvm_timer_cpu_notify(struct notifier_block *self,
				unsigned long action, void *cpu)
{
	switch (action) {
	case CPU_STARTING:
	case CPU_STARTING_FROZEN:
		kvm_timer_init_interrupt(NULL);
		break;
	case CPU_DYING:
	case CPU_DYING_FROZEN:
		disable_percpu_irq(host_vtimer_irq);
		break;
	}

	return NOTIFY_OK;
}

static struct notifier_block kvm_timer_cpu_nb = {
	.notifier_call = kvm_timer_cpu_notify,
};

static const struct of_device_id arch_timer_of_match[] = {
	{ .compatible	= "arm,armv7-timer",	},
	{ .compatible	= "arm,armv8-timer",	},
	{},
};

int kvm_timer_hyp_init(void)
{
	struct device_node *np;
	unsigned int ppi;
	int err;

	timecounter = arch_timer_get_timecounter();
	if (!timecounter)
		return -ENODEV;

	np = of_find_matching_node(NULL, arch_timer_of_match);
	if (!np) {
		kvm_err("kvm_arch_timer: can't find DT node\n");
		return -ENODEV;
	}

	ppi = irq_of_parse_and_map(np, 2);
	if (!ppi) {
		kvm_err("kvm_arch_timer: no virtual timer interrupt\n");
		err = -EINVAL;
		goto out;
	}

	err = request_percpu_irq(ppi, kvm_arch_timer_handler,
				 "kvm guest timer", kvm_get_running_vcpus());
	if (err) {
		kvm_err("kvm_arch_timer: can't request interrupt %d (%d)\n",
			ppi, err);
		goto out;
	}

	host_vtimer_irq = ppi;

	err = __register_cpu_notifier(&kvm_timer_cpu_nb);
	if (err) {
		kvm_err("Cannot register timer CPU notifier\n");
		goto out_free;
	}

	wqueue = create_singlethread_workqueue("kvm_arch_timer");
	if (!wqueue) {
		err = -ENOMEM;
		goto out_free;
	}

	kvm_info("%s IRQ%d\n", np->name, ppi);
	on_each_cpu(kvm_timer_init_interrupt, NULL, 1);

	goto out;
out_free:
	free_percpu_irq(ppi, kvm_get_running_vcpus());
out:
	of_node_put(np);
	return err;
}

void kvm_timer_vcpu_terminate(struct kvm_vcpu *vcpu)
{
	struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;

	timer_disarm(timer);
	if (timer->map)
		kvm_vgic_unmap_phys_irq(vcpu, timer->map);
}

void kvm_timer_enable(struct kvm *kvm)
{
	if (kvm->arch.timer.enabled)
		return;

	/*
	 * There is a potential race here between VCPUs starting for the first
	 * time, which may be enabling the timer multiple times.  That doesn't
	 * hurt though, because we're just setting a variable to the same
	 * variable that it already was.  The important thing is that all
	 * VCPUs have the enabled variable set, before entering the guest, if
	 * the arch timers are enabled.
	 */
	if (timecounter && wqueue)
		kvm->arch.timer.enabled = 1;
}

void kvm_timer_init(struct kvm *kvm)
{
	kvm->arch.timer.cntvoff = kvm_phys_timer_read();
}
OpenPOWER on IntegriCloud