2 * Copyright (C) 2012 ARM Ltd.
3 * Author: Marc Zyngier <marc.zyngier@arm.com>
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License version 2 as
7 * published by the Free Software Foundation.
9 * This program is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 * GNU General Public License for more details.
14 * You should have received a copy of the GNU General Public License
15 * along with this program; if not, write to the Free Software
16 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
19 #include <linux/cpu.h>
20 #include <linux/of_irq.h>
21 #include <linux/kvm.h>
22 #include <linux/kvm_host.h>
23 #include <linux/interrupt.h>
25 #include <clocksource/arm_arch_timer.h>
26 #include <asm/arch_timer.h>
28 #include <kvm/arm_vgic.h>
29 #include <kvm/arm_arch_timer.h>
33 static struct timecounter *timecounter;
34 static struct workqueue_struct *wqueue;
35 static unsigned int host_vtimer_irq;
37 static cycle_t kvm_phys_timer_read(void)
39 return timecounter->cc->read(timecounter->cc);
42 static bool timer_is_armed(struct arch_timer_cpu *timer)
47 /* timer_arm: as in "arm the timer", not as in ARM the company */
48 static void timer_arm(struct arch_timer_cpu *timer, u64 ns)
51 hrtimer_start(&timer->timer, ktime_add_ns(ktime_get(), ns),
55 static void timer_disarm(struct arch_timer_cpu *timer)
57 if (timer_is_armed(timer)) {
58 hrtimer_cancel(&timer->timer);
59 cancel_work_sync(&timer->expired);
64 static irqreturn_t kvm_arch_timer_handler(int irq, void *dev_id)
66 struct kvm_vcpu *vcpu = *(struct kvm_vcpu **)dev_id;
69 * We disable the timer in the world switch and let it be
70 * handled by kvm_timer_sync_hwstate(). Getting a timer
71 * interrupt at this point is a sure sign of some major
74 pr_warn("Unexpected interrupt %d on vcpu %p\n", irq, vcpu);
79 * Work function for handling the backup timer that we schedule when a vcpu is
80 * no longer running, but had a timer programmed to fire in the future.
82 static void kvm_timer_inject_irq_work(struct work_struct *work)
84 struct kvm_vcpu *vcpu;
86 vcpu = container_of(work, struct kvm_vcpu, arch.timer_cpu.expired);
89 * If the vcpu is blocked we want to wake it up so that it will see
90 * the timer has expired when entering the guest.
95 static u64 kvm_timer_compute_delta(struct kvm_vcpu *vcpu)
99 cval = vcpu->arch.timer_cpu.cntv_cval;
100 now = kvm_phys_timer_read() - vcpu->kvm->arch.timer.cntvoff;
105 ns = cyclecounter_cyc2ns(timecounter->cc,
115 static enum hrtimer_restart kvm_timer_expire(struct hrtimer *hrt)
117 struct arch_timer_cpu *timer;
118 struct kvm_vcpu *vcpu;
121 timer = container_of(hrt, struct arch_timer_cpu, timer);
122 vcpu = container_of(timer, struct kvm_vcpu, arch.timer_cpu);
125 * Check that the timer has really expired from the guest's
126 * PoV (NTP on the host may have forced it to expire
127 * early). If we should have slept longer, restart it.
129 ns = kvm_timer_compute_delta(vcpu);
131 hrtimer_forward_now(hrt, ns_to_ktime(ns));
132 return HRTIMER_RESTART;
135 queue_work(wqueue, &timer->expired);
136 return HRTIMER_NORESTART;
139 static bool kvm_timer_irq_can_fire(struct kvm_vcpu *vcpu)
141 struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
143 return !(timer->cntv_ctl & ARCH_TIMER_CTRL_IT_MASK) &&
144 (timer->cntv_ctl & ARCH_TIMER_CTRL_ENABLE);
147 bool kvm_timer_should_fire(struct kvm_vcpu *vcpu)
149 struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
152 if (!kvm_timer_irq_can_fire(vcpu))
155 cval = timer->cntv_cval;
156 now = kvm_phys_timer_read() - vcpu->kvm->arch.timer.cntvoff;
161 static void kvm_timer_update_irq(struct kvm_vcpu *vcpu, bool new_level)
164 struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
166 BUG_ON(!vgic_initialized(vcpu->kvm));
168 timer->irq.level = new_level;
169 trace_kvm_timer_update_irq(vcpu->vcpu_id, timer->map->virt_irq,
171 ret = kvm_vgic_inject_mapped_irq(vcpu->kvm, vcpu->vcpu_id,
178 * Check if there was a change in the timer state (should we raise or lower
179 * the line level to the GIC).
181 static int kvm_timer_update_state(struct kvm_vcpu *vcpu)
183 struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
186 * If userspace modified the timer registers via SET_ONE_REG before
187 * the vgic was initialized, we mustn't set the timer->irq.level value
188 * because the guest would never see the interrupt. Instead wait
189 * until we call this function from kvm_timer_flush_hwstate.
191 if (!vgic_initialized(vcpu->kvm))
194 if (kvm_timer_should_fire(vcpu) != timer->irq.level)
195 kvm_timer_update_irq(vcpu, !timer->irq.level);
201 * Schedule the background timer before calling kvm_vcpu_block, so that this
202 * thread is removed from its waitqueue and made runnable when there's a timer
203 * interrupt to handle.
205 void kvm_timer_schedule(struct kvm_vcpu *vcpu)
207 struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
209 BUG_ON(timer_is_armed(timer));
212 * No need to schedule a background timer if the guest timer has
213 * already expired, because kvm_vcpu_block will return before putting
214 * the thread to sleep.
216 if (kvm_timer_should_fire(vcpu))
220 * If the timer is not capable of raising interrupts (disabled or
221 * masked), then there's no more work for us to do.
223 if (!kvm_timer_irq_can_fire(vcpu))
226 /* The timer has not yet expired, schedule a background timer */
227 timer_arm(timer, kvm_timer_compute_delta(vcpu));
230 void kvm_timer_unschedule(struct kvm_vcpu *vcpu)
232 struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
237 * kvm_timer_flush_hwstate - prepare to move the virt timer to the cpu
238 * @vcpu: The vcpu pointer
240 * Check if the virtual timer has expired while we were running in the host,
241 * and inject an interrupt if that was the case.
243 void kvm_timer_flush_hwstate(struct kvm_vcpu *vcpu)
245 struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
249 if (kvm_timer_update_state(vcpu))
253 * If we enter the guest with the virtual input level to the VGIC
254 * asserted, then we have already told the VGIC what we need to, and
255 * we don't need to exit from the guest until the guest deactivates
256 * the already injected interrupt, so therefore we should set the
257 * hardware active state to prevent unnecessary exits from the guest.
259 * Also, if we enter the guest with the virtual timer interrupt active,
260 * then it must be active on the physical distributor, because we set
261 * the HW bit and the guest must be able to deactivate the virtual and
262 * physical interrupt at the same time.
264 * Conversely, if the virtual input level is deasserted and the virtual
265 * interrupt is not active, then always clear the hardware active state
266 * to ensure that hardware interrupts from the timer triggers a guest
269 if (timer->irq.level || kvm_vgic_map_is_active(vcpu, timer->map))
274 ret = irq_set_irqchip_state(timer->map->irq,
275 IRQCHIP_STATE_ACTIVE,
281 * kvm_timer_sync_hwstate - sync timer state from cpu
282 * @vcpu: The vcpu pointer
284 * Check if the virtual timer has expired while we were running in the guest,
285 * and inject an interrupt if that was the case.
287 void kvm_timer_sync_hwstate(struct kvm_vcpu *vcpu)
289 struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
291 BUG_ON(timer_is_armed(timer));
294 * The guest could have modified the timer registers or the timer
295 * could have expired, update the timer state.
297 kvm_timer_update_state(vcpu);
300 int kvm_timer_vcpu_reset(struct kvm_vcpu *vcpu,
301 const struct kvm_irq_level *irq)
303 struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
304 struct irq_phys_map *map;
307 * The vcpu timer irq number cannot be determined in
308 * kvm_timer_vcpu_init() because it is called much before
309 * kvm_vcpu_set_target(). To handle this, we determine
310 * vcpu timer irq number when the vcpu is reset.
312 timer->irq.irq = irq->irq;
315 * The bits in CNTV_CTL are architecturally reset to UNKNOWN for ARMv8
316 * and to 0 for ARMv7. We provide an implementation that always
317 * resets the timer to be disabled and unmasked and is compliant with
318 * the ARMv7 architecture.
321 kvm_timer_update_state(vcpu);
324 * Tell the VGIC that the virtual interrupt is tied to a
325 * physical interrupt. We do that once per VCPU.
327 map = kvm_vgic_map_phys_irq(vcpu, irq->irq, host_vtimer_irq);
328 if (WARN_ON(IS_ERR(map)))
335 void kvm_timer_vcpu_init(struct kvm_vcpu *vcpu)
337 struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
339 INIT_WORK(&timer->expired, kvm_timer_inject_irq_work);
340 hrtimer_init(&timer->timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS);
341 timer->timer.function = kvm_timer_expire;
344 static void kvm_timer_init_interrupt(void *info)
346 enable_percpu_irq(host_vtimer_irq, 0);
349 int kvm_arm_timer_set_reg(struct kvm_vcpu *vcpu, u64 regid, u64 value)
351 struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
354 case KVM_REG_ARM_TIMER_CTL:
355 timer->cntv_ctl = value;
357 case KVM_REG_ARM_TIMER_CNT:
358 vcpu->kvm->arch.timer.cntvoff = kvm_phys_timer_read() - value;
360 case KVM_REG_ARM_TIMER_CVAL:
361 timer->cntv_cval = value;
367 kvm_timer_update_state(vcpu);
371 u64 kvm_arm_timer_get_reg(struct kvm_vcpu *vcpu, u64 regid)
373 struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
376 case KVM_REG_ARM_TIMER_CTL:
377 return timer->cntv_ctl;
378 case KVM_REG_ARM_TIMER_CNT:
379 return kvm_phys_timer_read() - vcpu->kvm->arch.timer.cntvoff;
380 case KVM_REG_ARM_TIMER_CVAL:
381 return timer->cntv_cval;
386 static int kvm_timer_cpu_notify(struct notifier_block *self,
387 unsigned long action, void *cpu)
391 case CPU_STARTING_FROZEN:
392 kvm_timer_init_interrupt(NULL);
395 case CPU_DYING_FROZEN:
396 disable_percpu_irq(host_vtimer_irq);
403 static struct notifier_block kvm_timer_cpu_nb = {
404 .notifier_call = kvm_timer_cpu_notify,
407 static const struct of_device_id arch_timer_of_match[] = {
408 { .compatible = "arm,armv7-timer", },
409 { .compatible = "arm,armv8-timer", },
413 int kvm_timer_hyp_init(void)
415 struct device_node *np;
419 timecounter = arch_timer_get_timecounter();
423 np = of_find_matching_node(NULL, arch_timer_of_match);
425 kvm_err("kvm_arch_timer: can't find DT node\n");
429 ppi = irq_of_parse_and_map(np, 2);
431 kvm_err("kvm_arch_timer: no virtual timer interrupt\n");
436 err = request_percpu_irq(ppi, kvm_arch_timer_handler,
437 "kvm guest timer", kvm_get_running_vcpus());
439 kvm_err("kvm_arch_timer: can't request interrupt %d (%d)\n",
444 host_vtimer_irq = ppi;
446 err = __register_cpu_notifier(&kvm_timer_cpu_nb);
448 kvm_err("Cannot register timer CPU notifier\n");
452 wqueue = create_singlethread_workqueue("kvm_arch_timer");
458 kvm_info("%s IRQ%d\n", np->name, ppi);
459 on_each_cpu(kvm_timer_init_interrupt, NULL, 1);
463 free_percpu_irq(ppi, kvm_get_running_vcpus());
469 void kvm_timer_vcpu_terminate(struct kvm_vcpu *vcpu)
471 struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
475 kvm_vgic_unmap_phys_irq(vcpu, timer->map);
478 void kvm_timer_enable(struct kvm *kvm)
480 if (kvm->arch.timer.enabled)
484 * There is a potential race here between VCPUs starting for the first
485 * time, which may be enabling the timer multiple times. That doesn't
486 * hurt though, because we're just setting a variable to the same
487 * variable that it already was. The important thing is that all
488 * VCPUs have the enabled variable set, before entering the guest, if
489 * the arch timers are enabled.
491 if (timecounter && wqueue)
492 kvm->arch.timer.enabled = 1;
495 void kvm_timer_init(struct kvm *kvm)
497 kvm->arch.timer.cntvoff = kvm_phys_timer_read();