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);
87 vcpu->arch.timer_cpu.armed = false;
90 * If the vcpu is blocked we want to wake it up so that it will see
91 * the timer has expired when entering the guest.
96 static enum hrtimer_restart kvm_timer_expire(struct hrtimer *hrt)
98 struct arch_timer_cpu *timer;
99 timer = container_of(hrt, struct arch_timer_cpu, timer);
100 queue_work(wqueue, &timer->expired);
101 return HRTIMER_NORESTART;
104 static bool kvm_timer_irq_can_fire(struct kvm_vcpu *vcpu)
106 struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
108 return !(timer->cntv_ctl & ARCH_TIMER_CTRL_IT_MASK) &&
109 (timer->cntv_ctl & ARCH_TIMER_CTRL_ENABLE);
112 bool kvm_timer_should_fire(struct kvm_vcpu *vcpu)
114 struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
117 if (!kvm_timer_irq_can_fire(vcpu))
120 cval = timer->cntv_cval;
121 now = kvm_phys_timer_read() - vcpu->kvm->arch.timer.cntvoff;
126 static void kvm_timer_update_irq(struct kvm_vcpu *vcpu, bool new_level)
129 struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
131 BUG_ON(!vgic_initialized(vcpu->kvm));
133 timer->irq.level = new_level;
134 trace_kvm_timer_update_irq(vcpu->vcpu_id, timer->map->virt_irq,
136 ret = kvm_vgic_inject_mapped_irq(vcpu->kvm, vcpu->vcpu_id,
143 * Check if there was a change in the timer state (should we raise or lower
144 * the line level to the GIC).
146 static int kvm_timer_update_state(struct kvm_vcpu *vcpu)
148 struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
151 * If userspace modified the timer registers via SET_ONE_REG before
152 * the vgic was initialized, we mustn't set the timer->irq.level value
153 * because the guest would never see the interrupt. Instead wait
154 * until we call this function from kvm_timer_flush_hwstate.
156 if (!vgic_initialized(vcpu->kvm))
159 if (kvm_timer_should_fire(vcpu) != timer->irq.level)
160 kvm_timer_update_irq(vcpu, !timer->irq.level);
166 * Schedule the background timer before calling kvm_vcpu_block, so that this
167 * thread is removed from its waitqueue and made runnable when there's a timer
168 * interrupt to handle.
170 void kvm_timer_schedule(struct kvm_vcpu *vcpu)
172 struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
176 BUG_ON(timer_is_armed(timer));
179 * No need to schedule a background timer if the guest timer has
180 * already expired, because kvm_vcpu_block will return before putting
181 * the thread to sleep.
183 if (kvm_timer_should_fire(vcpu))
187 * If the timer is not capable of raising interrupts (disabled or
188 * masked), then there's no more work for us to do.
190 if (!kvm_timer_irq_can_fire(vcpu))
193 /* The timer has not yet expired, schedule a background timer */
194 cval = timer->cntv_cval;
195 now = kvm_phys_timer_read() - vcpu->kvm->arch.timer.cntvoff;
197 ns = cyclecounter_cyc2ns(timecounter->cc,
201 timer_arm(timer, ns);
204 void kvm_timer_unschedule(struct kvm_vcpu *vcpu)
206 struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
211 * kvm_timer_flush_hwstate - prepare to move the virt timer to the cpu
212 * @vcpu: The vcpu pointer
214 * Check if the virtual timer has expired while we were running in the host,
215 * and inject an interrupt if that was the case.
217 void kvm_timer_flush_hwstate(struct kvm_vcpu *vcpu)
219 struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
223 if (kvm_timer_update_state(vcpu))
227 * If we enter the guest with the virtual input level to the VGIC
228 * asserted, then we have already told the VGIC what we need to, and
229 * we don't need to exit from the guest until the guest deactivates
230 * the already injected interrupt, so therefore we should set the
231 * hardware active state to prevent unnecessary exits from the guest.
233 * Also, if we enter the guest with the virtual timer interrupt active,
234 * then it must be active on the physical distributor, because we set
235 * the HW bit and the guest must be able to deactivate the virtual and
236 * physical interrupt at the same time.
238 * Conversely, if the virtual input level is deasserted and the virtual
239 * interrupt is not active, then always clear the hardware active state
240 * to ensure that hardware interrupts from the timer triggers a guest
243 if (timer->irq.level || kvm_vgic_map_is_active(vcpu, timer->map))
248 ret = irq_set_irqchip_state(timer->map->irq,
249 IRQCHIP_STATE_ACTIVE,
255 * kvm_timer_sync_hwstate - sync timer state from cpu
256 * @vcpu: The vcpu pointer
258 * Check if the virtual timer has expired while we were running in the guest,
259 * and inject an interrupt if that was the case.
261 void kvm_timer_sync_hwstate(struct kvm_vcpu *vcpu)
263 struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
265 BUG_ON(timer_is_armed(timer));
268 * The guest could have modified the timer registers or the timer
269 * could have expired, update the timer state.
271 kvm_timer_update_state(vcpu);
274 int kvm_timer_vcpu_reset(struct kvm_vcpu *vcpu,
275 const struct kvm_irq_level *irq)
277 struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
278 struct irq_phys_map *map;
281 * The vcpu timer irq number cannot be determined in
282 * kvm_timer_vcpu_init() because it is called much before
283 * kvm_vcpu_set_target(). To handle this, we determine
284 * vcpu timer irq number when the vcpu is reset.
286 timer->irq.irq = irq->irq;
289 * The bits in CNTV_CTL are architecturally reset to UNKNOWN for ARMv8
290 * and to 0 for ARMv7. We provide an implementation that always
291 * resets the timer to be disabled and unmasked and is compliant with
292 * the ARMv7 architecture.
295 kvm_timer_update_state(vcpu);
298 * Tell the VGIC that the virtual interrupt is tied to a
299 * physical interrupt. We do that once per VCPU.
301 map = kvm_vgic_map_phys_irq(vcpu, irq->irq, host_vtimer_irq);
302 if (WARN_ON(IS_ERR(map)))
309 void kvm_timer_vcpu_init(struct kvm_vcpu *vcpu)
311 struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
313 INIT_WORK(&timer->expired, kvm_timer_inject_irq_work);
314 hrtimer_init(&timer->timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS);
315 timer->timer.function = kvm_timer_expire;
318 static void kvm_timer_init_interrupt(void *info)
320 enable_percpu_irq(host_vtimer_irq, 0);
323 int kvm_arm_timer_set_reg(struct kvm_vcpu *vcpu, u64 regid, u64 value)
325 struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
328 case KVM_REG_ARM_TIMER_CTL:
329 timer->cntv_ctl = value;
331 case KVM_REG_ARM_TIMER_CNT:
332 vcpu->kvm->arch.timer.cntvoff = kvm_phys_timer_read() - value;
334 case KVM_REG_ARM_TIMER_CVAL:
335 timer->cntv_cval = value;
341 kvm_timer_update_state(vcpu);
345 u64 kvm_arm_timer_get_reg(struct kvm_vcpu *vcpu, u64 regid)
347 struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
350 case KVM_REG_ARM_TIMER_CTL:
351 return timer->cntv_ctl;
352 case KVM_REG_ARM_TIMER_CNT:
353 return kvm_phys_timer_read() - vcpu->kvm->arch.timer.cntvoff;
354 case KVM_REG_ARM_TIMER_CVAL:
355 return timer->cntv_cval;
360 static int kvm_timer_cpu_notify(struct notifier_block *self,
361 unsigned long action, void *cpu)
365 case CPU_STARTING_FROZEN:
366 kvm_timer_init_interrupt(NULL);
369 case CPU_DYING_FROZEN:
370 disable_percpu_irq(host_vtimer_irq);
377 static struct notifier_block kvm_timer_cpu_nb = {
378 .notifier_call = kvm_timer_cpu_notify,
381 static const struct of_device_id arch_timer_of_match[] = {
382 { .compatible = "arm,armv7-timer", },
383 { .compatible = "arm,armv8-timer", },
387 int kvm_timer_hyp_init(void)
389 struct device_node *np;
393 timecounter = arch_timer_get_timecounter();
397 np = of_find_matching_node(NULL, arch_timer_of_match);
399 kvm_err("kvm_arch_timer: can't find DT node\n");
403 ppi = irq_of_parse_and_map(np, 2);
405 kvm_err("kvm_arch_timer: no virtual timer interrupt\n");
410 err = request_percpu_irq(ppi, kvm_arch_timer_handler,
411 "kvm guest timer", kvm_get_running_vcpus());
413 kvm_err("kvm_arch_timer: can't request interrupt %d (%d)\n",
418 host_vtimer_irq = ppi;
420 err = __register_cpu_notifier(&kvm_timer_cpu_nb);
422 kvm_err("Cannot register timer CPU notifier\n");
426 wqueue = create_singlethread_workqueue("kvm_arch_timer");
432 kvm_info("%s IRQ%d\n", np->name, ppi);
433 on_each_cpu(kvm_timer_init_interrupt, NULL, 1);
437 free_percpu_irq(ppi, kvm_get_running_vcpus());
443 void kvm_timer_vcpu_terminate(struct kvm_vcpu *vcpu)
445 struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
449 kvm_vgic_unmap_phys_irq(vcpu, timer->map);
452 void kvm_timer_enable(struct kvm *kvm)
454 if (kvm->arch.timer.enabled)
458 * There is a potential race here between VCPUs starting for the first
459 * time, which may be enabling the timer multiple times. That doesn't
460 * hurt though, because we're just setting a variable to the same
461 * variable that it already was. The important thing is that all
462 * VCPUs have the enabled variable set, before entering the guest, if
463 * the arch timers are enabled.
465 if (timecounter && wqueue)
466 kvm->arch.timer.enabled = 1;
469 void kvm_timer_init(struct kvm *kvm)
471 kvm->arch.timer.cntvoff = kvm_phys_timer_read();