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>
31 static struct timecounter *timecounter;
32 static struct workqueue_struct *wqueue;
33 static unsigned int host_vtimer_irq;
35 static cycle_t kvm_phys_timer_read(void)
37 return timecounter->cc->read(timecounter->cc);
40 static bool timer_is_armed(struct arch_timer_cpu *timer)
45 /* timer_arm: as in "arm the timer", not as in ARM the company */
46 static void timer_arm(struct arch_timer_cpu *timer, u64 ns)
49 hrtimer_start(&timer->timer, ktime_add_ns(ktime_get(), ns),
53 static void timer_disarm(struct arch_timer_cpu *timer)
55 if (timer_is_armed(timer)) {
56 hrtimer_cancel(&timer->timer);
57 cancel_work_sync(&timer->expired);
62 static void kvm_timer_inject_irq(struct kvm_vcpu *vcpu)
65 struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
67 kvm_vgic_set_phys_irq_active(timer->map, true);
68 ret = kvm_vgic_inject_mapped_irq(vcpu->kvm, vcpu->vcpu_id,
74 static irqreturn_t kvm_arch_timer_handler(int irq, void *dev_id)
76 struct kvm_vcpu *vcpu = *(struct kvm_vcpu **)dev_id;
79 * We disable the timer in the world switch and let it be
80 * handled by kvm_timer_sync_hwstate(). Getting a timer
81 * interrupt at this point is a sure sign of some major
84 pr_warn("Unexpected interrupt %d on vcpu %p\n", irq, vcpu);
89 * Work function for handling the backup timer that we schedule when a vcpu is
90 * no longer running, but had a timer programmed to fire in the future.
92 static void kvm_timer_inject_irq_work(struct work_struct *work)
94 struct kvm_vcpu *vcpu;
96 vcpu = container_of(work, struct kvm_vcpu, arch.timer_cpu.expired);
97 vcpu->arch.timer_cpu.armed = false;
100 * If the vcpu is blocked we want to wake it up so that it will see
101 * the timer has expired when entering the guest.
106 static enum hrtimer_restart kvm_timer_expire(struct hrtimer *hrt)
108 struct arch_timer_cpu *timer;
109 timer = container_of(hrt, struct arch_timer_cpu, timer);
110 queue_work(wqueue, &timer->expired);
111 return HRTIMER_NORESTART;
114 bool kvm_timer_should_fire(struct kvm_vcpu *vcpu)
116 struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
119 if ((timer->cntv_ctl & ARCH_TIMER_CTRL_IT_MASK) ||
120 !(timer->cntv_ctl & ARCH_TIMER_CTRL_ENABLE) ||
121 kvm_vgic_get_phys_irq_active(timer->map))
124 cval = timer->cntv_cval;
125 now = kvm_phys_timer_read() - vcpu->kvm->arch.timer.cntvoff;
131 * kvm_timer_flush_hwstate - prepare to move the virt timer to the cpu
132 * @vcpu: The vcpu pointer
134 * Disarm any pending soft timers, since the world-switch code will write the
135 * virtual timer state back to the physical CPU.
137 void kvm_timer_flush_hwstate(struct kvm_vcpu *vcpu)
139 struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
144 * We're about to run this vcpu again, so there is no need to
145 * keep the background timer running, as we're about to
146 * populate the CPU timer again.
151 * If the timer expired while we were not scheduled, now is the time
154 if (kvm_timer_should_fire(vcpu))
155 kvm_timer_inject_irq(vcpu);
158 * We keep track of whether the edge-triggered interrupt has been
159 * signalled to the vgic/guest, and if so, we mask the interrupt and
160 * the physical distributor to prevent the timer from raising a
161 * physical interrupt whenever we run a guest, preventing forward
164 if (kvm_vgic_get_phys_irq_active(timer->map))
169 ret = irq_set_irqchip_state(timer->map->irq,
170 IRQCHIP_STATE_ACTIVE,
176 * kvm_timer_sync_hwstate - sync timer state from cpu
177 * @vcpu: The vcpu pointer
179 * Check if the virtual timer was armed and either schedule a corresponding
180 * soft timer or inject directly if already expired.
182 void kvm_timer_sync_hwstate(struct kvm_vcpu *vcpu)
184 struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
188 BUG_ON(timer_is_armed(timer));
190 if (kvm_timer_should_fire(vcpu)) {
192 * Timer has already expired while we were not
193 * looking. Inject the interrupt and carry on.
195 kvm_timer_inject_irq(vcpu);
199 cval = timer->cntv_cval;
200 now = kvm_phys_timer_read() - vcpu->kvm->arch.timer.cntvoff;
202 ns = cyclecounter_cyc2ns(timecounter->cc, cval - now, timecounter->mask,
204 timer_arm(timer, ns);
207 int kvm_timer_vcpu_reset(struct kvm_vcpu *vcpu,
208 const struct kvm_irq_level *irq)
210 struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
211 struct irq_phys_map *map;
214 * The vcpu timer irq number cannot be determined in
215 * kvm_timer_vcpu_init() because it is called much before
216 * kvm_vcpu_set_target(). To handle this, we determine
217 * vcpu timer irq number when the vcpu is reset.
222 * The bits in CNTV_CTL are architecturally reset to UNKNOWN for ARMv8
223 * and to 0 for ARMv7. We provide an implementation that always
224 * resets the timer to be disabled and unmasked and is compliant with
225 * the ARMv7 architecture.
230 * Tell the VGIC that the virtual interrupt is tied to a
231 * physical interrupt. We do that once per VCPU.
233 map = kvm_vgic_map_phys_irq(vcpu, irq->irq, host_vtimer_irq);
234 if (WARN_ON(IS_ERR(map)))
241 void kvm_timer_vcpu_init(struct kvm_vcpu *vcpu)
243 struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
245 INIT_WORK(&timer->expired, kvm_timer_inject_irq_work);
246 hrtimer_init(&timer->timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS);
247 timer->timer.function = kvm_timer_expire;
250 static void kvm_timer_init_interrupt(void *info)
252 enable_percpu_irq(host_vtimer_irq, 0);
255 int kvm_arm_timer_set_reg(struct kvm_vcpu *vcpu, u64 regid, u64 value)
257 struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
260 case KVM_REG_ARM_TIMER_CTL:
261 timer->cntv_ctl = value;
263 case KVM_REG_ARM_TIMER_CNT:
264 vcpu->kvm->arch.timer.cntvoff = kvm_phys_timer_read() - value;
266 case KVM_REG_ARM_TIMER_CVAL:
267 timer->cntv_cval = value;
275 u64 kvm_arm_timer_get_reg(struct kvm_vcpu *vcpu, u64 regid)
277 struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
280 case KVM_REG_ARM_TIMER_CTL:
281 return timer->cntv_ctl;
282 case KVM_REG_ARM_TIMER_CNT:
283 return kvm_phys_timer_read() - vcpu->kvm->arch.timer.cntvoff;
284 case KVM_REG_ARM_TIMER_CVAL:
285 return timer->cntv_cval;
290 static int kvm_timer_cpu_notify(struct notifier_block *self,
291 unsigned long action, void *cpu)
295 case CPU_STARTING_FROZEN:
296 kvm_timer_init_interrupt(NULL);
299 case CPU_DYING_FROZEN:
300 disable_percpu_irq(host_vtimer_irq);
307 static struct notifier_block kvm_timer_cpu_nb = {
308 .notifier_call = kvm_timer_cpu_notify,
311 static const struct of_device_id arch_timer_of_match[] = {
312 { .compatible = "arm,armv7-timer", },
313 { .compatible = "arm,armv8-timer", },
317 int kvm_timer_hyp_init(void)
319 struct device_node *np;
323 timecounter = arch_timer_get_timecounter();
327 np = of_find_matching_node(NULL, arch_timer_of_match);
329 kvm_err("kvm_arch_timer: can't find DT node\n");
333 ppi = irq_of_parse_and_map(np, 2);
335 kvm_err("kvm_arch_timer: no virtual timer interrupt\n");
340 err = request_percpu_irq(ppi, kvm_arch_timer_handler,
341 "kvm guest timer", kvm_get_running_vcpus());
343 kvm_err("kvm_arch_timer: can't request interrupt %d (%d)\n",
348 host_vtimer_irq = ppi;
350 err = __register_cpu_notifier(&kvm_timer_cpu_nb);
352 kvm_err("Cannot register timer CPU notifier\n");
356 wqueue = create_singlethread_workqueue("kvm_arch_timer");
362 kvm_info("%s IRQ%d\n", np->name, ppi);
363 on_each_cpu(kvm_timer_init_interrupt, NULL, 1);
367 free_percpu_irq(ppi, kvm_get_running_vcpus());
373 void kvm_timer_vcpu_terminate(struct kvm_vcpu *vcpu)
375 struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
379 kvm_vgic_unmap_phys_irq(vcpu, timer->map);
382 void kvm_timer_enable(struct kvm *kvm)
384 if (kvm->arch.timer.enabled)
388 * There is a potential race here between VCPUs starting for the first
389 * time, which may be enabling the timer multiple times. That doesn't
390 * hurt though, because we're just setting a variable to the same
391 * variable that it already was. The important thing is that all
392 * VCPUs have the enabled variable set, before entering the guest, if
393 * the arch timers are enabled.
395 if (timecounter && wqueue)
396 kvm->arch.timer.enabled = 1;
399 void kvm_timer_init(struct kvm *kvm)
401 kvm->arch.timer.cntvoff = kvm_phys_timer_read();