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 void kvm_timer_vcpu_put(struct kvm_vcpu
*vcpu
)
39 vcpu
->arch
.timer_cpu
.active_cleared_last
= false;
42 static cycle_t
kvm_phys_timer_read(void)
44 return timecounter
->cc
->read(timecounter
->cc
);
47 static bool timer_is_armed(struct arch_timer_cpu
*timer
)
52 /* timer_arm: as in "arm the timer", not as in ARM the company */
53 static void timer_arm(struct arch_timer_cpu
*timer
, u64 ns
)
56 hrtimer_start(&timer
->timer
, ktime_add_ns(ktime_get(), ns
),
60 static void timer_disarm(struct arch_timer_cpu
*timer
)
62 if (timer_is_armed(timer
)) {
63 hrtimer_cancel(&timer
->timer
);
64 cancel_work_sync(&timer
->expired
);
69 static irqreturn_t
kvm_arch_timer_handler(int irq
, void *dev_id
)
71 struct kvm_vcpu
*vcpu
= *(struct kvm_vcpu
**)dev_id
;
74 * We disable the timer in the world switch and let it be
75 * handled by kvm_timer_sync_hwstate(). Getting a timer
76 * interrupt at this point is a sure sign of some major
79 pr_warn("Unexpected interrupt %d on vcpu %p\n", irq
, vcpu
);
84 * Work function for handling the backup timer that we schedule when a vcpu is
85 * no longer running, but had a timer programmed to fire in the future.
87 static void kvm_timer_inject_irq_work(struct work_struct
*work
)
89 struct kvm_vcpu
*vcpu
;
91 vcpu
= container_of(work
, struct kvm_vcpu
, arch
.timer_cpu
.expired
);
92 vcpu
->arch
.timer_cpu
.armed
= false;
95 * If the vcpu is blocked we want to wake it up so that it will see
96 * the timer has expired when entering the guest.
101 static enum hrtimer_restart
kvm_timer_expire(struct hrtimer
*hrt
)
103 struct arch_timer_cpu
*timer
;
104 timer
= container_of(hrt
, struct arch_timer_cpu
, timer
);
105 queue_work(wqueue
, &timer
->expired
);
106 return HRTIMER_NORESTART
;
109 static bool kvm_timer_irq_can_fire(struct kvm_vcpu
*vcpu
)
111 struct arch_timer_cpu
*timer
= &vcpu
->arch
.timer_cpu
;
113 return !(timer
->cntv_ctl
& ARCH_TIMER_CTRL_IT_MASK
) &&
114 (timer
->cntv_ctl
& ARCH_TIMER_CTRL_ENABLE
);
117 bool kvm_timer_should_fire(struct kvm_vcpu
*vcpu
)
119 struct arch_timer_cpu
*timer
= &vcpu
->arch
.timer_cpu
;
122 if (!kvm_timer_irq_can_fire(vcpu
))
125 cval
= timer
->cntv_cval
;
126 now
= kvm_phys_timer_read() - vcpu
->kvm
->arch
.timer
.cntvoff
;
131 static void kvm_timer_update_irq(struct kvm_vcpu
*vcpu
, bool new_level
)
134 struct arch_timer_cpu
*timer
= &vcpu
->arch
.timer_cpu
;
136 BUG_ON(!vgic_initialized(vcpu
->kvm
));
138 timer
->active_cleared_last
= false;
139 timer
->irq
.level
= new_level
;
140 trace_kvm_timer_update_irq(vcpu
->vcpu_id
, timer
->map
->virt_irq
,
142 ret
= kvm_vgic_inject_mapped_irq(vcpu
->kvm
, vcpu
->vcpu_id
,
149 * Check if there was a change in the timer state (should we raise or lower
150 * the line level to the GIC).
152 static int kvm_timer_update_state(struct kvm_vcpu
*vcpu
)
154 struct arch_timer_cpu
*timer
= &vcpu
->arch
.timer_cpu
;
157 * If userspace modified the timer registers via SET_ONE_REG before
158 * the vgic was initialized, we mustn't set the timer->irq.level value
159 * because the guest would never see the interrupt. Instead wait
160 * until we call this function from kvm_timer_flush_hwstate.
162 if (!vgic_initialized(vcpu
->kvm
))
165 if (kvm_timer_should_fire(vcpu
) != timer
->irq
.level
)
166 kvm_timer_update_irq(vcpu
, !timer
->irq
.level
);
172 * Schedule the background timer before calling kvm_vcpu_block, so that this
173 * thread is removed from its waitqueue and made runnable when there's a timer
174 * interrupt to handle.
176 void kvm_timer_schedule(struct kvm_vcpu
*vcpu
)
178 struct arch_timer_cpu
*timer
= &vcpu
->arch
.timer_cpu
;
182 BUG_ON(timer_is_armed(timer
));
185 * No need to schedule a background timer if the guest timer has
186 * already expired, because kvm_vcpu_block will return before putting
187 * the thread to sleep.
189 if (kvm_timer_should_fire(vcpu
))
193 * If the timer is not capable of raising interrupts (disabled or
194 * masked), then there's no more work for us to do.
196 if (!kvm_timer_irq_can_fire(vcpu
))
199 /* The timer has not yet expired, schedule a background timer */
200 cval
= timer
->cntv_cval
;
201 now
= kvm_phys_timer_read() - vcpu
->kvm
->arch
.timer
.cntvoff
;
203 ns
= cyclecounter_cyc2ns(timecounter
->cc
,
207 timer_arm(timer
, ns
);
210 void kvm_timer_unschedule(struct kvm_vcpu
*vcpu
)
212 struct arch_timer_cpu
*timer
= &vcpu
->arch
.timer_cpu
;
217 * kvm_timer_flush_hwstate - prepare to move the virt timer to the cpu
218 * @vcpu: The vcpu pointer
220 * Check if the virtual timer has expired while we were running in the host,
221 * and inject an interrupt if that was the case.
223 void kvm_timer_flush_hwstate(struct kvm_vcpu
*vcpu
)
225 struct arch_timer_cpu
*timer
= &vcpu
->arch
.timer_cpu
;
229 if (kvm_timer_update_state(vcpu
))
233 * If we enter the guest with the virtual input level to the VGIC
234 * asserted, then we have already told the VGIC what we need to, and
235 * we don't need to exit from the guest until the guest deactivates
236 * the already injected interrupt, so therefore we should set the
237 * hardware active state to prevent unnecessary exits from the guest.
239 * Also, if we enter the guest with the virtual timer interrupt active,
240 * then it must be active on the physical distributor, because we set
241 * the HW bit and the guest must be able to deactivate the virtual and
242 * physical interrupt at the same time.
244 * Conversely, if the virtual input level is deasserted and the virtual
245 * interrupt is not active, then always clear the hardware active state
246 * to ensure that hardware interrupts from the timer triggers a guest
249 if (timer
->irq
.level
|| kvm_vgic_map_is_active(vcpu
, timer
->map
))
255 * We want to avoid hitting the (re)distributor as much as
256 * possible, as this is a potentially expensive MMIO access
257 * (not to mention locks in the irq layer), and a solution for
258 * this is to cache the "active" state in memory.
260 * Things to consider: we cannot cache an "active set" state,
261 * because the HW can change this behind our back (it becomes
262 * "clear" in the HW). We must then restrict the caching to
265 * The cache is invalidated on:
266 * - vcpu put, indicating that the HW cannot be trusted to be
267 * in a sane state on the next vcpu load,
268 * - any change in the interrupt state
271 * - cached value is "active clear"
272 * - value to be programmed is "active clear"
274 if (timer
->active_cleared_last
&& !phys_active
)
277 ret
= irq_set_irqchip_state(timer
->map
->irq
,
278 IRQCHIP_STATE_ACTIVE
,
282 timer
->active_cleared_last
= !phys_active
;
286 * kvm_timer_sync_hwstate - sync timer state from cpu
287 * @vcpu: The vcpu pointer
289 * Check if the virtual timer has expired while we were running in the guest,
290 * and inject an interrupt if that was the case.
292 void kvm_timer_sync_hwstate(struct kvm_vcpu
*vcpu
)
294 struct arch_timer_cpu
*timer
= &vcpu
->arch
.timer_cpu
;
296 BUG_ON(timer_is_armed(timer
));
299 * The guest could have modified the timer registers or the timer
300 * could have expired, update the timer state.
302 kvm_timer_update_state(vcpu
);
305 int kvm_timer_vcpu_reset(struct kvm_vcpu
*vcpu
,
306 const struct kvm_irq_level
*irq
)
308 struct arch_timer_cpu
*timer
= &vcpu
->arch
.timer_cpu
;
309 struct irq_phys_map
*map
;
312 * The vcpu timer irq number cannot be determined in
313 * kvm_timer_vcpu_init() because it is called much before
314 * kvm_vcpu_set_target(). To handle this, we determine
315 * vcpu timer irq number when the vcpu is reset.
317 timer
->irq
.irq
= irq
->irq
;
320 * The bits in CNTV_CTL are architecturally reset to UNKNOWN for ARMv8
321 * and to 0 for ARMv7. We provide an implementation that always
322 * resets the timer to be disabled and unmasked and is compliant with
323 * the ARMv7 architecture.
326 kvm_timer_update_state(vcpu
);
329 * Tell the VGIC that the virtual interrupt is tied to a
330 * physical interrupt. We do that once per VCPU.
332 map
= kvm_vgic_map_phys_irq(vcpu
, irq
->irq
, host_vtimer_irq
);
333 if (WARN_ON(IS_ERR(map
)))
340 void kvm_timer_vcpu_init(struct kvm_vcpu
*vcpu
)
342 struct arch_timer_cpu
*timer
= &vcpu
->arch
.timer_cpu
;
344 INIT_WORK(&timer
->expired
, kvm_timer_inject_irq_work
);
345 hrtimer_init(&timer
->timer
, CLOCK_MONOTONIC
, HRTIMER_MODE_ABS
);
346 timer
->timer
.function
= kvm_timer_expire
;
349 static void kvm_timer_init_interrupt(void *info
)
351 enable_percpu_irq(host_vtimer_irq
, 0);
354 int kvm_arm_timer_set_reg(struct kvm_vcpu
*vcpu
, u64 regid
, u64 value
)
356 struct arch_timer_cpu
*timer
= &vcpu
->arch
.timer_cpu
;
359 case KVM_REG_ARM_TIMER_CTL
:
360 timer
->cntv_ctl
= value
;
362 case KVM_REG_ARM_TIMER_CNT
:
363 vcpu
->kvm
->arch
.timer
.cntvoff
= kvm_phys_timer_read() - value
;
365 case KVM_REG_ARM_TIMER_CVAL
:
366 timer
->cntv_cval
= value
;
372 kvm_timer_update_state(vcpu
);
376 u64
kvm_arm_timer_get_reg(struct kvm_vcpu
*vcpu
, u64 regid
)
378 struct arch_timer_cpu
*timer
= &vcpu
->arch
.timer_cpu
;
381 case KVM_REG_ARM_TIMER_CTL
:
382 return timer
->cntv_ctl
;
383 case KVM_REG_ARM_TIMER_CNT
:
384 return kvm_phys_timer_read() - vcpu
->kvm
->arch
.timer
.cntvoff
;
385 case KVM_REG_ARM_TIMER_CVAL
:
386 return timer
->cntv_cval
;
391 static int kvm_timer_cpu_notify(struct notifier_block
*self
,
392 unsigned long action
, void *cpu
)
396 case CPU_STARTING_FROZEN
:
397 kvm_timer_init_interrupt(NULL
);
400 case CPU_DYING_FROZEN
:
401 disable_percpu_irq(host_vtimer_irq
);
408 static struct notifier_block kvm_timer_cpu_nb
= {
409 .notifier_call
= kvm_timer_cpu_notify
,
412 static const struct of_device_id arch_timer_of_match
[] = {
413 { .compatible
= "arm,armv7-timer", },
414 { .compatible
= "arm,armv8-timer", },
418 int kvm_timer_hyp_init(void)
420 struct device_node
*np
;
424 timecounter
= arch_timer_get_timecounter();
428 np
= of_find_matching_node(NULL
, arch_timer_of_match
);
430 kvm_err("kvm_arch_timer: can't find DT node\n");
434 ppi
= irq_of_parse_and_map(np
, 2);
436 kvm_err("kvm_arch_timer: no virtual timer interrupt\n");
441 err
= request_percpu_irq(ppi
, kvm_arch_timer_handler
,
442 "kvm guest timer", kvm_get_running_vcpus());
444 kvm_err("kvm_arch_timer: can't request interrupt %d (%d)\n",
449 host_vtimer_irq
= ppi
;
451 err
= __register_cpu_notifier(&kvm_timer_cpu_nb
);
453 kvm_err("Cannot register timer CPU notifier\n");
457 wqueue
= create_singlethread_workqueue("kvm_arch_timer");
463 kvm_info("%s IRQ%d\n", np
->name
, ppi
);
464 on_each_cpu(kvm_timer_init_interrupt
, NULL
, 1);
468 free_percpu_irq(ppi
, kvm_get_running_vcpus());
474 void kvm_timer_vcpu_terminate(struct kvm_vcpu
*vcpu
)
476 struct arch_timer_cpu
*timer
= &vcpu
->arch
.timer_cpu
;
480 kvm_vgic_unmap_phys_irq(vcpu
, timer
->map
);
483 void kvm_timer_enable(struct kvm
*kvm
)
485 if (kvm
->arch
.timer
.enabled
)
489 * There is a potential race here between VCPUs starting for the first
490 * time, which may be enabling the timer multiple times. That doesn't
491 * hurt though, because we're just setting a variable to the same
492 * variable that it already was. The important thing is that all
493 * VCPUs have the enabled variable set, before entering the guest, if
494 * the arch timers are enabled.
496 if (timecounter
&& wqueue
)
497 kvm
->arch
.timer
.enabled
= 1;
500 void kvm_timer_init(struct kvm
*kvm
)
502 kvm
->arch
.timer
.cntvoff
= kvm_phys_timer_read();