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/kvm.h>
21 #include <linux/kvm_host.h>
22 #include <linux/interrupt.h>
23 #include <linux/irq.h>
25 #include <clocksource/arm_arch_timer.h>
26 #include <asm/arch_timer.h>
27 #include <asm/kvm_hyp.h>
29 #include <kvm/arm_vgic.h>
30 #include <kvm/arm_arch_timer.h>
34 static struct timecounter *timecounter;
35 static unsigned int host_vtimer_irq;
36 static u32 host_vtimer_irq_flags;
38 void kvm_timer_vcpu_put(struct kvm_vcpu *vcpu)
40 vcpu->arch.timer_cpu.active_cleared_last = false;
43 static u64 kvm_phys_timer_read(void)
45 return timecounter->cc->read(timecounter->cc);
48 static bool timer_is_armed(struct arch_timer_cpu *timer)
53 /* timer_arm: as in "arm the timer", not as in ARM the company */
54 static void timer_arm(struct arch_timer_cpu *timer, u64 ns)
57 hrtimer_start(&timer->timer, ktime_add_ns(ktime_get(), ns),
61 static void timer_disarm(struct arch_timer_cpu *timer)
63 if (timer_is_armed(timer)) {
64 hrtimer_cancel(&timer->timer);
65 cancel_work_sync(&timer->expired);
70 static irqreturn_t kvm_arch_timer_handler(int irq, void *dev_id)
72 struct kvm_vcpu *vcpu = *(struct kvm_vcpu **)dev_id;
75 * We disable the timer in the world switch and let it be
76 * handled by kvm_timer_sync_hwstate(). Getting a timer
77 * interrupt at this point is a sure sign of some major
80 pr_warn("Unexpected interrupt %d on vcpu %p\n", irq, vcpu);
85 * Work function for handling the backup timer that we schedule when a vcpu is
86 * no longer running, but had a timer programmed to fire in the future.
88 static void kvm_timer_inject_irq_work(struct work_struct *work)
90 struct kvm_vcpu *vcpu;
92 vcpu = container_of(work, struct kvm_vcpu, arch.timer_cpu.expired);
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 u64 kvm_timer_compute_delta(struct kvm_vcpu *vcpu)
105 cval = vcpu->arch.timer_cpu.cntv_cval;
106 now = kvm_phys_timer_read() - vcpu->kvm->arch.timer.cntvoff;
111 ns = cyclecounter_cyc2ns(timecounter->cc,
121 static enum hrtimer_restart kvm_timer_expire(struct hrtimer *hrt)
123 struct arch_timer_cpu *timer;
124 struct kvm_vcpu *vcpu;
127 timer = container_of(hrt, struct arch_timer_cpu, timer);
128 vcpu = container_of(timer, struct kvm_vcpu, arch.timer_cpu);
131 * Check that the timer has really expired from the guest's
132 * PoV (NTP on the host may have forced it to expire
133 * early). If we should have slept longer, restart it.
135 ns = kvm_timer_compute_delta(vcpu);
137 hrtimer_forward_now(hrt, ns_to_ktime(ns));
138 return HRTIMER_RESTART;
141 schedule_work(&timer->expired);
142 return HRTIMER_NORESTART;
145 static bool kvm_timer_irq_can_fire(struct kvm_vcpu *vcpu)
147 struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
149 return !(timer->cntv_ctl & ARCH_TIMER_CTRL_IT_MASK) &&
150 (timer->cntv_ctl & ARCH_TIMER_CTRL_ENABLE);
153 bool kvm_timer_should_fire(struct kvm_vcpu *vcpu)
155 struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
158 if (!kvm_timer_irq_can_fire(vcpu))
161 cval = timer->cntv_cval;
162 now = kvm_phys_timer_read() - vcpu->kvm->arch.timer.cntvoff;
167 static void kvm_timer_update_irq(struct kvm_vcpu *vcpu, bool new_level)
170 struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
172 BUG_ON(!vgic_initialized(vcpu->kvm));
174 timer->active_cleared_last = false;
175 timer->irq.level = new_level;
176 trace_kvm_timer_update_irq(vcpu->vcpu_id, timer->irq.irq,
178 ret = kvm_vgic_inject_mapped_irq(vcpu->kvm, vcpu->vcpu_id,
185 * Check if there was a change in the timer state (should we raise or lower
186 * the line level to the GIC).
188 static int kvm_timer_update_state(struct kvm_vcpu *vcpu)
190 struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
193 * If userspace modified the timer registers via SET_ONE_REG before
194 * the vgic was initialized, we mustn't set the timer->irq.level value
195 * because the guest would never see the interrupt. Instead wait
196 * until we call this function from kvm_timer_flush_hwstate.
198 if (!vgic_initialized(vcpu->kvm) || !timer->enabled)
201 if (kvm_timer_should_fire(vcpu) != timer->irq.level)
202 kvm_timer_update_irq(vcpu, !timer->irq.level);
208 * Schedule the background timer before calling kvm_vcpu_block, so that this
209 * thread is removed from its waitqueue and made runnable when there's a timer
210 * interrupt to handle.
212 void kvm_timer_schedule(struct kvm_vcpu *vcpu)
214 struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
216 BUG_ON(timer_is_armed(timer));
219 * No need to schedule a background timer if the guest timer has
220 * already expired, because kvm_vcpu_block will return before putting
221 * the thread to sleep.
223 if (kvm_timer_should_fire(vcpu))
227 * If the timer is not capable of raising interrupts (disabled or
228 * masked), then there's no more work for us to do.
230 if (!kvm_timer_irq_can_fire(vcpu))
233 /* The timer has not yet expired, schedule a background timer */
234 timer_arm(timer, kvm_timer_compute_delta(vcpu));
237 void kvm_timer_unschedule(struct kvm_vcpu *vcpu)
239 struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
244 * kvm_timer_flush_hwstate - prepare to move the virt timer to the cpu
245 * @vcpu: The vcpu pointer
247 * Check if the virtual timer has expired while we were running in the host,
248 * and inject an interrupt if that was the case.
250 void kvm_timer_flush_hwstate(struct kvm_vcpu *vcpu)
252 struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
256 if (kvm_timer_update_state(vcpu))
260 * If we enter the guest with the virtual input level to the VGIC
261 * asserted, then we have already told the VGIC what we need to, and
262 * we don't need to exit from the guest until the guest deactivates
263 * the already injected interrupt, so therefore we should set the
264 * hardware active state to prevent unnecessary exits from the guest.
266 * Also, if we enter the guest with the virtual timer interrupt active,
267 * then it must be active on the physical distributor, because we set
268 * the HW bit and the guest must be able to deactivate the virtual and
269 * physical interrupt at the same time.
271 * Conversely, if the virtual input level is deasserted and the virtual
272 * interrupt is not active, then always clear the hardware active state
273 * to ensure that hardware interrupts from the timer triggers a guest
276 phys_active = timer->irq.level ||
277 kvm_vgic_map_is_active(vcpu, timer->irq.irq);
280 * We want to avoid hitting the (re)distributor as much as
281 * possible, as this is a potentially expensive MMIO access
282 * (not to mention locks in the irq layer), and a solution for
283 * this is to cache the "active" state in memory.
285 * Things to consider: we cannot cache an "active set" state,
286 * because the HW can change this behind our back (it becomes
287 * "clear" in the HW). We must then restrict the caching to
290 * The cache is invalidated on:
291 * - vcpu put, indicating that the HW cannot be trusted to be
292 * in a sane state on the next vcpu load,
293 * - any change in the interrupt state
296 * - cached value is "active clear"
297 * - value to be programmed is "active clear"
299 if (timer->active_cleared_last && !phys_active)
302 ret = irq_set_irqchip_state(host_vtimer_irq,
303 IRQCHIP_STATE_ACTIVE,
307 timer->active_cleared_last = !phys_active;
311 * kvm_timer_sync_hwstate - sync timer state from cpu
312 * @vcpu: The vcpu pointer
314 * Check if the virtual timer has expired while we were running in the guest,
315 * and inject an interrupt if that was the case.
317 void kvm_timer_sync_hwstate(struct kvm_vcpu *vcpu)
319 struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
321 BUG_ON(timer_is_armed(timer));
324 * The guest could have modified the timer registers or the timer
325 * could have expired, update the timer state.
327 kvm_timer_update_state(vcpu);
330 int kvm_timer_vcpu_reset(struct kvm_vcpu *vcpu,
331 const struct kvm_irq_level *irq)
333 struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
336 * The vcpu timer irq number cannot be determined in
337 * kvm_timer_vcpu_init() because it is called much before
338 * kvm_vcpu_set_target(). To handle this, we determine
339 * vcpu timer irq number when the vcpu is reset.
341 timer->irq.irq = irq->irq;
344 * The bits in CNTV_CTL are architecturally reset to UNKNOWN for ARMv8
345 * and to 0 for ARMv7. We provide an implementation that always
346 * resets the timer to be disabled and unmasked and is compliant with
347 * the ARMv7 architecture.
350 kvm_timer_update_state(vcpu);
355 void kvm_timer_vcpu_init(struct kvm_vcpu *vcpu)
357 struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
359 INIT_WORK(&timer->expired, kvm_timer_inject_irq_work);
360 hrtimer_init(&timer->timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS);
361 timer->timer.function = kvm_timer_expire;
364 static void kvm_timer_init_interrupt(void *info)
366 enable_percpu_irq(host_vtimer_irq, host_vtimer_irq_flags);
369 int kvm_arm_timer_set_reg(struct kvm_vcpu *vcpu, u64 regid, u64 value)
371 struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
374 case KVM_REG_ARM_TIMER_CTL:
375 timer->cntv_ctl = value;
377 case KVM_REG_ARM_TIMER_CNT:
378 vcpu->kvm->arch.timer.cntvoff = kvm_phys_timer_read() - value;
380 case KVM_REG_ARM_TIMER_CVAL:
381 timer->cntv_cval = value;
387 kvm_timer_update_state(vcpu);
391 u64 kvm_arm_timer_get_reg(struct kvm_vcpu *vcpu, u64 regid)
393 struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
396 case KVM_REG_ARM_TIMER_CTL:
397 return timer->cntv_ctl;
398 case KVM_REG_ARM_TIMER_CNT:
399 return kvm_phys_timer_read() - vcpu->kvm->arch.timer.cntvoff;
400 case KVM_REG_ARM_TIMER_CVAL:
401 return timer->cntv_cval;
406 static int kvm_timer_starting_cpu(unsigned int cpu)
408 kvm_timer_init_interrupt(NULL);
412 static int kvm_timer_dying_cpu(unsigned int cpu)
414 disable_percpu_irq(host_vtimer_irq);
418 int kvm_timer_hyp_init(void)
420 struct arch_timer_kvm_info *info;
423 info = arch_timer_get_kvm_info();
424 timecounter = &info->timecounter;
426 if (!timecounter->cc) {
427 kvm_err("kvm_arch_timer: uninitialized timecounter\n");
431 if (info->virtual_irq <= 0) {
432 kvm_err("kvm_arch_timer: invalid virtual timer IRQ: %d\n",
436 host_vtimer_irq = info->virtual_irq;
438 host_vtimer_irq_flags = irq_get_trigger_type(host_vtimer_irq);
439 if (host_vtimer_irq_flags != IRQF_TRIGGER_HIGH &&
440 host_vtimer_irq_flags != IRQF_TRIGGER_LOW) {
441 kvm_err("Invalid trigger for IRQ%d, assuming level low\n",
443 host_vtimer_irq_flags = IRQF_TRIGGER_LOW;
446 err = request_percpu_irq(host_vtimer_irq, kvm_arch_timer_handler,
447 "kvm guest timer", kvm_get_running_vcpus());
449 kvm_err("kvm_arch_timer: can't request interrupt %d (%d)\n",
450 host_vtimer_irq, err);
454 kvm_info("virtual timer IRQ%d\n", host_vtimer_irq);
456 cpuhp_setup_state(CPUHP_AP_KVM_ARM_TIMER_STARTING,
457 "kvm/arm/timer:starting", kvm_timer_starting_cpu,
458 kvm_timer_dying_cpu);
462 void kvm_timer_vcpu_terminate(struct kvm_vcpu *vcpu)
464 struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
467 kvm_vgic_unmap_phys_irq(vcpu, timer->irq.irq);
470 int kvm_timer_enable(struct kvm_vcpu *vcpu)
472 struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
473 struct irq_desc *desc;
474 struct irq_data *data;
482 * Find the physical IRQ number corresponding to the host_vtimer_irq
484 desc = irq_to_desc(host_vtimer_irq);
486 kvm_err("%s: no interrupt descriptor\n", __func__);
490 data = irq_desc_get_irq_data(desc);
491 while (data->parent_data)
492 data = data->parent_data;
494 phys_irq = data->hwirq;
497 * Tell the VGIC that the virtual interrupt is tied to a
498 * physical interrupt. We do that once per VCPU.
500 ret = kvm_vgic_map_phys_irq(vcpu, timer->irq.irq, phys_irq);
509 void kvm_timer_init(struct kvm *kvm)
511 kvm->arch.timer.cntvoff = kvm_phys_timer_read();
515 * On VHE system, we only need to configure trap on physical timer and counter
516 * accesses in EL0 and EL1 once, not for every world switch.
517 * The host kernel runs at EL2 with HCR_EL2.TGE == 1,
518 * and this makes those bits have no effect for the host kernel execution.
520 void kvm_timer_init_vhe(void)
522 /* When HCR_EL2.E2H ==1, EL1PCEN and EL1PCTEN are shifted by 10 */
523 u32 cnthctl_shift = 10;
527 * Disallow physical timer access for the guest.
528 * Physical counter access is allowed.
530 val = read_sysreg(cnthctl_el2);
531 val &= ~(CNTHCTL_EL1PCEN << cnthctl_shift);
532 val |= (CNTHCTL_EL1PCTEN << cnthctl_shift);
533 write_sysreg(val, cnthctl_el2);