| /* |
| * Copyright (C) 2012 ARM Ltd. |
| * Author: Marc Zyngier <marc.zyngier@arm.com> |
| * |
| * This program is free software; you can redistribute it and/or modify |
| * it under the terms of the GNU General Public License version 2 as |
| * published by the Free Software Foundation. |
| * |
| * This program is distributed in the hope that it will be useful, |
| * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| * GNU General Public License for more details. |
| * |
| * You should have received a copy of the GNU General Public License |
| * along with this program; if not, write to the Free Software |
| * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA |
| */ |
| |
| #include <linux/cpu.h> |
| #include <linux/kvm.h> |
| #include <linux/kvm_host.h> |
| #include <linux/interrupt.h> |
| #include <linux/irq.h> |
| |
| #include <clocksource/arm_arch_timer.h> |
| #include <asm/arch_timer.h> |
| |
| #include <kvm/arm_vgic.h> |
| #include <kvm/arm_arch_timer.h> |
| |
| #include "trace.h" |
| |
| static struct timecounter *timecounter; |
| static struct workqueue_struct *wqueue; |
| static unsigned int host_vtimer_irq; |
| |
| void kvm_timer_vcpu_put(struct kvm_vcpu *vcpu) |
| { |
| vcpu->arch.timer_cpu.active_cleared_last = false; |
| } |
| |
| static cycle_t kvm_phys_timer_read(void) |
| { |
| return timecounter->cc->read(timecounter->cc); |
| } |
| |
| static bool timer_is_armed(struct arch_timer_cpu *timer) |
| { |
| return timer->armed; |
| } |
| |
| /* timer_arm: as in "arm the timer", not as in ARM the company */ |
| static void timer_arm(struct arch_timer_cpu *timer, u64 ns) |
| { |
| timer->armed = true; |
| hrtimer_start(&timer->timer, ktime_add_ns(ktime_get(), ns), |
| HRTIMER_MODE_ABS); |
| } |
| |
| static void timer_disarm(struct arch_timer_cpu *timer) |
| { |
| if (timer_is_armed(timer)) { |
| hrtimer_cancel(&timer->timer); |
| cancel_work_sync(&timer->expired); |
| timer->armed = false; |
| } |
| } |
| |
| static irqreturn_t kvm_arch_timer_handler(int irq, void *dev_id) |
| { |
| struct kvm_vcpu *vcpu = *(struct kvm_vcpu **)dev_id; |
| |
| /* |
| * We disable the timer in the world switch and let it be |
| * handled by kvm_timer_sync_hwstate(). Getting a timer |
| * interrupt at this point is a sure sign of some major |
| * breakage. |
| */ |
| pr_warn("Unexpected interrupt %d on vcpu %p\n", irq, vcpu); |
| return IRQ_HANDLED; |
| } |
| |
| /* |
| * Work function for handling the backup timer that we schedule when a vcpu is |
| * no longer running, but had a timer programmed to fire in the future. |
| */ |
| static void kvm_timer_inject_irq_work(struct work_struct *work) |
| { |
| struct kvm_vcpu *vcpu; |
| |
| vcpu = container_of(work, struct kvm_vcpu, arch.timer_cpu.expired); |
| vcpu->arch.timer_cpu.armed = false; |
| |
| WARN_ON(!kvm_timer_should_fire(vcpu)); |
| |
| /* |
| * If the vcpu is blocked we want to wake it up so that it will see |
| * the timer has expired when entering the guest. |
| */ |
| kvm_vcpu_kick(vcpu); |
| } |
| |
| static u64 kvm_timer_compute_delta(struct kvm_vcpu *vcpu) |
| { |
| cycle_t cval, now; |
| |
| cval = vcpu->arch.timer_cpu.cntv_cval; |
| now = kvm_phys_timer_read() - vcpu->kvm->arch.timer.cntvoff; |
| |
| if (now < cval) { |
| u64 ns; |
| |
| ns = cyclecounter_cyc2ns(timecounter->cc, |
| cval - now, |
| timecounter->mask, |
| &timecounter->frac); |
| return ns; |
| } |
| |
| return 0; |
| } |
| |
| static enum hrtimer_restart kvm_timer_expire(struct hrtimer *hrt) |
| { |
| struct arch_timer_cpu *timer; |
| struct kvm_vcpu *vcpu; |
| u64 ns; |
| |
| timer = container_of(hrt, struct arch_timer_cpu, timer); |
| vcpu = container_of(timer, struct kvm_vcpu, arch.timer_cpu); |
| |
| /* |
| * Check that the timer has really expired from the guest's |
| * PoV (NTP on the host may have forced it to expire |
| * early). If we should have slept longer, restart it. |
| */ |
| ns = kvm_timer_compute_delta(vcpu); |
| if (unlikely(ns)) { |
| hrtimer_forward_now(hrt, ns_to_ktime(ns)); |
| return HRTIMER_RESTART; |
| } |
| |
| queue_work(wqueue, &timer->expired); |
| return HRTIMER_NORESTART; |
| } |
| |
| static bool kvm_timer_irq_can_fire(struct kvm_vcpu *vcpu) |
| { |
| struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu; |
| |
| return !(timer->cntv_ctl & ARCH_TIMER_CTRL_IT_MASK) && |
| (timer->cntv_ctl & ARCH_TIMER_CTRL_ENABLE); |
| } |
| |
| bool kvm_timer_should_fire(struct kvm_vcpu *vcpu) |
| { |
| struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu; |
| cycle_t cval, now; |
| |
| if (!kvm_timer_irq_can_fire(vcpu)) |
| return false; |
| |
| cval = timer->cntv_cval; |
| now = kvm_phys_timer_read() - vcpu->kvm->arch.timer.cntvoff; |
| |
| return cval <= now; |
| } |
| |
| static void kvm_timer_update_irq(struct kvm_vcpu *vcpu, bool new_level) |
| { |
| int ret; |
| struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu; |
| |
| BUG_ON(!vgic_initialized(vcpu->kvm)); |
| |
| timer->active_cleared_last = false; |
| timer->irq.level = new_level; |
| trace_kvm_timer_update_irq(vcpu->vcpu_id, timer->irq.irq, |
| timer->irq.level); |
| ret = kvm_vgic_inject_mapped_irq(vcpu->kvm, vcpu->vcpu_id, |
| timer->irq.irq, |
| timer->irq.level); |
| WARN_ON(ret); |
| } |
| |
| /* |
| * Check if there was a change in the timer state (should we raise or lower |
| * the line level to the GIC). |
| */ |
| static int kvm_timer_update_state(struct kvm_vcpu *vcpu) |
| { |
| struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu; |
| |
| /* |
| * If userspace modified the timer registers via SET_ONE_REG before |
| * the vgic was initialized, we mustn't set the timer->irq.level value |
| * because the guest would never see the interrupt. Instead wait |
| * until we call this function from kvm_timer_flush_hwstate. |
| */ |
| if (!vgic_initialized(vcpu->kvm) || !timer->enabled) |
| return -ENODEV; |
| |
| if (kvm_timer_should_fire(vcpu) != timer->irq.level) |
| kvm_timer_update_irq(vcpu, !timer->irq.level); |
| |
| return 0; |
| } |
| |
| /* |
| * Schedule the background timer before calling kvm_vcpu_block, so that this |
| * thread is removed from its waitqueue and made runnable when there's a timer |
| * interrupt to handle. |
| */ |
| void kvm_timer_schedule(struct kvm_vcpu *vcpu) |
| { |
| struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu; |
| |
| BUG_ON(timer_is_armed(timer)); |
| |
| /* |
| * No need to schedule a background timer if the guest timer has |
| * already expired, because kvm_vcpu_block will return before putting |
| * the thread to sleep. |
| */ |
| if (kvm_timer_should_fire(vcpu)) |
| return; |
| |
| /* |
| * If the timer is not capable of raising interrupts (disabled or |
| * masked), then there's no more work for us to do. |
| */ |
| if (!kvm_timer_irq_can_fire(vcpu)) |
| return; |
| |
| /* The timer has not yet expired, schedule a background timer */ |
| timer_arm(timer, kvm_timer_compute_delta(vcpu)); |
| } |
| |
| void kvm_timer_unschedule(struct kvm_vcpu *vcpu) |
| { |
| struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu; |
| timer_disarm(timer); |
| } |
| |
| /** |
| * kvm_timer_flush_hwstate - prepare to move the virt timer to the cpu |
| * @vcpu: The vcpu pointer |
| * |
| * Check if the virtual timer has expired while we were running in the host, |
| * and inject an interrupt if that was the case. |
| */ |
| void kvm_timer_flush_hwstate(struct kvm_vcpu *vcpu) |
| { |
| struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu; |
| bool phys_active; |
| int ret; |
| |
| if (kvm_timer_update_state(vcpu)) |
| return; |
| |
| /* |
| * If we enter the guest with the virtual input level to the VGIC |
| * asserted, then we have already told the VGIC what we need to, and |
| * we don't need to exit from the guest until the guest deactivates |
| * the already injected interrupt, so therefore we should set the |
| * hardware active state to prevent unnecessary exits from the guest. |
| * |
| * Also, if we enter the guest with the virtual timer interrupt active, |
| * then it must be active on the physical distributor, because we set |
| * the HW bit and the guest must be able to deactivate the virtual and |
| * physical interrupt at the same time. |
| * |
| * Conversely, if the virtual input level is deasserted and the virtual |
| * interrupt is not active, then always clear the hardware active state |
| * to ensure that hardware interrupts from the timer triggers a guest |
| * exit. |
| */ |
| phys_active = timer->irq.level || |
| kvm_vgic_map_is_active(vcpu, timer->irq.irq); |
| |
| /* |
| * We want to avoid hitting the (re)distributor as much as |
| * possible, as this is a potentially expensive MMIO access |
| * (not to mention locks in the irq layer), and a solution for |
| * this is to cache the "active" state in memory. |
| * |
| * Things to consider: we cannot cache an "active set" state, |
| * because the HW can change this behind our back (it becomes |
| * "clear" in the HW). We must then restrict the caching to |
| * the "clear" state. |
| * |
| * The cache is invalidated on: |
| * - vcpu put, indicating that the HW cannot be trusted to be |
| * in a sane state on the next vcpu load, |
| * - any change in the interrupt state |
| * |
| * Usage conditions: |
| * - cached value is "active clear" |
| * - value to be programmed is "active clear" |
| */ |
| if (timer->active_cleared_last && !phys_active) |
| return; |
| |
| ret = irq_set_irqchip_state(host_vtimer_irq, |
| IRQCHIP_STATE_ACTIVE, |
| phys_active); |
| WARN_ON(ret); |
| |
| timer->active_cleared_last = !phys_active; |
| } |
| |
| /** |
| * kvm_timer_sync_hwstate - sync timer state from cpu |
| * @vcpu: The vcpu pointer |
| * |
| * Check if the virtual timer has expired while we were running in the guest, |
| * and inject an interrupt if that was the case. |
| */ |
| void kvm_timer_sync_hwstate(struct kvm_vcpu *vcpu) |
| { |
| struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu; |
| |
| BUG_ON(timer_is_armed(timer)); |
| |
| /* |
| * The guest could have modified the timer registers or the timer |
| * could have expired, update the timer state. |
| */ |
| kvm_timer_update_state(vcpu); |
| } |
| |
| int kvm_timer_vcpu_reset(struct kvm_vcpu *vcpu, |
| const struct kvm_irq_level *irq) |
| { |
| struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu; |
| |
| /* |
| * The vcpu timer irq number cannot be determined in |
| * kvm_timer_vcpu_init() because it is called much before |
| * kvm_vcpu_set_target(). To handle this, we determine |
| * vcpu timer irq number when the vcpu is reset. |
| */ |
| timer->irq.irq = irq->irq; |
| |
| /* |
| * The bits in CNTV_CTL are architecturally reset to UNKNOWN for ARMv8 |
| * and to 0 for ARMv7. We provide an implementation that always |
| * resets the timer to be disabled and unmasked and is compliant with |
| * the ARMv7 architecture. |
| */ |
| timer->cntv_ctl = 0; |
| kvm_timer_update_state(vcpu); |
| |
| return 0; |
| } |
| |
| void kvm_timer_vcpu_init(struct kvm_vcpu *vcpu) |
| { |
| struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu; |
| |
| INIT_WORK(&timer->expired, kvm_timer_inject_irq_work); |
| hrtimer_init(&timer->timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS); |
| timer->timer.function = kvm_timer_expire; |
| } |
| |
| static void kvm_timer_init_interrupt(void *info) |
| { |
| enable_percpu_irq(host_vtimer_irq, 0); |
| } |
| |
| int kvm_arm_timer_set_reg(struct kvm_vcpu *vcpu, u64 regid, u64 value) |
| { |
| struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu; |
| |
| switch (regid) { |
| case KVM_REG_ARM_TIMER_CTL: |
| timer->cntv_ctl = value; |
| break; |
| case KVM_REG_ARM_TIMER_CNT: |
| vcpu->kvm->arch.timer.cntvoff = kvm_phys_timer_read() - value; |
| break; |
| case KVM_REG_ARM_TIMER_CVAL: |
| timer->cntv_cval = value; |
| break; |
| default: |
| return -1; |
| } |
| |
| kvm_timer_update_state(vcpu); |
| return 0; |
| } |
| |
| u64 kvm_arm_timer_get_reg(struct kvm_vcpu *vcpu, u64 regid) |
| { |
| struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu; |
| |
| switch (regid) { |
| case KVM_REG_ARM_TIMER_CTL: |
| return timer->cntv_ctl; |
| case KVM_REG_ARM_TIMER_CNT: |
| return kvm_phys_timer_read() - vcpu->kvm->arch.timer.cntvoff; |
| case KVM_REG_ARM_TIMER_CVAL: |
| return timer->cntv_cval; |
| } |
| return (u64)-1; |
| } |
| |
| static int kvm_timer_starting_cpu(unsigned int cpu) |
| { |
| kvm_timer_init_interrupt(NULL); |
| return 0; |
| } |
| |
| static int kvm_timer_dying_cpu(unsigned int cpu) |
| { |
| disable_percpu_irq(host_vtimer_irq); |
| return 0; |
| } |
| |
| int kvm_timer_hyp_init(void) |
| { |
| struct arch_timer_kvm_info *info; |
| int err; |
| |
| info = arch_timer_get_kvm_info(); |
| timecounter = &info->timecounter; |
| |
| if (info->virtual_irq <= 0) { |
| kvm_err("kvm_arch_timer: invalid virtual timer IRQ: %d\n", |
| info->virtual_irq); |
| return -ENODEV; |
| } |
| host_vtimer_irq = info->virtual_irq; |
| |
| err = request_percpu_irq(host_vtimer_irq, kvm_arch_timer_handler, |
| "kvm guest timer", kvm_get_running_vcpus()); |
| if (err) { |
| kvm_err("kvm_arch_timer: can't request interrupt %d (%d)\n", |
| host_vtimer_irq, err); |
| goto out; |
| } |
| |
| wqueue = create_singlethread_workqueue("kvm_arch_timer"); |
| if (!wqueue) { |
| err = -ENOMEM; |
| goto out_free; |
| } |
| |
| kvm_info("virtual timer IRQ%d\n", host_vtimer_irq); |
| |
| cpuhp_setup_state(CPUHP_AP_KVM_ARM_TIMER_STARTING, |
| "AP_KVM_ARM_TIMER_STARTING", kvm_timer_starting_cpu, |
| kvm_timer_dying_cpu); |
| goto out; |
| out_free: |
| free_percpu_irq(host_vtimer_irq, kvm_get_running_vcpus()); |
| out: |
| return err; |
| } |
| |
| void kvm_timer_vcpu_terminate(struct kvm_vcpu *vcpu) |
| { |
| struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu; |
| |
| timer_disarm(timer); |
| kvm_vgic_unmap_phys_irq(vcpu, timer->irq.irq); |
| } |
| |
| int kvm_timer_enable(struct kvm_vcpu *vcpu) |
| { |
| struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu; |
| struct irq_desc *desc; |
| struct irq_data *data; |
| int phys_irq; |
| int ret; |
| |
| if (timer->enabled) |
| return 0; |
| |
| /* |
| * Find the physical IRQ number corresponding to the host_vtimer_irq |
| */ |
| desc = irq_to_desc(host_vtimer_irq); |
| if (!desc) { |
| kvm_err("%s: no interrupt descriptor\n", __func__); |
| return -EINVAL; |
| } |
| |
| data = irq_desc_get_irq_data(desc); |
| while (data->parent_data) |
| data = data->parent_data; |
| |
| phys_irq = data->hwirq; |
| |
| /* |
| * Tell the VGIC that the virtual interrupt is tied to a |
| * physical interrupt. We do that once per VCPU. |
| */ |
| ret = kvm_vgic_map_phys_irq(vcpu, timer->irq.irq, phys_irq); |
| if (ret) |
| return ret; |
| |
| |
| /* |
| * There is a potential race here between VCPUs starting for the first |
| * time, which may be enabling the timer multiple times. That doesn't |
| * hurt though, because we're just setting a variable to the same |
| * variable that it already was. The important thing is that all |
| * VCPUs have the enabled variable set, before entering the guest, if |
| * the arch timers are enabled. |
| */ |
| if (timecounter && wqueue) |
| timer->enabled = 1; |
| |
| return 0; |
| } |
| |
| void kvm_timer_init(struct kvm *kvm) |
| { |
| kvm->arch.timer.cntvoff = kvm_phys_timer_read(); |
| } |