arch/arm/kvm/arch_timer.c

   1 /*
   2  * Copyright (C) 2012 ARM Ltd.
   3  * Author: Marc Zyngier <marc.zyngier@arm.com>
   4  *
   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.
   8  *
   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.
  13  *
  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
  17  */
  18
  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>
  24
  25 #include <asm/arch_timer.h>
  26
  27 #include <asm/kvm_vgic.h>
  28 #include <asm/kvm_arch_timer.h>
  29
  30 static struct timecounter *timecounter;
  31 static struct workqueue_struct *wqueue;
  32 static struct kvm_irq_level timer_irq = {
  33         .level  = 1,
  34 };
  35
  36 static cycle_t kvm_phys_timer_read(void)
  37 {
  38         return timecounter->cc->read(timecounter->cc);
  39 }
  40
  41 static bool timer_is_armed(struct arch_timer_cpu *timer)
  42 {
  43         return timer->armed;
  44 }
  45
  46 /* timer_arm: as in "arm the timer", not as in ARM the company */
  47 static void timer_arm(struct arch_timer_cpu *timer, u64 ns)
  48 {
  49         timer->armed = true;
  50         hrtimer_start(&timer->timer, ktime_add_ns(ktime_get(), ns),
  51                       HRTIMER_MODE_ABS);
  52 }
  53
  54 static void timer_disarm(struct arch_timer_cpu *timer)
  55 {
  56         if (timer_is_armed(timer)) {
  57                 hrtimer_cancel(&timer->timer);
  58                 cancel_work_sync(&timer->expired);
  59                 timer->armed = false;
  60         }
  61 }
  62
  63 static void kvm_timer_inject_irq(struct kvm_vcpu *vcpu)
  64 {
  65         struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
  66
  67         timer->cntv_ctl |= 1 << 1; /* Mask the interrupt in the guest */
  68         kvm_vgic_inject_irq(vcpu->kvm, vcpu->vcpu_id,
  69                             vcpu->arch.timer_cpu.irq->irq,
  70                             vcpu->arch.timer_cpu.irq->level);
  71 }
  72
  73 static irqreturn_t kvm_arch_timer_handler(int irq, void *dev_id)
  74 {
  75         struct kvm_vcpu *vcpu = *(struct kvm_vcpu **)dev_id;
  76
  77         /*
  78          * We disable the timer in the world switch and let it be
  79          * handled by kvm_timer_sync_hwstate(). Getting a timer
  80          * interrupt at this point is a sure sign of some major
  81          * breakage.
  82          */
  83         pr_warn("Unexpected interrupt %d on vcpu %p\n", irq, vcpu);
  84         return IRQ_HANDLED;
  85 }
  86
  87 static void kvm_timer_inject_irq_work(struct work_struct *work)
  88 {
  89         struct kvm_vcpu *vcpu;
  90
  91         vcpu = container_of(work, struct kvm_vcpu, arch.timer_cpu.expired);
  92         vcpu->arch.timer_cpu.armed = false;
  93         kvm_timer_inject_irq(vcpu);
  94 }
  95
  96 static enum hrtimer_restart kvm_timer_expire(struct hrtimer *hrt)
  97 {
  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;
 102 }
 103
 104 /**
 105  * kvm_timer_flush_hwstate - prepare to move the virt timer to the cpu
 106  * @vcpu: The vcpu pointer
 107  *
 108  * Disarm any pending soft timers, since the world-switch code will write the
 109  * virtual timer state back to the physical CPU.
 110  */
 111 void kvm_timer_flush_hwstate(struct kvm_vcpu *vcpu)
 112 {
 113         struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
 114
 115         /*
 116          * We're about to run this vcpu again, so there is no need to
 117          * keep the background timer running, as we're about to
 118          * populate the CPU timer again.
 119          */
 120         timer_disarm(timer);
 121 }
 122
 123 /**
 124  * kvm_timer_sync_hwstate - sync timer state from cpu
 125  * @vcpu: The vcpu pointer
 126  *
 127  * Check if the virtual timer was armed and either schedule a corresponding
 128  * soft timer or inject directly if already expired.
 129  */
 130 void kvm_timer_sync_hwstate(struct kvm_vcpu *vcpu)
 131 {
 132         struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
 133         cycle_t cval, now;
 134         u64 ns;
 135
 136         /* Check if the timer is enabled and unmasked first */
 137         if ((timer->cntv_ctl & 3) != 1)
 138                 return;
 139
 140         cval = timer->cntv_cval;
 141         now = kvm_phys_timer_read() - vcpu->kvm->arch.timer.cntvoff;
 142
 143         BUG_ON(timer_is_armed(timer));
 144
 145         if (cval <= now) {
 146                 /*
 147                  * Timer has already expired while we were not
 148                  * looking. Inject the interrupt and carry on.
 149                  */
 150                 kvm_timer_inject_irq(vcpu);
 151                 return;
 152         }
 153
 154         ns = cyclecounter_cyc2ns(timecounter->cc, cval - now);
 155         timer_arm(timer, ns);
 156 }
 157
 158 void kvm_timer_vcpu_init(struct kvm_vcpu *vcpu)
 159 {
 160         struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
 161
 162         INIT_WORK(&timer->expired, kvm_timer_inject_irq_work);
 163         hrtimer_init(&timer->timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS);
 164         timer->timer.function = kvm_timer_expire;
 165         timer->irq = &timer_irq;
 166 }
 167
 168 static void kvm_timer_init_interrupt(void *info)
 169 {
 170         enable_percpu_irq(timer_irq.irq, 0);
 171 }
 172
 173
 174 static int kvm_timer_cpu_notify(struct notifier_block *self,
 175                                 unsigned long action, void *cpu)
 176 {
 177         switch (action) {
 178         case CPU_STARTING:
 179         case CPU_STARTING_FROZEN:
 180                 kvm_timer_init_interrupt(NULL);
 181                 break;
 182         case CPU_DYING:
 183         case CPU_DYING_FROZEN:
 184                 disable_percpu_irq(timer_irq.irq);
 185                 break;
 186         }
 187
 188         return NOTIFY_OK;
 189 }
 190
 191 static struct notifier_block kvm_timer_cpu_nb = {
 192         .notifier_call = kvm_timer_cpu_notify,
 193 };
 194
 195 static const struct of_device_id arch_timer_of_match[] = {
 196         { .compatible   = "arm,armv7-timer",    },
 197         {},
 198 };
 199
 200 int kvm_timer_hyp_init(void)
 201 {
 202         struct device_node *np;
 203         unsigned int ppi;
 204         int err;
 205
 206         timecounter = arch_timer_get_timecounter();
 207         if (!timecounter)
 208                 return -ENODEV;
 209
 210         np = of_find_matching_node(NULL, arch_timer_of_match);
 211         if (!np) {
 212                 kvm_err("kvm_arch_timer: can't find DT node\n");
 213                 return -ENODEV;
 214         }
 215
 216         ppi = irq_of_parse_and_map(np, 2);
 217         if (!ppi) {
 218                 kvm_err("kvm_arch_timer: no virtual timer interrupt\n");
 219                 err = -EINVAL;
 220                 goto out;
 221         }
 222
 223         err = request_percpu_irq(ppi, kvm_arch_timer_handler,
 224                                  "kvm guest timer", kvm_get_running_vcpus());
 225         if (err) {
 226                 kvm_err("kvm_arch_timer: can't request interrupt %d (%d)\n",
 227                         ppi, err);
 228                 goto out;
 229         }
 230
 231         timer_irq.irq = ppi;
 232
 233         err = register_cpu_notifier(&kvm_timer_cpu_nb);
 234         if (err) {
 235                 kvm_err("Cannot register timer CPU notifier\n");
 236                 goto out_free;
 237         }
 238
 239         wqueue = create_singlethread_workqueue("kvm_arch_timer");
 240         if (!wqueue) {
 241                 err = -ENOMEM;
 242                 goto out_free;
 243         }
 244
 245         kvm_info("%s IRQ%d\n", np->name, ppi);
 246         on_each_cpu(kvm_timer_init_interrupt, NULL, 1);
 247
 248         goto out;
 249 out_free:
 250         free_percpu_irq(ppi, kvm_get_running_vcpus());
 251 out:
 252         of_node_put(np);
 253         return err;
 254 }
 255
 256 void kvm_timer_vcpu_terminate(struct kvm_vcpu *vcpu)
 257 {
 258         struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
 259
 260         timer_disarm(timer);
 261 }
 262
 263 int kvm_timer_init(struct kvm *kvm)
 264 {
 265         if (timecounter && wqueue) {
 266                 kvm->arch.timer.cntvoff = kvm_phys_timer_read();
 267                 kvm->arch.timer.enabled = 1;
 268         }
 269
 270         return 0;
 271 }