arch/x86/kvm/timer.c

   1 #include <linux/kvm_host.h>
   2 #include <linux/kvm.h>
   3 #include <linux/hrtimer.h>
   4 #include <asm/atomic.h>
   5 #include "kvm_timer.h"
   6
   7 static int __kvm_timer_fn(struct kvm_vcpu *vcpu, struct kvm_timer *ktimer)
   8 {
   9         int restart_timer = 0;
  10         wait_queue_head_t *q = &vcpu->wq;
  11
  12         /*
  13          * There is a race window between reading and incrementing, but we do
  14          * not care about potentially loosing timer events in the !reinject
  15          * case anyway. Note: KVM_REQ_PENDING_TIMER is implicitly checked
  16          * in vcpu_enter_guest.
  17          */
  18         if (ktimer->reinject || !atomic_read(&ktimer->pending)) {
  19                 atomic_inc(&ktimer->pending);
  20                 /* FIXME: this code should not know anything about vcpus */
  21                 set_bit(KVM_REQ_PENDING_TIMER, &vcpu->requests);
  22         }
  23
  24         if (waitqueue_active(q))
  25                 wake_up_interruptible(q);
  26
  27         if (ktimer->t_ops->is_periodic(ktimer)) {
  28                 hrtimer_add_expires_ns(&ktimer->timer, ktimer->period);
  29                 restart_timer = 1;
  30         }
  31
  32         return restart_timer;
  33 }
  34
  35 enum hrtimer_restart kvm_timer_fn(struct hrtimer *data)
  36 {
  37         int restart_timer;
  38         struct kvm_vcpu *vcpu;
  39         struct kvm_timer *ktimer = container_of(data, struct kvm_timer, timer);
  40
  41         vcpu = ktimer->vcpu;
  42         if (!vcpu)
  43                 return HRTIMER_NORESTART;
  44
  45         restart_timer = __kvm_timer_fn(vcpu, ktimer);
  46         if (restart_timer)
  47                 return HRTIMER_RESTART;
  48         else
  49                 return HRTIMER_NORESTART;
  50 }
  51