LXR linux/arch/x86/kvm/timer.c

   1/*
   2 * Kernel-based Virtual Machine driver for Linux
   3 *
   4 * This module enables machines with Intel VT-x extensions to run virtual
   5 * machines without emulation or binary translation.
   6 *
   7 * timer support
   8 *
   9 * Copyright 2010 Red Hat, Inc. and/or its affiliates.
  10 *
  11 * This work is licensed under the terms of the GNU GPL, version 2.  See
  12 * the COPYING file in the top-level directory.
  13 */
  14
  15#include <linux/kvm_host.h>
  16#include <linux/kvm.h>
  17#include <linux/hrtimer.h>
  18#include <linux/atomic.h>
  19#include "kvm_timer.h"
  20
  21enum hrtimer_restart kvm_timer_fn(struct hrtimer *data)
  22{
  23        struct kvm_timer *ktimer = container_of(data, struct kvm_timer, timer);
  24        struct kvm_vcpu *vcpu = ktimer->vcpu;
  25        wait_queue_head_t *q = &vcpu->wq;
  26
  27        /*
  28         * There is a race window between reading and incrementing, but we do
  29         * not care about potentially losing timer events in the !reinject
  30         * case anyway. Note: KVM_REQ_PENDING_TIMER is implicitly checked
  31         * in vcpu_enter_guest.
  32         */
  33        if (ktimer->reinject || !atomic_read(&ktimer->pending)) {
  34                atomic_inc(&ktimer->pending);
  35                /* FIXME: this code should not know anything about vcpus */
  36                kvm_make_request(KVM_REQ_PENDING_TIMER, vcpu);
  37        }
  38
  39        if (waitqueue_active(q))
  40                wake_up_interruptible(q);
  41
  42        if (ktimer->t_ops->is_periodic(ktimer)) {
  43                hrtimer_add_expires_ns(&ktimer->timer, ktimer->period);
  44                return HRTIMER_RESTART;
  45        } else
  46                return HRTIMER_NORESTART;
  47}
  48