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 kvm_timer_fn(struct hrtimer * data)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