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 affilates. 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 <asm/atomic.h> 19#include "kvm_timer.h" 20 21static int __kvm_timer_fn(struct kvm_vcpu *vcpu, struct kvm_timer *ktimer) 22{ 23 int restart_timer = 0; 24 wait_queue_head_t *q = &vcpu->wq; 25 26 /* 27 * There is a race window between reading and incrementing, but we do 28 * not care about potentially loosing timer events in the !reinject 29 * case anyway. Note: KVM_REQ_PENDING_TIMER is implicitly checked 30 * in vcpu_enter_guest. 31 */ 32 if (ktimer->reinject || !atomic_read(&ktimer->pending)) { 33 atomic_inc(&ktimer->pending); 34 kvm_make_request(KVM_REQ_PENDING_TIMER, vcpu); 35 } 36 37 if (waitqueue_active(q)) 38 wake_up_interruptible(q); 39 40 if (ktimer->t_ops->is_periodic(ktimer)) { 41 hrtimer_add_expires_ns(&ktimer->timer, ktimer->period); 42 restart_timer = 1; 43 } 44 45 return restart_timer; 46} 47 48enum hrtimer_restart kvm_timer_fn(struct hrtimer *data) 49{ 50 int restart_timer; 51 struct kvm_vcpu *vcpu; 52 struct kvm_timer *ktimer = container_of(data, struct kvm_timer, timer); 53 54 vcpu = ktimer->vcpu; 55 if (!vcpu) 56 return HRTIMER_NORESTART; 57 58 restart_timer = __kvm_timer_fn(vcpu, ktimer); 59 if (restart_timer) 60 return HRTIMER_RESTART; 61 else 62 return HRTIMER_NORESTART; 63} 64