Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound-2.6
[pandora-kernel.git] / 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 <asm/atomic.h>
19 #include "kvm_timer.h"
20
21 static 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                 /* FIXME: this code should not know anything about vcpus */
35                 kvm_make_request(KVM_REQ_PENDING_TIMER, vcpu);
36         }
37
38         if (waitqueue_active(q))
39                 wake_up_interruptible(q);
40
41         if (ktimer->t_ops->is_periodic(ktimer)) {
42                 hrtimer_add_expires_ns(&ktimer->timer, ktimer->period);
43                 restart_timer = 1;
44         }
45
46         return restart_timer;
47 }
48
49 enum hrtimer_restart kvm_timer_fn(struct hrtimer *data)
50 {
51         int restart_timer;
52         struct kvm_vcpu *vcpu;
53         struct kvm_timer *ktimer = container_of(data, struct kvm_timer, timer);
54
55         vcpu = ktimer->vcpu;
56         if (!vcpu)
57                 return HRTIMER_NORESTART;
58
59         restart_timer = __kvm_timer_fn(vcpu, ktimer);
60         if (restart_timer)
61                 return HRTIMER_RESTART;
62         else
63                 return HRTIMER_NORESTART;
64 }
65