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authorMarcelo Tosatti <mtosatti@redhat.com>2009-02-23 10:57:40 -0300
committerAvi Kivity <avi@redhat.com>2009-06-10 11:48:25 +0300
commitfd66842370e32f3bbe429677280a326c07e508c1 (patch)
treebae75e056c10b362b4d8556021cf965e5c25117f /arch/x86/kvm/i8254.c
parent5a05d54554f19a128306eca7f7f5ed31f7d7eeb9 (diff)
downloadlinux-fd66842370e32f3bbe429677280a326c07e508c1.tar.bz2
KVM: PIT: remove usage of count_load_time for channel 0
We can infer elapsed time from hrtimer_expires_remaining. Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com> Signed-off-by: Avi Kivity <avi@redhat.com>
Diffstat (limited to 'arch/x86/kvm/i8254.c')
-rw-r--r--arch/x86/kvm/i8254.c37
1 files changed, 31 insertions, 6 deletions
diff --git a/arch/x86/kvm/i8254.c b/arch/x86/kvm/i8254.c
index 3eddae692c05..09ae841ff462 100644
--- a/arch/x86/kvm/i8254.c
+++ b/arch/x86/kvm/i8254.c
@@ -98,6 +98,32 @@ static int pit_get_gate(struct kvm *kvm, int channel)
return kvm->arch.vpit->pit_state.channels[channel].gate;
}
+static s64 __kpit_elapsed(struct kvm *kvm)
+{
+ s64 elapsed;
+ ktime_t remaining;
+ struct kvm_kpit_state *ps = &kvm->arch.vpit->pit_state;
+
+ remaining = hrtimer_expires_remaining(&ps->pit_timer.timer);
+ if (ktime_to_ns(remaining) < 0)
+ remaining = ktime_set(0, 0);
+
+ elapsed = ps->pit_timer.period;
+ if (ktime_to_ns(remaining) <= ps->pit_timer.period)
+ elapsed = ps->pit_timer.period - ktime_to_ns(remaining);
+
+ return elapsed;
+}
+
+static s64 kpit_elapsed(struct kvm *kvm, struct kvm_kpit_channel_state *c,
+ int channel)
+{
+ if (channel == 0)
+ return __kpit_elapsed(kvm);
+
+ return ktime_to_ns(ktime_sub(ktime_get(), c->count_load_time));
+}
+
static int pit_get_count(struct kvm *kvm, int channel)
{
struct kvm_kpit_channel_state *c =
@@ -107,7 +133,7 @@ static int pit_get_count(struct kvm *kvm, int channel)
WARN_ON(!mutex_is_locked(&kvm->arch.vpit->pit_state.lock));
- t = ktime_to_ns(ktime_sub(ktime_get(), c->count_load_time));
+ t = kpit_elapsed(kvm, c, channel);
d = muldiv64(t, KVM_PIT_FREQ, NSEC_PER_SEC);
switch (c->mode) {
@@ -137,7 +163,7 @@ static int pit_get_out(struct kvm *kvm, int channel)
WARN_ON(!mutex_is_locked(&kvm->arch.vpit->pit_state.lock));
- t = ktime_to_ns(ktime_sub(ktime_get(), c->count_load_time));
+ t = kpit_elapsed(kvm, c, channel);
d = muldiv64(t, KVM_PIT_FREQ, NSEC_PER_SEC);
switch (c->mode) {
@@ -208,8 +234,6 @@ static int __pit_timer_fn(struct kvm_kpit_state *ps)
wake_up_interruptible(&vcpu0->wq);
hrtimer_add_expires_ns(&pt->timer, pt->period);
- if (pt->period)
- ps->channels[0].count_load_time = ktime_get();
return (pt->period == 0 ? 0 : 1);
}
@@ -305,11 +329,12 @@ static void pit_load_count(struct kvm *kvm, int channel, u32 val)
if (val == 0)
val = 0x10000;
- ps->channels[channel].count_load_time = ktime_get();
ps->channels[channel].count = val;
- if (channel != 0)
+ if (channel != 0) {
+ ps->channels[channel].count_load_time = ktime_get();
return;
+ }
/* Two types of timer
* mode 1 is one shot, mode 2 is period, otherwise del timer */