diff options
Diffstat (limited to 'arch/x86/kvm/i8254.c')
| -rw-r--r-- | arch/x86/kvm/i8254.c | 26 |
1 files changed, 15 insertions, 11 deletions
diff --git a/arch/x86/kvm/i8254.c b/arch/x86/kvm/i8254.c index cf09bb6..4d6f0d2 100644 --- a/arch/x86/kvm/i8254.c +++ b/arch/x86/kvm/i8254.c @@ -104,13 +104,18 @@ static s64 __kpit_elapsed(struct kvm *kvm) ktime_t remaining; struct kvm_kpit_state *ps = &kvm->arch.vpit->pit_state; + /* + * The Counter does not stop when it reaches zero. In + * Modes 0, 1, 4, and 5 the Counter ``wraps around'' to + * the highest count, either FFFF hex for binary counting + * or 9999 for BCD counting, and continues counting. + * Modes 2 and 3 are periodic; the Counter reloads + * itself with the initial count and continues counting + * from there. + */ 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); + elapsed = ps->pit_timer.period - ktime_to_ns(remaining); + elapsed = mod_64(elapsed, ps->pit_timer.period); return elapsed; } @@ -280,7 +285,7 @@ static void create_pit_timer(struct kvm_kpit_state *ps, u32 val, int is_period) /* TODO The new value only affected after the retriggered */ hrtimer_cancel(&pt->timer); - pt->period = (is_period == 0) ? 0 : interval; + pt->period = interval; ps->is_periodic = is_period; pt->timer.function = kvm_timer_fn; @@ -304,10 +309,8 @@ static void pit_load_count(struct kvm *kvm, int channel, u32 val) pr_debug("pit: load_count val is %d, channel is %d\n", val, channel); /* - * Though spec said the state of 8254 is undefined after power-up, - * seems some tricky OS like Windows XP depends on IRQ0 interrupt - * when booting up. - * So here setting initialize rate for it, and not a specific number + * The largest possible initial count is 0; this is equivalent + * to 216 for binary counting and 104 for BCD counting. */ if (val == 0) val = 0x10000; @@ -322,6 +325,7 @@ static void pit_load_count(struct kvm *kvm, int channel, u32 val) /* Two types of timer * mode 1 is one shot, mode 2 is period, otherwise del timer */ switch (ps->channels[0].mode) { + case 0: case 1: /* FIXME: enhance mode 4 precision */ case 4: |
