On 10/10/19 14:30, Marcelo Tosatti wrote:
>
> commit 369b41359af46bded5799c9ef8be2b641d92e043 broke timer interrupt
> reinjection when there is no period change by the guest.
>
> In that case, old_period is 0, which ends up zeroing irq_coalesced
> (counter of reinjected interrupts).
>
> The consequence is Windows 7 is unable to synchronize time via NTP.
> Easily reproducible by playing a fullscreen video with cirrus and VNC.
>
> Fix by not updating s->irq_coalesced when old_period is 0.
>
> V2: reorganize code (Paolo Bonzini)
>
> Signed-off-by: Marcelo Tosatti <mtosa...@redhat.com>
>
> diff --git a/hw/timer/mc146818rtc.c b/hw/timer/mc146818rtc.c
> index 6cb378751b..0e7cf97042 100644
> --- a/hw/timer/mc146818rtc.c
> +++ b/hw/timer/mc146818rtc.c
> @@ -203,24 +203,28 @@ periodic_timer_update(RTCState *s, int64_t
> current_time, uint32_t old_period)
>
> period = rtc_periodic_clock_ticks(s);
>
> - if (period) {
> - /* compute 32 khz clock */
> - cur_clock =
> - muldiv64(current_time, RTC_CLOCK_RATE, NANOSECONDS_PER_SECOND);
> + if (!period) {
> + s->irq_coalesced = 0;
> + timer_del(s->periodic_timer);
> + return;
> + }
>
> - /*
> - * if the periodic timer's update is due to period re-configuration,
> - * we should count the clock since last interrupt.
> - */
> - if (old_period) {
> - int64_t last_periodic_clock, next_periodic_clock;
> -
> - next_periodic_clock = muldiv64(s->next_periodic_time,
> - RTC_CLOCK_RATE, NANOSECONDS_PER_SECOND);
> - last_periodic_clock = next_periodic_clock - old_period;
> - lost_clock = cur_clock - last_periodic_clock;
> - assert(lost_clock >= 0);
> - }
> + /* compute 32 khz clock */
> + cur_clock =
> + muldiv64(current_time, RTC_CLOCK_RATE, NANOSECONDS_PER_SECOND);
> +
> + /*
> + * if the periodic timer's update is due to period re-configuration,
> + * we should count the clock since last interrupt.
> + */
> + if (old_period) {
> + int64_t last_periodic_clock, next_periodic_clock;
> +
> + next_periodic_clock = muldiv64(s->next_periodic_time,
> + RTC_CLOCK_RATE, NANOSECONDS_PER_SECOND);
> + last_periodic_clock = next_periodic_clock - old_period;
> + lost_clock = cur_clock - last_periodic_clock;
> + assert(lost_clock >= 0);
>
> /*
> * s->irq_coalesced can change for two reasons:
> @@ -251,22 +255,19 @@ periodic_timer_update(RTCState *s, int64_t
> current_time, uint32_t old_period)
> rtc_coalesced_timer_update(s);
> }
> } else {
> - /*
> + /*
> * no way to compensate the interrupt if LOST_TICK_POLICY_SLEW
> * is not used, we should make the time progress anyway.
> */
> lost_clock = MIN(lost_clock, period);
> }
> + }
>
> - assert(lost_clock >= 0 && lost_clock <= period);
> + assert(lost_clock >= 0 && lost_clock <= period);
>
> - next_irq_clock = cur_clock + period - lost_clock;
> - s->next_periodic_time = periodic_clock_to_ns(next_irq_clock) + 1;
> - timer_mod(s->periodic_timer, s->next_periodic_time);
> - } else {
> - s->irq_coalesced = 0;
> - timer_del(s->periodic_timer);
> - }
> + next_irq_clock = cur_clock + period - lost_clock;
> + s->next_periodic_time = periodic_clock_to_ns(next_irq_clock) + 1;
> + timer_mod(s->periodic_timer, s->next_periodic_time);
> }
>
> static void rtc_periodic_timer(void *opaque)
>
Queued, thanks.
Paolo
