mc146818rtc: fix timer interrupt reinjection
commit 369b41359a
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 <mtosatti@redhat.com>
Message-Id: <20191010123008.GA19158@amt.cnet>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
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@ -203,7 +203,12 @@ periodic_timer_update(RTCState *s, int64_t current_time, uint32_t old_period)
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period = rtc_periodic_clock_ticks(s);
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if (period) {
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if (!period) {
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s->irq_coalesced = 0;
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timer_del(s->periodic_timer);
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return;
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}
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/* compute 32 khz clock */
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cur_clock =
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muldiv64(current_time, RTC_CLOCK_RATE, NANOSECONDS_PER_SECOND);
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@ -220,7 +225,6 @@ periodic_timer_update(RTCState *s, int64_t current_time, uint32_t old_period)
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last_periodic_clock = next_periodic_clock - old_period;
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lost_clock = cur_clock - last_periodic_clock;
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assert(lost_clock >= 0);
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}
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/*
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* s->irq_coalesced can change for two reasons:
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@ -257,16 +261,13 @@ periodic_timer_update(RTCState *s, int64_t current_time, uint32_t old_period)
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*/
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lost_clock = MIN(lost_clock, period);
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}
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}
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assert(lost_clock >= 0 && lost_clock <= period);
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next_irq_clock = cur_clock + period - lost_clock;
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s->next_periodic_time = periodic_clock_to_ns(next_irq_clock) + 1;
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timer_mod(s->periodic_timer, s->next_periodic_time);
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} else {
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s->irq_coalesced = 0;
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timer_del(s->periodic_timer);
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}
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}
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static void rtc_periodic_timer(void *opaque)
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