Commit 7a3e29b1 authored by Paolo Bonzini's avatar Paolo Bonzini
Browse files

mc146818rtc: fix timer interrupt reinjection again 



Commit 369b4135 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 passing s->period when periodic_timer_update is called due to
expiration of the timer.  With this change, old_period == 0 only
means that the periodic timer was off.

Reported-by: default avatarMarcelo Tosatti <mtosatti@redhat.com>
Co-developed-by: default avatarMarcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 3ae32adf

hw/rtc/mc146818rtc.c

+9 −7
Original line number Diff line number Diff line
@@ -168,12 +168,14 @@ static uint32_t rtc_periodic_clock_ticks(RTCState *s) 
 * is just due to period adjustment.

 */

static void

periodic_timer_update(RTCState *s, int64_t current_time, uint32_t old_period)

periodic_timer_update(RTCState *s, int64_t current_time, uint32_t old_period, bool period_change)

{

    uint32_t period;

    int64_t cur_clock, next_irq_clock, lost_clock = 0;



    period = rtc_periodic_clock_ticks(s);

    s->period = period;



    if (!period) {

        s->irq_coalesced = 0;

        timer_del(s->periodic_timer);
@@ -188,7 +190,7 @@ periodic_timer_update(RTCState *s, int64_t current_time, uint32_t old_period) 
     * if the periodic timer's update is due to period re-configuration,

     * we should count the clock since last interrupt.

     */

    if (old_period) {

    if (old_period && period_change) {

        int64_t last_periodic_clock, next_periodic_clock;



        next_periodic_clock = muldiv64(s->next_periodic_time,
@@ -215,7 +217,6 @@ periodic_timer_update(RTCState *s, int64_t current_time, uint32_t old_period) 
    if (s->lost_tick_policy == LOST_TICK_POLICY_SLEW) {

        uint32_t old_irq_coalesced = s->irq_coalesced;



        s->period = period;

        lost_clock += old_irq_coalesced * old_period;

        s->irq_coalesced = lost_clock / s->period;

        lost_clock %= s->period;
@@ -245,7 +246,7 @@ static void rtc_periodic_timer(void *opaque) 
{

    RTCState *s = opaque;



    periodic_timer_update(s, s->next_periodic_time, 0);

    periodic_timer_update(s, s->next_periodic_time, s->period, false);

    s->cmos_data[RTC_REG_C] |= REG_C_PF;

    if (s->cmos_data[RTC_REG_B] & REG_B_PIE) {

        s->cmos_data[RTC_REG_C] |= REG_C_IRQF;
@@ -511,7 +512,7 @@ static void cmos_ioport_write(void *opaque, hwaddr addr, 


            if (update_periodic_timer) {

                periodic_timer_update(s, qemu_clock_get_ns(rtc_clock),

                                      old_period);

                                      old_period, true);

            }



            check_update_timer(s);
@@ -550,7 +551,7 @@ static void cmos_ioport_write(void *opaque, hwaddr addr, 


            if (update_periodic_timer) {

                periodic_timer_update(s, qemu_clock_get_ns(rtc_clock),

                                      old_period);

                                      old_period, true);

            }



            check_update_timer(s);
@@ -794,6 +795,7 @@ static int rtc_post_load(void *opaque, int version_id) 
        s->offset = 0;

        check_update_timer(s);

    }

    s->period = rtc_periodic_clock_ticks(s);



    /* The periodic timer is deterministic in record/replay mode,

     * so there is no need to update it after loading the vmstate.
@@ -803,7 +805,7 @@ static int rtc_post_load(void *opaque, int version_id) 
        uint64_t now = qemu_clock_get_ns(rtc_clock);

        if (now < s->next_periodic_time ||

            now > (s->next_periodic_time + get_max_clock_jump())) {

            periodic_timer_update(s, qemu_clock_get_ns(rtc_clock), 0);

            periodic_timer_update(s, qemu_clock_get_ns(rtc_clock), s->period, false);

        }

    }