From 224a226b03d2c0503915bd1c1139b37b56afd62d Mon Sep 17 00:00:00 2001

From: Marcelo Tosatti <mtosatti@redhat.com>

Date: Wed, 4 Dec 2019 15:21:09 +0100

Subject: [PATCH 3/3] mc146818rtc: fix timer interrupt reinjection again

RH-Author: Marcelo Tosatti <mtosatti@redhat.com>

Message-id: <20191204152436.823942711@amt.cnet>

Patchwork-id: 92887

O-Subject: [RHEL-7.8 qemu-kvm-rhev PATCH 3/3] mc146818rtc: fix timer interrupt reinjection again

Bugzilla: 1639098

RH-Acked-by: Laszlo Ersek <lersek@redhat.com>

RH-Acked-by: Paolo Bonzini <pbonzini@redhat.com>

RH-Acked-by: Vitaly Kuznetsov <vkuznets@redhat.com>

BZ: 1639098

Brew: https://brewweb.engineering.redhat.com/brew/taskinfo?taskID=24854309

BRANCH: rhv7/master-2.12.0

Upstream: 7a3e29b12f5afe0106a5713bb4db6e23dc66ef91

of pbonzini's for-upstream tree.

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 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: Marcelo Tosatti <mtosatti@redhat.com>

Co-developed-by: Marcelo Tosatti <mtosatti@redhat.com>

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>

---

 hw/timer/mc146818rtc.c | 18 ++++++++++--------

 1 file changed, 10 insertions(+), 8 deletions(-)

diff --git a/hw/timer/mc146818rtc.c b/hw/timer/mc146818rtc.c

index d848911..7459040 100644

--- a/hw/timer/mc146818rtc.c

+++ b/hw/timer/mc146818rtc.c

@@ -190,12 +190,14 @@ 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);

@@ -210,7 +212,7 @@ 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,

@@ -237,7 +239,6 @@ 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;

@@ -267,7 +268,7 @@ 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;

@@ -533,7 +534,7 @@ 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);

@@ -572,7 +573,7 @@ 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);

@@ -816,6 +817,7 @@ 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.

@@ -825,7 +827,7 @@ 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);

         }

     }

@@ -893,7 +895,7 @@ static void rtc_notify_clock_reset(Notifier *notifier, void *data)

     int64_t now = *(int64_t *)data;

     rtc_set_date_from_host(ISA_DEVICE(s));

-    periodic_timer_update(s, now, 0);

+    periodic_timer_update(s, now, s->period, false);

     check_update_timer(s);

     if (s->lost_tick_policy == LOST_TICK_POLICY_SLEW) {

-- 

1.8.3.1