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From 8af16b9722f5bdeacf3a30c21490846e24b989b2 Mon Sep 17 00:00:00 2001
From: Marcelo Tosatti <mtosatti@redhat.com>
Date: Wed, 4 Dec 2019 15:21:08 +0100
Subject: [PATCH 2/3] Revert "mc146818rtc: fix timer interrupt reinjection"

RH-Author: Marcelo Tosatti <mtosatti@redhat.com>
Message-id: <20191204152436.753293175@amt.cnet>
Patchwork-id: 92888
O-Subject: [RHEL-7.8 qemu-kvm-rhev PATCH 2/3] Revert "mc146818rtc: fix timer interrupt reinjection"
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: 3ae32adff17226bc6a5f3fd7bb9804e6779e0660
of pbonzini's for-upstream tree.

This reverts commit b429de730174b388ea5760e3debb0d542ea3c261, except
that the reversal of the outer "if (period)" is left in.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
---
 hw/timer/mc146818rtc.c | 67 +++++++++++++++++++++++++-------------------------
 1 file changed, 33 insertions(+), 34 deletions(-)

diff --git a/hw/timer/mc146818rtc.c b/hw/timer/mc146818rtc.c
index 296d974..d848911 100644
--- a/hw/timer/mc146818rtc.c
+++ b/hw/timer/mc146818rtc.c
@@ -196,7 +196,6 @@ periodic_timer_update(RTCState *s, int64_t current_time, uint32_t old_period)
     int64_t cur_clock, next_irq_clock, lost_clock = 0;
 
     period = rtc_periodic_clock_ticks(s);
-
     if (!period) {
         s->irq_coalesced = 0;
         timer_del(s->periodic_timer);
@@ -219,42 +218,42 @@ periodic_timer_update(RTCState *s, int64_t current_time, uint32_t old_period)
         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:
+     *
+     * a) if one or more periodic timer interrupts have been lost,
+     *    lost_clock will be more that a period.
+     *
+     * b) when the period may be reconfigured, we expect the OS to
+     *    treat delayed tick as the new period.  So, when switching
+     *    from a shorter to a longer period, scale down the missing,
+     *    because the OS will treat past delayed ticks as longer
+     *    (leftovers are put back into lost_clock).  When switching
+     *    to a shorter period, scale up the missing ticks since the
+     *    OS handler will treat past delayed ticks as shorter.
+     */
+    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;
+        if (old_irq_coalesced != s->irq_coalesced ||
+            old_period != s->period) {
+            DPRINTF_C("cmos: coalesced irqs scaled from %d to %d, "
+                      "period scaled from %d to %d\n", old_irq_coalesced,
+                      s->irq_coalesced, old_period, s->period);
+            rtc_coalesced_timer_update(s);
+        }
+    } else {
         /*
-         * s->irq_coalesced can change for two reasons:
-         *
-         * a) if one or more periodic timer interrupts have been lost,
-         *    lost_clock will be more that a period.
-         *
-         * b) when the period may be reconfigured, we expect the OS to
-         *    treat delayed tick as the new period.  So, when switching
-         *    from a shorter to a longer period, scale down the missing,
-         *    because the OS will treat past delayed ticks as longer
-         *    (leftovers are put back into lost_clock).  When switching
-         *    to a shorter period, scale up the missing ticks since the
-         *    OS handler will treat past delayed ticks as shorter.
+         * no way to compensate the interrupt if LOST_TICK_POLICY_SLEW
+         * is not used, we should make the time progress anyway.
          */
-        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;
-            if (old_irq_coalesced != s->irq_coalesced ||
-                old_period != s->period) {
-                DPRINTF_C("cmos: coalesced irqs scaled from %d to %d, "
-                          "period scaled from %d to %d\n", old_irq_coalesced,
-                          s->irq_coalesced, old_period, s->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);
-        }
+        lost_clock = MIN(lost_clock, period);
     }
 
     assert(lost_clock >= 0 && lost_clock <= period);
-- 
1.8.3.1