From 1ed13b9373d2fdfdf898ac864b024d55ef28890d Mon Sep 17 00:00:00 2001
From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Date: Wed, 24 Jun 2015 13:39:56 +0200
Subject: [PATCH 041/217] Serial: Migration compatibility pre 2.2/7.2

Message-id: <1435153196-26350-3-git-send-email-dgilbert@redhat.com>
Patchwork-id: 66380
O-Subject: [RHEL-7.2 qemu-kvm-rhev PATCH v3 2/2] Serial: Migration compatibility pre 2.2/7.2
Bugzilla: 1215087
RH-Acked-by: Juan Quintela <quintela@redhat.com>
RH-Acked-by: Laszlo Ersek <lersek@redhat.com>
RH-Acked-by: Michael S. Tsirkin <mst@redhat.com>
RH-Acked-by: Paolo Bonzini <pbonzini@redhat.com>

From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>

Disable subsections added in qemu 2.3

Newer qemu fixed migration corner cases for serial by adding subsections,
however if these are generated it will break backwards migration.
Disabling these subsections on older machine types should leave it no
worse than existing qemu, from which we're not aware of having any reports
of problems, and still allow these improvements on new machine types.
Even when a user isn't actively using a serial port a guest will
probably initialise it and may send stuff (e.g. a copy of the console messages
or the login: prompt).

Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
---
 hw/char/serial.c | 29 +++++++++++++++++++++++++++++
 1 file changed, 29 insertions(+)

diff --git a/hw/char/serial.c b/hw/char/serial.c
index 55011cf..248bf8b 100644
--- a/hw/char/serial.c
+++ b/hw/char/serial.c
@@ -28,6 +28,7 @@
 #include "qemu/timer.h"
 #include "exec/address-spaces.h"
 #include "qemu/error-report.h"
+#include "migration/migration.h"
 
 //#define DEBUG_SERIAL
 
@@ -646,6 +647,10 @@ static bool serial_thr_ipending_needed(void *opaque)
 {
     SerialState *s = opaque;
 
+    if (migrate_pre_2_2) {
+        return false;
+    }
+
     if (s->ier & UART_IER_THRI) {
         bool expected_value = ((s->iir & UART_IIR_ID) == UART_IIR_THRI);
         return s->thr_ipending != expected_value;
@@ -671,6 +676,10 @@ static const VMStateDescription vmstate_serial_thr_ipending = {
 static bool serial_tsr_needed(void *opaque)
 {
     SerialState *s = (SerialState *)opaque;
+    if (migrate_pre_2_2) {
+        return false;
+    }
+
     return s->tsr_retry != 0;
 }
 
@@ -689,6 +698,10 @@ static const VMStateDescription vmstate_serial_tsr = {
 static bool serial_recv_fifo_needed(void *opaque)
 {
     SerialState *s = (SerialState *)opaque;
+    if (migrate_pre_2_2) {
+        return false;
+    }
+
     return !fifo8_is_empty(&s->recv_fifo);
 
 }
@@ -706,6 +719,10 @@ static const VMStateDescription vmstate_serial_recv_fifo = {
 static bool serial_xmit_fifo_needed(void *opaque)
 {
     SerialState *s = (SerialState *)opaque;
+    if (migrate_pre_2_2) {
+        return false;
+    }
+
     return !fifo8_is_empty(&s->xmit_fifo);
 }
 
@@ -722,6 +739,10 @@ static const VMStateDescription vmstate_serial_xmit_fifo = {
 static bool serial_fifo_timeout_timer_needed(void *opaque)
 {
     SerialState *s = (SerialState *)opaque;
+    if (migrate_pre_2_2) {
+        return false;
+    }
+
     return timer_pending(s->fifo_timeout_timer);
 }
 
@@ -738,6 +759,10 @@ static const VMStateDescription vmstate_serial_fifo_timeout_timer = {
 static bool serial_timeout_ipending_needed(void *opaque)
 {
     SerialState *s = (SerialState *)opaque;
+    if (migrate_pre_2_2) {
+        return false;
+    }
+
     return s->timeout_ipending != 0;
 }
 
@@ -754,6 +779,10 @@ static const VMStateDescription vmstate_serial_timeout_ipending = {
 static bool serial_poll_needed(void *opaque)
 {
     SerialState *s = (SerialState *)opaque;
+    if (migrate_pre_2_2) {
+        return false;
+    }
+
     return s->poll_msl >= 0;
 }
 
-- 
1.8.3.1