[RFC PATCH v2 3/8] failover: virtio-net: remove failover_primary_hidden flag

[Laurent Vivier <lvivier@redhat.com>]

We dont't need a flag to know if the primary device must be hidden, we
can rely on the machine state:
Device is hidden if the machine is in prelaunch state (src) or
in inmigrate state with migration status set to none (dst).
We don't need to check the flag in virtio_net_handle_migration_primary()
because this function is only registered if the failover is enabled
and the flag also set to false. This function also sets it back to
true after a successful unplug during the migration but we don't
need to know it is hidden because nothing will try to plug it back
after the migration (except in case of error but the flag is set
back to false).

Signed-off-by: Laurent Vivier <lvivier@redhat.com>
---
 include/hw/virtio/virtio-net.h |  2 --
 hw/net/virtio-net.c            | 25 +++++++++++++++----------
 2 files changed, 15 insertions(+), 12 deletions(-)

diff --git a/include/hw/virtio/virtio-net.h b/include/hw/virtio/virtio-net.h
index 824a69c23f06..21d8c3aa5f3a 100644
--- a/include/hw/virtio/virtio-net.h
+++ b/include/hw/virtio/virtio-net.h
@@ -205,8 +205,6 @@ struct VirtIONet {
     AnnounceTimer announce_timer;
     bool needs_vnet_hdr_swap;
     bool mtu_bypass_backend;
-    /* primary failover device is hidden*/
-    bool failover_primary_hidden;
     bool failover;
     DeviceListener primary_listener;
     Notifier migration_state;
diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
index 0c5ec930356b..c81466f6efb7 100644
--- a/hw/net/virtio-net.c
+++ b/hw/net/virtio-net.c
@@ -36,8 +36,10 @@
 #include "qapi/qapi-types-migration.h"
 #include "qapi/qapi-events-migration.h"
 #include "hw/virtio/virtio-access.h"
+#include "migration/migration.h"
 #include "migration/misc.h"
 #include "standard-headers/linux/ethtool.h"
+#include "sysemu/runstate.h"
 #include "sysemu/sysemu.h"
 #include "trace.h"
 #include "monitor/qdev.h"
@@ -937,7 +939,6 @@ static void virtio_net_set_features(VirtIODevice *vdev, uint64_t features)
 
     if (virtio_has_feature(features, VIRTIO_NET_F_STANDBY)) {
         qapi_event_send_failover_negotiated(n->netclient_name);
-        qatomic_set(&n->failover_primary_hidden, false);
         failover_add_primary(n, &err);
         if (err) {
             warn_report_err(err);
@@ -3225,7 +3226,6 @@ static bool failover_replug_primary(VirtIONet *n, DeviceState *dev,
         return false;
     }
     qdev_set_parent_bus(dev, primary_bus, &error_abort);
-    qatomic_set(&n->failover_primary_hidden, false);
     hotplug_ctrl = qdev_get_hotplug_handler(dev);
     if (hotplug_ctrl) {
         hotplug_handler_pre_plug(hotplug_ctrl, dev, &err);
@@ -3243,7 +3243,6 @@ out:
 
 static void virtio_net_handle_migration_primary(VirtIONet *n, MigrationState *s)
 {
-    bool should_be_hidden;
     Error *err = NULL;
     DeviceState *dev = failover_find_primary_device(n);
 
@@ -3251,13 +3250,10 @@ static void virtio_net_handle_migration_primary(VirtIONet *n, MigrationState *s)
         return;
     }
 
-    should_be_hidden = qatomic_read(&n->failover_primary_hidden);
-
-    if (migration_in_setup(s) && !should_be_hidden) {
+    if (migration_in_setup(s)) {
         if (failover_unplug_primary(n, dev)) {
             vmstate_unregister(VMSTATE_IF(dev), qdev_get_vmsd(dev), dev);
             qapi_event_send_unplug_primary(dev->id);
-            qatomic_set(&n->failover_primary_hidden, true);
         } else {
             warn_report("couldn't unplug primary device");
         }
@@ -3299,8 +3295,18 @@ static bool failover_hide_primary_device(DeviceListener *listener,
         return false;
     }
 
-    /* failover_primary_hidden is set during feature negotiation */
-    return qatomic_read(&n->failover_primary_hidden);
+    if (runstate_check(RUN_STATE_PRELAUNCH)) {
+        /* hide the failover primary on src on startup */
+        return true;
+    }
+
+    if (runstate_check(RUN_STATE_INMIGRATE) &&
+        migration_incoming_get_current()->state == MIGRATION_STATUS_NONE) {
+        /* hide the failover primary on dest on startup */
+        return true;
+    }
+
+    return false;
 }
 
 static void virtio_net_device_realize(DeviceState *dev, Error **errp)
@@ -3338,7 +3344,6 @@ static void virtio_net_device_realize(DeviceState *dev, Error **errp)
 
     if (n->failover) {
         n->primary_listener.hide_device = failover_hide_primary_device;
-        qatomic_set(&n->failover_primary_hidden, true);
         device_listener_register(&n->primary_listener);
         n->migration_state.notify = virtio_net_migration_state_notifier;
         add_migration_state_change_notifier(&n->migration_state);
-- 
2.31.1