hw/net/virtio-net: Remove VirtIONet::mtu_bypass_backend field

The VirtIONet::mtu_bypass_backend boolean was only set in
the hw_compat_2_9[] array, via the 'x-mtu-bypass-backend=off'
property. We removed all machines using that array, lets remove
that property and all the code around it.

Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-ID: <20250501210456.89071-17-philmd@linaro.org>
Reviewed-by: Igor Mammedov <imammedo@redhat.com>
[thuth: Adjusted patch for latest changes in the master branch]
Signed-off-by: Thomas Huth <thuth@redhat.com>
Message-ID: <20260225092024.794595-14-thuth@redhat.com>

hw/net/virtio-net.c

@@ -935,8 +935,7 @@ static void virtio_net_set_features(VirtIODevice *vdev,
     int i;
 
     virtio_features_copy(features, in_features);
-    if (n->mtu_bypass_backend &&
-            !virtio_has_feature(vdev->backend_features, VIRTIO_NET_F_MTU)) {
+    if (!virtio_has_feature(vdev->backend_features, VIRTIO_NET_F_MTU)) {
         virtio_clear_feature_ex(features, VIRTIO_NET_F_MTU);
     }
 
@@ -3160,8 +3159,7 @@ static void virtio_net_get_features(VirtIODevice *vdev, uint64_t *features,
     vhost_net_get_features_ex(get_vhost_net(nc->peer), features);
     virtio_features_copy(vdev->backend_features_ex, features);
 
-    if (n->mtu_bypass_backend &&
-            (n->host_features & 1ULL << VIRTIO_NET_F_MTU)) {
+    if ((n->host_features & 1ULL << VIRTIO_NET_F_MTU) != 0) {
         virtio_add_feature_ex(features, VIRTIO_NET_F_MTU);
     }
 
@@ -4251,8 +4249,6 @@ static const Property virtio_net_properties[] = {
     DEFINE_PROP_UINT16("tx_queue_size", VirtIONet, net_conf.tx_queue_size,
                        VIRTIO_NET_TX_QUEUE_DEFAULT_SIZE),
     DEFINE_PROP_UINT16("host_mtu", VirtIONet, net_conf.mtu, 0),
-    DEFINE_PROP_BOOL("x-mtu-bypass-backend", VirtIONet, mtu_bypass_backend,
-                     true),
     DEFINE_PROP_INT32("speed", VirtIONet, net_conf.speed, SPEED_UNKNOWN),
     DEFINE_PROP_STRING("duplex", VirtIONet, net_conf.duplex_str),
     DEFINE_PROP_BOOL("failover", VirtIONet, failover, false),

include/hw/virtio/virtio-net.h

@@ -218,7 +218,6 @@ struct VirtIONet {
     uint64_t saved_guest_offloads;
     AnnounceTimer announce_timer;
     bool needs_vnet_hdr_swap;
-    bool mtu_bypass_backend;
     /* primary failover device is hidden*/
     bool failover_primary_hidden;
     bool failover;