[RFC] virtio-net: check the mac address for vdpa device

[Cindy Lu]

When using VDPA device, we should verify whether the MAC address in the
hardware matches the MAC address from the QEMU command line. If not,
we will need to update the related information.

Signed-off-by: Cindy Lu <l...@redhat.com>
---
 hw/net/virtio-net.c | 15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)

diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
index 9c7e85caea..db04331b82 100644
--- a/hw/net/virtio-net.c
+++ b/hw/net/virtio-net.c
@@ -3739,10 +3739,17 @@ static void virtio_net_device_realize(DeviceState *dev, 
Error **errp)
     nc->rxfilter_notify_enabled = 1;
 
    if (nc->peer && nc->peer->info->type == NET_CLIENT_DRIVER_VHOST_VDPA) {
-        struct virtio_net_config netcfg = {};
-        memcpy(&netcfg.mac, &n->nic_conf.macaddr, ETH_ALEN);
-        vhost_net_set_config(get_vhost_net(nc->peer),
-            (uint8_t *)&netcfg, 0, ETH_ALEN, VHOST_SET_CONFIG_TYPE_FRONTEND);
+     struct virtio_net_config netcfg = {};
+     static const MACAddr zero = {.a = {0, 0, 0, 0, 0, 0}};
+     vhost_net_get_config(get_vhost_net(nc->peer), (uint8_t *)&netcfg,
+                          ETH_ALEN);
+     if ((memcmp(&netcfg.mac, &n->nic_conf.macaddr, sizeof(MACAddr)) != 0) &&
+         memcmp(&netcfg.mac, &zero, sizeof(zero) != 0)) {
+       memcpy(&n->nic_conf.macaddr, &netcfg.mac, sizeof(MACAddr));
+       memcpy(&n->mac[0], &netcfg.mac, sizeof(MACAddr));
+     }
+     vhost_net_set_config(get_vhost_net(nc->peer), (uint8_t *)&netcfg, 0,
+                          ETH_ALEN, VHOST_SET_CONFIG_TYPE_FRONTEND);
     }
     QTAILQ_INIT(&n->rsc_chains);
     n->qdev = dev;
-- 
2.45.0