[RFC v2] virtio-net: check the mac address for vdpa device

[Cindy Lu]

When using a VDPA device, it is important to ensure that the MAC address
in the hardware matches the MAC address from the QEMU command line.

There are only two acceptable situations:
1. The hardware MAC address is the same as the MAC address specified in the QEMU
command line, and both MAC addresses are not 0.
2. The hardware MAC address is not 0, and the MAC address in the QEMU command 
line is 0.
In this situation, the hardware MAC address will overwrite the QEMU command 
line address.

Signed-off-by: Cindy Lu <lulu@redhat.com>
---
 hw/net/virtio-net.c | 43 +++++++++++++++++++++++++++++++++++++------
 1 file changed, 37 insertions(+), 6 deletions(-)

diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
index 9c7e85caea..8f79785f59 100644
--- a/hw/net/virtio-net.c
+++ b/hw/net/virtio-net.c
@@ -178,8 +178,8 @@ static void virtio_net_get_config(VirtIODevice *vdev, 
uint8_t *config)
          * correctly elsewhere - just not reported by the device.
          */
         if (memcmp(&netcfg.mac, &zero, sizeof(zero)) == 0) {
-            info_report("Zero hardware mac address detected. Ignoring.");
-            memcpy(netcfg.mac, n->mac, ETH_ALEN);
+          error_report("Zero hardware mac address detected in vdpa device. "
+                       "please check the vdpa device!");
         }
 
         netcfg.status |= virtio_tswap16(vdev,
@@ -3579,12 +3579,42 @@ static bool failover_hide_primary_device(DeviceListener 
*listener,
     /* failover_primary_hidden is set during feature negotiation */
     return qatomic_read(&n->failover_primary_hidden);
 }
+static bool virtio_net_check_vdpa_mac(NetClientState *nc, VirtIONet *n,
+                                      MACAddr *cmdline_mac, Error **errp) {
+  struct virtio_net_config hwcfg = {};
+  static const MACAddr zero = {.a = {0, 0, 0, 0, 0, 0}};
 
+  vhost_net_get_config(get_vhost_net(nc->peer), (uint8_t *)&hwcfg, ETH_ALEN);
+
+  /* For VDPA device: Only two situations are acceptable:
+   * 1.The hardware MAC address is the same as the QEMU command line MAC
+   *   address, and both of them are not 0.
+   * 2.The hardware MAC address is NOT 0, and the QEMU command line MAC address
+   *   is 0. In this situation, the hardware MAC address will overwrite the 
QEMU
+   *   command line address.
+   */
+
+  if (memcmp(&hwcfg.mac, &zero, sizeof(MACAddr)) != 0) {
+    if ((memcmp(&hwcfg.mac, cmdline_mac, sizeof(MACAddr)) == 0) ||
+        (memcmp(cmdline_mac, &zero, sizeof(MACAddr)) == 0)) {
+      /* overwrite the mac address with hardware address*/
+      memcpy(&n->mac[0], &hwcfg.mac, sizeof(n->mac));
+      memcpy(&n->nic_conf.macaddr, &hwcfg.mac, sizeof(n->mac));
+
+      return true;
+    }
+  }
+  error_setg(errp, "vdpa hardware mac != the mac address from "
+                   "qemu cmdline, please check the the vdpa device's 
setting.");
+
+  return false;
+}
 static void virtio_net_device_realize(DeviceState *dev, Error **errp)
 {
     VirtIODevice *vdev = VIRTIO_DEVICE(dev);
     VirtIONet *n = VIRTIO_NET(dev);
     NetClientState *nc;
+    MACAddr macaddr_cmdline;
     int i;
 
     if (n->net_conf.mtu) {
@@ -3692,6 +3722,7 @@ static void virtio_net_device_realize(DeviceState *dev, 
Error **errp)
     virtio_net_add_queue(n, 0);
 
     n->ctrl_vq = virtio_add_queue(vdev, 64, virtio_net_handle_ctrl);
+    memcpy(&macaddr_cmdline, &n->nic_conf.macaddr, sizeof(n->mac));
     qemu_macaddr_default_if_unset(&n->nic_conf.macaddr);
     memcpy(&n->mac[0], &n->nic_conf.macaddr, sizeof(n->mac));
     n->status = VIRTIO_NET_S_LINK_UP;
@@ -3739,10 +3770,10 @@ 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);
+     if (!virtio_net_check_vdpa_mac(nc, n, &macaddr_cmdline, errp)) {
+       virtio_cleanup(vdev);
+       return;
+     }
     }
     QTAILQ_INIT(&n->rsc_chains);
     n->qdev = dev;
-- 
2.45.0