When using a VDPA device, it is important to ensure that the MAC
address is correctly set. The MAC address in the hardware should
match the MAC address from the QEMU command line. This is a recommended
configuration and will allow the system to boot.

Signed-off-by: Cindy Lu <lulu@redhat.com>
---
 hw/net/virtio-net.c | 40 ++++++++++++++++++++++++++++++++++++----
 1 file changed, 36 insertions(+), 4 deletions(-)

diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
index fb84d142ee..7aa7308244 100644
--- a/hw/net/virtio-net.c
+++ b/hw/net/virtio-net.c
@@ -3589,12 +3589,43 @@ 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 following situations are acceptable:*/
 
+    if (memcmp(&hwcfg.mac, &zero, sizeof(MACAddr)) != 0) {
+        /*
+         * 1.The hardware MAC address is the same as the QEMU command line MAC
+         *   address, and both of them are not 0.
+         */
+        if ((memcmp(&hwcfg.mac, cmdline_mac, sizeof(MACAddr)) == 0)) {
+            return true;
+        }
+    }
+
+    error_setg(errp,
+               "vDPA device's mac %02x:%02x:%02x:%02x:%02x:%02x"
+               "not same with the cmdline's mac %02x:%02x:%02x:%02x:%02x:%02x,"
+               "Please check.",
+               hwcfg.mac[0], hwcfg.mac[1], hwcfg.mac[2], hwcfg.mac[3],
+               hwcfg.mac[4], hwcfg.mac[5], cmdline_mac->a[0], cmdline_mac->a[1],
+               cmdline_mac->a[2], cmdline_mac->a[3], cmdline_mac->a[4],
+               cmdline_mac->a[5]);
+
+    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) {
@@ -3702,6 +3733,7 @@ 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;
@@ -3749,10 +3781,10 @@ 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

On Mon, Sep 30, 2024 at 12:01 AM Cindy Lu <lulu@redhat.com> wrote:
>
> When using a VDPA device, it is important to ensure that the MAC
> address is correctly set. The MAC address in the hardware should
> match the MAC address from the QEMU command line. This is a recommended
> configuration and will allow the system to boot.

Would there be a case that the system can boot even without the
suggested setting here? Can we even know about that?

I'm asking since if there's one, we break them. At least we can have a
new parameter for strict checking.

Thanks