vdpa_sim: store parsed MAC address in a buffer

As preparation for the next patches, we store the MAC address,
parsed during the vdpasim_create(), in a buffer that will be used
to fill 'config' together with other configurations.
Acked-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
Link: https://lore.kernel.org/r/20201215144256.155342-11-sgarzare@redhat.comSigned-off-by: Michael S. Tsirkin <mst@redhat.com>

drivers/vdpa/vdpa_sim/vdpa_sim.c

@@ -40,6 +40,8 @@ static char *macaddr;
 module_param(macaddr, charp, 0);
 MODULE_PARM_DESC(macaddr, "Ethernet MAC address");
 
+u8 macaddr_buf[ETH_ALEN];
+
 struct vdpasim_virtqueue {
 	struct vringh vring;
 	struct vringh_kiov iov;
@@ -396,13 +398,13 @@ static struct vdpasim *vdpasim_create(struct vdpasim_dev_attr *dev_attr)
 		goto err_iommu;
 
 	if (macaddr) {
-		mac_pton(macaddr, vdpasim->config.mac);
-		if (!is_valid_ether_addr(vdpasim->config.mac)) {
+		mac_pton(macaddr, macaddr_buf);
+		if (!is_valid_ether_addr(macaddr_buf)) {
 			ret = -EADDRNOTAVAIL;
 			goto err_iommu;
 		}
 	} else {
-		eth_random_addr(vdpasim->config.mac);
+		eth_random_addr(macaddr_buf);
 	}
 
 	for (i = 0; i < dev_attr->nvqs; i++)
@@ -538,6 +540,8 @@ static int vdpasim_set_features(struct vdpa_device *vdpa, u64 features)
 
 	config->mtu = cpu_to_vdpasim16(vdpasim, 1500);
 	config->status = cpu_to_vdpasim16(vdpasim, VIRTIO_NET_S_LINK_UP);
+	memcpy(config->mac, macaddr_buf, ETH_ALEN);
+
 	return 0;
 }