vdpa_sim: filter destination mac address

This patch implements a simple unicast filter for vDPA simulator.
Signed-off-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Gautam Dawar <gdawar@xilinx.com>
Message-Id: <20220330180436.24644-19-gdawar@xilinx.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

drivers/vdpa/vdpa_sim/vdpa_sim_net.c

@@ -47,13 +47,28 @@ static void vdpasim_net_complete(struct vdpasim_virtqueue *vq, size_t len)
 	local_bh_enable();
 }
 
+static bool receive_filter(struct vdpasim *vdpasim, size_t len)
+{
+	bool modern = vdpasim->features & (1ULL << VIRTIO_F_VERSION_1);
+	size_t hdr_len = modern ? sizeof(struct virtio_net_hdr_v1) :
+				  sizeof(struct virtio_net_hdr);
+	struct virtio_net_config *vio_config = vdpasim->config;
+
+	if (len < ETH_ALEN + hdr_len)
+		return false;
+
+	if (!strncmp(vdpasim->buffer + hdr_len, vio_config->mac, ETH_ALEN))
+		return true;
+
+	return false;
+}
+
 static void vdpasim_net_work(struct work_struct *work)
 {
 	struct vdpasim *vdpasim = container_of(work, struct vdpasim, work);
 	struct vdpasim_virtqueue *txq = &vdpasim->vqs[1];
 	struct vdpasim_virtqueue *rxq = &vdpasim->vqs[0];
 	ssize_t read, write;
-	size_t total_write;
 	int pkts = 0;
 	int err;
 
@@ -66,36 +81,34 @@ static void vdpasim_net_work(struct work_struct *work)
 		goto out;
 
 	while (true) {
-		total_write = 0;
 		err = vringh_getdesc_iotlb(&txq->vring, &txq->out_iov, NULL,
 					   &txq->head, GFP_ATOMIC);
 		if (err <= 0)
 			break;
 
+		read = vringh_iov_pull_iotlb(&txq->vring, &txq->out_iov,
+					     vdpasim->buffer,
+					     PAGE_SIZE);
+
+		if (!receive_filter(vdpasim, read)) {
+			vdpasim_net_complete(txq, 0);
+			continue;
+		}
+
 		err = vringh_getdesc_iotlb(&rxq->vring, NULL, &rxq->in_iov,
 					   &rxq->head, GFP_ATOMIC);
 		if (err <= 0) {
-			vringh_complete_iotlb(&txq->vring, txq->head, 0);
+			vdpasim_net_complete(txq, 0);
 			break;
 		}
 
-		while (true) {
-			read = vringh_iov_pull_iotlb(&txq->vring, &txq->out_iov,
-						     vdpasim->buffer,
-						     PAGE_SIZE);
-			if (read <= 0)
-				break;
-
-			write = vringh_iov_push_iotlb(&rxq->vring, &rxq->in_iov,
-						      vdpasim->buffer, read);
-			if (write <= 0)
-				break;
-
-			total_write += write;
-		}
+		write = vringh_iov_push_iotlb(&rxq->vring, &rxq->in_iov,
+					      vdpasim->buffer, read);
+		if (write <= 0)
+			break;
 
 		vdpasim_net_complete(txq, 0);
-		vdpasim_net_complete(rxq, total_write);
+		vdpasim_net_complete(rxq, write);
 
 		if (++pkts > 4) {
 			schedule_work(&vdpasim->work);