lguest: Use the IFF_GSO_HDR option to tap. This actually simplifies the lguest launcher, since it can now pass the whole packet (with gso header) straight to the tap device. Signed-off-by: Rusty Russell --- Documentation/lguest/lguest.c | 29 ++++++++++++++--------------- 1 file changed, 14 insertions(+), 15 deletions(-) diff -r 2eab16ea3ef1 Documentation/lguest/lguest.c --- a/Documentation/lguest/lguest.c Tue Jan 15 19:21:27 2008 +1100 +++ b/Documentation/lguest/lguest.c Tue Jan 15 20:47:08 2008 +1100 @@ -852,11 +852,9 @@ static void handle_net_output(int fd, st while ((head = get_vq_desc(vq, iov, &out, &in)) != vq->vring.num) { if (in) errx(1, "Input buffers in output queue?"); - /* Check header, but otherwise ignore it (we told the Guest we - * supported no features, so it shouldn't have anything - * interesting). */ - (void)convert(&iov[0], struct virtio_net_hdr); - len = writev(vq->dev->fd, iov+1, out-1); + /* With IFF_GSO_HDR, tap takes the same format header as + * virtio_net, so we just pass it through. */ + len = writev(vq->dev->fd, iov, out); add_used_and_trigger(fd, vq, head, len); } } @@ -868,7 +866,6 @@ static bool handle_tun_input(int fd, str unsigned int head, in_num, out_num; int len; struct iovec iov[dev->vq->vring.num]; - struct virtio_net_hdr *hdr; /* First we need a network buffer from the Guests's recv virtqueue. */ head = get_vq_desc(dev->vq, iov, &out_num, &in_num); @@ -884,18 +881,14 @@ static bool handle_tun_input(int fd, str } else if (out_num) errx(1, "Output buffers in network recv queue?"); - /* First element is the header: we set it to 0 (no features). */ - hdr = convert(&iov[0], struct virtio_net_hdr); - hdr->flags = 0; - hdr->gso_type = VIRTIO_NET_HDR_GSO_NONE; - - /* Read the packet from the device directly into the Guest's buffer. */ - len = readv(dev->fd, iov+1, in_num-1); + /* Read the GSO header and packet from the tun device directly into the + * Guest's buffer. */ + len = readv(dev->fd, iov, in_num); if (len <= 0) err(1, "reading network"); /* Tell the Guest about the new packet. */ - add_used_and_trigger(fd, dev->vq, head, sizeof(*hdr) + len); + add_used_and_trigger(fd, dev->vq, head, len); verbose("tun input packet len %i [%02x %02x] (%s)\n", len, ((u8 *)iov[1].iov_base)[0], ((u8 *)iov[1].iov_base)[1], @@ -1266,7 +1259,7 @@ static void setup_tun_net(const char *ar * works now! */ netfd = open_or_die("/dev/net/tun", O_RDWR); memset(&ifr, 0, sizeof(ifr)); - ifr.ifr_flags = IFF_TAP | IFF_NO_PI; + ifr.ifr_flags = IFF_TAP | IFF_NO_PI | IFF_GSO_HDR; strcpy(ifr.ifr_name, "tap%d"); if (ioctl(netfd, TUNSETIFF, &ifr) != 0) err(1, "configuring /dev/net/tun"); @@ -1302,6 +1295,12 @@ static void setup_tun_net(const char *ar /* Tell Guest what MAC address to use. */ add_feature(dev, VIRTIO_NET_F_MAC); set_config(dev, sizeof(conf), &conf); + /* Tap device can handle no csum, and all types of GSO. */ + add_feature(dev, VIRTIO_NET_F_NO_CSUM); + add_feature(dev, VIRTIO_NET_F_TSO4); + add_feature(dev, VIRTIO_NET_F_UFO); + add_feature(dev, VIRTIO_NET_F_TSO4_ECN); + add_feature(dev, VIRTIO_NET_F_TSO6); /* We don't need the socket any more; setup is done. */ close(ipfd);