virtio: Tweak virtio_net defines

1) Turn GSO on virtio net into an all-or-nothing (keep checksumming
   separate).  Having multiple bits is a pain: if you can't support something
   you should handle it in software, which is still a performance win.

2) Make VIRTIO_NET_HDR_GSO_ECN a flag in the header, so it can apply to
   IPv6 or v4.

3) Rename VIRTIO_NET_F_NO_CSUM to VIRTIO_NET_F_CSUM (ie. means we do
   checksumming).

4) Add csum and gso params to virtio_net to allow more testing.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

2 files changed, 20 insertions, 24 deletions

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 3492ae0951de..73f01db59ab9 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -24,6 +24,10 @@
 #include <linux/virtio_net.h>
 #include <linux/scatterlist.h>
 
+static int csum = 1, gso = 1;
+module_param(csum, bool, 0444);
+module_param(gso, bool, 0444);
+
 /* FIXME: MTU in config. */
 #define MAX_PACKET_LEN (ETH_HLEN+ETH_DATA_LEN)
 
@@ -88,13 +92,10 @@ static void receive_skb(struct net_device *dev, struct sk_buff *skb,
 
         if (hdr->gso_type != VIRTIO_NET_HDR_GSO_NONE) {
                 pr_debug("GSO!\n");
-                switch (hdr->gso_type) {
+                switch (hdr->gso_type & ~VIRTIO_NET_HDR_GSO_ECN) {
                 case VIRTIO_NET_HDR_GSO_TCPV4:
                         skb_shinfo(skb)->gso_type = SKB_GSO_TCPV4;
                         break;
-                case VIRTIO_NET_HDR_GSO_TCPV4_ECN:
-                        skb_shinfo(skb)->gso_type = SKB_GSO_TCP_ECN;
-                        break;
                 case VIRTIO_NET_HDR_GSO_UDP:
                         skb_shinfo(skb)->gso_type = SKB_GSO_UDP;
                         break;
@@ -108,6 +109,9 @@ static void receive_skb(struct net_device *dev, struct sk_buff *skb,
                         goto frame_err;
                 }
 
+                if (hdr->gso_type & VIRTIO_NET_HDR_GSO_ECN)
+                        skb_shinfo(skb)->gso_type |= SKB_GSO_TCP_ECN;
+
                 skb_shinfo(skb)->gso_size = hdr->gso_size;
                 if (skb_shinfo(skb)->gso_size == 0) {
                         if (net_ratelimit())
@@ -244,9 +248,7 @@ static int start_xmit(struct sk_buff *skb, struct net_device *dev)
         if (skb_is_gso(skb)) {
                 hdr->hdr_len = skb_transport_header(skb) - skb->data;
                 hdr->gso_size = skb_shinfo(skb)->gso_size;
-                if (skb_shinfo(skb)->gso_type & SKB_GSO_TCP_ECN)
-                        hdr->gso_type = VIRTIO_NET_HDR_GSO_TCPV4_ECN;
-                else if (skb_shinfo(skb)->gso_type & SKB_GSO_TCPV4)
+                if (skb_shinfo(skb)->gso_type & SKB_GSO_TCPV4)
                         hdr->gso_type = VIRTIO_NET_HDR_GSO_TCPV4;
                 else if (skb_shinfo(skb)->gso_type & SKB_GSO_TCPV6)
                         hdr->gso_type = VIRTIO_NET_HDR_GSO_TCPV6;
@@ -254,6 +256,8 @@ static int start_xmit(struct sk_buff *skb, struct net_device *dev)
                         hdr->gso_type = VIRTIO_NET_HDR_GSO_UDP;
                 else
                         BUG();
+                if (skb_shinfo(skb)->gso_type & SKB_GSO_TCP_ECN)
+                        hdr->gso_type |= VIRTIO_NET_HDR_GSO_ECN;
         } else {
                 hdr->gso_type = VIRTIO_NET_HDR_GSO_NONE;
                 hdr->gso_size = hdr->hdr_len = 0;
@@ -330,17 +334,13 @@ static int virtnet_probe(struct virtio_device *vdev)
         SET_NETDEV_DEV(dev, &vdev->dev);
 
         /* Do we support "hardware" checksums? */
-        if (vdev->config->feature(vdev, VIRTIO_NET_F_NO_CSUM)) {
+        if (csum && vdev->config->feature(vdev, VIRTIO_NET_F_CSUM)) {
                 /* This opens up the world of extra features. */
                 dev->features |= NETIF_F_HW_CSUM|NETIF_F_SG|NETIF_F_FRAGLIST;
-                if (vdev->config->feature(vdev, VIRTIO_NET_F_TSO4))
-                        dev->features |= NETIF_F_TSO;
-                if (vdev->config->feature(vdev, VIRTIO_NET_F_UFO))
-                        dev->features |= NETIF_F_UFO;
-                if (vdev->config->feature(vdev, VIRTIO_NET_F_TSO4_ECN))
-                        dev->features |= NETIF_F_TSO_ECN;
-                if (vdev->config->feature(vdev, VIRTIO_NET_F_TSO6))
-                        dev->features |= NETIF_F_TSO6;
+                if (gso && vdev->config->feature(vdev, VIRTIO_NET_F_GSO)) {
+                        dev->features |= NETIF_F_TSO | NETIF_F_UFO
+                                | NETIF_F_TSO_ECN | NETIF_F_TSO6;
+                }
         }
 
         /* Configuration may specify what MAC to use.  Otherwise random. */
diff --git a/include/linux/virtio_net.h b/include/linux/virtio_net.h
index 1456f7b936d0..1ea3351df609 100644
--- a/include/linux/virtio_net.h
+++ b/include/linux/virtio_net.h
@@ -6,12 +6,9 @@
 #define VIRTIO_ID_NET   1
 
 /* The feature bitmap for virtio net */
-#define VIRTIO_NET_F_NO_CSUM    0
-#define VIRTIO_NET_F_TSO4       1
-#define VIRTIO_NET_F_UFO        2
-#define VIRTIO_NET_F_TSO4_ECN   3
-#define VIRTIO_NET_F_TSO6       4
-#define VIRTIO_NET_F_MAC        5
+#define VIRTIO_NET_F_CSUM       0       /* Can handle pkts w/ partial csum */
+#define VIRTIO_NET_F_MAC        5       /* Host has given MAC address. */
+#define VIRTIO_NET_F_GSO        6       /* Can handle pkts w/ any GSO type */
 
 struct virtio_net_config
 {
@@ -27,10 +24,9 @@ struct virtio_net_hdr
         __u8 flags;
 #define VIRTIO_NET_HDR_GSO_NONE         0       // Not a GSO frame
 #define VIRTIO_NET_HDR_GSO_TCPV4        1       // GSO frame, IPv4 TCP (TSO)
-/* FIXME: Do we need this?  If they said they can handle ECN, do they care? */
-#define VIRTIO_NET_HDR_GSO_TCPV4_ECN    2       // GSO frame, IPv4 TCP w/ ECN
 #define VIRTIO_NET_HDR_GSO_UDP          3       // GSO frame, IPv4 UDP (UFO)
 #define VIRTIO_NET_HDR_GSO_TCPV6        4       // GSO frame, IPv6 TCP
+#define VIRTIO_NET_HDR_GSO_ECN          0x80    // TCP has ECN set
         __u8 gso_type;
         __u16 hdr_len;          /* Ethernet + IP + tcp/udp hdrs */
         __u16 gso_size;         /* Bytes to append to gso_hdr_len per frame */