virtio_net: introduce virtio_net_hdr_{from,to}_skb

The code for conversion between virtio_net_hdr and skb GSO info is
duplicated at several places. Let's put it to a common place to allow
reuse.

Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/linux/virtio_net.h b/include/linux/virtio_net.h
new file mode 100644 (file)
index 0000000..1c912f8
--- /dev/null
+++ b/include/linux/virtio_net.h
@@ -0,0 +1,101 @@
+#ifndef _LINUX_VIRTIO_NET_H
+#define _LINUX_VIRTIO_NET_H
+
+#include <linux/if_vlan.h>
+#include <uapi/linux/virtio_net.h>
+
+static inline int virtio_net_hdr_to_skb(struct sk_buff *skb,
+                                       const struct virtio_net_hdr *hdr,
+                                       bool little_endian)
+{
+       unsigned short gso_type = 0;
+
+       if (hdr->gso_type != VIRTIO_NET_HDR_GSO_NONE) {
+               switch (hdr->gso_type & ~VIRTIO_NET_HDR_GSO_ECN) {
+               case VIRTIO_NET_HDR_GSO_TCPV4:
+                       gso_type = SKB_GSO_TCPV4;
+                       break;
+               case VIRTIO_NET_HDR_GSO_TCPV6:
+                       gso_type = SKB_GSO_TCPV6;
+                       break;
+               case VIRTIO_NET_HDR_GSO_UDP:
+                       gso_type = SKB_GSO_UDP;
+                       break;
+               default:
+                       return -EINVAL;
+               }
+
+               if (hdr->gso_type & VIRTIO_NET_HDR_GSO_ECN)
+                       gso_type |= SKB_GSO_TCP_ECN;
+
+               if (hdr->gso_size == 0)
+                       return -EINVAL;
+       }
+
+       if (hdr->flags & VIRTIO_NET_HDR_F_NEEDS_CSUM) {
+               u16 start = __virtio16_to_cpu(little_endian, hdr->csum_start);
+               u16 off = __virtio16_to_cpu(little_endian, hdr->csum_offset);
+
+               if (!skb_partial_csum_set(skb, start, off))
+                       return -EINVAL;
+       }
+
+       if (hdr->gso_type != VIRTIO_NET_HDR_GSO_NONE) {
+               u16 gso_size = __virtio16_to_cpu(little_endian, hdr->gso_size);
+
+               skb_shinfo(skb)->gso_size = gso_size;
+               skb_shinfo(skb)->gso_type = gso_type;
+
+               /* Header must be checked, and gso_segs computed. */
+               skb_shinfo(skb)->gso_type |= SKB_GSO_DODGY;
+               skb_shinfo(skb)->gso_segs = 0;
+       }
+
+       return 0;
+}
+
+static inline int virtio_net_hdr_from_skb(const struct sk_buff *skb,
+                                         struct virtio_net_hdr *hdr,
+                                         bool little_endian)
+{
+       memset(hdr, 0, sizeof(*hdr));
+
+       if (skb_is_gso(skb)) {
+               struct skb_shared_info *sinfo = skb_shinfo(skb);
+
+               /* This is a hint as to how much should be linear. */
+               hdr->hdr_len = __cpu_to_virtio16(little_endian,
+                                                skb_headlen(skb));
+               hdr->gso_size = __cpu_to_virtio16(little_endian,
+                                                 sinfo->gso_size);
+               if (sinfo->gso_type & SKB_GSO_TCPV4)
+                       hdr->gso_type = VIRTIO_NET_HDR_GSO_TCPV4;
+               else if (sinfo->gso_type & SKB_GSO_TCPV6)
+                       hdr->gso_type = VIRTIO_NET_HDR_GSO_TCPV6;
+               else if (sinfo->gso_type & SKB_GSO_UDP)
+                       hdr->gso_type = VIRTIO_NET_HDR_GSO_UDP;
+               else
+                       return -EINVAL;
+               if (sinfo->gso_type & SKB_GSO_TCP_ECN)
+                       hdr->gso_type |= VIRTIO_NET_HDR_GSO_ECN;
+       } else
+               hdr->gso_type = VIRTIO_NET_HDR_GSO_NONE;
+
+       if (skb->ip_summed == CHECKSUM_PARTIAL) {
+               hdr->flags = VIRTIO_NET_HDR_F_NEEDS_CSUM;
+               if (skb_vlan_tag_present(skb))
+                       hdr->csum_start = __cpu_to_virtio16(little_endian,
+                               skb_checksum_start_offset(skb) + VLAN_HLEN);
+               else
+                       hdr->csum_start = __cpu_to_virtio16(little_endian,
+                               skb_checksum_start_offset(skb));
+               hdr->csum_offset = __cpu_to_virtio16(little_endian,
+                               skb->csum_offset);
+       } else if (skb->ip_summed == CHECKSUM_UNNECESSARY) {
+               hdr->flags = VIRTIO_NET_HDR_F_DATA_VALID;
+       } /* else everything is zero */
+
+       return 0;
+}
+
+#endif /* _LINUX_VIRTIO_BYTEORDER */