net/eth: Always add VLAN tag

It is possible to have another VLAN tag even if the packet is already
tagged.

Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>

hw/net/net_tx_pkt.c

@@ -40,7 +40,10 @@ struct NetTxPkt {
 
     struct iovec *vec;
 
-    uint8_t l2_hdr[ETH_MAX_L2_HDR_LEN];
+    struct {
+        struct eth_header eth;
+        struct vlan_header vlan[3];
+    } l2_hdr;
     union {
         struct ip_header ip;
         struct ip6_header ip6;
@@ -365,18 +368,13 @@ bool net_tx_pkt_build_vheader(struct NetTxPkt *pkt, bool tso_enable,
 void net_tx_pkt_setup_vlan_header_ex(struct NetTxPkt *pkt,
     uint16_t vlan, uint16_t vlan_ethtype)
 {
-    bool is_new;
     assert(pkt);
 
     eth_setup_vlan_headers(pkt->vec[NET_TX_PKT_L2HDR_FRAG].iov_base,
-        vlan, vlan_ethtype, &is_new);
+                           &pkt->vec[NET_TX_PKT_L2HDR_FRAG].iov_len,
+                           vlan, vlan_ethtype);
 
-    /* update l2hdrlen */
-    if (is_new) {
-        pkt->hdr_len += sizeof(struct vlan_header);
-        pkt->vec[NET_TX_PKT_L2HDR_FRAG].iov_len +=
-            sizeof(struct vlan_header);
-    }
+    pkt->hdr_len += sizeof(struct vlan_header);
 }
 
 bool net_tx_pkt_add_raw_fragment(struct NetTxPkt *pkt, void *base, size_t len)

include/net/eth.h

@@ -353,8 +353,8 @@ eth_strip_vlan_ex(const struct iovec *iov, int iovcnt, size_t iovoff,
 uint16_t
 eth_get_l3_proto(const struct iovec *l2hdr_iov, int iovcnt, size_t l2hdr_len);
 
-void eth_setup_vlan_headers(struct eth_header *ehdr, uint16_t vlan_tag,
-    uint16_t vlan_ethtype, bool *is_new);
+void eth_setup_vlan_headers(struct eth_header *ehdr, size_t *ehdr_size,
+                            uint16_t vlan_tag, uint16_t vlan_ethtype);
 
 
 uint8_t eth_get_gso_type(uint16_t l3_proto, uint8_t *l3_hdr, uint8_t l4proto);

net/eth.c

@@ -21,26 +21,16 @@
 #include "net/checksum.h"
 #include "net/tap.h"
 
-void eth_setup_vlan_headers(struct eth_header *ehdr, uint16_t vlan_tag,
-    uint16_t vlan_ethtype, bool *is_new)
+void eth_setup_vlan_headers(struct eth_header *ehdr, size_t *ehdr_size,
+                            uint16_t vlan_tag, uint16_t vlan_ethtype)
 {
     struct vlan_header *vhdr = PKT_GET_VLAN_HDR(ehdr);
 
-    switch (be16_to_cpu(ehdr->h_proto)) {
-    case ETH_P_VLAN:
-    case ETH_P_DVLAN:
-        /* vlan hdr exists */
-        *is_new = false;
-        break;
-
-    default:
-        /* No VLAN header, put a new one */
-        vhdr->h_proto = ehdr->h_proto;
-        ehdr->h_proto = cpu_to_be16(vlan_ethtype);
-        *is_new = true;
-        break;
-    }
+    memmove(vhdr + 1, vhdr, *ehdr_size - ETH_HLEN);
     vhdr->h_tci = cpu_to_be16(vlan_tag);
+    vhdr->h_proto = ehdr->h_proto;
+    ehdr->h_proto = cpu_to_be16(vlan_ethtype);
+    *ehdr_size += sizeof(*vhdr);
 }
 
 uint8_t