[PATCH] Fixed IPv6 payload lenght without jumbo option

[andrew@daynix.com]

From: Andrew Melnychenko <andrew@daynix.com>

Buglink: https://bugzilla.redhat.com/show_bug.cgi?id=1708065
e1000e driver doesn't sets 'plen' field for IPv6 for big packets
if TSO is enabled. Jumbo option isn't added yet, until
qemu supports packets greater than 64K.

Signed-off-by: Andrew Melnychenko <andrew@daynix.com>
---
 hw/net/e1000e_core.c |  1 +
 hw/net/net_tx_pkt.c  | 31 +++++++++++++++++++++++++++++++
 hw/net/net_tx_pkt.h  |  7 +++++++
 include/net/eth.h    |  1 +
 4 files changed, 40 insertions(+)

diff --git a/hw/net/e1000e_core.c b/hw/net/e1000e_core.c
index d5676871fa..a1ec55598b 100644
--- a/hw/net/e1000e_core.c
+++ b/hw/net/e1000e_core.c
@@ -656,6 +656,7 @@ e1000e_tx_pkt_send(E1000ECore *core, struct e1000e_tx *tx, int queue_index)
     NetClientState *queue = qemu_get_subqueue(core->owner_nic, target_queue);
 
     e1000e_setup_tx_offloads(core, tx);
+    net_tx_pkt_fix_ip6_payload_len(tx->tx_pkt);
 
     net_tx_pkt_dump(tx->tx_pkt);
 
diff --git a/hw/net/net_tx_pkt.c b/hw/net/net_tx_pkt.c
index 162f802dd7..b05d554ac3 100644
--- a/hw/net/net_tx_pkt.c
+++ b/hw/net/net_tx_pkt.c
@@ -635,3 +635,34 @@ bool net_tx_pkt_send_loopback(struct NetTxPkt *pkt, NetClientState *nc)
 
     return res;
 }
+
+void net_tx_pkt_fix_ip6_payload_len(struct NetTxPkt *pkt)
+{
+    /*
+     * If ipv6 payload length field is 0 - then there should be Hop-by-Hop
+     * option for packets greater than 65,535.
+     * For packets with payload less than 65,535: fix 'plen' field.
+     * For now, qemu drops every packet with size greater 64K
+     * (see net_tx_pkt_send()) so, there is no reason to add jumbo option to ip6
+     * hop-by-hop extension if it's missed
+     */
+
+    struct iovec *l2 = &pkt->vec[NET_TX_PKT_L2HDR_FRAG];
+    if (eth_get_l3_proto(l2, 1, l2->iov_len) == ETH_P_IPV6) {
+        struct ip6_header *ip6 = (struct ip6_header *) pkt->l3_hdr;
+        /*
+         * TODO: if qemu would support >64K packets - add jumbo option check
+         * something like that:
+         * 'if (ip6->ip6_plen == 0 && !has_jumbo_option(ip6)) {'
+         */
+        if (ip6->ip6_plen == 0) {
+            if (pkt->payload_len <= ETH_MAX_IP_DGRAM_LEN) {
+                ip6->ip6_plen = htons(pkt->payload_len);
+            }
+            /*
+             * TODO: if qemu would support >64K packets
+             * add jumbo option for packets greater then 65,535 bytes
+             */
+        }
+    }
+}
diff --git a/hw/net/net_tx_pkt.h b/hw/net/net_tx_pkt.h
index 212ecc62fc..912d56ef13 100644
--- a/hw/net/net_tx_pkt.h
+++ b/hw/net/net_tx_pkt.h
@@ -187,4 +187,11 @@ bool net_tx_pkt_parse(struct NetTxPkt *pkt);
 */
 bool net_tx_pkt_has_fragments(struct NetTxPkt *pkt);
 
+/**
+ * Fix IPv6 'plen' field.
+ *
+ * @pkt            packet
+ */
+void net_tx_pkt_fix_ip6_payload_len(struct NetTxPkt *pkt);
+
 #endif
diff --git a/include/net/eth.h b/include/net/eth.h
index 7f45c678e7..0671be6916 100644
--- a/include/net/eth.h
+++ b/include/net/eth.h
@@ -186,6 +186,7 @@ struct tcp_hdr {
 
 #define ip6_nxt      ip6_ctlun.ip6_un1.ip6_un1_nxt
 #define ip6_ecn_acc  ip6_ctlun.ip6_un3.ip6_un3_ecn
+#define ip6_plen     ip6_ctlun.ip6_un1.ip6_un1_plen
 
 #define PKT_GET_ETH_HDR(p)        \
     ((struct eth_header *)(p))
-- 
2.24.1