net/af_xdp: fix maximum MTU

The maximum MTU for af_xdp zero copy is equal to the page size less the
frame overhead introduced by AF_XDP (XDP HR = 256) and DPDK (frame
headroom = 320). The patch updates this value to reflect this.

This change also makes it possible to remove unneeded constants for both
zero-copy and copy mode.

Fixes: d8a210774e1d ("net/af_xdp: support unaligned umem chunks")
Cc: stable@dpdk.org
Signed-off-by: Ciara Loftus <ciara.loftus@intel.com>
Reviewed-by: Xiaolong Ye <xiaolong.ye@intel.com>

diff --git a/drivers/net/af_xdp/rte_eth_af_xdp.c b/drivers/net/af_xdp/rte_eth_af_xdp.c
index a0edfc3..06124ba 100644 (file)
--- a/drivers/net/af_xdp/rte_eth_af_xdp.c
+++ b/drivers/net/af_xdp/rte_eth_af_xdp.c
@@ -58,13 +58,6 @@ static int af_xdp_logtype;
 
 #define ETH_AF_XDP_FRAME_SIZE          2048
 #define ETH_AF_XDP_NUM_BUFFERS         4096
-#ifdef XDP_UMEM_UNALIGNED_CHUNK_FLAG
-#define ETH_AF_XDP_MBUF_OVERHEAD       128 /* sizeof(struct rte_mbuf) */
-#define ETH_AF_XDP_DATA_HEADROOM \
-       (ETH_AF_XDP_MBUF_OVERHEAD + RTE_PKTMBUF_HEADROOM)
-#else
-#define ETH_AF_XDP_DATA_HEADROOM       0
-#endif
 #define ETH_AF_XDP_DFLT_NUM_DESCS      XSK_RING_CONS__DEFAULT_NUM_DESCS
 #define ETH_AF_XDP_DFLT_START_QUEUE_IDX        0
 #define ETH_AF_XDP_DFLT_QUEUE_COUNT    1
@@ -601,7 +594,14 @@ eth_dev_info(struct rte_eth_dev *dev, struct rte_eth_dev_info *dev_info)
        dev_info->max_tx_queues = internals->queue_cnt;
 
        dev_info->min_mtu = RTE_ETHER_MIN_MTU;
-       dev_info->max_mtu = ETH_AF_XDP_FRAME_SIZE - ETH_AF_XDP_DATA_HEADROOM;
+#if defined(XDP_UMEM_UNALIGNED_CHUNK_FLAG)
+       dev_info->max_mtu = getpagesize() -
+                               sizeof(struct rte_mempool_objhdr) -
+                               sizeof(struct rte_mbuf) -
+                               RTE_PKTMBUF_HEADROOM - XDP_PACKET_HEADROOM;
+#else
+       dev_info->max_mtu = ETH_AF_XDP_FRAME_SIZE - XDP_PACKET_HEADROOM;
+#endif
 
        dev_info->default_rxportconf.nb_queues = 1;
        dev_info->default_txportconf.nb_queues = 1;
@@ -803,7 +803,7 @@ xsk_umem_info *xdp_umem_configure(struct pmd_internals *internals,
                .fill_size = ETH_AF_XDP_DFLT_NUM_DESCS,
                .comp_size = ETH_AF_XDP_DFLT_NUM_DESCS,
                .frame_size = ETH_AF_XDP_FRAME_SIZE,
-               .frame_headroom = ETH_AF_XDP_DATA_HEADROOM };
+               .frame_headroom = 0 };
        char ring_name[RTE_RING_NAMESIZE];
        char mz_name[RTE_MEMZONE_NAMESIZE];
        int ret;
@@ -828,8 +828,7 @@ xsk_umem_info *xdp_umem_configure(struct pmd_internals *internals,
 
        for (i = 0; i < ETH_AF_XDP_NUM_BUFFERS; i++)
                rte_ring_enqueue(umem->buf_ring,
-                                (void *)(i * ETH_AF_XDP_FRAME_SIZE +
-                                         ETH_AF_XDP_DATA_HEADROOM));
+                                (void *)(i * ETH_AF_XDP_FRAME_SIZE));
 
        snprintf(mz_name, sizeof(mz_name), "af_xdp_umem_%s_%u",
                       internals->if_name, rxq->xsk_queue_idx);
@@ -938,7 +937,7 @@ eth_rx_queue_setup(struct rte_eth_dev *dev,
        /* Now get the space available for data in the mbuf */
        buf_size = rte_pktmbuf_data_room_size(mb_pool) -
                RTE_PKTMBUF_HEADROOM;
-       data_size = ETH_AF_XDP_FRAME_SIZE - ETH_AF_XDP_DATA_HEADROOM;
+       data_size = ETH_AF_XDP_FRAME_SIZE;
 
        if (data_size > buf_size) {
                AF_XDP_LOG(ERR, "%s: %d bytes will not fit in mbuf (%d bytes)\n",