ena: Add XDP frame size to amazon NIC driver

Frame size ENA_PAGE_SIZE is limited to 16K on systems with larger
PAGE_SIZE than 16K. Change ENA_XDP_MAX_MTU to also take into account
the reserved tailroom.
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Sameeh Jubran <sameehj@amazon.com>
Cc: Arthur Kiyanovski <akiyano@amazon.com>
Link: https://lore.kernel.org/bpf/158945341384.97035.907403694833419456.stgit@firesoul

drivers/net/ethernet/amazon/ena/ena_netdev.c

@@ -1606,6 +1606,7 @@ static int ena_clean_rx_irq(struct ena_ring *rx_ring, struct napi_struct *napi,
 		  "%s qid %d\n", __func__, rx_ring->qid);
 	res_budget = budget;
 	xdp.rxq = &rx_ring->xdp_rxq;
+	xdp.frame_sz = ENA_PAGE_SIZE;
 
 	do {
 		xdp_verdict = XDP_PASS;

drivers/net/ethernet/amazon/ena/ena_netdev.h

@@ -151,8 +151,9 @@
  * The buffer size we share with the device is defined to be ENA_PAGE_SIZE
  */
 
-#define ENA_XDP_MAX_MTU (ENA_PAGE_SIZE - ETH_HLEN - ETH_FCS_LEN - \
-				VLAN_HLEN - XDP_PACKET_HEADROOM)
+#define ENA_XDP_MAX_MTU (ENA_PAGE_SIZE - ETH_HLEN - ETH_FCS_LEN -	\
+			 VLAN_HLEN - XDP_PACKET_HEADROOM -		\
+			 SKB_DATA_ALIGN(sizeof(struct skb_shared_info)))
 
 #define ENA_IS_XDP_INDEX(adapter, index) (((index) >= (adapter)->xdp_first_ring) && \
 	((index) < (adapter)->xdp_first_ring + (adapter)->xdp_num_queues))