1 /*
2 * Copyright (c) 2017 Mellanox Technologies. All rights reserved.
3 *
4 * This software is available to you under a choice of one of two
5 * licenses. You may choose to be licensed under the terms of the GNU
6 * General Public License (GPL) Version 2, available from the file
7 * COPYING in the main directory of this source tree, or the
8 * OpenIB.org BSD license below:
9 *
10 * Redistribution and use in source and binary forms, with or
11 * without modification, are permitted provided that the following
12 * conditions are met:
13 *
14 * - Redistributions of source code must retain the above
15 * copyright notice, this list of conditions and the following
16 * disclaimer.
17 *
18 * - Redistributions in binary form must reproduce the above
19 * copyright notice, this list of conditions and the following
20 * disclaimer in the documentation and/or other materials
21 * provided with the distribution.
22 *
23 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
24 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
25 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
26 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
27 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
28 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
29 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
30 * SOFTWARE.
31 *
32 */
33
34 #include <crypto/aead.h>
35 #include <net/xfrm.h>
36 #include <net/esp.h>
37 #include "accel/ipsec_offload.h"
38 #include "en_accel/ipsec_rxtx.h"
39 #include "en_accel/ipsec.h"
40 #include "accel/accel.h"
41 #include "en.h"
42
43 enum {
44 MLX5E_IPSEC_RX_SYNDROME_DECRYPTED = 0x11,
45 MLX5E_IPSEC_RX_SYNDROME_AUTH_FAILED = 0x12,
46 MLX5E_IPSEC_RX_SYNDROME_BAD_PROTO = 0x17,
47 };
48
49 struct mlx5e_ipsec_rx_metadata {
50 unsigned char nexthdr;
51 __be32 sa_handle;
52 } __packed;
53
54 enum {
55 MLX5E_IPSEC_TX_SYNDROME_OFFLOAD = 0x8,
56 MLX5E_IPSEC_TX_SYNDROME_OFFLOAD_WITH_LSO_TCP = 0x9,
57 };
58
59 struct mlx5e_ipsec_tx_metadata {
60 __be16 mss_inv; /* 1/MSS in 16bit fixed point, only for LSO */
61 __be16 seq; /* LSBs of the first TCP seq, only for LSO */
62 u8 esp_next_proto; /* Next protocol of ESP */
63 } __packed;
64
65 struct mlx5e_ipsec_metadata {
66 unsigned char syndrome;
67 union {
68 unsigned char raw[5];
69 /* from FPGA to host, on successful decrypt */
70 struct mlx5e_ipsec_rx_metadata rx;
71 /* from host to FPGA */
72 struct mlx5e_ipsec_tx_metadata tx;
73 } __packed content;
74 /* packet type ID field */
75 __be16 ethertype;
76 } __packed;
77
78 #define MAX_LSO_MSS 2048
79
80 /* Pre-calculated (Q0.16) fixed-point inverse 1/x function */
81 static __be16 mlx5e_ipsec_inverse_table[MAX_LSO_MSS];
82
mlx5e_ipsec_mss_inv(struct sk_buff * skb)83 static inline __be16 mlx5e_ipsec_mss_inv(struct sk_buff *skb)
84 {
85 return mlx5e_ipsec_inverse_table[skb_shinfo(skb)->gso_size];
86 }
87
mlx5e_ipsec_add_metadata(struct sk_buff * skb)88 static struct mlx5e_ipsec_metadata *mlx5e_ipsec_add_metadata(struct sk_buff *skb)
89 {
90 struct mlx5e_ipsec_metadata *mdata;
91 struct ethhdr *eth;
92
93 if (unlikely(skb_cow_head(skb, sizeof(*mdata))))
94 return ERR_PTR(-ENOMEM);
95
96 eth = (struct ethhdr *)skb_push(skb, sizeof(*mdata));
97 skb->mac_header -= sizeof(*mdata);
98 mdata = (struct mlx5e_ipsec_metadata *)(eth + 1);
99
100 memmove(skb->data, skb->data + sizeof(*mdata),
101 2 * ETH_ALEN);
102
103 eth->h_proto = cpu_to_be16(MLX5E_METADATA_ETHER_TYPE);
104
105 memset(mdata->content.raw, 0, sizeof(mdata->content.raw));
106 return mdata;
107 }
108
mlx5e_ipsec_remove_trailer(struct sk_buff * skb,struct xfrm_state * x)109 static int mlx5e_ipsec_remove_trailer(struct sk_buff *skb, struct xfrm_state *x)
110 {
111 unsigned int alen = crypto_aead_authsize(x->data);
112 struct ipv6hdr *ipv6hdr = ipv6_hdr(skb);
113 struct iphdr *ipv4hdr = ip_hdr(skb);
114 unsigned int trailer_len;
115 u8 plen;
116 int ret;
117
118 ret = skb_copy_bits(skb, skb->len - alen - 2, &plen, 1);
119 if (unlikely(ret))
120 return ret;
121
122 trailer_len = alen + plen + 2;
123
124 pskb_trim(skb, skb->len - trailer_len);
125 if (skb->protocol == htons(ETH_P_IP)) {
126 ipv4hdr->tot_len = htons(ntohs(ipv4hdr->tot_len) - trailer_len);
127 ip_send_check(ipv4hdr);
128 } else {
129 ipv6hdr->payload_len = htons(ntohs(ipv6hdr->payload_len) -
130 trailer_len);
131 }
132 return 0;
133 }
134
mlx5e_ipsec_set_swp(struct sk_buff * skb,struct mlx5_wqe_eth_seg * eseg,u8 mode,struct xfrm_offload * xo)135 static void mlx5e_ipsec_set_swp(struct sk_buff *skb,
136 struct mlx5_wqe_eth_seg *eseg, u8 mode,
137 struct xfrm_offload *xo)
138 {
139 struct mlx5e_swp_spec swp_spec = {};
140
141 /* Tunnel Mode:
142 * SWP: OutL3 InL3 InL4
143 * Pkt: MAC IP ESP IP L4
144 *
145 * Transport Mode:
146 * SWP: OutL3 InL4
147 * InL3
148 * Pkt: MAC IP ESP L4
149 */
150 swp_spec.l3_proto = skb->protocol;
151 swp_spec.is_tun = mode == XFRM_MODE_TUNNEL;
152 if (swp_spec.is_tun) {
153 if (xo->proto == IPPROTO_IPV6) {
154 swp_spec.tun_l3_proto = htons(ETH_P_IPV6);
155 swp_spec.tun_l4_proto = inner_ipv6_hdr(skb)->nexthdr;
156 } else {
157 swp_spec.tun_l3_proto = htons(ETH_P_IP);
158 swp_spec.tun_l4_proto = inner_ip_hdr(skb)->protocol;
159 }
160 } else {
161 swp_spec.tun_l3_proto = skb->protocol;
162 swp_spec.tun_l4_proto = xo->proto;
163 }
164
165 mlx5e_set_eseg_swp(skb, eseg, &swp_spec);
166 }
167
mlx5e_ipsec_set_iv_esn(struct sk_buff * skb,struct xfrm_state * x,struct xfrm_offload * xo)168 void mlx5e_ipsec_set_iv_esn(struct sk_buff *skb, struct xfrm_state *x,
169 struct xfrm_offload *xo)
170 {
171 struct xfrm_replay_state_esn *replay_esn = x->replay_esn;
172 __u32 oseq = replay_esn->oseq;
173 int iv_offset;
174 __be64 seqno;
175 u32 seq_hi;
176
177 if (unlikely(skb_is_gso(skb) && oseq < MLX5E_IPSEC_ESN_SCOPE_MID &&
178 MLX5E_IPSEC_ESN_SCOPE_MID < (oseq - skb_shinfo(skb)->gso_segs))) {
179 seq_hi = xo->seq.hi - 1;
180 } else {
181 seq_hi = xo->seq.hi;
182 }
183
184 /* Place the SN in the IV field */
185 seqno = cpu_to_be64(xo->seq.low + ((u64)seq_hi << 32));
186 iv_offset = skb_transport_offset(skb) + sizeof(struct ip_esp_hdr);
187 skb_store_bits(skb, iv_offset, &seqno, 8);
188 }
189
mlx5e_ipsec_set_iv(struct sk_buff * skb,struct xfrm_state * x,struct xfrm_offload * xo)190 void mlx5e_ipsec_set_iv(struct sk_buff *skb, struct xfrm_state *x,
191 struct xfrm_offload *xo)
192 {
193 int iv_offset;
194 __be64 seqno;
195
196 /* Place the SN in the IV field */
197 seqno = cpu_to_be64(xo->seq.low + ((u64)xo->seq.hi << 32));
198 iv_offset = skb_transport_offset(skb) + sizeof(struct ip_esp_hdr);
199 skb_store_bits(skb, iv_offset, &seqno, 8);
200 }
201
mlx5e_ipsec_set_metadata(struct sk_buff * skb,struct mlx5e_ipsec_metadata * mdata,struct xfrm_offload * xo)202 static void mlx5e_ipsec_set_metadata(struct sk_buff *skb,
203 struct mlx5e_ipsec_metadata *mdata,
204 struct xfrm_offload *xo)
205 {
206 struct ip_esp_hdr *esph;
207 struct tcphdr *tcph;
208
209 if (skb_is_gso(skb)) {
210 /* Add LSO metadata indication */
211 esph = ip_esp_hdr(skb);
212 tcph = inner_tcp_hdr(skb);
213 netdev_dbg(skb->dev, " Offloading GSO packet outer L3 %u; L4 %u; Inner L3 %u; L4 %u\n",
214 skb->network_header,
215 skb->transport_header,
216 skb->inner_network_header,
217 skb->inner_transport_header);
218 netdev_dbg(skb->dev, " Offloading GSO packet of len %u; mss %u; TCP sp %u dp %u seq 0x%x ESP seq 0x%x\n",
219 skb->len, skb_shinfo(skb)->gso_size,
220 ntohs(tcph->source), ntohs(tcph->dest),
221 ntohl(tcph->seq), ntohl(esph->seq_no));
222 mdata->syndrome = MLX5E_IPSEC_TX_SYNDROME_OFFLOAD_WITH_LSO_TCP;
223 mdata->content.tx.mss_inv = mlx5e_ipsec_mss_inv(skb);
224 mdata->content.tx.seq = htons(ntohl(tcph->seq) & 0xFFFF);
225 } else {
226 mdata->syndrome = MLX5E_IPSEC_TX_SYNDROME_OFFLOAD;
227 }
228 mdata->content.tx.esp_next_proto = xo->proto;
229
230 netdev_dbg(skb->dev, " TX metadata syndrome %u proto %u mss_inv %04x seq %04x\n",
231 mdata->syndrome, mdata->content.tx.esp_next_proto,
232 ntohs(mdata->content.tx.mss_inv),
233 ntohs(mdata->content.tx.seq));
234 }
235
mlx5e_ipsec_handle_tx_wqe(struct mlx5e_tx_wqe * wqe,struct mlx5e_accel_tx_ipsec_state * ipsec_st,struct mlx5_wqe_inline_seg * inlseg)236 void mlx5e_ipsec_handle_tx_wqe(struct mlx5e_tx_wqe *wqe,
237 struct mlx5e_accel_tx_ipsec_state *ipsec_st,
238 struct mlx5_wqe_inline_seg *inlseg)
239 {
240 inlseg->byte_count = cpu_to_be32(ipsec_st->tailen | MLX5_INLINE_SEG);
241 esp_output_fill_trailer((u8 *)inlseg->data, 0, ipsec_st->plen, ipsec_st->xo->proto);
242 }
243
mlx5e_ipsec_set_state(struct mlx5e_priv * priv,struct sk_buff * skb,struct xfrm_state * x,struct xfrm_offload * xo,struct mlx5e_accel_tx_ipsec_state * ipsec_st)244 static int mlx5e_ipsec_set_state(struct mlx5e_priv *priv,
245 struct sk_buff *skb,
246 struct xfrm_state *x,
247 struct xfrm_offload *xo,
248 struct mlx5e_accel_tx_ipsec_state *ipsec_st)
249 {
250 unsigned int blksize, clen, alen, plen;
251 struct crypto_aead *aead;
252 unsigned int tailen;
253
254 ipsec_st->x = x;
255 ipsec_st->xo = xo;
256 if (mlx5_is_ipsec_device(priv->mdev)) {
257 aead = x->data;
258 alen = crypto_aead_authsize(aead);
259 blksize = ALIGN(crypto_aead_blocksize(aead), 4);
260 clen = ALIGN(skb->len + 2, blksize);
261 plen = max_t(u32, clen - skb->len, 4);
262 tailen = plen + alen;
263 ipsec_st->plen = plen;
264 ipsec_st->tailen = tailen;
265 }
266
267 return 0;
268 }
269
mlx5e_ipsec_tx_build_eseg(struct mlx5e_priv * priv,struct sk_buff * skb,struct mlx5_wqe_eth_seg * eseg)270 void mlx5e_ipsec_tx_build_eseg(struct mlx5e_priv *priv, struct sk_buff *skb,
271 struct mlx5_wqe_eth_seg *eseg)
272 {
273 struct xfrm_offload *xo = xfrm_offload(skb);
274 struct xfrm_encap_tmpl *encap;
275 struct xfrm_state *x;
276 struct sec_path *sp;
277 u8 l3_proto;
278
279 sp = skb_sec_path(skb);
280 if (unlikely(sp->len != 1))
281 return;
282
283 x = xfrm_input_state(skb);
284 if (unlikely(!x))
285 return;
286
287 if (unlikely(!x->xso.offload_handle ||
288 (skb->protocol != htons(ETH_P_IP) &&
289 skb->protocol != htons(ETH_P_IPV6))))
290 return;
291
292 mlx5e_ipsec_set_swp(skb, eseg, x->props.mode, xo);
293
294 l3_proto = (x->props.family == AF_INET) ?
295 ((struct iphdr *)skb_network_header(skb))->protocol :
296 ((struct ipv6hdr *)skb_network_header(skb))->nexthdr;
297
298 if (mlx5_is_ipsec_device(priv->mdev)) {
299 eseg->flow_table_metadata |= cpu_to_be32(MLX5_ETH_WQE_FT_META_IPSEC);
300 eseg->trailer |= cpu_to_be32(MLX5_ETH_WQE_INSERT_TRAILER);
301 encap = x->encap;
302 if (!encap) {
303 eseg->trailer |= (l3_proto == IPPROTO_ESP) ?
304 cpu_to_be32(MLX5_ETH_WQE_TRAILER_HDR_OUTER_IP_ASSOC) :
305 cpu_to_be32(MLX5_ETH_WQE_TRAILER_HDR_OUTER_L4_ASSOC);
306 } else if (encap->encap_type == UDP_ENCAP_ESPINUDP) {
307 eseg->trailer |= (l3_proto == IPPROTO_ESP) ?
308 cpu_to_be32(MLX5_ETH_WQE_TRAILER_HDR_INNER_IP_ASSOC) :
309 cpu_to_be32(MLX5_ETH_WQE_TRAILER_HDR_INNER_L4_ASSOC);
310 }
311 }
312 }
313
mlx5e_ipsec_handle_tx_skb(struct net_device * netdev,struct sk_buff * skb,struct mlx5e_accel_tx_ipsec_state * ipsec_st)314 bool mlx5e_ipsec_handle_tx_skb(struct net_device *netdev,
315 struct sk_buff *skb,
316 struct mlx5e_accel_tx_ipsec_state *ipsec_st)
317 {
318 struct mlx5e_priv *priv = netdev_priv(netdev);
319 struct xfrm_offload *xo = xfrm_offload(skb);
320 struct mlx5e_ipsec_sa_entry *sa_entry;
321 struct mlx5e_ipsec_metadata *mdata;
322 struct xfrm_state *x;
323 struct sec_path *sp;
324
325 sp = skb_sec_path(skb);
326 if (unlikely(sp->len != 1)) {
327 atomic64_inc(&priv->ipsec->sw_stats.ipsec_tx_drop_bundle);
328 goto drop;
329 }
330
331 x = xfrm_input_state(skb);
332 if (unlikely(!x)) {
333 atomic64_inc(&priv->ipsec->sw_stats.ipsec_tx_drop_no_state);
334 goto drop;
335 }
336
337 if (unlikely(!x->xso.offload_handle ||
338 (skb->protocol != htons(ETH_P_IP) &&
339 skb->protocol != htons(ETH_P_IPV6)))) {
340 atomic64_inc(&priv->ipsec->sw_stats.ipsec_tx_drop_not_ip);
341 goto drop;
342 }
343
344 if (!skb_is_gso(skb))
345 if (unlikely(mlx5e_ipsec_remove_trailer(skb, x))) {
346 atomic64_inc(&priv->ipsec->sw_stats.ipsec_tx_drop_trailer);
347 goto drop;
348 }
349
350 if (MLX5_CAP_GEN(priv->mdev, fpga)) {
351 mdata = mlx5e_ipsec_add_metadata(skb);
352 if (IS_ERR(mdata)) {
353 atomic64_inc(&priv->ipsec->sw_stats.ipsec_tx_drop_metadata);
354 goto drop;
355 }
356 }
357
358 sa_entry = (struct mlx5e_ipsec_sa_entry *)x->xso.offload_handle;
359 sa_entry->set_iv_op(skb, x, xo);
360 if (MLX5_CAP_GEN(priv->mdev, fpga))
361 mlx5e_ipsec_set_metadata(skb, mdata, xo);
362
363 mlx5e_ipsec_set_state(priv, skb, x, xo, ipsec_st);
364
365 return true;
366
367 drop:
368 kfree_skb(skb);
369 return false;
370 }
371
372 static inline struct xfrm_state *
mlx5e_ipsec_build_sp(struct net_device * netdev,struct sk_buff * skb,struct mlx5e_ipsec_metadata * mdata)373 mlx5e_ipsec_build_sp(struct net_device *netdev, struct sk_buff *skb,
374 struct mlx5e_ipsec_metadata *mdata)
375 {
376 struct mlx5e_priv *priv = netdev_priv(netdev);
377 struct xfrm_offload *xo;
378 struct xfrm_state *xs;
379 struct sec_path *sp;
380 u32 sa_handle;
381
382 sp = secpath_set(skb);
383 if (unlikely(!sp)) {
384 atomic64_inc(&priv->ipsec->sw_stats.ipsec_rx_drop_sp_alloc);
385 return NULL;
386 }
387
388 sa_handle = be32_to_cpu(mdata->content.rx.sa_handle);
389 xs = mlx5e_ipsec_sadb_rx_lookup(priv->ipsec, sa_handle);
390 if (unlikely(!xs)) {
391 atomic64_inc(&priv->ipsec->sw_stats.ipsec_rx_drop_sadb_miss);
392 return NULL;
393 }
394
395 sp = skb_sec_path(skb);
396 sp->xvec[sp->len++] = xs;
397 sp->olen++;
398
399 xo = xfrm_offload(skb);
400 xo->flags = CRYPTO_DONE;
401 switch (mdata->syndrome) {
402 case MLX5E_IPSEC_RX_SYNDROME_DECRYPTED:
403 xo->status = CRYPTO_SUCCESS;
404 if (likely(priv->ipsec->no_trailer)) {
405 xo->flags |= XFRM_ESP_NO_TRAILER;
406 xo->proto = mdata->content.rx.nexthdr;
407 }
408 break;
409 case MLX5E_IPSEC_RX_SYNDROME_AUTH_FAILED:
410 xo->status = CRYPTO_TUNNEL_ESP_AUTH_FAILED;
411 break;
412 case MLX5E_IPSEC_RX_SYNDROME_BAD_PROTO:
413 xo->status = CRYPTO_INVALID_PROTOCOL;
414 break;
415 default:
416 atomic64_inc(&priv->ipsec->sw_stats.ipsec_rx_drop_syndrome);
417 return NULL;
418 }
419 return xs;
420 }
421
mlx5e_ipsec_handle_rx_skb(struct net_device * netdev,struct sk_buff * skb,u32 * cqe_bcnt)422 struct sk_buff *mlx5e_ipsec_handle_rx_skb(struct net_device *netdev,
423 struct sk_buff *skb, u32 *cqe_bcnt)
424 {
425 struct mlx5e_ipsec_metadata *mdata;
426 struct xfrm_state *xs;
427
428 if (!is_metadata_hdr_valid(skb))
429 return skb;
430
431 /* Use the metadata */
432 mdata = (struct mlx5e_ipsec_metadata *)(skb->data + ETH_HLEN);
433 xs = mlx5e_ipsec_build_sp(netdev, skb, mdata);
434 if (unlikely(!xs)) {
435 kfree_skb(skb);
436 return NULL;
437 }
438
439 remove_metadata_hdr(skb);
440 *cqe_bcnt -= MLX5E_METADATA_ETHER_LEN;
441
442 return skb;
443 }
444
445 enum {
446 MLX5E_IPSEC_OFFLOAD_RX_SYNDROME_DECRYPTED,
447 MLX5E_IPSEC_OFFLOAD_RX_SYNDROME_AUTH_FAILED,
448 MLX5E_IPSEC_OFFLOAD_RX_SYNDROME_BAD_TRAILER,
449 };
450
mlx5e_ipsec_offload_handle_rx_skb(struct net_device * netdev,struct sk_buff * skb,struct mlx5_cqe64 * cqe)451 void mlx5e_ipsec_offload_handle_rx_skb(struct net_device *netdev,
452 struct sk_buff *skb,
453 struct mlx5_cqe64 *cqe)
454 {
455 u32 ipsec_meta_data = be32_to_cpu(cqe->ft_metadata);
456 struct mlx5e_priv *priv;
457 struct xfrm_offload *xo;
458 struct xfrm_state *xs;
459 struct sec_path *sp;
460 u32 sa_handle;
461
462 sa_handle = MLX5_IPSEC_METADATA_HANDLE(ipsec_meta_data);
463 priv = netdev_priv(netdev);
464 sp = secpath_set(skb);
465 if (unlikely(!sp)) {
466 atomic64_inc(&priv->ipsec->sw_stats.ipsec_rx_drop_sp_alloc);
467 return;
468 }
469
470 xs = mlx5e_ipsec_sadb_rx_lookup(priv->ipsec, sa_handle);
471 if (unlikely(!xs)) {
472 atomic64_inc(&priv->ipsec->sw_stats.ipsec_rx_drop_sadb_miss);
473 return;
474 }
475
476 sp = skb_sec_path(skb);
477 sp->xvec[sp->len++] = xs;
478 sp->olen++;
479
480 xo = xfrm_offload(skb);
481 xo->flags = CRYPTO_DONE;
482
483 switch (MLX5_IPSEC_METADATA_SYNDROM(ipsec_meta_data)) {
484 case MLX5E_IPSEC_OFFLOAD_RX_SYNDROME_DECRYPTED:
485 xo->status = CRYPTO_SUCCESS;
486 if (WARN_ON_ONCE(priv->ipsec->no_trailer))
487 xo->flags |= XFRM_ESP_NO_TRAILER;
488 break;
489 case MLX5E_IPSEC_OFFLOAD_RX_SYNDROME_AUTH_FAILED:
490 xo->status = CRYPTO_TUNNEL_ESP_AUTH_FAILED;
491 break;
492 case MLX5E_IPSEC_OFFLOAD_RX_SYNDROME_BAD_TRAILER:
493 xo->status = CRYPTO_INVALID_PACKET_SYNTAX;
494 break;
495 default:
496 atomic64_inc(&priv->ipsec->sw_stats.ipsec_rx_drop_syndrome);
497 }
498 }
499
mlx5e_ipsec_feature_check(struct sk_buff * skb,struct net_device * netdev,netdev_features_t features)500 bool mlx5e_ipsec_feature_check(struct sk_buff *skb, struct net_device *netdev,
501 netdev_features_t features)
502 {
503 struct sec_path *sp = skb_sec_path(skb);
504 struct xfrm_state *x;
505
506 if (sp && sp->len) {
507 x = sp->xvec[0];
508 if (x && x->xso.offload_handle)
509 return true;
510 }
511 return false;
512 }
513
mlx5e_ipsec_build_inverse_table(void)514 void mlx5e_ipsec_build_inverse_table(void)
515 {
516 u16 mss_inv;
517 u32 mss;
518
519 /* Calculate 1/x inverse table for use in GSO data path.
520 * Using this table, we provide the IPSec accelerator with the value of
521 * 1/gso_size so that it can infer the position of each segment inside
522 * the GSO, and increment the ESP sequence number, and generate the IV.
523 * The HW needs this value in Q0.16 fixed-point number format
524 */
525 mlx5e_ipsec_inverse_table[1] = htons(0xFFFF);
526 for (mss = 2; mss < MAX_LSO_MSS; mss++) {
527 mss_inv = div_u64(1ULL << 32, mss) >> 16;
528 mlx5e_ipsec_inverse_table[mss] = htons(mss_inv);
529 }
530 }
531