xref: /openbmc/linux/drivers/infiniband/hw/qib/qib_ud.c (revision a48c7709)
1 /*
2  * Copyright (c) 2006, 2007, 2008, 2009 QLogic Corporation. All rights reserved.
3  * Copyright (c) 2005, 2006 PathScale, Inc. All rights reserved.
4  *
5  * This software is available to you under a choice of one of two
6  * licenses.  You may choose to be licensed under the terms of the GNU
7  * General Public License (GPL) Version 2, available from the file
8  * COPYING in the main directory of this source tree, or the
9  * OpenIB.org BSD license below:
10  *
11  *     Redistribution and use in source and binary forms, with or
12  *     without modification, are permitted provided that the following
13  *     conditions are met:
14  *
15  *      - Redistributions of source code must retain the above
16  *        copyright notice, this list of conditions and the following
17  *        disclaimer.
18  *
19  *      - Redistributions in binary form must reproduce the above
20  *        copyright notice, this list of conditions and the following
21  *        disclaimer in the documentation and/or other materials
22  *        provided with the distribution.
23  *
24  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
25  * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
26  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
27  * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
28  * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
29  * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
30  * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
31  * SOFTWARE.
32  */
33 
34 #include <rdma/ib_smi.h>
35 #include <rdma/ib_verbs.h>
36 
37 #include "qib.h"
38 #include "qib_mad.h"
39 
40 /**
41  * qib_ud_loopback - handle send on loopback QPs
42  * @sqp: the sending QP
43  * @swqe: the send work request
44  *
45  * This is called from qib_make_ud_req() to forward a WQE addressed
46  * to the same HCA.
47  * Note that the receive interrupt handler may be calling qib_ud_rcv()
48  * while this is being called.
49  */
50 static void qib_ud_loopback(struct rvt_qp *sqp, struct rvt_swqe *swqe)
51 {
52 	struct qib_ibport *ibp = to_iport(sqp->ibqp.device, sqp->port_num);
53 	struct qib_pportdata *ppd = ppd_from_ibp(ibp);
54 	struct qib_devdata *dd = ppd->dd;
55 	struct rvt_dev_info *rdi = &dd->verbs_dev.rdi;
56 	struct rvt_qp *qp;
57 	struct rdma_ah_attr *ah_attr;
58 	unsigned long flags;
59 	struct rvt_sge_state ssge;
60 	struct rvt_sge *sge;
61 	struct ib_wc wc;
62 	u32 length;
63 	enum ib_qp_type sqptype, dqptype;
64 
65 	rcu_read_lock();
66 	qp = rvt_lookup_qpn(rdi, &ibp->rvp, swqe->ud_wr.remote_qpn);
67 	if (!qp) {
68 		ibp->rvp.n_pkt_drops++;
69 		goto drop;
70 	}
71 
72 	sqptype = sqp->ibqp.qp_type == IB_QPT_GSI ?
73 			IB_QPT_UD : sqp->ibqp.qp_type;
74 	dqptype = qp->ibqp.qp_type == IB_QPT_GSI ?
75 			IB_QPT_UD : qp->ibqp.qp_type;
76 
77 	if (dqptype != sqptype ||
78 	    !(ib_rvt_state_ops[qp->state] & RVT_PROCESS_RECV_OK)) {
79 		ibp->rvp.n_pkt_drops++;
80 		goto drop;
81 	}
82 
83 	ah_attr = &ibah_to_rvtah(swqe->ud_wr.ah)->attr;
84 	ppd = ppd_from_ibp(ibp);
85 
86 	if (qp->ibqp.qp_num > 1) {
87 		u16 pkey1;
88 		u16 pkey2;
89 		u16 lid;
90 
91 		pkey1 = qib_get_pkey(ibp, sqp->s_pkey_index);
92 		pkey2 = qib_get_pkey(ibp, qp->s_pkey_index);
93 		if (unlikely(!qib_pkey_ok(pkey1, pkey2))) {
94 			lid = ppd->lid | (rdma_ah_get_path_bits(ah_attr) &
95 					  ((1 << ppd->lmc) - 1));
96 			qib_bad_pkey(ibp, pkey1,
97 				     rdma_ah_get_sl(ah_attr),
98 				     sqp->ibqp.qp_num, qp->ibqp.qp_num,
99 				     cpu_to_be16(lid),
100 				     cpu_to_be16(rdma_ah_get_dlid(ah_attr)));
101 			goto drop;
102 		}
103 	}
104 
105 	/*
106 	 * Check that the qkey matches (except for QP0, see 9.6.1.4.1).
107 	 * Qkeys with the high order bit set mean use the
108 	 * qkey from the QP context instead of the WR (see 10.2.5).
109 	 */
110 	if (qp->ibqp.qp_num) {
111 		u32 qkey;
112 
113 		qkey = (int)swqe->ud_wr.remote_qkey < 0 ?
114 			sqp->qkey : swqe->ud_wr.remote_qkey;
115 		if (unlikely(qkey != qp->qkey))
116 			goto drop;
117 	}
118 
119 	/*
120 	 * A GRH is expected to precede the data even if not
121 	 * present on the wire.
122 	 */
123 	length = swqe->length;
124 	memset(&wc, 0, sizeof(wc));
125 	wc.byte_len = length + sizeof(struct ib_grh);
126 
127 	if (swqe->wr.opcode == IB_WR_SEND_WITH_IMM) {
128 		wc.wc_flags = IB_WC_WITH_IMM;
129 		wc.ex.imm_data = swqe->wr.ex.imm_data;
130 	}
131 
132 	spin_lock_irqsave(&qp->r_lock, flags);
133 
134 	/*
135 	 * Get the next work request entry to find where to put the data.
136 	 */
137 	if (qp->r_flags & RVT_R_REUSE_SGE)
138 		qp->r_flags &= ~RVT_R_REUSE_SGE;
139 	else {
140 		int ret;
141 
142 		ret = qib_get_rwqe(qp, 0);
143 		if (ret < 0) {
144 			rvt_rc_error(qp, IB_WC_LOC_QP_OP_ERR);
145 			goto bail_unlock;
146 		}
147 		if (!ret) {
148 			if (qp->ibqp.qp_num == 0)
149 				ibp->rvp.n_vl15_dropped++;
150 			goto bail_unlock;
151 		}
152 	}
153 	/* Silently drop packets which are too big. */
154 	if (unlikely(wc.byte_len > qp->r_len)) {
155 		qp->r_flags |= RVT_R_REUSE_SGE;
156 		ibp->rvp.n_pkt_drops++;
157 		goto bail_unlock;
158 	}
159 
160 	if (rdma_ah_get_ah_flags(ah_attr) & IB_AH_GRH) {
161 		struct ib_grh grh;
162 		const struct ib_global_route *grd = rdma_ah_read_grh(ah_attr);
163 
164 		qib_make_grh(ibp, &grh, grd, 0, 0);
165 		qib_copy_sge(&qp->r_sge, &grh,
166 			     sizeof(grh), 1);
167 		wc.wc_flags |= IB_WC_GRH;
168 	} else
169 		rvt_skip_sge(&qp->r_sge, sizeof(struct ib_grh), true);
170 	ssge.sg_list = swqe->sg_list + 1;
171 	ssge.sge = *swqe->sg_list;
172 	ssge.num_sge = swqe->wr.num_sge;
173 	sge = &ssge.sge;
174 	while (length) {
175 		u32 len = sge->length;
176 
177 		if (len > length)
178 			len = length;
179 		if (len > sge->sge_length)
180 			len = sge->sge_length;
181 		BUG_ON(len == 0);
182 		qib_copy_sge(&qp->r_sge, sge->vaddr, len, 1);
183 		sge->vaddr += len;
184 		sge->length -= len;
185 		sge->sge_length -= len;
186 		if (sge->sge_length == 0) {
187 			if (--ssge.num_sge)
188 				*sge = *ssge.sg_list++;
189 		} else if (sge->length == 0 && sge->mr->lkey) {
190 			if (++sge->n >= RVT_SEGSZ) {
191 				if (++sge->m >= sge->mr->mapsz)
192 					break;
193 				sge->n = 0;
194 			}
195 			sge->vaddr =
196 				sge->mr->map[sge->m]->segs[sge->n].vaddr;
197 			sge->length =
198 				sge->mr->map[sge->m]->segs[sge->n].length;
199 		}
200 		length -= len;
201 	}
202 	rvt_put_ss(&qp->r_sge);
203 	if (!test_and_clear_bit(RVT_R_WRID_VALID, &qp->r_aflags))
204 		goto bail_unlock;
205 	wc.wr_id = qp->r_wr_id;
206 	wc.status = IB_WC_SUCCESS;
207 	wc.opcode = IB_WC_RECV;
208 	wc.qp = &qp->ibqp;
209 	wc.src_qp = sqp->ibqp.qp_num;
210 	wc.pkey_index = qp->ibqp.qp_type == IB_QPT_GSI ?
211 		swqe->ud_wr.pkey_index : 0;
212 	wc.slid = ppd->lid | (rdma_ah_get_path_bits(ah_attr) &
213 				((1 << ppd->lmc) - 1));
214 	wc.sl = rdma_ah_get_sl(ah_attr);
215 	wc.dlid_path_bits = rdma_ah_get_dlid(ah_attr) & ((1 << ppd->lmc) - 1);
216 	wc.port_num = qp->port_num;
217 	/* Signal completion event if the solicited bit is set. */
218 	rvt_cq_enter(ibcq_to_rvtcq(qp->ibqp.recv_cq), &wc,
219 		     swqe->wr.send_flags & IB_SEND_SOLICITED);
220 	ibp->rvp.n_loop_pkts++;
221 bail_unlock:
222 	spin_unlock_irqrestore(&qp->r_lock, flags);
223 drop:
224 	rcu_read_unlock();
225 }
226 
227 /**
228  * qib_make_ud_req - construct a UD request packet
229  * @qp: the QP
230  *
231  * Assumes the s_lock is held.
232  *
233  * Return 1 if constructed; otherwise, return 0.
234  */
235 int qib_make_ud_req(struct rvt_qp *qp, unsigned long *flags)
236 {
237 	struct qib_qp_priv *priv = qp->priv;
238 	struct ib_other_headers *ohdr;
239 	struct rdma_ah_attr *ah_attr;
240 	struct qib_pportdata *ppd;
241 	struct qib_ibport *ibp;
242 	struct rvt_swqe *wqe;
243 	u32 nwords;
244 	u32 extra_bytes;
245 	u32 bth0;
246 	u16 lrh0;
247 	u16 lid;
248 	int ret = 0;
249 	int next_cur;
250 
251 	if (!(ib_rvt_state_ops[qp->state] & RVT_PROCESS_NEXT_SEND_OK)) {
252 		if (!(ib_rvt_state_ops[qp->state] & RVT_FLUSH_SEND))
253 			goto bail;
254 		/* We are in the error state, flush the work request. */
255 		if (qp->s_last == READ_ONCE(qp->s_head))
256 			goto bail;
257 		/* If DMAs are in progress, we can't flush immediately. */
258 		if (atomic_read(&priv->s_dma_busy)) {
259 			qp->s_flags |= RVT_S_WAIT_DMA;
260 			goto bail;
261 		}
262 		wqe = rvt_get_swqe_ptr(qp, qp->s_last);
263 		qib_send_complete(qp, wqe, IB_WC_WR_FLUSH_ERR);
264 		goto done;
265 	}
266 
267 	/* see post_one_send() */
268 	if (qp->s_cur == READ_ONCE(qp->s_head))
269 		goto bail;
270 
271 	wqe = rvt_get_swqe_ptr(qp, qp->s_cur);
272 	next_cur = qp->s_cur + 1;
273 	if (next_cur >= qp->s_size)
274 		next_cur = 0;
275 
276 	/* Construct the header. */
277 	ibp = to_iport(qp->ibqp.device, qp->port_num);
278 	ppd = ppd_from_ibp(ibp);
279 	ah_attr = &ibah_to_rvtah(wqe->ud_wr.ah)->attr;
280 	if (rdma_ah_get_dlid(ah_attr) >= be16_to_cpu(IB_MULTICAST_LID_BASE)) {
281 		if (rdma_ah_get_dlid(ah_attr) !=
282 				be16_to_cpu(IB_LID_PERMISSIVE))
283 			this_cpu_inc(ibp->pmastats->n_multicast_xmit);
284 		else
285 			this_cpu_inc(ibp->pmastats->n_unicast_xmit);
286 	} else {
287 		this_cpu_inc(ibp->pmastats->n_unicast_xmit);
288 		lid = rdma_ah_get_dlid(ah_attr) & ~((1 << ppd->lmc) - 1);
289 		if (unlikely(lid == ppd->lid)) {
290 			unsigned long tflags = *flags;
291 			/*
292 			 * If DMAs are in progress, we can't generate
293 			 * a completion for the loopback packet since
294 			 * it would be out of order.
295 			 * XXX Instead of waiting, we could queue a
296 			 * zero length descriptor so we get a callback.
297 			 */
298 			if (atomic_read(&priv->s_dma_busy)) {
299 				qp->s_flags |= RVT_S_WAIT_DMA;
300 				goto bail;
301 			}
302 			qp->s_cur = next_cur;
303 			spin_unlock_irqrestore(&qp->s_lock, tflags);
304 			qib_ud_loopback(qp, wqe);
305 			spin_lock_irqsave(&qp->s_lock, tflags);
306 			*flags = tflags;
307 			qib_send_complete(qp, wqe, IB_WC_SUCCESS);
308 			goto done;
309 		}
310 	}
311 
312 	qp->s_cur = next_cur;
313 	extra_bytes = -wqe->length & 3;
314 	nwords = (wqe->length + extra_bytes) >> 2;
315 
316 	/* header size in 32-bit words LRH+BTH+DETH = (8+12+8)/4. */
317 	qp->s_hdrwords = 7;
318 	qp->s_cur_size = wqe->length;
319 	qp->s_cur_sge = &qp->s_sge;
320 	qp->s_srate = rdma_ah_get_static_rate(ah_attr);
321 	qp->s_wqe = wqe;
322 	qp->s_sge.sge = wqe->sg_list[0];
323 	qp->s_sge.sg_list = wqe->sg_list + 1;
324 	qp->s_sge.num_sge = wqe->wr.num_sge;
325 	qp->s_sge.total_len = wqe->length;
326 
327 	if (rdma_ah_get_ah_flags(ah_attr) & IB_AH_GRH) {
328 		/* Header size in 32-bit words. */
329 		qp->s_hdrwords += qib_make_grh(ibp, &priv->s_hdr->u.l.grh,
330 					       rdma_ah_read_grh(ah_attr),
331 					       qp->s_hdrwords, nwords);
332 		lrh0 = QIB_LRH_GRH;
333 		ohdr = &priv->s_hdr->u.l.oth;
334 		/*
335 		 * Don't worry about sending to locally attached multicast
336 		 * QPs.  It is unspecified by the spec. what happens.
337 		 */
338 	} else {
339 		/* Header size in 32-bit words. */
340 		lrh0 = QIB_LRH_BTH;
341 		ohdr = &priv->s_hdr->u.oth;
342 	}
343 	if (wqe->wr.opcode == IB_WR_SEND_WITH_IMM) {
344 		qp->s_hdrwords++;
345 		ohdr->u.ud.imm_data = wqe->wr.ex.imm_data;
346 		bth0 = IB_OPCODE_UD_SEND_ONLY_WITH_IMMEDIATE << 24;
347 	} else
348 		bth0 = IB_OPCODE_UD_SEND_ONLY << 24;
349 	lrh0 |= rdma_ah_get_sl(ah_attr) << 4;
350 	if (qp->ibqp.qp_type == IB_QPT_SMI)
351 		lrh0 |= 0xF000; /* Set VL (see ch. 13.5.3.1) */
352 	else
353 		lrh0 |= ibp->sl_to_vl[rdma_ah_get_sl(ah_attr)] << 12;
354 	priv->s_hdr->lrh[0] = cpu_to_be16(lrh0);
355 	priv->s_hdr->lrh[1] =
356 			cpu_to_be16(rdma_ah_get_dlid(ah_attr));  /* DEST LID */
357 	priv->s_hdr->lrh[2] =
358 			cpu_to_be16(qp->s_hdrwords + nwords + SIZE_OF_CRC);
359 	lid = ppd->lid;
360 	if (lid) {
361 		lid |= rdma_ah_get_path_bits(ah_attr) &
362 			((1 << ppd->lmc) - 1);
363 		priv->s_hdr->lrh[3] = cpu_to_be16(lid);
364 	} else
365 		priv->s_hdr->lrh[3] = IB_LID_PERMISSIVE;
366 	if (wqe->wr.send_flags & IB_SEND_SOLICITED)
367 		bth0 |= IB_BTH_SOLICITED;
368 	bth0 |= extra_bytes << 20;
369 	bth0 |= qp->ibqp.qp_type == IB_QPT_SMI ? QIB_DEFAULT_P_KEY :
370 		qib_get_pkey(ibp, qp->ibqp.qp_type == IB_QPT_GSI ?
371 			     wqe->ud_wr.pkey_index : qp->s_pkey_index);
372 	ohdr->bth[0] = cpu_to_be32(bth0);
373 	/*
374 	 * Use the multicast QP if the destination LID is a multicast LID.
375 	 */
376 	ohdr->bth[1] = rdma_ah_get_dlid(ah_attr) >=
377 			be16_to_cpu(IB_MULTICAST_LID_BASE) &&
378 		rdma_ah_get_dlid(ah_attr) != be16_to_cpu(IB_LID_PERMISSIVE) ?
379 		cpu_to_be32(QIB_MULTICAST_QPN) :
380 		cpu_to_be32(wqe->ud_wr.remote_qpn);
381 	ohdr->bth[2] = cpu_to_be32(wqe->psn & QIB_PSN_MASK);
382 	/*
383 	 * Qkeys with the high order bit set mean use the
384 	 * qkey from the QP context instead of the WR (see 10.2.5).
385 	 */
386 	ohdr->u.ud.deth[0] = cpu_to_be32((int)wqe->ud_wr.remote_qkey < 0 ?
387 					 qp->qkey : wqe->ud_wr.remote_qkey);
388 	ohdr->u.ud.deth[1] = cpu_to_be32(qp->ibqp.qp_num);
389 
390 done:
391 	return 1;
392 bail:
393 	qp->s_flags &= ~RVT_S_BUSY;
394 	return ret;
395 }
396 
397 static unsigned qib_lookup_pkey(struct qib_ibport *ibp, u16 pkey)
398 {
399 	struct qib_pportdata *ppd = ppd_from_ibp(ibp);
400 	struct qib_devdata *dd = ppd->dd;
401 	unsigned ctxt = ppd->hw_pidx;
402 	unsigned i;
403 
404 	pkey &= 0x7fff;	/* remove limited/full membership bit */
405 
406 	for (i = 0; i < ARRAY_SIZE(dd->rcd[ctxt]->pkeys); ++i)
407 		if ((dd->rcd[ctxt]->pkeys[i] & 0x7fff) == pkey)
408 			return i;
409 
410 	/*
411 	 * Should not get here, this means hardware failed to validate pkeys.
412 	 * Punt and return index 0.
413 	 */
414 	return 0;
415 }
416 
417 /**
418  * qib_ud_rcv - receive an incoming UD packet
419  * @ibp: the port the packet came in on
420  * @hdr: the packet header
421  * @has_grh: true if the packet has a GRH
422  * @data: the packet data
423  * @tlen: the packet length
424  * @qp: the QP the packet came on
425  *
426  * This is called from qib_qp_rcv() to process an incoming UD packet
427  * for the given QP.
428  * Called at interrupt level.
429  */
430 void qib_ud_rcv(struct qib_ibport *ibp, struct ib_header *hdr,
431 		int has_grh, void *data, u32 tlen, struct rvt_qp *qp)
432 {
433 	struct ib_other_headers *ohdr;
434 	int opcode;
435 	u32 hdrsize;
436 	u32 pad;
437 	struct ib_wc wc;
438 	u32 qkey;
439 	u32 src_qp;
440 	u16 dlid;
441 
442 	/* Check for GRH */
443 	if (!has_grh) {
444 		ohdr = &hdr->u.oth;
445 		hdrsize = 8 + 12 + 8;   /* LRH + BTH + DETH */
446 	} else {
447 		ohdr = &hdr->u.l.oth;
448 		hdrsize = 8 + 40 + 12 + 8; /* LRH + GRH + BTH + DETH */
449 	}
450 	qkey = be32_to_cpu(ohdr->u.ud.deth[0]);
451 	src_qp = be32_to_cpu(ohdr->u.ud.deth[1]) & RVT_QPN_MASK;
452 
453 	/*
454 	 * Get the number of bytes the message was padded by
455 	 * and drop incomplete packets.
456 	 */
457 	pad = (be32_to_cpu(ohdr->bth[0]) >> 20) & 3;
458 	if (unlikely(tlen < (hdrsize + pad + 4)))
459 		goto drop;
460 
461 	tlen -= hdrsize + pad + 4;
462 
463 	/*
464 	 * Check that the permissive LID is only used on QP0
465 	 * and the QKEY matches (see 9.6.1.4.1 and 9.6.1.5.1).
466 	 */
467 	if (qp->ibqp.qp_num) {
468 		if (unlikely(hdr->lrh[1] == IB_LID_PERMISSIVE ||
469 			     hdr->lrh[3] == IB_LID_PERMISSIVE))
470 			goto drop;
471 		if (qp->ibqp.qp_num > 1) {
472 			u16 pkey1, pkey2;
473 
474 			pkey1 = be32_to_cpu(ohdr->bth[0]);
475 			pkey2 = qib_get_pkey(ibp, qp->s_pkey_index);
476 			if (unlikely(!qib_pkey_ok(pkey1, pkey2))) {
477 				qib_bad_pkey(ibp,
478 					     pkey1,
479 					     (be16_to_cpu(hdr->lrh[0]) >> 4) &
480 						0xF,
481 					     src_qp, qp->ibqp.qp_num,
482 					     hdr->lrh[3], hdr->lrh[1]);
483 				return;
484 			}
485 		}
486 		if (unlikely(qkey != qp->qkey))
487 			return;
488 
489 		/* Drop invalid MAD packets (see 13.5.3.1). */
490 		if (unlikely(qp->ibqp.qp_num == 1 &&
491 			     (tlen != 256 ||
492 			      (be16_to_cpu(hdr->lrh[0]) >> 12) == 15)))
493 			goto drop;
494 	} else {
495 		struct ib_smp *smp;
496 
497 		/* Drop invalid MAD packets (see 13.5.3.1). */
498 		if (tlen != 256 || (be16_to_cpu(hdr->lrh[0]) >> 12) != 15)
499 			goto drop;
500 		smp = (struct ib_smp *) data;
501 		if ((hdr->lrh[1] == IB_LID_PERMISSIVE ||
502 		     hdr->lrh[3] == IB_LID_PERMISSIVE) &&
503 		    smp->mgmt_class != IB_MGMT_CLASS_SUBN_DIRECTED_ROUTE)
504 			goto drop;
505 	}
506 
507 	/*
508 	 * The opcode is in the low byte when its in network order
509 	 * (top byte when in host order).
510 	 */
511 	opcode = be32_to_cpu(ohdr->bth[0]) >> 24;
512 	if (qp->ibqp.qp_num > 1 &&
513 	    opcode == IB_OPCODE_UD_SEND_ONLY_WITH_IMMEDIATE) {
514 		wc.ex.imm_data = ohdr->u.ud.imm_data;
515 		wc.wc_flags = IB_WC_WITH_IMM;
516 		tlen -= sizeof(u32);
517 	} else if (opcode == IB_OPCODE_UD_SEND_ONLY) {
518 		wc.ex.imm_data = 0;
519 		wc.wc_flags = 0;
520 	} else
521 		goto drop;
522 
523 	/*
524 	 * A GRH is expected to precede the data even if not
525 	 * present on the wire.
526 	 */
527 	wc.byte_len = tlen + sizeof(struct ib_grh);
528 
529 	/*
530 	 * Get the next work request entry to find where to put the data.
531 	 */
532 	if (qp->r_flags & RVT_R_REUSE_SGE)
533 		qp->r_flags &= ~RVT_R_REUSE_SGE;
534 	else {
535 		int ret;
536 
537 		ret = qib_get_rwqe(qp, 0);
538 		if (ret < 0) {
539 			rvt_rc_error(qp, IB_WC_LOC_QP_OP_ERR);
540 			return;
541 		}
542 		if (!ret) {
543 			if (qp->ibqp.qp_num == 0)
544 				ibp->rvp.n_vl15_dropped++;
545 			return;
546 		}
547 	}
548 	/* Silently drop packets which are too big. */
549 	if (unlikely(wc.byte_len > qp->r_len)) {
550 		qp->r_flags |= RVT_R_REUSE_SGE;
551 		goto drop;
552 	}
553 	if (has_grh) {
554 		qib_copy_sge(&qp->r_sge, &hdr->u.l.grh,
555 			     sizeof(struct ib_grh), 1);
556 		wc.wc_flags |= IB_WC_GRH;
557 	} else
558 		rvt_skip_sge(&qp->r_sge, sizeof(struct ib_grh), true);
559 	qib_copy_sge(&qp->r_sge, data, wc.byte_len - sizeof(struct ib_grh), 1);
560 	rvt_put_ss(&qp->r_sge);
561 	if (!test_and_clear_bit(RVT_R_WRID_VALID, &qp->r_aflags))
562 		return;
563 	wc.wr_id = qp->r_wr_id;
564 	wc.status = IB_WC_SUCCESS;
565 	wc.opcode = IB_WC_RECV;
566 	wc.vendor_err = 0;
567 	wc.qp = &qp->ibqp;
568 	wc.src_qp = src_qp;
569 	wc.pkey_index = qp->ibqp.qp_type == IB_QPT_GSI ?
570 		qib_lookup_pkey(ibp, be32_to_cpu(ohdr->bth[0])) : 0;
571 	wc.slid = be16_to_cpu(hdr->lrh[3]);
572 	wc.sl = (be16_to_cpu(hdr->lrh[0]) >> 4) & 0xF;
573 	dlid = be16_to_cpu(hdr->lrh[1]);
574 	/*
575 	 * Save the LMC lower bits if the destination LID is a unicast LID.
576 	 */
577 	wc.dlid_path_bits = dlid >= be16_to_cpu(IB_MULTICAST_LID_BASE) ? 0 :
578 		dlid & ((1 << ppd_from_ibp(ibp)->lmc) - 1);
579 	wc.port_num = qp->port_num;
580 	/* Signal completion event if the solicited bit is set. */
581 	rvt_cq_enter(ibcq_to_rvtcq(qp->ibqp.recv_cq), &wc,
582 		     ib_bth_is_solicited(ohdr));
583 	return;
584 
585 drop:
586 	ibp->rvp.n_pkt_drops++;
587 }
588