1 // SPDX-License-Identifier: GPL-2.0
3 * Copyright (c) 2015, 2017 Oracle. All rights reserved.
4 * Copyright (c) 2003-2007 Network Appliance, Inc. All rights reserved.
7 /* Lightweight memory registration using Fast Registration Work
10 * FRWR features ordered asynchronous registration and invalidation
11 * of arbitrarily-sized memory regions. This is the fastest and safest
12 * but most complex memory registration mode.
17 * A Memory Region is prepared for RDMA Read or Write using a FAST_REG
18 * Work Request (frwr_map). When the RDMA operation is finished, this
19 * Memory Region is invalidated using a LOCAL_INV Work Request
20 * (frwr_unmap_async and frwr_unmap_sync).
22 * Typically FAST_REG Work Requests are not signaled, and neither are
23 * RDMA Send Work Requests (with the exception of signaling occasionally
24 * to prevent provider work queue overflows). This greatly reduces HCA
30 * frwr_map and frwr_unmap_* cannot run at the same time the transport
31 * connect worker is running. The connect worker holds the transport
32 * send lock, just as ->send_request does. This prevents frwr_map and
33 * the connect worker from running concurrently. When a connection is
34 * closed, the Receive completion queue is drained before the allowing
35 * the connect worker to get control. This prevents frwr_unmap and the
36 * connect worker from running concurrently.
38 * When the underlying transport disconnects, MRs that are in flight
39 * are flushed and are likely unusable. Thus all MRs are destroyed.
40 * New MRs are created on demand.
43 #include <linux/sunrpc/svc_rdma.h>
45 #include "xprt_rdma.h"
46 #include <trace/events/rpcrdma.h>
48 #if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
49 # define RPCDBG_FACILITY RPCDBG_TRANS
52 static void frwr_cid_init(struct rpcrdma_ep *ep,
53 struct rpcrdma_mr *mr)
55 struct rpc_rdma_cid *cid = &mr->mr_cid;
57 cid->ci_queue_id = ep->re_attr.send_cq->res.id;
58 cid->ci_completion_id = mr->mr_ibmr->res.id;
61 static void frwr_mr_unmap(struct rpcrdma_xprt *r_xprt, struct rpcrdma_mr *mr)
64 trace_xprtrdma_mr_unmap(mr);
65 ib_dma_unmap_sg(mr->mr_device, mr->mr_sg, mr->mr_nents,
72 * frwr_mr_release - Destroy one MR
73 * @mr: MR allocated by frwr_mr_init
76 void frwr_mr_release(struct rpcrdma_mr *mr)
80 frwr_mr_unmap(mr->mr_xprt, mr);
82 rc = ib_dereg_mr(mr->mr_ibmr);
84 trace_xprtrdma_frwr_dereg(mr, rc);
89 static void frwr_mr_put(struct rpcrdma_mr *mr)
91 frwr_mr_unmap(mr->mr_xprt, mr);
93 /* The MR is returned to the req's MR free list instead
94 * of to the xprt's MR free list. No spinlock is needed.
96 rpcrdma_mr_push(mr, &mr->mr_req->rl_free_mrs);
99 /* frwr_reset - Place MRs back on the free list
100 * @req: request to reset
102 * Used after a failed marshal. For FRWR, this means the MRs
103 * don't have to be fully released and recreated.
105 * NB: This is safe only as long as none of @req's MRs are
106 * involved with an ongoing asynchronous FAST_REG or LOCAL_INV
109 void frwr_reset(struct rpcrdma_req *req)
111 struct rpcrdma_mr *mr;
113 while ((mr = rpcrdma_mr_pop(&req->rl_registered)))
118 * frwr_mr_init - Initialize one MR
119 * @r_xprt: controlling transport instance
120 * @mr: generic MR to prepare for FRWR
122 * Returns zero if successful. Otherwise a negative errno
125 int frwr_mr_init(struct rpcrdma_xprt *r_xprt, struct rpcrdma_mr *mr)
127 struct rpcrdma_ep *ep = r_xprt->rx_ep;
128 unsigned int depth = ep->re_max_fr_depth;
129 struct scatterlist *sg;
133 frmr = ib_alloc_mr(ep->re_pd, ep->re_mrtype, depth);
137 sg = kmalloc_array(depth, sizeof(*sg), GFP_NOFS);
141 mr->mr_xprt = r_xprt;
143 mr->mr_device = NULL;
144 INIT_LIST_HEAD(&mr->mr_list);
145 init_completion(&mr->mr_linv_done);
146 frwr_cid_init(ep, mr);
148 sg_init_table(sg, depth);
154 trace_xprtrdma_frwr_alloc(mr, rc);
163 * frwr_query_device - Prepare a transport for use with FRWR
164 * @ep: endpoint to fill in
165 * @device: RDMA device to query
169 * ep->re_max_requests
170 * ep->re_max_rdma_segs
171 * ep->re_max_fr_depth
175 * On success, returns zero.
176 * %-EINVAL - the device does not support FRWR memory registration
177 * %-ENOMEM - the device is not sufficiently capable for NFS/RDMA
179 int frwr_query_device(struct rpcrdma_ep *ep, const struct ib_device *device)
181 const struct ib_device_attr *attrs = &device->attrs;
182 int max_qp_wr, depth, delta;
183 unsigned int max_sge;
185 if (!(attrs->device_cap_flags & IB_DEVICE_MEM_MGT_EXTENSIONS) ||
186 attrs->max_fast_reg_page_list_len == 0) {
187 pr_err("rpcrdma: 'frwr' mode is not supported by device %s\n",
192 max_sge = min_t(unsigned int, attrs->max_send_sge,
193 RPCRDMA_MAX_SEND_SGES);
194 if (max_sge < RPCRDMA_MIN_SEND_SGES) {
195 pr_err("rpcrdma: HCA provides only %u send SGEs\n", max_sge);
198 ep->re_attr.cap.max_send_sge = max_sge;
199 ep->re_attr.cap.max_recv_sge = 1;
201 ep->re_mrtype = IB_MR_TYPE_MEM_REG;
202 if (attrs->device_cap_flags & IB_DEVICE_SG_GAPS_REG)
203 ep->re_mrtype = IB_MR_TYPE_SG_GAPS;
205 /* Quirk: Some devices advertise a large max_fast_reg_page_list_len
206 * capability, but perform optimally when the MRs are not larger
209 if (attrs->max_sge_rd > RPCRDMA_MAX_HDR_SEGS)
210 ep->re_max_fr_depth = attrs->max_sge_rd;
212 ep->re_max_fr_depth = attrs->max_fast_reg_page_list_len;
213 if (ep->re_max_fr_depth > RPCRDMA_MAX_DATA_SEGS)
214 ep->re_max_fr_depth = RPCRDMA_MAX_DATA_SEGS;
216 /* Add room for frwr register and invalidate WRs.
217 * 1. FRWR reg WR for head
218 * 2. FRWR invalidate WR for head
219 * 3. N FRWR reg WRs for pagelist
220 * 4. N FRWR invalidate WRs for pagelist
221 * 5. FRWR reg WR for tail
222 * 6. FRWR invalidate WR for tail
223 * 7. The RDMA_SEND WR
227 /* Calculate N if the device max FRWR depth is smaller than
228 * RPCRDMA_MAX_DATA_SEGS.
230 if (ep->re_max_fr_depth < RPCRDMA_MAX_DATA_SEGS) {
231 delta = RPCRDMA_MAX_DATA_SEGS - ep->re_max_fr_depth;
233 depth += 2; /* FRWR reg + invalidate */
234 delta -= ep->re_max_fr_depth;
238 max_qp_wr = attrs->max_qp_wr;
239 max_qp_wr -= RPCRDMA_BACKWARD_WRS;
241 if (max_qp_wr < RPCRDMA_MIN_SLOT_TABLE)
243 if (ep->re_max_requests > max_qp_wr)
244 ep->re_max_requests = max_qp_wr;
245 ep->re_attr.cap.max_send_wr = ep->re_max_requests * depth;
246 if (ep->re_attr.cap.max_send_wr > max_qp_wr) {
247 ep->re_max_requests = max_qp_wr / depth;
248 if (!ep->re_max_requests)
250 ep->re_attr.cap.max_send_wr = ep->re_max_requests * depth;
252 ep->re_attr.cap.max_send_wr += RPCRDMA_BACKWARD_WRS;
253 ep->re_attr.cap.max_send_wr += 1; /* for ib_drain_sq */
254 ep->re_attr.cap.max_recv_wr = ep->re_max_requests;
255 ep->re_attr.cap.max_recv_wr += RPCRDMA_BACKWARD_WRS;
256 ep->re_attr.cap.max_recv_wr += RPCRDMA_MAX_RECV_BATCH;
257 ep->re_attr.cap.max_recv_wr += 1; /* for ib_drain_rq */
259 ep->re_max_rdma_segs =
260 DIV_ROUND_UP(RPCRDMA_MAX_DATA_SEGS, ep->re_max_fr_depth);
261 /* Reply chunks require segments for head and tail buffers */
262 ep->re_max_rdma_segs += 2;
263 if (ep->re_max_rdma_segs > RPCRDMA_MAX_HDR_SEGS)
264 ep->re_max_rdma_segs = RPCRDMA_MAX_HDR_SEGS;
266 /* Ensure the underlying device is capable of conveying the
267 * largest r/wsize NFS will ask for. This guarantees that
268 * failing over from one RDMA device to another will not
271 if ((ep->re_max_rdma_segs * ep->re_max_fr_depth) < RPCRDMA_MAX_SEGS)
278 * frwr_map - Register a memory region
279 * @r_xprt: controlling transport
280 * @seg: memory region co-ordinates
281 * @nsegs: number of segments remaining
282 * @writing: true when RDMA Write will be used
283 * @xid: XID of RPC using the registered memory
286 * Prepare a REG_MR Work Request to register a memory region
287 * for remote access via RDMA READ or RDMA WRITE.
289 * Returns the next segment or a negative errno pointer.
290 * On success, @mr is filled in.
292 struct rpcrdma_mr_seg *frwr_map(struct rpcrdma_xprt *r_xprt,
293 struct rpcrdma_mr_seg *seg,
294 int nsegs, bool writing, __be32 xid,
295 struct rpcrdma_mr *mr)
297 struct rpcrdma_ep *ep = r_xprt->rx_ep;
298 struct ib_reg_wr *reg_wr;
303 if (nsegs > ep->re_max_fr_depth)
304 nsegs = ep->re_max_fr_depth;
305 for (i = 0; i < nsegs;) {
306 sg_set_page(&mr->mr_sg[i], seg->mr_page,
307 seg->mr_len, seg->mr_offset);
311 if (ep->re_mrtype == IB_MR_TYPE_SG_GAPS)
313 if ((i < nsegs && seg->mr_offset) ||
314 offset_in_page((seg-1)->mr_offset + (seg-1)->mr_len))
317 mr->mr_dir = rpcrdma_data_dir(writing);
320 dma_nents = ib_dma_map_sg(ep->re_id->device, mr->mr_sg, mr->mr_nents,
324 mr->mr_device = ep->re_id->device;
327 n = ib_map_mr_sg(ibmr, mr->mr_sg, dma_nents, NULL, PAGE_SIZE);
331 ibmr->iova &= 0x00000000ffffffff;
332 ibmr->iova |= ((u64)be32_to_cpu(xid)) << 32;
333 key = (u8)(ibmr->rkey & 0x000000FF);
334 ib_update_fast_reg_key(ibmr, ++key);
336 reg_wr = &mr->mr_regwr;
338 reg_wr->key = ibmr->rkey;
339 reg_wr->access = writing ?
340 IB_ACCESS_REMOTE_WRITE | IB_ACCESS_LOCAL_WRITE :
341 IB_ACCESS_REMOTE_READ;
343 mr->mr_handle = ibmr->rkey;
344 mr->mr_length = ibmr->length;
345 mr->mr_offset = ibmr->iova;
346 trace_xprtrdma_mr_map(mr);
351 trace_xprtrdma_frwr_sgerr(mr, i);
352 return ERR_PTR(-EIO);
355 trace_xprtrdma_frwr_maperr(mr, n);
356 return ERR_PTR(-EIO);
360 * frwr_wc_fastreg - Invoked by RDMA provider for a flushed FastReg WC
361 * @cq: completion queue
362 * @wc: WCE for a completed FastReg WR
364 * Each flushed MR gets destroyed after the QP has drained.
366 static void frwr_wc_fastreg(struct ib_cq *cq, struct ib_wc *wc)
368 struct ib_cqe *cqe = wc->wr_cqe;
369 struct rpcrdma_mr *mr = container_of(cqe, struct rpcrdma_mr, mr_cqe);
371 /* WARNING: Only wr_cqe and status are reliable at this point */
372 trace_xprtrdma_wc_fastreg(wc, &mr->mr_cid);
374 rpcrdma_flush_disconnect(cq->cq_context, wc);
378 * frwr_send - post Send WRs containing the RPC Call message
379 * @r_xprt: controlling transport instance
380 * @req: prepared RPC Call
382 * For FRWR, chain any FastReg WRs to the Send WR. Only a
383 * single ib_post_send call is needed to register memory
384 * and then post the Send WR.
386 * Returns the return code from ib_post_send.
388 * Caller must hold the transport send lock to ensure that the
389 * pointers to the transport's rdma_cm_id and QP are stable.
391 int frwr_send(struct rpcrdma_xprt *r_xprt, struct rpcrdma_req *req)
393 struct ib_send_wr *post_wr, *send_wr = &req->rl_wr;
394 struct rpcrdma_ep *ep = r_xprt->rx_ep;
395 struct rpcrdma_mr *mr;
396 unsigned int num_wrs;
401 list_for_each_entry(mr, &req->rl_registered, mr_list) {
402 trace_xprtrdma_mr_fastreg(mr);
404 mr->mr_cqe.done = frwr_wc_fastreg;
405 mr->mr_regwr.wr.next = post_wr;
406 mr->mr_regwr.wr.wr_cqe = &mr->mr_cqe;
407 mr->mr_regwr.wr.num_sge = 0;
408 mr->mr_regwr.wr.opcode = IB_WR_REG_MR;
409 mr->mr_regwr.wr.send_flags = 0;
410 post_wr = &mr->mr_regwr.wr;
414 if ((kref_read(&req->rl_kref) > 1) || num_wrs > ep->re_send_count) {
415 send_wr->send_flags |= IB_SEND_SIGNALED;
416 ep->re_send_count = min_t(unsigned int, ep->re_send_batch,
417 num_wrs - ep->re_send_count);
419 send_wr->send_flags &= ~IB_SEND_SIGNALED;
420 ep->re_send_count -= num_wrs;
423 trace_xprtrdma_post_send(req);
424 ret = ib_post_send(ep->re_id->qp, post_wr, NULL);
426 trace_xprtrdma_post_send_err(r_xprt, req, ret);
431 * frwr_reminv - handle a remotely invalidated mr on the @mrs list
432 * @rep: Received reply
433 * @mrs: list of MRs to check
436 void frwr_reminv(struct rpcrdma_rep *rep, struct list_head *mrs)
438 struct rpcrdma_mr *mr;
440 list_for_each_entry(mr, mrs, mr_list)
441 if (mr->mr_handle == rep->rr_inv_rkey) {
442 list_del_init(&mr->mr_list);
443 trace_xprtrdma_mr_reminv(mr);
445 break; /* only one invalidated MR per RPC */
449 static void frwr_mr_done(struct ib_wc *wc, struct rpcrdma_mr *mr)
451 if (likely(wc->status == IB_WC_SUCCESS))
456 * frwr_wc_localinv - Invoked by RDMA provider for a LOCAL_INV WC
457 * @cq: completion queue
458 * @wc: WCE for a completed LocalInv WR
461 static void frwr_wc_localinv(struct ib_cq *cq, struct ib_wc *wc)
463 struct ib_cqe *cqe = wc->wr_cqe;
464 struct rpcrdma_mr *mr = container_of(cqe, struct rpcrdma_mr, mr_cqe);
466 /* WARNING: Only wr_cqe and status are reliable at this point */
467 trace_xprtrdma_wc_li(wc, &mr->mr_cid);
468 frwr_mr_done(wc, mr);
470 rpcrdma_flush_disconnect(cq->cq_context, wc);
474 * frwr_wc_localinv_wake - Invoked by RDMA provider for a LOCAL_INV WC
475 * @cq: completion queue
476 * @wc: WCE for a completed LocalInv WR
478 * Awaken anyone waiting for an MR to finish being fenced.
480 static void frwr_wc_localinv_wake(struct ib_cq *cq, struct ib_wc *wc)
482 struct ib_cqe *cqe = wc->wr_cqe;
483 struct rpcrdma_mr *mr = container_of(cqe, struct rpcrdma_mr, mr_cqe);
485 /* WARNING: Only wr_cqe and status are reliable at this point */
486 trace_xprtrdma_wc_li_wake(wc, &mr->mr_cid);
487 frwr_mr_done(wc, mr);
488 complete(&mr->mr_linv_done);
490 rpcrdma_flush_disconnect(cq->cq_context, wc);
494 * frwr_unmap_sync - invalidate memory regions that were registered for @req
495 * @r_xprt: controlling transport instance
496 * @req: rpcrdma_req with a non-empty list of MRs to process
498 * Sleeps until it is safe for the host CPU to access the previously mapped
499 * memory regions. This guarantees that registered MRs are properly fenced
500 * from the server before the RPC consumer accesses the data in them. It
501 * also ensures proper Send flow control: waking the next RPC waits until
502 * this RPC has relinquished all its Send Queue entries.
504 void frwr_unmap_sync(struct rpcrdma_xprt *r_xprt, struct rpcrdma_req *req)
506 struct ib_send_wr *first, **prev, *last;
507 struct rpcrdma_ep *ep = r_xprt->rx_ep;
508 const struct ib_send_wr *bad_wr;
509 struct rpcrdma_mr *mr;
512 /* ORDER: Invalidate all of the MRs first
514 * Chain the LOCAL_INV Work Requests and post them with
515 * a single ib_post_send() call.
518 while ((mr = rpcrdma_mr_pop(&req->rl_registered))) {
520 trace_xprtrdma_mr_localinv(mr);
521 r_xprt->rx_stats.local_inv_needed++;
523 last = &mr->mr_invwr;
525 last->wr_cqe = &mr->mr_cqe;
526 last->sg_list = NULL;
528 last->opcode = IB_WR_LOCAL_INV;
529 last->send_flags = IB_SEND_SIGNALED;
530 last->ex.invalidate_rkey = mr->mr_handle;
532 last->wr_cqe->done = frwr_wc_localinv;
537 mr = container_of(last, struct rpcrdma_mr, mr_invwr);
539 /* Strong send queue ordering guarantees that when the
540 * last WR in the chain completes, all WRs in the chain
543 last->wr_cqe->done = frwr_wc_localinv_wake;
544 reinit_completion(&mr->mr_linv_done);
546 /* Transport disconnect drains the receive CQ before it
547 * replaces the QP. The RPC reply handler won't call us
548 * unless re_id->qp is a valid pointer.
551 rc = ib_post_send(ep->re_id->qp, first, &bad_wr);
553 /* The final LOCAL_INV WR in the chain is supposed to
554 * do the wake. If it was never posted, the wake will
555 * not happen, so don't wait in that case.
558 wait_for_completion(&mr->mr_linv_done);
562 /* On error, the MRs get destroyed once the QP has drained. */
563 trace_xprtrdma_post_linv_err(req, rc);
565 /* Force a connection loss to ensure complete recovery.
567 rpcrdma_force_disconnect(ep);
571 * frwr_wc_localinv_done - Invoked by RDMA provider for a signaled LOCAL_INV WC
572 * @cq: completion queue
573 * @wc: WCE for a completed LocalInv WR
576 static void frwr_wc_localinv_done(struct ib_cq *cq, struct ib_wc *wc)
578 struct ib_cqe *cqe = wc->wr_cqe;
579 struct rpcrdma_mr *mr = container_of(cqe, struct rpcrdma_mr, mr_cqe);
580 struct rpcrdma_rep *rep;
582 /* WARNING: Only wr_cqe and status are reliable at this point */
583 trace_xprtrdma_wc_li_done(wc, &mr->mr_cid);
585 /* Ensure that @rep is generated before the MR is released */
586 rep = mr->mr_req->rl_reply;
589 if (wc->status != IB_WC_SUCCESS) {
591 rpcrdma_unpin_rqst(rep);
592 rpcrdma_flush_disconnect(cq->cq_context, wc);
596 rpcrdma_complete_rqst(rep);
600 * frwr_unmap_async - invalidate memory regions that were registered for @req
601 * @r_xprt: controlling transport instance
602 * @req: rpcrdma_req with a non-empty list of MRs to process
604 * This guarantees that registered MRs are properly fenced from the
605 * server before the RPC consumer accesses the data in them. It also
606 * ensures proper Send flow control: waking the next RPC waits until
607 * this RPC has relinquished all its Send Queue entries.
609 void frwr_unmap_async(struct rpcrdma_xprt *r_xprt, struct rpcrdma_req *req)
611 struct ib_send_wr *first, *last, **prev;
612 struct rpcrdma_ep *ep = r_xprt->rx_ep;
613 struct rpcrdma_mr *mr;
616 /* Chain the LOCAL_INV Work Requests and post them with
617 * a single ib_post_send() call.
620 while ((mr = rpcrdma_mr_pop(&req->rl_registered))) {
622 trace_xprtrdma_mr_localinv(mr);
623 r_xprt->rx_stats.local_inv_needed++;
625 last = &mr->mr_invwr;
627 last->wr_cqe = &mr->mr_cqe;
628 last->sg_list = NULL;
630 last->opcode = IB_WR_LOCAL_INV;
631 last->send_flags = IB_SEND_SIGNALED;
632 last->ex.invalidate_rkey = mr->mr_handle;
634 last->wr_cqe->done = frwr_wc_localinv;
640 /* Strong send queue ordering guarantees that when the
641 * last WR in the chain completes, all WRs in the chain
642 * are complete. The last completion will wake up the
645 last->wr_cqe->done = frwr_wc_localinv_done;
647 /* Transport disconnect drains the receive CQ before it
648 * replaces the QP. The RPC reply handler won't call us
649 * unless re_id->qp is a valid pointer.
651 rc = ib_post_send(ep->re_id->qp, first, NULL);
655 /* On error, the MRs get destroyed once the QP has drained. */
656 trace_xprtrdma_post_linv_err(req, rc);
658 /* The final LOCAL_INV WR in the chain is supposed to
659 * do the wake. If it was never posted, the wake does
660 * not happen. Unpin the rqst in preparation for its
663 rpcrdma_unpin_rqst(req->rl_reply);
665 /* Force a connection loss to ensure complete recovery.
667 rpcrdma_force_disconnect(ep);