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
53 * frwr_release_mr - Destroy one MR
54 * @mr: MR allocated by frwr_mr_init
57 void frwr_release_mr(struct rpcrdma_mr *mr)
61 rc = ib_dereg_mr(mr->frwr.fr_mr);
63 trace_xprtrdma_frwr_dereg(mr, rc);
68 static void frwr_mr_recycle(struct rpcrdma_mr *mr)
70 struct rpcrdma_xprt *r_xprt = mr->mr_xprt;
72 trace_xprtrdma_mr_recycle(mr);
74 if (mr->mr_dir != DMA_NONE) {
75 trace_xprtrdma_mr_unmap(mr);
76 ib_dma_unmap_sg(r_xprt->rx_ep->re_id->device,
77 mr->mr_sg, mr->mr_nents, mr->mr_dir);
78 mr->mr_dir = DMA_NONE;
81 spin_lock(&r_xprt->rx_buf.rb_lock);
82 list_del(&mr->mr_all);
83 r_xprt->rx_stats.mrs_recycled++;
84 spin_unlock(&r_xprt->rx_buf.rb_lock);
89 /* frwr_reset - Place MRs back on the free list
90 * @req: request to reset
92 * Used after a failed marshal. For FRWR, this means the MRs
93 * don't have to be fully released and recreated.
95 * NB: This is safe only as long as none of @req's MRs are
96 * involved with an ongoing asynchronous FAST_REG or LOCAL_INV
99 void frwr_reset(struct rpcrdma_req *req)
101 struct rpcrdma_mr *mr;
103 while ((mr = rpcrdma_mr_pop(&req->rl_registered)))
108 * frwr_mr_init - Initialize one MR
109 * @r_xprt: controlling transport instance
110 * @mr: generic MR to prepare for FRWR
112 * Returns zero if successful. Otherwise a negative errno
115 int frwr_mr_init(struct rpcrdma_xprt *r_xprt, struct rpcrdma_mr *mr)
117 struct rpcrdma_ep *ep = r_xprt->rx_ep;
118 unsigned int depth = ep->re_max_fr_depth;
119 struct scatterlist *sg;
123 frmr = ib_alloc_mr(ep->re_pd, ep->re_mrtype, depth);
127 sg = kmalloc_array(depth, sizeof(*sg), GFP_NOFS);
131 mr->mr_xprt = r_xprt;
132 mr->frwr.fr_mr = frmr;
133 mr->mr_dir = DMA_NONE;
134 INIT_LIST_HEAD(&mr->mr_list);
135 init_completion(&mr->frwr.fr_linv_done);
137 sg_init_table(sg, depth);
143 trace_xprtrdma_frwr_alloc(mr, rc);
152 * frwr_query_device - Prepare a transport for use with FRWR
153 * @ep: endpoint to fill in
154 * @device: RDMA device to query
158 * ep->re_max_requests
159 * ep->re_max_rdma_segs
160 * ep->re_max_fr_depth
164 * On success, returns zero.
165 * %-EINVAL - the device does not support FRWR memory registration
166 * %-ENOMEM - the device is not sufficiently capable for NFS/RDMA
168 int frwr_query_device(struct rpcrdma_ep *ep, const struct ib_device *device)
170 const struct ib_device_attr *attrs = &device->attrs;
171 int max_qp_wr, depth, delta;
172 unsigned int max_sge;
174 if (!(attrs->device_cap_flags & IB_DEVICE_MEM_MGT_EXTENSIONS) ||
175 attrs->max_fast_reg_page_list_len == 0) {
176 pr_err("rpcrdma: 'frwr' mode is not supported by device %s\n",
181 max_sge = min_t(unsigned int, attrs->max_send_sge,
182 RPCRDMA_MAX_SEND_SGES);
183 if (max_sge < RPCRDMA_MIN_SEND_SGES) {
184 pr_err("rpcrdma: HCA provides only %u send SGEs\n", max_sge);
187 ep->re_attr.cap.max_send_sge = max_sge;
188 ep->re_attr.cap.max_recv_sge = 1;
190 ep->re_mrtype = IB_MR_TYPE_MEM_REG;
191 if (attrs->device_cap_flags & IB_DEVICE_SG_GAPS_REG)
192 ep->re_mrtype = IB_MR_TYPE_SG_GAPS;
194 /* Quirk: Some devices advertise a large max_fast_reg_page_list_len
195 * capability, but perform optimally when the MRs are not larger
198 if (attrs->max_sge_rd > RPCRDMA_MAX_HDR_SEGS)
199 ep->re_max_fr_depth = attrs->max_sge_rd;
201 ep->re_max_fr_depth = attrs->max_fast_reg_page_list_len;
202 if (ep->re_max_fr_depth > RPCRDMA_MAX_DATA_SEGS)
203 ep->re_max_fr_depth = RPCRDMA_MAX_DATA_SEGS;
205 /* Add room for frwr register and invalidate WRs.
206 * 1. FRWR reg WR for head
207 * 2. FRWR invalidate WR for head
208 * 3. N FRWR reg WRs for pagelist
209 * 4. N FRWR invalidate WRs for pagelist
210 * 5. FRWR reg WR for tail
211 * 6. FRWR invalidate WR for tail
212 * 7. The RDMA_SEND WR
216 /* Calculate N if the device max FRWR depth is smaller than
217 * RPCRDMA_MAX_DATA_SEGS.
219 if (ep->re_max_fr_depth < RPCRDMA_MAX_DATA_SEGS) {
220 delta = RPCRDMA_MAX_DATA_SEGS - ep->re_max_fr_depth;
222 depth += 2; /* FRWR reg + invalidate */
223 delta -= ep->re_max_fr_depth;
227 max_qp_wr = attrs->max_qp_wr;
228 max_qp_wr -= RPCRDMA_BACKWARD_WRS;
230 if (max_qp_wr < RPCRDMA_MIN_SLOT_TABLE)
232 if (ep->re_max_requests > max_qp_wr)
233 ep->re_max_requests = max_qp_wr;
234 ep->re_attr.cap.max_send_wr = ep->re_max_requests * depth;
235 if (ep->re_attr.cap.max_send_wr > max_qp_wr) {
236 ep->re_max_requests = max_qp_wr / depth;
237 if (!ep->re_max_requests)
239 ep->re_attr.cap.max_send_wr = ep->re_max_requests * depth;
241 ep->re_attr.cap.max_send_wr += RPCRDMA_BACKWARD_WRS;
242 ep->re_attr.cap.max_send_wr += 1; /* for ib_drain_sq */
243 ep->re_attr.cap.max_recv_wr = ep->re_max_requests;
244 ep->re_attr.cap.max_recv_wr += RPCRDMA_BACKWARD_WRS;
245 ep->re_attr.cap.max_recv_wr += RPCRDMA_MAX_RECV_BATCH;
246 ep->re_attr.cap.max_recv_wr += 1; /* for ib_drain_rq */
248 ep->re_max_rdma_segs =
249 DIV_ROUND_UP(RPCRDMA_MAX_DATA_SEGS, ep->re_max_fr_depth);
250 /* Reply chunks require segments for head and tail buffers */
251 ep->re_max_rdma_segs += 2;
252 if (ep->re_max_rdma_segs > RPCRDMA_MAX_HDR_SEGS)
253 ep->re_max_rdma_segs = RPCRDMA_MAX_HDR_SEGS;
255 /* Ensure the underlying device is capable of conveying the
256 * largest r/wsize NFS will ask for. This guarantees that
257 * failing over from one RDMA device to another will not
260 if ((ep->re_max_rdma_segs * ep->re_max_fr_depth) < RPCRDMA_MAX_SEGS)
267 * frwr_map - Register a memory region
268 * @r_xprt: controlling transport
269 * @seg: memory region co-ordinates
270 * @nsegs: number of segments remaining
271 * @writing: true when RDMA Write will be used
272 * @xid: XID of RPC using the registered memory
275 * Prepare a REG_MR Work Request to register a memory region
276 * for remote access via RDMA READ or RDMA WRITE.
278 * Returns the next segment or a negative errno pointer.
279 * On success, @mr is filled in.
281 struct rpcrdma_mr_seg *frwr_map(struct rpcrdma_xprt *r_xprt,
282 struct rpcrdma_mr_seg *seg,
283 int nsegs, bool writing, __be32 xid,
284 struct rpcrdma_mr *mr)
286 struct rpcrdma_ep *ep = r_xprt->rx_ep;
287 struct ib_reg_wr *reg_wr;
292 if (nsegs > ep->re_max_fr_depth)
293 nsegs = ep->re_max_fr_depth;
294 for (i = 0; i < nsegs;) {
296 sg_set_page(&mr->mr_sg[i],
299 offset_in_page(seg->mr_offset));
301 sg_set_buf(&mr->mr_sg[i], seg->mr_offset,
306 if (ep->re_mrtype == IB_MR_TYPE_SG_GAPS)
308 if ((i < nsegs && offset_in_page(seg->mr_offset)) ||
309 offset_in_page((seg-1)->mr_offset + (seg-1)->mr_len))
312 mr->mr_dir = rpcrdma_data_dir(writing);
315 dma_nents = ib_dma_map_sg(ep->re_id->device, mr->mr_sg, mr->mr_nents,
320 ibmr = mr->frwr.fr_mr;
321 n = ib_map_mr_sg(ibmr, mr->mr_sg, dma_nents, NULL, PAGE_SIZE);
325 ibmr->iova &= 0x00000000ffffffff;
326 ibmr->iova |= ((u64)be32_to_cpu(xid)) << 32;
327 key = (u8)(ibmr->rkey & 0x000000FF);
328 ib_update_fast_reg_key(ibmr, ++key);
330 reg_wr = &mr->frwr.fr_regwr;
332 reg_wr->key = ibmr->rkey;
333 reg_wr->access = writing ?
334 IB_ACCESS_REMOTE_WRITE | IB_ACCESS_LOCAL_WRITE :
335 IB_ACCESS_REMOTE_READ;
337 mr->mr_handle = ibmr->rkey;
338 mr->mr_length = ibmr->length;
339 mr->mr_offset = ibmr->iova;
340 trace_xprtrdma_mr_map(mr);
345 mr->mr_dir = DMA_NONE;
346 trace_xprtrdma_frwr_sgerr(mr, i);
347 return ERR_PTR(-EIO);
350 trace_xprtrdma_frwr_maperr(mr, n);
351 return ERR_PTR(-EIO);
355 * frwr_wc_fastreg - Invoked by RDMA provider for a flushed FastReg WC
356 * @cq: completion queue
357 * @wc: WCE for a completed FastReg WR
360 static void frwr_wc_fastreg(struct ib_cq *cq, struct ib_wc *wc)
362 struct ib_cqe *cqe = wc->wr_cqe;
363 struct rpcrdma_frwr *frwr =
364 container_of(cqe, struct rpcrdma_frwr, fr_cqe);
366 /* WARNING: Only wr_cqe and status are reliable at this point */
367 trace_xprtrdma_wc_fastreg(wc, frwr);
368 /* The MR will get recycled when the associated req is retransmitted */
370 rpcrdma_flush_disconnect(cq->cq_context, wc);
374 * frwr_send - post Send WRs containing the RPC Call message
375 * @r_xprt: controlling transport instance
376 * @req: prepared RPC Call
378 * For FRWR, chain any FastReg WRs to the Send WR. Only a
379 * single ib_post_send call is needed to register memory
380 * and then post the Send WR.
382 * Returns the return code from ib_post_send.
384 * Caller must hold the transport send lock to ensure that the
385 * pointers to the transport's rdma_cm_id and QP are stable.
387 int frwr_send(struct rpcrdma_xprt *r_xprt, struct rpcrdma_req *req)
389 struct ib_send_wr *post_wr;
390 struct rpcrdma_mr *mr;
392 post_wr = &req->rl_wr;
393 list_for_each_entry(mr, &req->rl_registered, mr_list) {
394 struct rpcrdma_frwr *frwr;
398 frwr->fr_cqe.done = frwr_wc_fastreg;
399 frwr->fr_regwr.wr.next = post_wr;
400 frwr->fr_regwr.wr.wr_cqe = &frwr->fr_cqe;
401 frwr->fr_regwr.wr.num_sge = 0;
402 frwr->fr_regwr.wr.opcode = IB_WR_REG_MR;
403 frwr->fr_regwr.wr.send_flags = 0;
405 post_wr = &frwr->fr_regwr.wr;
408 return ib_post_send(r_xprt->rx_ep->re_id->qp, post_wr, NULL);
412 * frwr_reminv - handle a remotely invalidated mr on the @mrs list
413 * @rep: Received reply
414 * @mrs: list of MRs to check
417 void frwr_reminv(struct rpcrdma_rep *rep, struct list_head *mrs)
419 struct rpcrdma_mr *mr;
421 list_for_each_entry(mr, mrs, mr_list)
422 if (mr->mr_handle == rep->rr_inv_rkey) {
423 list_del_init(&mr->mr_list);
424 trace_xprtrdma_mr_reminv(mr);
426 break; /* only one invalidated MR per RPC */
430 static void __frwr_release_mr(struct ib_wc *wc, struct rpcrdma_mr *mr)
432 if (wc->status != IB_WC_SUCCESS)
439 * frwr_wc_localinv - Invoked by RDMA provider for a LOCAL_INV WC
440 * @cq: completion queue
441 * @wc: WCE for a completed LocalInv WR
444 static void frwr_wc_localinv(struct ib_cq *cq, struct ib_wc *wc)
446 struct ib_cqe *cqe = wc->wr_cqe;
447 struct rpcrdma_frwr *frwr =
448 container_of(cqe, struct rpcrdma_frwr, fr_cqe);
449 struct rpcrdma_mr *mr = container_of(frwr, struct rpcrdma_mr, frwr);
451 /* WARNING: Only wr_cqe and status are reliable at this point */
452 trace_xprtrdma_wc_li(wc, frwr);
453 __frwr_release_mr(wc, mr);
455 rpcrdma_flush_disconnect(cq->cq_context, wc);
459 * frwr_wc_localinv_wake - Invoked by RDMA provider for a LOCAL_INV WC
460 * @cq: completion queue
461 * @wc: WCE for a completed LocalInv WR
463 * Awaken anyone waiting for an MR to finish being fenced.
465 static void frwr_wc_localinv_wake(struct ib_cq *cq, struct ib_wc *wc)
467 struct ib_cqe *cqe = wc->wr_cqe;
468 struct rpcrdma_frwr *frwr =
469 container_of(cqe, struct rpcrdma_frwr, fr_cqe);
470 struct rpcrdma_mr *mr = container_of(frwr, struct rpcrdma_mr, frwr);
472 /* WARNING: Only wr_cqe and status are reliable at this point */
473 trace_xprtrdma_wc_li_wake(wc, frwr);
474 __frwr_release_mr(wc, mr);
475 complete(&frwr->fr_linv_done);
477 rpcrdma_flush_disconnect(cq->cq_context, wc);
481 * frwr_unmap_sync - invalidate memory regions that were registered for @req
482 * @r_xprt: controlling transport instance
483 * @req: rpcrdma_req with a non-empty list of MRs to process
485 * Sleeps until it is safe for the host CPU to access the previously mapped
486 * memory regions. This guarantees that registered MRs are properly fenced
487 * from the server before the RPC consumer accesses the data in them. It
488 * also ensures proper Send flow control: waking the next RPC waits until
489 * this RPC has relinquished all its Send Queue entries.
491 void frwr_unmap_sync(struct rpcrdma_xprt *r_xprt, struct rpcrdma_req *req)
493 struct ib_send_wr *first, **prev, *last;
494 const struct ib_send_wr *bad_wr;
495 struct rpcrdma_frwr *frwr;
496 struct rpcrdma_mr *mr;
499 /* ORDER: Invalidate all of the MRs first
501 * Chain the LOCAL_INV Work Requests and post them with
502 * a single ib_post_send() call.
506 while ((mr = rpcrdma_mr_pop(&req->rl_registered))) {
508 trace_xprtrdma_mr_localinv(mr);
509 r_xprt->rx_stats.local_inv_needed++;
512 frwr->fr_cqe.done = frwr_wc_localinv;
513 last = &frwr->fr_invwr;
515 last->wr_cqe = &frwr->fr_cqe;
516 last->sg_list = NULL;
518 last->opcode = IB_WR_LOCAL_INV;
519 last->send_flags = IB_SEND_SIGNALED;
520 last->ex.invalidate_rkey = mr->mr_handle;
526 /* Strong send queue ordering guarantees that when the
527 * last WR in the chain completes, all WRs in the chain
530 frwr->fr_cqe.done = frwr_wc_localinv_wake;
531 reinit_completion(&frwr->fr_linv_done);
533 /* Transport disconnect drains the receive CQ before it
534 * replaces the QP. The RPC reply handler won't call us
535 * unless re_id->qp is a valid pointer.
538 rc = ib_post_send(r_xprt->rx_ep->re_id->qp, first, &bad_wr);
540 /* The final LOCAL_INV WR in the chain is supposed to
541 * do the wake. If it was never posted, the wake will
542 * not happen, so don't wait in that case.
545 wait_for_completion(&frwr->fr_linv_done);
549 /* Recycle MRs in the LOCAL_INV chain that did not get posted.
551 trace_xprtrdma_post_linv(req, rc);
553 frwr = container_of(bad_wr, struct rpcrdma_frwr,
555 mr = container_of(frwr, struct rpcrdma_mr, frwr);
556 bad_wr = bad_wr->next;
563 * frwr_wc_localinv_done - Invoked by RDMA provider for a signaled LOCAL_INV WC
564 * @cq: completion queue
565 * @wc: WCE for a completed LocalInv WR
568 static void frwr_wc_localinv_done(struct ib_cq *cq, struct ib_wc *wc)
570 struct ib_cqe *cqe = wc->wr_cqe;
571 struct rpcrdma_frwr *frwr =
572 container_of(cqe, struct rpcrdma_frwr, fr_cqe);
573 struct rpcrdma_mr *mr = container_of(frwr, struct rpcrdma_mr, frwr);
574 struct rpcrdma_rep *rep = mr->mr_req->rl_reply;
576 /* WARNING: Only wr_cqe and status are reliable at this point */
577 trace_xprtrdma_wc_li_done(wc, frwr);
578 __frwr_release_mr(wc, mr);
580 /* Ensure @rep is generated before __frwr_release_mr */
582 rpcrdma_complete_rqst(rep);
584 rpcrdma_flush_disconnect(cq->cq_context, wc);
588 * frwr_unmap_async - invalidate memory regions that were registered for @req
589 * @r_xprt: controlling transport instance
590 * @req: rpcrdma_req with a non-empty list of MRs to process
592 * This guarantees that registered MRs are properly fenced from the
593 * server before the RPC consumer accesses the data in them. It also
594 * ensures proper Send flow control: waking the next RPC waits until
595 * this RPC has relinquished all its Send Queue entries.
597 void frwr_unmap_async(struct rpcrdma_xprt *r_xprt, struct rpcrdma_req *req)
599 struct ib_send_wr *first, *last, **prev;
600 const struct ib_send_wr *bad_wr;
601 struct rpcrdma_frwr *frwr;
602 struct rpcrdma_mr *mr;
605 /* Chain the LOCAL_INV Work Requests and post them with
606 * a single ib_post_send() call.
610 while ((mr = rpcrdma_mr_pop(&req->rl_registered))) {
612 trace_xprtrdma_mr_localinv(mr);
613 r_xprt->rx_stats.local_inv_needed++;
616 frwr->fr_cqe.done = frwr_wc_localinv;
617 last = &frwr->fr_invwr;
619 last->wr_cqe = &frwr->fr_cqe;
620 last->sg_list = NULL;
622 last->opcode = IB_WR_LOCAL_INV;
623 last->send_flags = IB_SEND_SIGNALED;
624 last->ex.invalidate_rkey = mr->mr_handle;
630 /* Strong send queue ordering guarantees that when the
631 * last WR in the chain completes, all WRs in the chain
632 * are complete. The last completion will wake up the
635 frwr->fr_cqe.done = frwr_wc_localinv_done;
637 /* Transport disconnect drains the receive CQ before it
638 * replaces the QP. The RPC reply handler won't call us
639 * unless re_id->qp is a valid pointer.
642 rc = ib_post_send(r_xprt->rx_ep->re_id->qp, first, &bad_wr);
646 /* Recycle MRs in the LOCAL_INV chain that did not get posted.
648 trace_xprtrdma_post_linv(req, rc);
650 frwr = container_of(bad_wr, struct rpcrdma_frwr, fr_invwr);
651 mr = container_of(frwr, struct rpcrdma_mr, frwr);
652 bad_wr = bad_wr->next;
657 /* The final LOCAL_INV WR in the chain is supposed to
658 * do the wake. If it was never posted, the wake will
659 * not happen, so wake here in that case.
661 rpcrdma_complete_rqst(req->rl_reply);