2 * Copyright (c) 2015 Oracle. All rights reserved.
3 * Copyright (c) 2003-2007 Network Appliance, Inc. All rights reserved.
6 /* Lightweight memory registration using Fast Memory Regions (FMR).
7 * Referred to sometimes as MTHCAFMR mode.
9 * FMR uses synchronous memory registration and deregistration.
10 * FMR registration is known to be fast, but FMR deregistration
11 * can take tens of usecs to complete.
16 * A Memory Region is prepared for RDMA READ or WRITE using the
17 * ib_map_phys_fmr verb (fmr_op_map). When the RDMA operation is
18 * finished, the Memory Region is unmapped using the ib_unmap_fmr
19 * verb (fmr_op_unmap).
24 * After a transport reconnect, fmr_op_map re-uses the MR already
25 * allocated for the RPC, but generates a fresh rkey then maps the
26 * MR again. This process is synchronous.
29 #include "xprt_rdma.h"
31 #if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
32 # define RPCDBG_FACILITY RPCDBG_TRANS
35 /* Maximum scatter/gather per FMR */
36 #define RPCRDMA_MAX_FMR_SGES (64)
39 fmr_op_open(struct rpcrdma_ia *ia, struct rpcrdma_ep *ep,
40 struct rpcrdma_create_data_internal *cdata)
45 /* FMR mode conveys up to 64 pages of payload per chunk segment.
48 fmr_op_maxpages(struct rpcrdma_xprt *r_xprt)
50 return min_t(unsigned int, RPCRDMA_MAX_DATA_SEGS,
51 rpcrdma_max_segments(r_xprt) * RPCRDMA_MAX_FMR_SGES);
55 fmr_op_init(struct rpcrdma_xprt *r_xprt)
57 struct rpcrdma_buffer *buf = &r_xprt->rx_buf;
58 int mr_access_flags = IB_ACCESS_REMOTE_WRITE | IB_ACCESS_REMOTE_READ;
59 struct ib_fmr_attr fmr_attr = {
60 .max_pages = RPCRDMA_MAX_FMR_SGES,
62 .page_shift = PAGE_SHIFT
64 struct ib_pd *pd = r_xprt->rx_ia.ri_pd;
68 spin_lock_init(&buf->rb_mwlock);
69 INIT_LIST_HEAD(&buf->rb_mws);
70 INIT_LIST_HEAD(&buf->rb_all);
72 i = max_t(int, RPCRDMA_MAX_DATA_SEGS / RPCRDMA_MAX_FMR_SGES, 1);
73 i += 2; /* head + tail */
74 i *= buf->rb_max_requests; /* one set for each RPC slot */
75 dprintk("RPC: %s: initalizing %d FMRs\n", __func__, i);
79 r = kzalloc(sizeof(*r), GFP_KERNEL);
83 r->r.fmr.physaddrs = kmalloc(RPCRDMA_MAX_FMR_SGES *
84 sizeof(u64), GFP_KERNEL);
85 if (!r->r.fmr.physaddrs)
88 r->r.fmr.fmr = ib_alloc_fmr(pd, mr_access_flags, &fmr_attr);
89 if (IS_ERR(r->r.fmr.fmr))
92 list_add(&r->mw_list, &buf->rb_mws);
93 list_add(&r->mw_all, &buf->rb_all);
98 rc = PTR_ERR(r->r.fmr.fmr);
99 dprintk("RPC: %s: ib_alloc_fmr status %i\n", __func__, rc);
100 kfree(r->r.fmr.physaddrs);
108 __fmr_unmap(struct rpcrdma_mw *r)
112 list_add(&r->r.fmr.fmr->list, &l);
113 return ib_unmap_fmr(&l);
116 /* Use the ib_map_phys_fmr() verb to register a memory region
117 * for remote access via RDMA READ or RDMA WRITE.
120 fmr_op_map(struct rpcrdma_xprt *r_xprt, struct rpcrdma_mr_seg *seg,
121 int nsegs, bool writing)
123 struct rpcrdma_ia *ia = &r_xprt->rx_ia;
124 struct ib_device *device = ia->ri_device;
125 enum dma_data_direction direction = rpcrdma_data_dir(writing);
126 struct rpcrdma_mr_seg *seg1 = seg;
127 int len, pageoff, i, rc;
128 struct rpcrdma_mw *mw;
133 mw = rpcrdma_get_mw(r_xprt);
137 /* this is a retransmit; generate a fresh rkey */
138 rc = __fmr_unmap(mw);
143 pageoff = offset_in_page(seg1->mr_offset);
144 seg1->mr_offset -= pageoff; /* start of page */
145 seg1->mr_len += pageoff;
147 if (nsegs > RPCRDMA_MAX_FMR_SGES)
148 nsegs = RPCRDMA_MAX_FMR_SGES;
149 for (i = 0; i < nsegs;) {
150 rpcrdma_map_one(device, seg, direction);
151 mw->r.fmr.physaddrs[i] = seg->mr_dma;
155 /* Check for holes */
156 if ((i < nsegs && offset_in_page(seg->mr_offset)) ||
157 offset_in_page((seg-1)->mr_offset + (seg-1)->mr_len))
161 rc = ib_map_phys_fmr(mw->r.fmr.fmr, mw->r.fmr.physaddrs,
167 seg1->mr_rkey = mw->r.fmr.fmr->rkey;
168 seg1->mr_base = seg1->mr_dma + pageoff;
174 dprintk("RPC: %s: ib_map_phys_fmr %u@0x%llx+%i (%d) status %i\n",
175 __func__, len, (unsigned long long)seg1->mr_dma,
178 rpcrdma_unmap_one(device, --seg);
183 __fmr_dma_unmap(struct rpcrdma_xprt *r_xprt, struct rpcrdma_mr_seg *seg)
185 struct ib_device *device = r_xprt->rx_ia.ri_device;
186 struct rpcrdma_mw *mw = seg->rl_mw;
187 int nsegs = seg->mr_nsegs;
192 rpcrdma_unmap_one(device, seg++);
194 rpcrdma_put_mw(r_xprt, mw);
197 /* Invalidate all memory regions that were registered for "req".
199 * Sleeps until it is safe for the host CPU to access the
200 * previously mapped memory regions.
203 fmr_op_unmap_sync(struct rpcrdma_xprt *r_xprt, struct rpcrdma_req *req)
205 struct rpcrdma_mr_seg *seg;
206 unsigned int i, nchunks;
207 struct rpcrdma_mw *mw;
208 LIST_HEAD(unmap_list);
211 dprintk("RPC: %s: req %p\n", __func__, req);
213 /* ORDER: Invalidate all of the req's MRs first
215 * ib_unmap_fmr() is slow, so use a single call instead
216 * of one call per mapped MR.
218 for (i = 0, nchunks = req->rl_nchunks; nchunks; nchunks--) {
219 seg = &req->rl_segments[i];
222 list_add(&mw->r.fmr.fmr->list, &unmap_list);
226 rc = ib_unmap_fmr(&unmap_list);
228 pr_warn("%s: ib_unmap_fmr failed (%i)\n", __func__, rc);
230 /* ORDER: Now DMA unmap all of the req's MRs, and return
231 * them to the free MW list.
233 for (i = 0, nchunks = req->rl_nchunks; nchunks; nchunks--) {
234 seg = &req->rl_segments[i];
236 __fmr_dma_unmap(r_xprt, seg);
245 /* Use the ib_unmap_fmr() verb to prevent further remote
246 * access via RDMA READ or RDMA WRITE.
249 fmr_op_unmap(struct rpcrdma_xprt *r_xprt, struct rpcrdma_mr_seg *seg)
251 struct rpcrdma_ia *ia = &r_xprt->rx_ia;
252 struct rpcrdma_mr_seg *seg1 = seg;
253 struct rpcrdma_mw *mw = seg1->rl_mw;
254 int rc, nsegs = seg->mr_nsegs;
256 dprintk("RPC: %s: FMR %p\n", __func__, mw);
259 while (seg1->mr_nsegs--)
260 rpcrdma_unmap_one(ia->ri_device, seg++);
261 rc = __fmr_unmap(mw);
264 rpcrdma_put_mw(r_xprt, mw);
268 /* The FMR is abandoned, but remains in rb_all. fmr_op_destroy
269 * will attempt to release it when the transport is destroyed.
271 dprintk("RPC: %s: ib_unmap_fmr status %i\n", __func__, rc);
276 fmr_op_destroy(struct rpcrdma_buffer *buf)
278 struct rpcrdma_mw *r;
281 while (!list_empty(&buf->rb_all)) {
282 r = list_entry(buf->rb_all.next, struct rpcrdma_mw, mw_all);
283 list_del(&r->mw_all);
284 kfree(r->r.fmr.physaddrs);
286 rc = ib_dealloc_fmr(r->r.fmr.fmr);
288 dprintk("RPC: %s: ib_dealloc_fmr failed %i\n",
295 const struct rpcrdma_memreg_ops rpcrdma_fmr_memreg_ops = {
296 .ro_map = fmr_op_map,
297 .ro_unmap_sync = fmr_op_unmap_sync,
298 .ro_unmap = fmr_op_unmap,
299 .ro_open = fmr_op_open,
300 .ro_maxpages = fmr_op_maxpages,
301 .ro_init = fmr_op_init,
302 .ro_destroy = fmr_op_destroy,
303 .ro_displayname = "fmr",