net/sunrpc/xprtrdma/fmr_ops.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (c) 2015, 2017 Oracle.  All rights reserved.
   4  * Copyright (c) 2003-2007 Network Appliance, Inc. All rights reserved.
   5  */
   6
   7 /* Lightweight memory registration using Fast Memory Regions (FMR).
   8  * Referred to sometimes as MTHCAFMR mode.
   9  *
  10  * FMR uses synchronous memory registration and deregistration.
  11  * FMR registration is known to be fast, but FMR deregistration
  12  * can take tens of usecs to complete.
  13  */
  14
  15 /* Normal operation
  16  *
  17  * A Memory Region is prepared for RDMA READ or WRITE using the
  18  * ib_map_phys_fmr verb (fmr_op_map). When the RDMA operation is
  19  * finished, the Memory Region is unmapped using the ib_unmap_fmr
  20  * verb (fmr_op_unmap).
  21  */
  22
  23 #include <linux/sunrpc/svc_rdma.h>
  24
  25 #include "xprt_rdma.h"
  26 #include <trace/events/rpcrdma.h>
  27
  28 #if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
  29 # define RPCDBG_FACILITY        RPCDBG_TRANS
  30 #endif
  31
  32 /* Maximum scatter/gather per FMR */
  33 #define RPCRDMA_MAX_FMR_SGES    (64)
  34
  35 /* Access mode of externally registered pages */
  36 enum {
  37         RPCRDMA_FMR_ACCESS_FLAGS        = IB_ACCESS_REMOTE_WRITE |
  38                                           IB_ACCESS_REMOTE_READ,
  39 };
  40
  41 bool
  42 fmr_is_supported(struct rpcrdma_ia *ia)
  43 {
  44         if (!ia->ri_device->alloc_fmr) {
  45                 pr_info("rpcrdma: 'fmr' mode is not supported by device %s\n",
  46                         ia->ri_device->name);
  47                 return false;
  48         }
  49         return true;
  50 }
  51
  52 static void
  53 __fmr_unmap(struct rpcrdma_mr *mr)
  54 {
  55         LIST_HEAD(l);
  56         int rc;
  57
  58         list_add(&mr->fmr.fm_mr->list, &l);
  59         rc = ib_unmap_fmr(&l);
  60         list_del(&mr->fmr.fm_mr->list);
  61         if (rc)
  62                 pr_err("rpcrdma: final ib_unmap_fmr for %p failed %i\n",
  63                        mr, rc);
  64 }
  65
  66 /* Release an MR.
  67  */
  68 static void
  69 fmr_op_release_mr(struct rpcrdma_mr *mr)
  70 {
  71         int rc;
  72
  73         kfree(mr->fmr.fm_physaddrs);
  74         kfree(mr->mr_sg);
  75
  76         /* In case this one was left mapped, try to unmap it
  77          * to prevent dealloc_fmr from failing with EBUSY
  78          */
  79         __fmr_unmap(mr);
  80
  81         rc = ib_dealloc_fmr(mr->fmr.fm_mr);
  82         if (rc)
  83                 pr_err("rpcrdma: final ib_dealloc_fmr for %p returned %i\n",
  84                        mr, rc);
  85
  86         kfree(mr);
  87 }
  88
  89 /* MRs are dynamically allocated, so simply clean up and release the MR.
  90  * A replacement MR will subsequently be allocated on demand.
  91  */
  92 static void
  93 fmr_mr_recycle_worker(struct work_struct *work)
  94 {
  95         struct rpcrdma_mr *mr = container_of(work, struct rpcrdma_mr, mr_recycle);
  96         struct rpcrdma_xprt *r_xprt = mr->mr_xprt;
  97
  98         trace_xprtrdma_mr_recycle(mr);
  99
 100         trace_xprtrdma_mr_unmap(mr);
 101         ib_dma_unmap_sg(r_xprt->rx_ia.ri_device,
 102                         mr->mr_sg, mr->mr_nents, mr->mr_dir);
 103
 104         spin_lock(&r_xprt->rx_buf.rb_mrlock);
 105         list_del(&mr->mr_all);
 106         r_xprt->rx_stats.mrs_recycled++;
 107         spin_unlock(&r_xprt->rx_buf.rb_mrlock);
 108         fmr_op_release_mr(mr);
 109 }
 110
 111 static int
 112 fmr_op_init_mr(struct rpcrdma_ia *ia, struct rpcrdma_mr *mr)
 113 {
 114         static struct ib_fmr_attr fmr_attr = {
 115                 .max_pages      = RPCRDMA_MAX_FMR_SGES,
 116                 .max_maps       = 1,
 117                 .page_shift     = PAGE_SHIFT
 118         };
 119
 120         mr->fmr.fm_physaddrs = kcalloc(RPCRDMA_MAX_FMR_SGES,
 121                                        sizeof(u64), GFP_KERNEL);
 122         if (!mr->fmr.fm_physaddrs)
 123                 goto out_free;
 124
 125         mr->mr_sg = kcalloc(RPCRDMA_MAX_FMR_SGES,
 126                             sizeof(*mr->mr_sg), GFP_KERNEL);
 127         if (!mr->mr_sg)
 128                 goto out_free;
 129
 130         sg_init_table(mr->mr_sg, RPCRDMA_MAX_FMR_SGES);
 131
 132         mr->fmr.fm_mr = ib_alloc_fmr(ia->ri_pd, RPCRDMA_FMR_ACCESS_FLAGS,
 133                                      &fmr_attr);
 134         if (IS_ERR(mr->fmr.fm_mr))
 135                 goto out_fmr_err;
 136
 137         INIT_LIST_HEAD(&mr->mr_list);
 138         INIT_WORK(&mr->mr_recycle, fmr_mr_recycle_worker);
 139         return 0;
 140
 141 out_fmr_err:
 142         dprintk("RPC:       %s: ib_alloc_fmr returned %ld\n", __func__,
 143                 PTR_ERR(mr->fmr.fm_mr));
 144
 145 out_free:
 146         kfree(mr->mr_sg);
 147         kfree(mr->fmr.fm_physaddrs);
 148         return -ENOMEM;
 149 }
 150
 151 /* On success, sets:
 152  *      ep->rep_attr.cap.max_send_wr
 153  *      ep->rep_attr.cap.max_recv_wr
 154  *      cdata->max_requests
 155  *      ia->ri_max_segs
 156  */
 157 static int
 158 fmr_op_open(struct rpcrdma_ia *ia, struct rpcrdma_ep *ep,
 159             struct rpcrdma_create_data_internal *cdata)
 160 {
 161         int max_qp_wr;
 162
 163         max_qp_wr = ia->ri_device->attrs.max_qp_wr;
 164         max_qp_wr -= RPCRDMA_BACKWARD_WRS;
 165         max_qp_wr -= 1;
 166         if (max_qp_wr < RPCRDMA_MIN_SLOT_TABLE)
 167                 return -ENOMEM;
 168         if (cdata->max_requests > max_qp_wr)
 169                 cdata->max_requests = max_qp_wr;
 170         ep->rep_attr.cap.max_send_wr = cdata->max_requests;
 171         ep->rep_attr.cap.max_send_wr += RPCRDMA_BACKWARD_WRS;
 172         ep->rep_attr.cap.max_send_wr += 1; /* for ib_drain_sq */
 173         ep->rep_attr.cap.max_recv_wr = cdata->max_requests;
 174         ep->rep_attr.cap.max_recv_wr += RPCRDMA_BACKWARD_WRS;
 175         ep->rep_attr.cap.max_recv_wr += 1; /* for ib_drain_rq */
 176
 177         ia->ri_max_segs = max_t(unsigned int, 1, RPCRDMA_MAX_DATA_SEGS /
 178                                 RPCRDMA_MAX_FMR_SGES);
 179         ia->ri_max_segs += 2;   /* segments for head and tail buffers */
 180         return 0;
 181 }
 182
 183 /* FMR mode conveys up to 64 pages of payload per chunk segment.
 184  */
 185 static size_t
 186 fmr_op_maxpages(struct rpcrdma_xprt *r_xprt)
 187 {
 188         return min_t(unsigned int, RPCRDMA_MAX_DATA_SEGS,
 189                      RPCRDMA_MAX_HDR_SEGS * RPCRDMA_MAX_FMR_SGES);
 190 }
 191
 192 /* Use the ib_map_phys_fmr() verb to register a memory region
 193  * for remote access via RDMA READ or RDMA WRITE.
 194  */
 195 static struct rpcrdma_mr_seg *
 196 fmr_op_map(struct rpcrdma_xprt *r_xprt, struct rpcrdma_mr_seg *seg,
 197            int nsegs, bool writing, struct rpcrdma_mr **out)
 198 {
 199         struct rpcrdma_mr_seg *seg1 = seg;
 200         int len, pageoff, i, rc;
 201         struct rpcrdma_mr *mr;
 202         u64 *dma_pages;
 203
 204         mr = rpcrdma_mr_get(r_xprt);
 205         if (!mr)
 206                 return ERR_PTR(-EAGAIN);
 207
 208         pageoff = offset_in_page(seg1->mr_offset);
 209         seg1->mr_offset -= pageoff;     /* start of page */
 210         seg1->mr_len += pageoff;
 211         len = -pageoff;
 212         if (nsegs > RPCRDMA_MAX_FMR_SGES)
 213                 nsegs = RPCRDMA_MAX_FMR_SGES;
 214         for (i = 0; i < nsegs;) {
 215                 if (seg->mr_page)
 216                         sg_set_page(&mr->mr_sg[i],
 217                                     seg->mr_page,
 218                                     seg->mr_len,
 219                                     offset_in_page(seg->mr_offset));
 220                 else
 221                         sg_set_buf(&mr->mr_sg[i], seg->mr_offset,
 222                                    seg->mr_len);
 223                 len += seg->mr_len;
 224                 ++seg;
 225                 ++i;
 226                 /* Check for holes */
 227                 if ((i < nsegs && offset_in_page(seg->mr_offset)) ||
 228                     offset_in_page((seg-1)->mr_offset + (seg-1)->mr_len))
 229                         break;
 230         }
 231         mr->mr_dir = rpcrdma_data_dir(writing);
 232
 233         mr->mr_nents = ib_dma_map_sg(r_xprt->rx_ia.ri_device,
 234                                      mr->mr_sg, i, mr->mr_dir);
 235         if (!mr->mr_nents)
 236                 goto out_dmamap_err;
 237         trace_xprtrdma_mr_map(mr);
 238
 239         for (i = 0, dma_pages = mr->fmr.fm_physaddrs; i < mr->mr_nents; i++)
 240                 dma_pages[i] = sg_dma_address(&mr->mr_sg[i]);
 241         rc = ib_map_phys_fmr(mr->fmr.fm_mr, dma_pages, mr->mr_nents,
 242                              dma_pages[0]);
 243         if (rc)
 244                 goto out_maperr;
 245
 246         mr->mr_handle = mr->fmr.fm_mr->rkey;
 247         mr->mr_length = len;
 248         mr->mr_offset = dma_pages[0] + pageoff;
 249
 250         *out = mr;
 251         return seg;
 252
 253 out_dmamap_err:
 254         pr_err("rpcrdma: failed to DMA map sg %p sg_nents %d\n",
 255                mr->mr_sg, i);
 256         rpcrdma_mr_put(mr);
 257         return ERR_PTR(-EIO);
 258
 259 out_maperr:
 260         pr_err("rpcrdma: ib_map_phys_fmr %u@0x%llx+%i (%d) status %i\n",
 261                len, (unsigned long long)dma_pages[0],
 262                pageoff, mr->mr_nents, rc);
 263         rpcrdma_mr_unmap_and_put(mr);
 264         return ERR_PTR(-EIO);
 265 }
 266
 267 /* Post Send WR containing the RPC Call message.
 268  */
 269 static int
 270 fmr_op_send(struct rpcrdma_ia *ia, struct rpcrdma_req *req)
 271 {
 272         return ib_post_send(ia->ri_id->qp, &req->rl_sendctx->sc_wr, NULL);
 273 }
 274
 275 /* Invalidate all memory regions that were registered for "req".
 276  *
 277  * Sleeps until it is safe for the host CPU to access the
 278  * previously mapped memory regions.
 279  *
 280  * Caller ensures that @mrs is not empty before the call. This
 281  * function empties the list.
 282  */
 283 static void
 284 fmr_op_unmap_sync(struct rpcrdma_xprt *r_xprt, struct list_head *mrs)
 285 {
 286         struct rpcrdma_mr *mr;
 287         LIST_HEAD(unmap_list);
 288         int rc;
 289
 290         /* ORDER: Invalidate all of the req's MRs first
 291          *
 292          * ib_unmap_fmr() is slow, so use a single call instead
 293          * of one call per mapped FMR.
 294          */
 295         list_for_each_entry(mr, mrs, mr_list) {
 296                 dprintk("RPC:       %s: unmapping fmr %p\n",
 297                         __func__, &mr->fmr);
 298                 trace_xprtrdma_mr_localinv(mr);
 299                 list_add_tail(&mr->fmr.fm_mr->list, &unmap_list);
 300         }
 301         r_xprt->rx_stats.local_inv_needed++;
 302         rc = ib_unmap_fmr(&unmap_list);
 303         if (rc)
 304                 goto out_release;
 305
 306         /* ORDER: Now DMA unmap all of the req's MRs, and return
 307          * them to the free MW list.
 308          */
 309         while (!list_empty(mrs)) {
 310                 mr = rpcrdma_mr_pop(mrs);
 311                 list_del(&mr->fmr.fm_mr->list);
 312                 rpcrdma_mr_unmap_and_put(mr);
 313         }
 314
 315         return;
 316
 317 out_release:
 318         pr_err("rpcrdma: ib_unmap_fmr failed (%i)\n", rc);
 319
 320         while (!list_empty(mrs)) {
 321                 mr = rpcrdma_mr_pop(mrs);
 322                 list_del(&mr->fmr.fm_mr->list);
 323                 rpcrdma_mr_recycle(mr);
 324         }
 325 }
 326
 327 const struct rpcrdma_memreg_ops rpcrdma_fmr_memreg_ops = {
 328         .ro_map                         = fmr_op_map,
 329         .ro_send                        = fmr_op_send,
 330         .ro_unmap_sync                  = fmr_op_unmap_sync,
 331         .ro_open                        = fmr_op_open,
 332         .ro_maxpages                    = fmr_op_maxpages,
 333         .ro_init_mr                     = fmr_op_init_mr,
 334         .ro_release_mr                  = fmr_op_release_mr,
 335         .ro_displayname                 = "fmr",
 336         .ro_send_w_inv_ok               = 0,
 337 };