net/sunrpc/xprtrdma/fmr_ops.c

   1 /*
   2  * Copyright (c) 2015 Oracle.  All rights reserved.
   3  * Copyright (c) 2003-2007 Network Appliance, Inc. All rights reserved.
   4  */
   5
   6 /* Lightweight memory registration using Fast Memory Regions (FMR).
   7  * Referred to sometimes as MTHCAFMR mode.
   8  *
   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.
  12  */
  13
  14 /* Normal operation
  15  *
  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).
  20  */
  21
  22 #include "xprt_rdma.h"
  23
  24 #if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
  25 # define RPCDBG_FACILITY        RPCDBG_TRANS
  26 #endif
  27
  28 /* Maximum scatter/gather per FMR */
  29 #define RPCRDMA_MAX_FMR_SGES    (64)
  30
  31 /* Access mode of externally registered pages */
  32 enum {
  33         RPCRDMA_FMR_ACCESS_FLAGS        = IB_ACCESS_REMOTE_WRITE |
  34                                           IB_ACCESS_REMOTE_READ,
  35 };
  36
  37 bool
  38 fmr_is_supported(struct rpcrdma_ia *ia)
  39 {
  40         if (!ia->ri_device->alloc_fmr) {
  41                 pr_info("rpcrdma: 'fmr' mode is not supported by device %s\n",
  42                         ia->ri_device->name);
  43                 return false;
  44         }
  45         return true;
  46 }
  47
  48 static int
  49 fmr_op_init_mr(struct rpcrdma_ia *ia, struct rpcrdma_mw *mw)
  50 {
  51         static struct ib_fmr_attr fmr_attr = {
  52                 .max_pages      = RPCRDMA_MAX_FMR_SGES,
  53                 .max_maps       = 1,
  54                 .page_shift     = PAGE_SHIFT
  55         };
  56
  57         mw->fmr.fm_physaddrs = kcalloc(RPCRDMA_MAX_FMR_SGES,
  58                                        sizeof(u64), GFP_KERNEL);
  59         if (!mw->fmr.fm_physaddrs)
  60                 goto out_free;
  61
  62         mw->mw_sg = kcalloc(RPCRDMA_MAX_FMR_SGES,
  63                             sizeof(*mw->mw_sg), GFP_KERNEL);
  64         if (!mw->mw_sg)
  65                 goto out_free;
  66
  67         sg_init_table(mw->mw_sg, RPCRDMA_MAX_FMR_SGES);
  68
  69         mw->fmr.fm_mr = ib_alloc_fmr(ia->ri_pd, RPCRDMA_FMR_ACCESS_FLAGS,
  70                                      &fmr_attr);
  71         if (IS_ERR(mw->fmr.fm_mr))
  72                 goto out_fmr_err;
  73
  74         return 0;
  75
  76 out_fmr_err:
  77         dprintk("RPC:       %s: ib_alloc_fmr returned %ld\n", __func__,
  78                 PTR_ERR(mw->fmr.fm_mr));
  79
  80 out_free:
  81         kfree(mw->mw_sg);
  82         kfree(mw->fmr.fm_physaddrs);
  83         return -ENOMEM;
  84 }
  85
  86 static int
  87 __fmr_unmap(struct rpcrdma_mw *mw)
  88 {
  89         LIST_HEAD(l);
  90         int rc;
  91
  92         list_add(&mw->fmr.fm_mr->list, &l);
  93         rc = ib_unmap_fmr(&l);
  94         list_del_init(&mw->fmr.fm_mr->list);
  95         return rc;
  96 }
  97
  98 static void
  99 fmr_op_release_mr(struct rpcrdma_mw *r)
 100 {
 101         LIST_HEAD(unmap_list);
 102         int rc;
 103
 104         /* Ensure MW is not on any rl_registered list */
 105         if (!list_empty(&r->mw_list))
 106                 list_del(&r->mw_list);
 107
 108         kfree(r->fmr.fm_physaddrs);
 109         kfree(r->mw_sg);
 110
 111         /* In case this one was left mapped, try to unmap it
 112          * to prevent dealloc_fmr from failing with EBUSY
 113          */
 114         rc = __fmr_unmap(r);
 115         if (rc)
 116                 pr_err("rpcrdma: final ib_unmap_fmr for %p failed %i\n",
 117                        r, rc);
 118
 119         rc = ib_dealloc_fmr(r->fmr.fm_mr);
 120         if (rc)
 121                 pr_err("rpcrdma: final ib_dealloc_fmr for %p returned %i\n",
 122                        r, rc);
 123
 124         kfree(r);
 125 }
 126
 127 /* Reset of a single FMR.
 128  */
 129 static void
 130 fmr_op_recover_mr(struct rpcrdma_mw *mw)
 131 {
 132         struct rpcrdma_xprt *r_xprt = mw->mw_xprt;
 133         int rc;
 134
 135         /* ORDER: invalidate first */
 136         rc = __fmr_unmap(mw);
 137
 138         /* ORDER: then DMA unmap */
 139         ib_dma_unmap_sg(r_xprt->rx_ia.ri_device,
 140                         mw->mw_sg, mw->mw_nents, mw->mw_dir);
 141         if (rc)
 142                 goto out_release;
 143
 144         rpcrdma_put_mw(r_xprt, mw);
 145         r_xprt->rx_stats.mrs_recovered++;
 146         return;
 147
 148 out_release:
 149         pr_err("rpcrdma: FMR reset failed (%d), %p released\n", rc, mw);
 150         r_xprt->rx_stats.mrs_orphaned++;
 151
 152         spin_lock(&r_xprt->rx_buf.rb_mwlock);
 153         list_del(&mw->mw_all);
 154         spin_unlock(&r_xprt->rx_buf.rb_mwlock);
 155
 156         fmr_op_release_mr(mw);
 157 }
 158
 159 static int
 160 fmr_op_open(struct rpcrdma_ia *ia, struct rpcrdma_ep *ep,
 161             struct rpcrdma_create_data_internal *cdata)
 162 {
 163         ia->ri_max_segs = max_t(unsigned int, 1, RPCRDMA_MAX_DATA_SEGS /
 164                                 RPCRDMA_MAX_FMR_SGES);
 165         return 0;
 166 }
 167
 168 /* FMR mode conveys up to 64 pages of payload per chunk segment.
 169  */
 170 static size_t
 171 fmr_op_maxpages(struct rpcrdma_xprt *r_xprt)
 172 {
 173         return min_t(unsigned int, RPCRDMA_MAX_DATA_SEGS,
 174                      RPCRDMA_MAX_HDR_SEGS * RPCRDMA_MAX_FMR_SGES);
 175 }
 176
 177 /* Use the ib_map_phys_fmr() verb to register a memory region
 178  * for remote access via RDMA READ or RDMA WRITE.
 179  */
 180 static int
 181 fmr_op_map(struct rpcrdma_xprt *r_xprt, struct rpcrdma_mr_seg *seg,
 182            int nsegs, bool writing, struct rpcrdma_mw **out)
 183 {
 184         struct rpcrdma_mr_seg *seg1 = seg;
 185         int len, pageoff, i, rc;
 186         struct rpcrdma_mw *mw;
 187         u64 *dma_pages;
 188
 189         mw = rpcrdma_get_mw(r_xprt);
 190         if (!mw)
 191                 return -ENOBUFS;
 192
 193         pageoff = offset_in_page(seg1->mr_offset);
 194         seg1->mr_offset -= pageoff;     /* start of page */
 195         seg1->mr_len += pageoff;
 196         len = -pageoff;
 197         if (nsegs > RPCRDMA_MAX_FMR_SGES)
 198                 nsegs = RPCRDMA_MAX_FMR_SGES;
 199         for (i = 0; i < nsegs;) {
 200                 if (seg->mr_page)
 201                         sg_set_page(&mw->mw_sg[i],
 202                                     seg->mr_page,
 203                                     seg->mr_len,
 204                                     offset_in_page(seg->mr_offset));
 205                 else
 206                         sg_set_buf(&mw->mw_sg[i], seg->mr_offset,
 207                                    seg->mr_len);
 208                 len += seg->mr_len;
 209                 ++seg;
 210                 ++i;
 211                 /* Check for holes */
 212                 if ((i < nsegs && offset_in_page(seg->mr_offset)) ||
 213                     offset_in_page((seg-1)->mr_offset + (seg-1)->mr_len))
 214                         break;
 215         }
 216         mw->mw_nents = i;
 217         mw->mw_dir = rpcrdma_data_dir(writing);
 218         if (i == 0)
 219                 goto out_dmamap_err;
 220
 221         if (!ib_dma_map_sg(r_xprt->rx_ia.ri_device,
 222                            mw->mw_sg, mw->mw_nents, mw->mw_dir))
 223                 goto out_dmamap_err;
 224
 225         for (i = 0, dma_pages = mw->fmr.fm_physaddrs; i < mw->mw_nents; i++)
 226                 dma_pages[i] = sg_dma_address(&mw->mw_sg[i]);
 227         rc = ib_map_phys_fmr(mw->fmr.fm_mr, dma_pages, mw->mw_nents,
 228                              dma_pages[0]);
 229         if (rc)
 230                 goto out_maperr;
 231
 232         mw->mw_handle = mw->fmr.fm_mr->rkey;
 233         mw->mw_length = len;
 234         mw->mw_offset = dma_pages[0] + pageoff;
 235
 236         *out = mw;
 237         return mw->mw_nents;
 238
 239 out_dmamap_err:
 240         pr_err("rpcrdma: failed to dma map sg %p sg_nents %u\n",
 241                mw->mw_sg, mw->mw_nents);
 242         rpcrdma_defer_mr_recovery(mw);
 243         return -EIO;
 244
 245 out_maperr:
 246         pr_err("rpcrdma: ib_map_phys_fmr %u@0x%llx+%i (%d) status %i\n",
 247                len, (unsigned long long)dma_pages[0],
 248                pageoff, mw->mw_nents, rc);
 249         rpcrdma_defer_mr_recovery(mw);
 250         return -EIO;
 251 }
 252
 253 /* Invalidate all memory regions that were registered for "req".
 254  *
 255  * Sleeps until it is safe for the host CPU to access the
 256  * previously mapped memory regions.
 257  *
 258  * Caller ensures that req->rl_registered is not empty.
 259  */
 260 static void
 261 fmr_op_unmap_sync(struct rpcrdma_xprt *r_xprt, struct rpcrdma_req *req)
 262 {
 263         struct rpcrdma_mw *mw, *tmp;
 264         LIST_HEAD(unmap_list);
 265         int rc;
 266
 267         dprintk("RPC:       %s: req %p\n", __func__, req);
 268
 269         /* ORDER: Invalidate all of the req's MRs first
 270          *
 271          * ib_unmap_fmr() is slow, so use a single call instead
 272          * of one call per mapped FMR.
 273          */
 274         list_for_each_entry(mw, &req->rl_registered, mw_list)
 275                 list_add_tail(&mw->fmr.fm_mr->list, &unmap_list);
 276         r_xprt->rx_stats.local_inv_needed++;
 277         rc = ib_unmap_fmr(&unmap_list);
 278         if (rc)
 279                 goto out_reset;
 280
 281         /* ORDER: Now DMA unmap all of the req's MRs, and return
 282          * them to the free MW list.
 283          */
 284         list_for_each_entry_safe(mw, tmp, &req->rl_registered, mw_list) {
 285                 list_del_init(&mw->mw_list);
 286                 list_del_init(&mw->fmr.fm_mr->list);
 287                 ib_dma_unmap_sg(r_xprt->rx_ia.ri_device,
 288                                 mw->mw_sg, mw->mw_nents, mw->mw_dir);
 289                 rpcrdma_put_mw(r_xprt, mw);
 290         }
 291
 292         return;
 293
 294 out_reset:
 295         pr_err("rpcrdma: ib_unmap_fmr failed (%i)\n", rc);
 296
 297         list_for_each_entry_safe(mw, tmp, &req->rl_registered, mw_list) {
 298                 list_del_init(&mw->fmr.fm_mr->list);
 299                 fmr_op_recover_mr(mw);
 300         }
 301 }
 302
 303 /* Use a slow, safe mechanism to invalidate all memory regions
 304  * that were registered for "req".
 305  */
 306 static void
 307 fmr_op_unmap_safe(struct rpcrdma_xprt *r_xprt, struct rpcrdma_req *req,
 308                   bool sync)
 309 {
 310         struct rpcrdma_mw *mw;
 311
 312         while (!list_empty(&req->rl_registered)) {
 313                 mw = rpcrdma_pop_mw(&req->rl_registered);
 314                 if (sync)
 315                         fmr_op_recover_mr(mw);
 316                 else
 317                         rpcrdma_defer_mr_recovery(mw);
 318         }
 319 }
 320
 321 const struct rpcrdma_memreg_ops rpcrdma_fmr_memreg_ops = {
 322         .ro_map                         = fmr_op_map,
 323         .ro_unmap_sync                  = fmr_op_unmap_sync,
 324         .ro_unmap_safe                  = fmr_op_unmap_safe,
 325         .ro_recover_mr                  = fmr_op_recover_mr,
 326         .ro_open                        = fmr_op_open,
 327         .ro_maxpages                    = fmr_op_maxpages,
 328         .ro_init_mr                     = fmr_op_init_mr,
 329         .ro_release_mr                  = fmr_op_release_mr,
 330         .ro_displayname                 = "fmr",
 331         .ro_send_w_inv_ok               = 0,
 332 };