net/sunrpc/xprtrdma/physical_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 /* No-op chunk preparation. All client memory is pre-registered.
   7  * Sometimes referred to as ALLPHYSICAL mode.
   8  *
   9  * Physical registration is simple because all client memory is
  10  * pre-registered and never deregistered. This mode is good for
  11  * adapter bring up, but is considered not safe: the server is
  12  * trusted not to abuse its access to client memory not involved
  13  * in RDMA I/O.
  14  */
  15
  16 #include "xprt_rdma.h"
  17
  18 #if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
  19 # define RPCDBG_FACILITY        RPCDBG_TRANS
  20 #endif
  21
  22 static int
  23 physical_op_open(struct rpcrdma_ia *ia, struct rpcrdma_ep *ep,
  24                  struct rpcrdma_create_data_internal *cdata)
  25 {
  26         struct ib_mr *mr;
  27
  28         /* Obtain an rkey to use for RPC data payloads.
  29          */
  30         mr = ib_get_dma_mr(ia->ri_pd,
  31                            IB_ACCESS_LOCAL_WRITE |
  32                            IB_ACCESS_REMOTE_WRITE |
  33                            IB_ACCESS_REMOTE_READ);
  34         if (IS_ERR(mr)) {
  35                 pr_err("%s: ib_get_dma_mr for failed with %lX\n",
  36                        __func__, PTR_ERR(mr));
  37                 return -ENOMEM;
  38         }
  39
  40         ia->ri_dma_mr = mr;
  41         return 0;
  42 }
  43
  44 /* PHYSICAL memory registration conveys one page per chunk segment.
  45  */
  46 static size_t
  47 physical_op_maxpages(struct rpcrdma_xprt *r_xprt)
  48 {
  49         return min_t(unsigned int, RPCRDMA_MAX_DATA_SEGS,
  50                      rpcrdma_max_segments(r_xprt));
  51 }
  52
  53 static int
  54 physical_op_init(struct rpcrdma_xprt *r_xprt)
  55 {
  56         return 0;
  57 }
  58
  59 /* The client's physical memory is already exposed for
  60  * remote access via RDMA READ or RDMA WRITE.
  61  */
  62 static int
  63 physical_op_map(struct rpcrdma_xprt *r_xprt, struct rpcrdma_mr_seg *seg,
  64                 int nsegs, bool writing)
  65 {
  66         struct rpcrdma_ia *ia = &r_xprt->rx_ia;
  67
  68         rpcrdma_map_one(ia->ri_device, seg, rpcrdma_data_dir(writing));
  69         seg->mr_rkey = ia->ri_dma_mr->rkey;
  70         seg->mr_base = seg->mr_dma;
  71         seg->mr_nsegs = 1;
  72         return 1;
  73 }
  74
  75 /* Unmap a memory region, but leave it registered.
  76  */
  77 static int
  78 physical_op_unmap(struct rpcrdma_xprt *r_xprt, struct rpcrdma_mr_seg *seg)
  79 {
  80         struct rpcrdma_ia *ia = &r_xprt->rx_ia;
  81
  82         rpcrdma_unmap_one(ia->ri_device, seg);
  83         return 1;
  84 }
  85
  86 /* DMA unmap all memory regions that were mapped for "req".
  87  */
  88 static void
  89 physical_op_unmap_sync(struct rpcrdma_xprt *r_xprt, struct rpcrdma_req *req)
  90 {
  91         struct ib_device *device = r_xprt->rx_ia.ri_device;
  92         unsigned int i;
  93
  94         for (i = 0; req->rl_nchunks; --req->rl_nchunks)
  95                 rpcrdma_unmap_one(device, &req->rl_segments[i++]);
  96 }
  97
  98 static void
  99 physical_op_destroy(struct rpcrdma_buffer *buf)
 100 {
 101 }
 102
 103 const struct rpcrdma_memreg_ops rpcrdma_physical_memreg_ops = {
 104         .ro_map                         = physical_op_map,
 105         .ro_unmap_sync                  = physical_op_unmap_sync,
 106         .ro_unmap                       = physical_op_unmap,
 107         .ro_open                        = physical_op_open,
 108         .ro_maxpages                    = physical_op_maxpages,
 109         .ro_init                        = physical_op_init,
 110         .ro_destroy                     = physical_op_destroy,
 111         .ro_displayname                 = "physical",
 112 };