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_device_attr *devattr = &ia->ri_devattr;
  27         struct ib_mr *mr;
  28
  29         /* Obtain an rkey to use for RPC data payloads.
  30          */
  31         mr = ib_get_dma_mr(ia->ri_pd,
  32                            IB_ACCESS_LOCAL_WRITE |
  33                            IB_ACCESS_REMOTE_WRITE |
  34                            IB_ACCESS_REMOTE_READ);
  35         if (IS_ERR(mr)) {
  36                 pr_err("%s: ib_get_dma_mr for failed with %lX\n",
  37                        __func__, PTR_ERR(mr));
  38                 return -ENOMEM;
  39         }
  40         ia->ri_dma_mr = mr;
  41
  42         /* Obtain an lkey to use for regbufs.
  43          */
  44         if (devattr->device_cap_flags & IB_DEVICE_LOCAL_DMA_LKEY)
  45                 ia->ri_dma_lkey = ia->ri_device->local_dma_lkey;
  46         else
  47                 ia->ri_dma_lkey = ia->ri_dma_mr->lkey;
  48
  49         return 0;
  50 }
  51
  52 /* PHYSICAL memory registration conveys one page per chunk segment.
  53  */
  54 static size_t
  55 physical_op_maxpages(struct rpcrdma_xprt *r_xprt)
  56 {
  57         return min_t(unsigned int, RPCRDMA_MAX_DATA_SEGS,
  58                      rpcrdma_max_segments(r_xprt));
  59 }
  60
  61 static int
  62 physical_op_init(struct rpcrdma_xprt *r_xprt)
  63 {
  64         return 0;
  65 }
  66
  67 /* The client's physical memory is already exposed for
  68  * remote access via RDMA READ or RDMA WRITE.
  69  */
  70 static int
  71 physical_op_map(struct rpcrdma_xprt *r_xprt, struct rpcrdma_mr_seg *seg,
  72                 int nsegs, bool writing)
  73 {
  74         struct rpcrdma_ia *ia = &r_xprt->rx_ia;
  75
  76         rpcrdma_map_one(ia->ri_device, seg, rpcrdma_data_dir(writing));
  77         seg->mr_rkey = ia->ri_dma_mr->rkey;
  78         seg->mr_base = seg->mr_dma;
  79         seg->mr_nsegs = 1;
  80         return 1;
  81 }
  82
  83 /* Unmap a memory region, but leave it registered.
  84  */
  85 static int
  86 physical_op_unmap(struct rpcrdma_xprt *r_xprt, struct rpcrdma_mr_seg *seg)
  87 {
  88         struct rpcrdma_ia *ia = &r_xprt->rx_ia;
  89
  90         rpcrdma_unmap_one(ia->ri_device, seg);
  91         return 1;
  92 }
  93
  94 static void
  95 physical_op_destroy(struct rpcrdma_buffer *buf)
  96 {
  97 }
  98
  99 const struct rpcrdma_memreg_ops rpcrdma_physical_memreg_ops = {
 100         .ro_map                         = physical_op_map,
 101         .ro_unmap                       = physical_op_unmap,
 102         .ro_open                        = physical_op_open,
 103         .ro_maxpages                    = physical_op_maxpages,
 104         .ro_init                        = physical_op_init,
 105         .ro_destroy                     = physical_op_destroy,
 106         .ro_displayname                 = "physical",
 107 };