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#include "xprt_rdma.h"
15
16#if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
17# define RPCDBG_FACILITY	RPCDBG_TRANS
18#endif
19
20/* Maximum scatter/gather per FMR */
21#define RPCRDMA_MAX_FMR_SGES	(64)
22
23static int
24fmr_op_open(struct rpcrdma_ia *ia, struct rpcrdma_ep *ep,
25	    struct rpcrdma_create_data_internal *cdata)
26{
27	return 0;
28}
29
30/* FMR mode conveys up to 64 pages of payload per chunk segment.
31 */
32static size_t
33fmr_op_maxpages(struct rpcrdma_xprt *r_xprt)
34{
35	return min_t(unsigned int, RPCRDMA_MAX_DATA_SEGS,
36		     rpcrdma_max_segments(r_xprt) * RPCRDMA_MAX_FMR_SGES);
37}
38
39static int
40fmr_op_init(struct rpcrdma_xprt *r_xprt)
41{
42	struct rpcrdma_buffer *buf = &r_xprt->rx_buf;
43	int mr_access_flags = IB_ACCESS_REMOTE_WRITE | IB_ACCESS_REMOTE_READ;
44	struct ib_fmr_attr fmr_attr = {
45		.max_pages	= RPCRDMA_MAX_FMR_SGES,
46		.max_maps	= 1,
47		.page_shift	= PAGE_SHIFT
48	};
49	struct ib_pd *pd = r_xprt->rx_ia.ri_pd;
50	struct rpcrdma_mw *r;
51	int i, rc;
52
53	INIT_LIST_HEAD(&buf->rb_mws);
54	INIT_LIST_HEAD(&buf->rb_all);
55
56	i = (buf->rb_max_requests + 1) * RPCRDMA_MAX_SEGS;
57	dprintk("RPC:       %s: initializing %d FMRs\n", __func__, i);
58
59	while (i--) {
60		r = kzalloc(sizeof(*r), GFP_KERNEL);
61		if (!r)
62			return -ENOMEM;
63
64		r->r.fmr = ib_alloc_fmr(pd, mr_access_flags, &fmr_attr);
65		if (IS_ERR(r->r.fmr))
66			goto out_fmr_err;
67
68		list_add(&r->mw_list, &buf->rb_mws);
69		list_add(&r->mw_all, &buf->rb_all);
70	}
71	return 0;
72
73out_fmr_err:
74	rc = PTR_ERR(r->r.fmr);
75	dprintk("RPC:       %s: ib_alloc_fmr status %i\n", __func__, rc);
76	kfree(r);
77	return rc;
78}
79
80/* Use the ib_map_phys_fmr() verb to register a memory region
81 * for remote access via RDMA READ or RDMA WRITE.
82 */
83static int
84fmr_op_map(struct rpcrdma_xprt *r_xprt, struct rpcrdma_mr_seg *seg,
85	   int nsegs, bool writing)
86{
87	struct rpcrdma_ia *ia = &r_xprt->rx_ia;
88	struct ib_device *device = ia->ri_id->device;
89	enum dma_data_direction direction = rpcrdma_data_dir(writing);
90	struct rpcrdma_mr_seg *seg1 = seg;
91	struct rpcrdma_mw *mw = seg1->rl_mw;
92	u64 physaddrs[RPCRDMA_MAX_DATA_SEGS];
93	int len, pageoff, i, rc;
94
95	pageoff = offset_in_page(seg1->mr_offset);
96	seg1->mr_offset -= pageoff;	/* start of page */
97	seg1->mr_len += pageoff;
98	len = -pageoff;
99	if (nsegs > RPCRDMA_MAX_FMR_SGES)
100		nsegs = RPCRDMA_MAX_FMR_SGES;
101	for (i = 0; i < nsegs;) {
102		rpcrdma_map_one(device, seg, direction);
103		physaddrs[i] = seg->mr_dma;
104		len += seg->mr_len;
105		++seg;
106		++i;
107		/* Check for holes */
108		if ((i < nsegs && offset_in_page(seg->mr_offset)) ||
109		    offset_in_page((seg-1)->mr_offset + (seg-1)->mr_len))
110			break;
111	}
112
113	rc = ib_map_phys_fmr(mw->r.fmr, physaddrs, i, seg1->mr_dma);
114	if (rc)
115		goto out_maperr;
116
117	seg1->mr_rkey = mw->r.fmr->rkey;
118	seg1->mr_base = seg1->mr_dma + pageoff;
119	seg1->mr_nsegs = i;
120	seg1->mr_len = len;
121	return i;
122
123out_maperr:
124	dprintk("RPC:       %s: ib_map_phys_fmr %u@0x%llx+%i (%d) status %i\n",
125		__func__, len, (unsigned long long)seg1->mr_dma,
126		pageoff, i, rc);
127	while (i--)
128		rpcrdma_unmap_one(device, --seg);
129	return rc;
130}
131
132/* Use the ib_unmap_fmr() verb to prevent further remote
133 * access via RDMA READ or RDMA WRITE.
134 */
135static int
136fmr_op_unmap(struct rpcrdma_xprt *r_xprt, struct rpcrdma_mr_seg *seg)
137{
138	struct rpcrdma_ia *ia = &r_xprt->rx_ia;
139	struct rpcrdma_mr_seg *seg1 = seg;
140	struct ib_device *device;
141	int rc, nsegs = seg->mr_nsegs;
142	LIST_HEAD(l);
143
144	list_add(&seg1->rl_mw->r.fmr->list, &l);
145	rc = ib_unmap_fmr(&l);
146	read_lock(&ia->ri_qplock);
147	device = ia->ri_id->device;
148	while (seg1->mr_nsegs--)
149		rpcrdma_unmap_one(device, seg++);
150	read_unlock(&ia->ri_qplock);
151	if (rc)
152		goto out_err;
153	return nsegs;
154
155out_err:
156	dprintk("RPC:       %s: ib_unmap_fmr status %i\n", __func__, rc);
157	return nsegs;
158}
159
160/* After a disconnect, unmap all FMRs.
161 *
162 * This is invoked only in the transport connect worker in order
163 * to serialize with rpcrdma_register_fmr_external().
164 */
165static void
166fmr_op_reset(struct rpcrdma_xprt *r_xprt)
167{
168	struct rpcrdma_buffer *buf = &r_xprt->rx_buf;
169	struct rpcrdma_mw *r;
170	LIST_HEAD(list);
171	int rc;
172
173	list_for_each_entry(r, &buf->rb_all, mw_all)
174		list_add(&r->r.fmr->list, &list);
175
176	rc = ib_unmap_fmr(&list);
177	if (rc)
178		dprintk("RPC:       %s: ib_unmap_fmr failed %i\n",
179			__func__, rc);
180}
181
182static void
183fmr_op_destroy(struct rpcrdma_buffer *buf)
184{
185	struct rpcrdma_mw *r;
186	int rc;
187
188	while (!list_empty(&buf->rb_all)) {
189		r = list_entry(buf->rb_all.next, struct rpcrdma_mw, mw_all);
190		list_del(&r->mw_all);
191		rc = ib_dealloc_fmr(r->r.fmr);
192		if (rc)
193			dprintk("RPC:       %s: ib_dealloc_fmr failed %i\n",
194				__func__, rc);
195		kfree(r);
196	}
197}
198
199const struct rpcrdma_memreg_ops rpcrdma_fmr_memreg_ops = {
200	.ro_map				= fmr_op_map,
201	.ro_unmap			= fmr_op_unmap,
202	.ro_open			= fmr_op_open,
203	.ro_maxpages			= fmr_op_maxpages,
204	.ro_init			= fmr_op_init,
205	.ro_reset			= fmr_op_reset,
206	.ro_destroy			= fmr_op_destroy,
207	.ro_displayname			= "fmr",
208};
209