xref: /openbmc/linux/net/sunrpc/xprtrdma/frwr_ops.c (revision 3d3337de)
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 Registration Work
7  * Requests (FRWR). Also referred to sometimes as FRMR mode.
8  *
9  * FRWR features ordered asynchronous registration and deregistration
10  * of arbitrarily sized memory regions. This is the fastest and safest
11  * but most complex memory registration mode.
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 static int
21 __frwr_init(struct rpcrdma_mw *r, struct ib_pd *pd, struct ib_device *device,
22 	    unsigned int depth)
23 {
24 	struct rpcrdma_frmr *f = &r->r.frmr;
25 	int rc;
26 
27 	f->fr_mr = ib_alloc_fast_reg_mr(pd, depth);
28 	if (IS_ERR(f->fr_mr))
29 		goto out_mr_err;
30 	f->fr_pgl = ib_alloc_fast_reg_page_list(device, depth);
31 	if (IS_ERR(f->fr_pgl))
32 		goto out_list_err;
33 	return 0;
34 
35 out_mr_err:
36 	rc = PTR_ERR(f->fr_mr);
37 	dprintk("RPC:       %s: ib_alloc_fast_reg_mr status %i\n",
38 		__func__, rc);
39 	return rc;
40 
41 out_list_err:
42 	rc = PTR_ERR(f->fr_pgl);
43 	dprintk("RPC:       %s: ib_alloc_fast_reg_page_list status %i\n",
44 		__func__, rc);
45 	ib_dereg_mr(f->fr_mr);
46 	return rc;
47 }
48 
49 static void
50 __frwr_release(struct rpcrdma_mw *r)
51 {
52 	int rc;
53 
54 	rc = ib_dereg_mr(r->r.frmr.fr_mr);
55 	if (rc)
56 		dprintk("RPC:       %s: ib_dereg_mr status %i\n",
57 			__func__, rc);
58 	ib_free_fast_reg_page_list(r->r.frmr.fr_pgl);
59 }
60 
61 static int
62 frwr_op_open(struct rpcrdma_ia *ia, struct rpcrdma_ep *ep,
63 	     struct rpcrdma_create_data_internal *cdata)
64 {
65 	struct ib_device_attr *devattr = &ia->ri_devattr;
66 	int depth, delta;
67 
68 	ia->ri_max_frmr_depth =
69 			min_t(unsigned int, RPCRDMA_MAX_DATA_SEGS,
70 			      devattr->max_fast_reg_page_list_len);
71 	dprintk("RPC:       %s: device's max FR page list len = %u\n",
72 		__func__, ia->ri_max_frmr_depth);
73 
74 	/* Add room for frmr register and invalidate WRs.
75 	 * 1. FRMR reg WR for head
76 	 * 2. FRMR invalidate WR for head
77 	 * 3. N FRMR reg WRs for pagelist
78 	 * 4. N FRMR invalidate WRs for pagelist
79 	 * 5. FRMR reg WR for tail
80 	 * 6. FRMR invalidate WR for tail
81 	 * 7. The RDMA_SEND WR
82 	 */
83 	depth = 7;
84 
85 	/* Calculate N if the device max FRMR depth is smaller than
86 	 * RPCRDMA_MAX_DATA_SEGS.
87 	 */
88 	if (ia->ri_max_frmr_depth < RPCRDMA_MAX_DATA_SEGS) {
89 		delta = RPCRDMA_MAX_DATA_SEGS - ia->ri_max_frmr_depth;
90 		do {
91 			depth += 2; /* FRMR reg + invalidate */
92 			delta -= ia->ri_max_frmr_depth;
93 		} while (delta > 0);
94 	}
95 
96 	ep->rep_attr.cap.max_send_wr *= depth;
97 	if (ep->rep_attr.cap.max_send_wr > devattr->max_qp_wr) {
98 		cdata->max_requests = devattr->max_qp_wr / depth;
99 		if (!cdata->max_requests)
100 			return -EINVAL;
101 		ep->rep_attr.cap.max_send_wr = cdata->max_requests *
102 					       depth;
103 	}
104 
105 	return 0;
106 }
107 
108 /* FRWR mode conveys a list of pages per chunk segment. The
109  * maximum length of that list is the FRWR page list depth.
110  */
111 static size_t
112 frwr_op_maxpages(struct rpcrdma_xprt *r_xprt)
113 {
114 	struct rpcrdma_ia *ia = &r_xprt->rx_ia;
115 
116 	return min_t(unsigned int, RPCRDMA_MAX_DATA_SEGS,
117 		     rpcrdma_max_segments(r_xprt) * ia->ri_max_frmr_depth);
118 }
119 
120 /* If FAST_REG or LOCAL_INV failed, indicate the frmr needs to be reset. */
121 static void
122 frwr_sendcompletion(struct ib_wc *wc)
123 {
124 	struct rpcrdma_mw *r;
125 
126 	if (likely(wc->status == IB_WC_SUCCESS))
127 		return;
128 
129 	/* WARNING: Only wr_id and status are reliable at this point */
130 	r = (struct rpcrdma_mw *)(unsigned long)wc->wr_id;
131 	dprintk("RPC:       %s: frmr %p (stale), status %d\n",
132 		__func__, r, wc->status);
133 	r->r.frmr.fr_state = FRMR_IS_STALE;
134 }
135 
136 static int
137 frwr_op_init(struct rpcrdma_xprt *r_xprt)
138 {
139 	struct rpcrdma_buffer *buf = &r_xprt->rx_buf;
140 	struct ib_device *device = r_xprt->rx_ia.ri_id->device;
141 	unsigned int depth = r_xprt->rx_ia.ri_max_frmr_depth;
142 	struct ib_pd *pd = r_xprt->rx_ia.ri_pd;
143 	int i;
144 
145 	INIT_LIST_HEAD(&buf->rb_mws);
146 	INIT_LIST_HEAD(&buf->rb_all);
147 
148 	i = (buf->rb_max_requests + 1) * RPCRDMA_MAX_SEGS;
149 	dprintk("RPC:       %s: initializing %d FRMRs\n", __func__, i);
150 
151 	while (i--) {
152 		struct rpcrdma_mw *r;
153 		int rc;
154 
155 		r = kzalloc(sizeof(*r), GFP_KERNEL);
156 		if (!r)
157 			return -ENOMEM;
158 
159 		rc = __frwr_init(r, pd, device, depth);
160 		if (rc) {
161 			kfree(r);
162 			return rc;
163 		}
164 
165 		list_add(&r->mw_list, &buf->rb_mws);
166 		list_add(&r->mw_all, &buf->rb_all);
167 		r->mw_sendcompletion = frwr_sendcompletion;
168 	}
169 
170 	return 0;
171 }
172 
173 /* Post a FAST_REG Work Request to register a memory region
174  * for remote access via RDMA READ or RDMA WRITE.
175  */
176 static int
177 frwr_op_map(struct rpcrdma_xprt *r_xprt, struct rpcrdma_mr_seg *seg,
178 	    int nsegs, bool writing)
179 {
180 	struct rpcrdma_ia *ia = &r_xprt->rx_ia;
181 	struct ib_device *device = ia->ri_id->device;
182 	enum dma_data_direction direction = rpcrdma_data_dir(writing);
183 	struct rpcrdma_mr_seg *seg1 = seg;
184 	struct rpcrdma_mw *mw = seg1->rl_mw;
185 	struct rpcrdma_frmr *frmr = &mw->r.frmr;
186 	struct ib_mr *mr = frmr->fr_mr;
187 	struct ib_send_wr fastreg_wr, *bad_wr;
188 	u8 key;
189 	int len, pageoff;
190 	int i, rc;
191 	int seg_len;
192 	u64 pa;
193 	int page_no;
194 
195 	pageoff = offset_in_page(seg1->mr_offset);
196 	seg1->mr_offset -= pageoff;	/* start of page */
197 	seg1->mr_len += pageoff;
198 	len = -pageoff;
199 	if (nsegs > ia->ri_max_frmr_depth)
200 		nsegs = ia->ri_max_frmr_depth;
201 	for (page_no = i = 0; i < nsegs;) {
202 		rpcrdma_map_one(device, seg, direction);
203 		pa = seg->mr_dma;
204 		for (seg_len = seg->mr_len; seg_len > 0; seg_len -= PAGE_SIZE) {
205 			frmr->fr_pgl->page_list[page_no++] = pa;
206 			pa += PAGE_SIZE;
207 		}
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 	dprintk("RPC:       %s: Using frmr %p to map %d segments (%d bytes)\n",
217 		__func__, mw, i, len);
218 
219 	frmr->fr_state = FRMR_IS_VALID;
220 
221 	memset(&fastreg_wr, 0, sizeof(fastreg_wr));
222 	fastreg_wr.wr_id = (unsigned long)(void *)mw;
223 	fastreg_wr.opcode = IB_WR_FAST_REG_MR;
224 	fastreg_wr.wr.fast_reg.iova_start = seg1->mr_dma + pageoff;
225 	fastreg_wr.wr.fast_reg.page_list = frmr->fr_pgl;
226 	fastreg_wr.wr.fast_reg.page_shift = PAGE_SHIFT;
227 	fastreg_wr.wr.fast_reg.page_list_len = page_no;
228 	fastreg_wr.wr.fast_reg.length = len;
229 	fastreg_wr.wr.fast_reg.access_flags = writing ?
230 				IB_ACCESS_REMOTE_WRITE | IB_ACCESS_LOCAL_WRITE :
231 				IB_ACCESS_REMOTE_READ;
232 	key = (u8)(mr->rkey & 0x000000FF);
233 	ib_update_fast_reg_key(mr, ++key);
234 	fastreg_wr.wr.fast_reg.rkey = mr->rkey;
235 
236 	DECR_CQCOUNT(&r_xprt->rx_ep);
237 	rc = ib_post_send(ia->ri_id->qp, &fastreg_wr, &bad_wr);
238 	if (rc)
239 		goto out_senderr;
240 
241 	seg1->mr_rkey = mr->rkey;
242 	seg1->mr_base = seg1->mr_dma + pageoff;
243 	seg1->mr_nsegs = i;
244 	seg1->mr_len = len;
245 	return i;
246 
247 out_senderr:
248 	dprintk("RPC:       %s: ib_post_send status %i\n", __func__, rc);
249 	ib_update_fast_reg_key(mr, --key);
250 	frmr->fr_state = FRMR_IS_INVALID;
251 	while (i--)
252 		rpcrdma_unmap_one(device, --seg);
253 	return rc;
254 }
255 
256 /* Post a LOCAL_INV Work Request to prevent further remote access
257  * via RDMA READ or RDMA WRITE.
258  */
259 static int
260 frwr_op_unmap(struct rpcrdma_xprt *r_xprt, struct rpcrdma_mr_seg *seg)
261 {
262 	struct rpcrdma_mr_seg *seg1 = seg;
263 	struct rpcrdma_ia *ia = &r_xprt->rx_ia;
264 	struct ib_send_wr invalidate_wr, *bad_wr;
265 	int rc, nsegs = seg->mr_nsegs;
266 	struct ib_device *device;
267 
268 	seg1->rl_mw->r.frmr.fr_state = FRMR_IS_INVALID;
269 
270 	memset(&invalidate_wr, 0, sizeof(invalidate_wr));
271 	invalidate_wr.wr_id = (unsigned long)(void *)seg1->rl_mw;
272 	invalidate_wr.opcode = IB_WR_LOCAL_INV;
273 	invalidate_wr.ex.invalidate_rkey = seg1->rl_mw->r.frmr.fr_mr->rkey;
274 	DECR_CQCOUNT(&r_xprt->rx_ep);
275 
276 	read_lock(&ia->ri_qplock);
277 	device = ia->ri_id->device;
278 	while (seg1->mr_nsegs--)
279 		rpcrdma_unmap_one(device, seg++);
280 	rc = ib_post_send(ia->ri_id->qp, &invalidate_wr, &bad_wr);
281 	read_unlock(&ia->ri_qplock);
282 	if (rc)
283 		goto out_err;
284 	return nsegs;
285 
286 out_err:
287 	/* Force rpcrdma_buffer_get() to retry */
288 	seg1->rl_mw->r.frmr.fr_state = FRMR_IS_STALE;
289 	dprintk("RPC:       %s: ib_post_send status %i\n", __func__, rc);
290 	return nsegs;
291 }
292 
293 /* After a disconnect, a flushed FAST_REG_MR can leave an FRMR in
294  * an unusable state. Find FRMRs in this state and dereg / reg
295  * each.  FRMRs that are VALID and attached to an rpcrdma_req are
296  * also torn down.
297  *
298  * This gives all in-use FRMRs a fresh rkey and leaves them INVALID.
299  *
300  * This is invoked only in the transport connect worker in order
301  * to serialize with rpcrdma_register_frmr_external().
302  */
303 static void
304 frwr_op_reset(struct rpcrdma_xprt *r_xprt)
305 {
306 	struct rpcrdma_buffer *buf = &r_xprt->rx_buf;
307 	struct ib_device *device = r_xprt->rx_ia.ri_id->device;
308 	unsigned int depth = r_xprt->rx_ia.ri_max_frmr_depth;
309 	struct ib_pd *pd = r_xprt->rx_ia.ri_pd;
310 	struct rpcrdma_mw *r;
311 	int rc;
312 
313 	list_for_each_entry(r, &buf->rb_all, mw_all) {
314 		if (r->r.frmr.fr_state == FRMR_IS_INVALID)
315 			continue;
316 
317 		__frwr_release(r);
318 		rc = __frwr_init(r, pd, device, depth);
319 		if (rc) {
320 			dprintk("RPC:       %s: mw %p left %s\n",
321 				__func__, r,
322 				(r->r.frmr.fr_state == FRMR_IS_STALE ?
323 					"stale" : "valid"));
324 			continue;
325 		}
326 
327 		r->r.frmr.fr_state = FRMR_IS_INVALID;
328 	}
329 }
330 
331 static void
332 frwr_op_destroy(struct rpcrdma_buffer *buf)
333 {
334 	struct rpcrdma_mw *r;
335 
336 	while (!list_empty(&buf->rb_all)) {
337 		r = list_entry(buf->rb_all.next, struct rpcrdma_mw, mw_all);
338 		list_del(&r->mw_all);
339 		__frwr_release(r);
340 		kfree(r);
341 	}
342 }
343 
344 const struct rpcrdma_memreg_ops rpcrdma_frwr_memreg_ops = {
345 	.ro_map				= frwr_op_map,
346 	.ro_unmap			= frwr_op_unmap,
347 	.ro_open			= frwr_op_open,
348 	.ro_maxpages			= frwr_op_maxpages,
349 	.ro_init			= frwr_op_init,
350 	.ro_reset			= frwr_op_reset,
351 	.ro_destroy			= frwr_op_destroy,
352 	.ro_displayname			= "frwr",
353 };
354