1 files changed, 348 insertions, 0 deletions
diff --git a/net/sunrpc/xprtrdma/fmr_ops.c b/net/sunrpc/xprtrdma/fmr_ops.c
new file mode 100644
index 000000000..0f7c465d9
--- /dev/null
+++ b/net/sunrpc/xprtrdma/fmr_ops.c
@@ -0,0 +1,348 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2015, 2017 Oracle.  All rights reserved.
+ * Copyright (c) 2003-2007 Network Appliance, Inc. All rights reserved.
+ */
+
+/* Lightweight memory registration using Fast Memory Regions (FMR).
+ * Referred to sometimes as MTHCAFMR mode.
+ *
+ * FMR uses synchronous memory registration and deregistration.
+ * FMR registration is known to be fast, but FMR deregistration
+ * can take tens of usecs to complete.
+ */
+
+/* Normal operation
+ *
+ * A Memory Region is prepared for RDMA READ or WRITE using the
+ * ib_map_phys_fmr verb (fmr_op_map). When the RDMA operation is
+ * finished, the Memory Region is unmapped using the ib_unmap_fmr
+ * verb (fmr_op_unmap).
+ */
+
+#include <linux/sunrpc/svc_rdma.h>
+
+#include "xprt_rdma.h"
+#include <trace/events/rpcrdma.h>
+
+#if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
+# define RPCDBG_FACILITY	RPCDBG_TRANS
+#endif
+
+/* Maximum scatter/gather per FMR */
+#define RPCRDMA_MAX_FMR_SGES	(64)
+
+/* Access mode of externally registered pages */
+enum {
+	RPCRDMA_FMR_ACCESS_FLAGS	= IB_ACCESS_REMOTE_WRITE |
+					  IB_ACCESS_REMOTE_READ,
+};
+
+bool
+fmr_is_supported(struct rpcrdma_ia *ia)
+{
+	if (!ia->ri_device->alloc_fmr) {
+		pr_info("rpcrdma: 'fmr' mode is not supported by device %s\n",
+			ia->ri_device->name);
+		return false;
+	}
+	return true;
+}
+
+static int
+fmr_op_init_mr(struct rpcrdma_ia *ia, struct rpcrdma_mr *mr)
+{
+	static struct ib_fmr_attr fmr_attr = {
+		.max_pages	= RPCRDMA_MAX_FMR_SGES,
+		.max_maps	= 1,
+		.page_shift	= PAGE_SHIFT
+	};
+
+	mr->fmr.fm_physaddrs = kcalloc(RPCRDMA_MAX_FMR_SGES,
+				       sizeof(u64), GFP_KERNEL);
+	if (!mr->fmr.fm_physaddrs)
+		goto out_free;
+
+	mr->mr_sg = kcalloc(RPCRDMA_MAX_FMR_SGES,
+			    sizeof(*mr->mr_sg), GFP_KERNEL);
+	if (!mr->mr_sg)
+		goto out_free;
+
+	sg_init_table(mr->mr_sg, RPCRDMA_MAX_FMR_SGES);
+
+	mr->fmr.fm_mr = ib_alloc_fmr(ia->ri_pd, RPCRDMA_FMR_ACCESS_FLAGS,
+				     &fmr_attr);
+	if (IS_ERR(mr->fmr.fm_mr))
+		goto out_fmr_err;
+
+	INIT_LIST_HEAD(&mr->mr_list);
+	return 0;
+
+out_fmr_err:
+	dprintk("RPC:       %s: ib_alloc_fmr returned %ld\n", __func__,
+		PTR_ERR(mr->fmr.fm_mr));
+
+out_free:
+	kfree(mr->mr_sg);
+	kfree(mr->fmr.fm_physaddrs);
+	return -ENOMEM;
+}
+
+static int
+__fmr_unmap(struct rpcrdma_mr *mr)
+{
+	LIST_HEAD(l);
+	int rc;
+
+	list_add(&mr->fmr.fm_mr->list, &l);
+	rc = ib_unmap_fmr(&l);
+	list_del(&mr->fmr.fm_mr->list);
+	return rc;
+}
+
+static void
+fmr_op_release_mr(struct rpcrdma_mr *mr)
+{
+	LIST_HEAD(unmap_list);
+	int rc;
+
+	kfree(mr->fmr.fm_physaddrs);
+	kfree(mr->mr_sg);
+
+	/* In case this one was left mapped, try to unmap it
+	 * to prevent dealloc_fmr from failing with EBUSY
+	 */
+	rc = __fmr_unmap(mr);
+	if (rc)
+		pr_err("rpcrdma: final ib_unmap_fmr for %p failed %i\n",
+		       mr, rc);
+
+	rc = ib_dealloc_fmr(mr->fmr.fm_mr);
+	if (rc)
+		pr_err("rpcrdma: final ib_dealloc_fmr for %p returned %i\n",
+		       mr, rc);
+
+	kfree(mr);
+}
+
+/* Reset of a single FMR.
+ */
+static void
+fmr_op_recover_mr(struct rpcrdma_mr *mr)
+{
+	struct rpcrdma_xprt *r_xprt = mr->mr_xprt;
+	int rc;
+
+	/* ORDER: invalidate first */
+	rc = __fmr_unmap(mr);
+	if (rc)
+		goto out_release;
+
+	/* ORDER: then DMA unmap */
+	rpcrdma_mr_unmap_and_put(mr);
+
+	r_xprt->rx_stats.mrs_recovered++;
+	return;
+
+out_release:
+	pr_err("rpcrdma: FMR reset failed (%d), %p released\n", rc, mr);
+	r_xprt->rx_stats.mrs_orphaned++;
+
+	trace_xprtrdma_dma_unmap(mr);
+	ib_dma_unmap_sg(r_xprt->rx_ia.ri_device,
+			mr->mr_sg, mr->mr_nents, mr->mr_dir);
+
+	spin_lock(&r_xprt->rx_buf.rb_mrlock);
+	list_del(&mr->mr_all);
+	spin_unlock(&r_xprt->rx_buf.rb_mrlock);
+
+	fmr_op_release_mr(mr);
+}
+
+/* On success, sets:
+ *	ep->rep_attr.cap.max_send_wr
+ *	ep->rep_attr.cap.max_recv_wr
+ *	cdata->max_requests
+ *	ia->ri_max_segs
+ */
+static int
+fmr_op_open(struct rpcrdma_ia *ia, struct rpcrdma_ep *ep,
+	    struct rpcrdma_create_data_internal *cdata)
+{
+	int max_qp_wr;
+
+	max_qp_wr = ia->ri_device->attrs.max_qp_wr;
+	max_qp_wr -= RPCRDMA_BACKWARD_WRS;
+	max_qp_wr -= 1;
+	if (max_qp_wr < RPCRDMA_MIN_SLOT_TABLE)
+		return -ENOMEM;
+	if (cdata->max_requests > max_qp_wr)
+		cdata->max_requests = max_qp_wr;
+	ep->rep_attr.cap.max_send_wr = cdata->max_requests;
+	ep->rep_attr.cap.max_send_wr += RPCRDMA_BACKWARD_WRS;
+	ep->rep_attr.cap.max_send_wr += 1; /* for ib_drain_sq */
+	ep->rep_attr.cap.max_recv_wr = cdata->max_requests;
+	ep->rep_attr.cap.max_recv_wr += RPCRDMA_BACKWARD_WRS;
+	ep->rep_attr.cap.max_recv_wr += 1; /* for ib_drain_rq */
+
+	ia->ri_max_segs = max_t(unsigned int, 1, RPCRDMA_MAX_DATA_SEGS /
+				RPCRDMA_MAX_FMR_SGES);
+	return 0;
+}
+
+/* FMR mode conveys up to 64 pages of payload per chunk segment.
+ */
+static size_t
+fmr_op_maxpages(struct rpcrdma_xprt *r_xprt)
+{
+	return min_t(unsigned int, RPCRDMA_MAX_DATA_SEGS,
+		     RPCRDMA_MAX_HDR_SEGS * RPCRDMA_MAX_FMR_SGES);
+}
+
+/* Use the ib_map_phys_fmr() verb to register a memory region
+ * for remote access via RDMA READ or RDMA WRITE.
+ */
+static struct rpcrdma_mr_seg *
+fmr_op_map(struct rpcrdma_xprt *r_xprt, struct rpcrdma_mr_seg *seg,
+	   int nsegs, bool writing, struct rpcrdma_mr **out)
+{
+	struct rpcrdma_mr_seg *seg1 = seg;
+	int len, pageoff, i, rc;
+	struct rpcrdma_mr *mr;
+	u64 *dma_pages;
+
+	mr = rpcrdma_mr_get(r_xprt);
+	if (!mr)
+		return ERR_PTR(-EAGAIN);
+
+	pageoff = offset_in_page(seg1->mr_offset);
+	seg1->mr_offset -= pageoff;	/* start of page */
+	seg1->mr_len += pageoff;
+	len = -pageoff;
+	if (nsegs > RPCRDMA_MAX_FMR_SGES)
+		nsegs = RPCRDMA_MAX_FMR_SGES;
+	for (i = 0; i < nsegs;) {
+		if (seg->mr_page)
+			sg_set_page(&mr->mr_sg[i],
+				    seg->mr_page,
+				    seg->mr_len,
+				    offset_in_page(seg->mr_offset));
+		else
+			sg_set_buf(&mr->mr_sg[i], seg->mr_offset,
+				   seg->mr_len);
+		len += seg->mr_len;
+		++seg;
+		++i;
+		/* Check for holes */
+		if ((i < nsegs && offset_in_page(seg->mr_offset)) ||
+		    offset_in_page((seg-1)->mr_offset + (seg-1)->mr_len))
+			break;
+	}
+	mr->mr_dir = rpcrdma_data_dir(writing);
+
+	mr->mr_nents = ib_dma_map_sg(r_xprt->rx_ia.ri_device,
+				     mr->mr_sg, i, mr->mr_dir);
+	if (!mr->mr_nents)
+		goto out_dmamap_err;
+	trace_xprtrdma_dma_map(mr);
+
+	for (i = 0, dma_pages = mr->fmr.fm_physaddrs; i < mr->mr_nents; i++)
+		dma_pages[i] = sg_dma_address(&mr->mr_sg[i]);
+	rc = ib_map_phys_fmr(mr->fmr.fm_mr, dma_pages, mr->mr_nents,
+			     dma_pages[0]);
+	if (rc)
+		goto out_maperr;
+
+	mr->mr_handle = mr->fmr.fm_mr->rkey;
+	mr->mr_length = len;
+	mr->mr_offset = dma_pages[0] + pageoff;
+
+	*out = mr;
+	return seg;
+
+out_dmamap_err:
+	pr_err("rpcrdma: failed to DMA map sg %p sg_nents %d\n",
+	       mr->mr_sg, i);
+	rpcrdma_mr_put(mr);
+	return ERR_PTR(-EIO);
+
+out_maperr:
+	pr_err("rpcrdma: ib_map_phys_fmr %u@0x%llx+%i (%d) status %i\n",
+	       len, (unsigned long long)dma_pages[0],
+	       pageoff, mr->mr_nents, rc);
+	rpcrdma_mr_unmap_and_put(mr);
+	return ERR_PTR(-EIO);
+}
+
+/* Post Send WR containing the RPC Call message.
+ */
+static int
+fmr_op_send(struct rpcrdma_ia *ia, struct rpcrdma_req *req)
+{
+	return ib_post_send(ia->ri_id->qp, &req->rl_sendctx->sc_wr, NULL);
+}
+
+/* Invalidate all memory regions that were registered for "req".
+ *
+ * Sleeps until it is safe for the host CPU to access the
+ * previously mapped memory regions.
+ *
+ * Caller ensures that @mrs is not empty before the call. This
+ * function empties the list.
+ */
+static void
+fmr_op_unmap_sync(struct rpcrdma_xprt *r_xprt, struct list_head *mrs)
+{
+	struct rpcrdma_mr *mr;
+	LIST_HEAD(unmap_list);
+	int rc;
+
+	/* ORDER: Invalidate all of the req's MRs first
+	 *
+	 * ib_unmap_fmr() is slow, so use a single call instead
+	 * of one call per mapped FMR.
+	 */
+	list_for_each_entry(mr, mrs, mr_list) {
+		dprintk("RPC:       %s: unmapping fmr %p\n",
+			__func__, &mr->fmr);
+		trace_xprtrdma_localinv(mr);
+		list_add_tail(&mr->fmr.fm_mr->list, &unmap_list);
+	}
+	r_xprt->rx_stats.local_inv_needed++;
+	rc = ib_unmap_fmr(&unmap_list);
+	if (rc)
+		goto out_reset;
+
+	/* ORDER: Now DMA unmap all of the req's MRs, and return
+	 * them to the free MW list.
+	 */
+	while (!list_empty(mrs)) {
+		mr = rpcrdma_mr_pop(mrs);
+		list_del(&mr->fmr.fm_mr->list);
+		rpcrdma_mr_unmap_and_put(mr);
+	}
+
+	return;
+
+out_reset:
+	pr_err("rpcrdma: ib_unmap_fmr failed (%i)\n", rc);
+
+	while (!list_empty(mrs)) {
+		mr = rpcrdma_mr_pop(mrs);
+		list_del(&mr->fmr.fm_mr->list);
+		fmr_op_recover_mr(mr);
+	}
+}
+
+const struct rpcrdma_memreg_ops rpcrdma_fmr_memreg_ops = {
+	.ro_map				= fmr_op_map,
+	.ro_send			= fmr_op_send,
+	.ro_unmap_sync			= fmr_op_unmap_sync,
+	.ro_recover_mr			= fmr_op_recover_mr,
+	.ro_open			= fmr_op_open,
+	.ro_maxpages			= fmr_op_maxpages,
+	.ro_init_mr			= fmr_op_init_mr,
+	.ro_release_mr			= fmr_op_release_mr,
+	.ro_displayname			= "fmr",
+	.ro_send_w_inv_ok		= 0,
+};