// SPDX-License-Identifier: GPL-2.0 OR BSD-3-Clause /* * Copyright (c) 2016 Oracle. All rights reserved. * Copyright (c) 2014 Open Grid Computing, Inc. All rights reserved. * Copyright (c) 2005-2006 Network Appliance, Inc. All rights reserved. * * This software is available to you under a choice of one of two * licenses. You may choose to be licensed under the terms of the GNU * General Public License (GPL) Version 2, available from the file * COPYING in the main directory of this source tree, or the BSD-type * license below: * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * * Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * * Redistributions in binary form must reproduce the above * copyright notice, this list of conditions and the following * disclaimer in the documentation and/or other materials provided * with the distribution. * * Neither the name of the Network Appliance, Inc. nor the names of * its contributors may be used to endorse or promote products * derived from this software without specific prior written * permission. * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. * * Author: Tom Tucker */ /* Operation * * The main entry point is svc_rdma_sendto. This is called by the * RPC server when an RPC Reply is ready to be transmitted to a client. * * The passed-in svc_rqst contains a struct xdr_buf which holds an * XDR-encoded RPC Reply message. sendto must construct the RPC-over-RDMA * transport header, post all Write WRs needed for this Reply, then post * a Send WR conveying the transport header and the RPC message itself to * the client. * * svc_rdma_sendto must fully transmit the Reply before returning, as * the svc_rqst will be recycled as soon as sendto returns. Remaining * resources referred to by the svc_rqst are also recycled at that time. * Therefore any resources that must remain longer must be detached * from the svc_rqst and released later. * * Page Management * * The I/O that performs Reply transmission is asynchronous, and may * complete well after sendto returns. Thus pages under I/O must be * removed from the svc_rqst before sendto returns. * * The logic here depends on Send Queue and completion ordering. Since * the Send WR is always posted last, it will always complete last. Thus * when it completes, it is guaranteed that all previous Write WRs have * also completed. * * Write WRs are constructed and posted. Each Write segment gets its own * svc_rdma_rw_ctxt, allowing the Write completion handler to find and * DMA-unmap the pages under I/O for that Write segment. The Write * completion handler does not release any pages. * * When the Send WR is constructed, it also gets its own svc_rdma_op_ctxt. * The ownership of all of the Reply's pages are transferred into that * ctxt, the Send WR is posted, and sendto returns. * * The svc_rdma_op_ctxt is presented when the Send WR completes. The * Send completion handler finally releases the Reply's pages. * * This mechanism also assumes that completions on the transport's Send * Completion Queue do not run in parallel. Otherwise a Write completion * and Send completion running at the same time could release pages that * are still DMA-mapped. * * Error Handling * * - If the Send WR is posted successfully, it will either complete * successfully, or get flushed. Either way, the Send completion * handler releases the Reply's pages. * - If the Send WR cannot be not posted, the forward path releases * the Reply's pages. * * This handles the case, without the use of page reference counting, * where two different Write segments send portions of the same page. */ #include #include #include #include #include #include #include #include "xprt_rdma.h" #include #define RPCDBG_FACILITY RPCDBG_SVCXPRT static u32 xdr_padsize(u32 len) { return (len & 3) ? (4 - (len & 3)) : 0; } /* Returns length of transport header, in bytes. */ static unsigned int svc_rdma_reply_hdr_len(__be32 *rdma_resp) { unsigned int nsegs; __be32 *p; p = rdma_resp; /* RPC-over-RDMA V1 replies never have a Read list. */ p += rpcrdma_fixed_maxsz + 1; /* Skip Write list. */ while (*p++ != xdr_zero) { nsegs = be32_to_cpup(p++); p += nsegs * rpcrdma_segment_maxsz; } /* Skip Reply chunk. */ if (*p++ != xdr_zero) { nsegs = be32_to_cpup(p++); p += nsegs * rpcrdma_segment_maxsz; } return (unsigned long)p - (unsigned long)rdma_resp; } /* One Write chunk is copied from Call transport header to Reply * transport header. Each segment's length field is updated to * reflect number of bytes consumed in the segment. * * Returns number of segments in this chunk. */ static unsigned int xdr_encode_write_chunk(__be32 *dst, __be32 *src, unsigned int remaining) { unsigned int i, nsegs; u32 seg_len; /* Write list discriminator */ *dst++ = *src++; /* number of segments in this chunk */ nsegs = be32_to_cpup(src); *dst++ = *src++; for (i = nsegs; i; i--) { /* segment's RDMA handle */ *dst++ = *src++; /* bytes returned in this segment */ seg_len = be32_to_cpu(*src); if (remaining >= seg_len) { /* entire segment was consumed */ *dst = *src; remaining -= seg_len; } else { /* segment only partly filled */ *dst = cpu_to_be32(remaining); remaining = 0; } dst++; src++; /* segment's RDMA offset */ *dst++ = *src++; *dst++ = *src++; } return nsegs; } /* The client provided a Write list in the Call message. Fill in * the segments in the first Write chunk in the Reply's transport * header with the number of bytes consumed in each segment. * Remaining chunks are returned unused. * * Assumptions: * - Client has provided only one Write chunk */ static void svc_rdma_xdr_encode_write_list(__be32 *rdma_resp, __be32 *wr_ch, unsigned int consumed) { unsigned int nsegs; __be32 *p, *q; /* RPC-over-RDMA V1 replies never have a Read list. */ p = rdma_resp + rpcrdma_fixed_maxsz + 1; q = wr_ch; while (*q != xdr_zero) { nsegs = xdr_encode_write_chunk(p, q, consumed); q += 2 + nsegs * rpcrdma_segment_maxsz; p += 2 + nsegs * rpcrdma_segment_maxsz; consumed = 0; } /* Terminate Write list */ *p++ = xdr_zero; /* Reply chunk discriminator; may be replaced later */ *p = xdr_zero; } /* The client provided a Reply chunk in the Call message. Fill in * the segments in the Reply chunk in the Reply message with the * number of bytes consumed in each segment. * * Assumptions: * - Reply can always fit in the provided Reply chunk */ static void svc_rdma_xdr_encode_reply_chunk(__be32 *rdma_resp, __be32 *rp_ch, unsigned int consumed) { __be32 *p; /* Find the Reply chunk in the Reply's xprt header. * RPC-over-RDMA V1 replies never have a Read list. */ p = rdma_resp + rpcrdma_fixed_maxsz + 1; /* Skip past Write list */ while (*p++ != xdr_zero) p += 1 + be32_to_cpup(p) * rpcrdma_segment_maxsz; xdr_encode_write_chunk(p, rp_ch, consumed); } /* Parse the RPC Call's transport header. */ static void svc_rdma_get_write_arrays(__be32 *rdma_argp, __be32 **write, __be32 **reply) { __be32 *p; p = rdma_argp + rpcrdma_fixed_maxsz; /* Read list */ while (*p++ != xdr_zero) p += 5; /* Write list */ if (*p != xdr_zero) { *write = p; while (*p++ != xdr_zero) p += 1 + be32_to_cpu(*p) * 4; } else { *write = NULL; p++; } /* Reply chunk */ if (*p != xdr_zero) *reply = p; else *reply = NULL; } /* RPC-over-RDMA Version One private extension: Remote Invalidation. * Responder's choice: requester signals it can handle Send With * Invalidate, and responder chooses one rkey to invalidate. * * Find a candidate rkey to invalidate when sending a reply. Picks the * first R_key it finds in the chunk lists. * * Returns zero if RPC's chunk lists are empty. */ static u32 svc_rdma_get_inv_rkey(__be32 *rdma_argp, __be32 *wr_lst, __be32 *rp_ch) { __be32 *p; p = rdma_argp + rpcrdma_fixed_maxsz; if (*p != xdr_zero) p += 2; else if (wr_lst && be32_to_cpup(wr_lst + 1)) p = wr_lst + 2; else if (rp_ch && be32_to_cpup(rp_ch + 1)) p = rp_ch + 2; else return 0; return be32_to_cpup(p); } /* ib_dma_map_page() is used here because svc_rdma_dma_unmap() * is used during completion to DMA-unmap this memory, and * it uses ib_dma_unmap_page() exclusively. */ static int svc_rdma_dma_map_buf(struct svcxprt_rdma *rdma, struct svc_rdma_op_ctxt *ctxt, unsigned int sge_no, unsigned char *base, unsigned int len) { unsigned long offset = (unsigned long)base & ~PAGE_MASK; struct ib_device *dev = rdma->sc_cm_id->device; dma_addr_t dma_addr; dma_addr = ib_dma_map_page(dev, virt_to_page(base), offset, len, DMA_TO_DEVICE); if (ib_dma_mapping_error(dev, dma_addr)) goto out_maperr; ctxt->sge[sge_no].addr = dma_addr; ctxt->sge[sge_no].length = len; ctxt->sge[sge_no].lkey = rdma->sc_pd->local_dma_lkey; svc_rdma_count_mappings(rdma, ctxt); return 0; out_maperr: pr_err("svcrdma: failed to map buffer\n"); return -EIO; } static int svc_rdma_dma_map_page(struct svcxprt_rdma *rdma, struct svc_rdma_op_ctxt *ctxt, unsigned int sge_no, struct page *page, unsigned int offset, unsigned int len) { struct ib_device *dev = rdma->sc_cm_id->device; dma_addr_t dma_addr; dma_addr = ib_dma_map_page(dev, page, offset, len, DMA_TO_DEVICE); if (ib_dma_mapping_error(dev, dma_addr)) goto out_maperr; ctxt->sge[sge_no].addr = dma_addr; ctxt->sge[sge_no].length = len; ctxt->sge[sge_no].lkey = rdma->sc_pd->local_dma_lkey; svc_rdma_count_mappings(rdma, ctxt); return 0; out_maperr: trace_svcrdma_dma_map_page(rdma, page); return -EIO; } /** * svc_rdma_map_reply_hdr - DMA map the transport header buffer * @rdma: controlling transport * @ctxt: op_ctxt for the Send WR * @rdma_resp: buffer containing transport header * @len: length of transport header * * Returns: * %0 if the header is DMA mapped, * %-EIO if DMA mapping failed. */ int svc_rdma_map_reply_hdr(struct svcxprt_rdma *rdma, struct svc_rdma_op_ctxt *ctxt, __be32 *rdma_resp, unsigned int len) { ctxt->direction = DMA_TO_DEVICE; ctxt->pages[0] = virt_to_page(rdma_resp); ctxt->count = 1; return svc_rdma_dma_map_page(rdma, ctxt, 0, ctxt->pages[0], 0, len); } /* Load the xdr_buf into the ctxt's sge array, and DMA map each * element as it is added. * * Returns the number of sge elements loaded on success, or * a negative errno on failure. */ static int svc_rdma_map_reply_msg(struct svcxprt_rdma *rdma, struct svc_rdma_op_ctxt *ctxt, struct xdr_buf *xdr, __be32 *wr_lst) { unsigned int len, sge_no, remaining, page_off; struct page **ppages; unsigned char *base; u32 xdr_pad; int ret; sge_no = 1; ret = svc_rdma_dma_map_buf(rdma, ctxt, sge_no++, xdr->head[0].iov_base, xdr->head[0].iov_len); if (ret < 0) return ret; /* If a Write chunk is present, the xdr_buf's page list * is not included inline. However the Upper Layer may * have added XDR padding in the tail buffer, and that * should not be included inline. */ if (wr_lst) { base = xdr->tail[0].iov_base; len = xdr->tail[0].iov_len; xdr_pad = xdr_padsize(xdr->page_len); if (len && xdr_pad) { base += xdr_pad; len -= xdr_pad; } goto tail; } ppages = xdr->pages + (xdr->page_base >> PAGE_SHIFT); page_off = xdr->page_base & ~PAGE_MASK; remaining = xdr->page_len; while (remaining) { len = min_t(u32, PAGE_SIZE - page_off, remaining); ret = svc_rdma_dma_map_page(rdma, ctxt, sge_no++, *ppages++, page_off, len); if (ret < 0) return ret; remaining -= len; page_off = 0; } base = xdr->tail[0].iov_base; len = xdr->tail[0].iov_len; tail: if (len) { ret = svc_rdma_dma_map_buf(rdma, ctxt, sge_no++, base, len); if (ret < 0) return ret; } return sge_no - 1; } /* The svc_rqst and all resources it owns are released as soon as * svc_rdma_sendto returns. Transfer pages under I/O to the ctxt * so they are released by the Send completion handler. */ static void svc_rdma_save_io_pages(struct svc_rqst *rqstp, struct svc_rdma_op_ctxt *ctxt) { int i, pages = rqstp->rq_next_page - rqstp->rq_respages; ctxt->count += pages; for (i = 0; i < pages; i++) { ctxt->pages[i + 1] = rqstp->rq_respages[i]; rqstp->rq_respages[i] = NULL; } rqstp->rq_next_page = rqstp->rq_respages + 1; } /** * svc_rdma_post_send_wr - Set up and post one Send Work Request * @rdma: controlling transport * @ctxt: op_ctxt for transmitting the Send WR * @num_sge: number of SGEs to send * @inv_rkey: R_key argument to Send With Invalidate, or zero * * Returns: * %0 if the Send* was posted successfully, * %-ENOTCONN if the connection was lost or dropped, * %-EINVAL if there was a problem with the Send we built, * %-ENOMEM if ib_post_send failed. */ int svc_rdma_post_send_wr(struct svcxprt_rdma *rdma, struct svc_rdma_op_ctxt *ctxt, int num_sge, u32 inv_rkey) { struct ib_send_wr *send_wr = &ctxt->send_wr; dprintk("svcrdma: posting Send WR with %u sge(s)\n", num_sge); send_wr->next = NULL; ctxt->cqe.done = svc_rdma_wc_send; send_wr->wr_cqe = &ctxt->cqe; send_wr->sg_list = ctxt->sge; send_wr->num_sge = num_sge; send_wr->send_flags = IB_SEND_SIGNALED; if (inv_rkey) { send_wr->opcode = IB_WR_SEND_WITH_INV; send_wr->ex.invalidate_rkey = inv_rkey; } else { send_wr->opcode = IB_WR_SEND; } return svc_rdma_send(rdma, send_wr); } /* Prepare the portion of the RPC Reply that will be transmitted * via RDMA Send. The RPC-over-RDMA transport header is prepared * in sge[0], and the RPC xdr_buf is prepared in following sges. * * Depending on whether a Write list or Reply chunk is present, * the server may send all, a portion of, or none of the xdr_buf. * In the latter case, only the transport header (sge[0]) is * transmitted. * * RDMA Send is the last step of transmitting an RPC reply. Pages * involved in the earlier RDMA Writes are here transferred out * of the rqstp and into the ctxt's page array. These pages are * DMA unmapped by each Write completion, but the subsequent Send * completion finally releases these pages. * * Assumptions: * - The Reply's transport header will never be larger than a page. */ static int svc_rdma_send_reply_msg(struct svcxprt_rdma *rdma, __be32 *rdma_argp, __be32 *rdma_resp, struct svc_rqst *rqstp, __be32 *wr_lst, __be32 *rp_ch) { struct svc_rdma_op_ctxt *ctxt; u32 inv_rkey; int ret; ctxt = svc_rdma_get_context(rdma); ret = svc_rdma_map_reply_hdr(rdma, ctxt, rdma_resp, svc_rdma_reply_hdr_len(rdma_resp)); if (ret < 0) goto err; if (!rp_ch) { ret = svc_rdma_map_reply_msg(rdma, ctxt, &rqstp->rq_res, wr_lst); if (ret < 0) goto err; } svc_rdma_save_io_pages(rqstp, ctxt); inv_rkey = 0; if (rdma->sc_snd_w_inv) inv_rkey = svc_rdma_get_inv_rkey(rdma_argp, wr_lst, rp_ch); ret = svc_rdma_post_send_wr(rdma, ctxt, 1 + ret, inv_rkey); if (ret) goto err; return 0; err: svc_rdma_unmap_dma(ctxt); svc_rdma_put_context(ctxt, 1); return ret; } /* Given the client-provided Write and Reply chunks, the server was not * able to form a complete reply. Return an RDMA_ERROR message so the * client can retire this RPC transaction. As above, the Send completion * routine releases payload pages that were part of a previous RDMA Write. * * Remote Invalidation is skipped for simplicity. */ static int svc_rdma_send_error_msg(struct svcxprt_rdma *rdma, __be32 *rdma_resp, struct svc_rqst *rqstp) { struct svc_rdma_op_ctxt *ctxt; __be32 *p; int ret; ctxt = svc_rdma_get_context(rdma); /* Replace the original transport header with an * RDMA_ERROR response. XID etc are preserved. */ trace_svcrdma_err_chunk(*rdma_resp); p = rdma_resp + 3; *p++ = rdma_error; *p = err_chunk; ret = svc_rdma_map_reply_hdr(rdma, ctxt, rdma_resp, 20); if (ret < 0) goto err; svc_rdma_save_io_pages(rqstp, ctxt); ret = svc_rdma_post_send_wr(rdma, ctxt, 1 + ret, 0); if (ret) goto err; return 0; err: svc_rdma_unmap_dma(ctxt); svc_rdma_put_context(ctxt, 1); return ret; } void svc_rdma_prep_reply_hdr(struct svc_rqst *rqstp) { } /** * svc_rdma_sendto - Transmit an RPC reply * @rqstp: processed RPC request, reply XDR already in ::rq_res * * Any resources still associated with @rqstp are released upon return. * If no reply message was possible, the connection is closed. * * Returns: * %0 if an RPC reply has been successfully posted, * %-ENOMEM if a resource shortage occurred (connection is lost), * %-ENOTCONN if posting failed (connection is lost). */ int svc_rdma_sendto(struct svc_rqst *rqstp) { struct svc_xprt *xprt = rqstp->rq_xprt; struct svcxprt_rdma *rdma = container_of(xprt, struct svcxprt_rdma, sc_xprt); __be32 *p, *rdma_argp, *rdma_resp, *wr_lst, *rp_ch; struct xdr_buf *xdr = &rqstp->rq_res; struct page *res_page; int ret; /* Find the call's chunk lists to decide how to send the reply. * Receive places the Call's xprt header at the start of page 0. */ rdma_argp = page_address(rqstp->rq_pages[0]); svc_rdma_get_write_arrays(rdma_argp, &wr_lst, &rp_ch); /* Create the RDMA response header. xprt->xpt_mutex, * acquired in svc_send(), serializes RPC replies. The * code path below that inserts the credit grant value * into each transport header runs only inside this * critical section. */ ret = -ENOMEM; res_page = alloc_page(GFP_KERNEL); if (!res_page) goto err0; rdma_resp = page_address(res_page); p = rdma_resp; *p++ = *rdma_argp; *p++ = *(rdma_argp + 1); *p++ = rdma->sc_fc_credits; *p++ = rp_ch ? rdma_nomsg : rdma_msg; /* Start with empty chunks */ *p++ = xdr_zero; *p++ = xdr_zero; *p = xdr_zero; if (wr_lst) { /* XXX: Presume the client sent only one Write chunk */ ret = svc_rdma_send_write_chunk(rdma, wr_lst, xdr); if (ret < 0) goto err2; svc_rdma_xdr_encode_write_list(rdma_resp, wr_lst, ret); } if (rp_ch) { ret = svc_rdma_send_reply_chunk(rdma, rp_ch, wr_lst, xdr); if (ret < 0) goto err2; svc_rdma_xdr_encode_reply_chunk(rdma_resp, rp_ch, ret); } ret = svc_rdma_send_reply_msg(rdma, rdma_argp, rdma_resp, rqstp, wr_lst, rp_ch); if (ret < 0) goto err0; return 0; err2: if (ret != -E2BIG && ret != -EINVAL) goto err1; ret = svc_rdma_send_error_msg(rdma, rdma_resp, rqstp); if (ret < 0) goto err0; return 0; err1: put_page(res_page); err0: trace_svcrdma_send_failed(rqstp, ret); set_bit(XPT_CLOSE, &xprt->xpt_flags); return -ENOTCONN; }