--- /dev/null
+/*
+ * Shared Memory Communications over RDMA (SMC-R) and RoCE
+ *
+ * Work Requests exploiting Infiniband API
+ *
+ * Work requests (WR) of type ib_post_send or ib_post_recv respectively
+ * are submitted to either RC SQ or RC RQ respectively
+ * (reliably connected send/receive queue)
+ * and become work queue entries (WQEs).
+ * While an SQ WR/WQE is pending, we track it until transmission completion.
+ * Through a send or receive completion queue (CQ) respectively,
+ * we get completion queue entries (CQEs) [aka work completions (WCs)].
+ * Since the CQ callback is called from IRQ context, we split work by using
+ * bottom halves implemented by tasklets.
+ *
+ * SMC uses this to exchange LLC (link layer control)
+ * and CDC (connection data control) messages.
+ *
+ * Copyright IBM Corp. 2016
+ *
+ * Author(s): Steffen Maier <maier@linux.vnet.ibm.com>
+ */
+
+#include <linux/atomic.h>
+#include <linux/hashtable.h>
+#include <linux/wait.h>
+#include <rdma/ib_verbs.h>
+#include <asm/div64.h>
+
+#include "smc.h"
+#include "smc_wr.h"
+
+#define SMC_WR_MAX_POLL_CQE 10 /* max. # of compl. queue elements in 1 poll */
+
+#define SMC_WR_RX_HASH_BITS 4
+static DEFINE_HASHTABLE(smc_wr_rx_hash, SMC_WR_RX_HASH_BITS);
+static DEFINE_SPINLOCK(smc_wr_rx_hash_lock);
+
+struct smc_wr_tx_pend { /* control data for a pending send request */
+ u64 wr_id; /* work request id sent */
+ smc_wr_tx_handler handler;
+ enum ib_wc_status wc_status; /* CQE status */
+ struct smc_link *link;
+ u32 idx;
+ struct smc_wr_tx_pend_priv priv;
+};
+
+/******************************** send queue *********************************/
+
+/*------------------------------- completion --------------------------------*/
+
+static inline int smc_wr_tx_find_pending_index(struct smc_link *link, u64 wr_id)
+{
+ u32 i;
+
+ for (i = 0; i < link->wr_tx_cnt; i++) {
+ if (link->wr_tx_pends[i].wr_id == wr_id)
+ return i;
+ }
+ return link->wr_tx_cnt;
+}
+
+static inline void smc_wr_tx_process_cqe(struct ib_wc *wc)
+{
+ struct smc_wr_tx_pend pnd_snd;
+ struct smc_link *link;
+ u32 pnd_snd_idx;
+ int i;
+
+ link = wc->qp->qp_context;
+ pnd_snd_idx = smc_wr_tx_find_pending_index(link, wc->wr_id);
+ if (pnd_snd_idx == link->wr_tx_cnt)
+ return;
+ link->wr_tx_pends[pnd_snd_idx].wc_status = wc->status;
+ memcpy(&pnd_snd, &link->wr_tx_pends[pnd_snd_idx], sizeof(pnd_snd));
+ /* clear the full struct smc_wr_tx_pend including .priv */
+ memset(&link->wr_tx_pends[pnd_snd_idx], 0,
+ sizeof(link->wr_tx_pends[pnd_snd_idx]));
+ memset(&link->wr_tx_bufs[pnd_snd_idx], 0,
+ sizeof(link->wr_tx_bufs[pnd_snd_idx]));
+ if (!test_and_clear_bit(pnd_snd_idx, link->wr_tx_mask))
+ return;
+ if (wc->status) {
+ for_each_set_bit(i, link->wr_tx_mask, link->wr_tx_cnt) {
+ /* clear full struct smc_wr_tx_pend including .priv */
+ memset(&link->wr_tx_pends[i], 0,
+ sizeof(link->wr_tx_pends[i]));
+ memset(&link->wr_tx_bufs[i], 0,
+ sizeof(link->wr_tx_bufs[i]));
+ clear_bit(i, link->wr_tx_mask);
+ }
+ /* tbd in future patch: terminate connections of this link
+ * group abnormally
+ */
+ }
+ if (pnd_snd.handler)
+ pnd_snd.handler(&pnd_snd.priv, link, wc->status);
+ wake_up(&link->wr_tx_wait);
+}
+
+static void smc_wr_tx_tasklet_fn(unsigned long data)
+{
+ struct smc_ib_device *dev = (struct smc_ib_device *)data;
+ struct ib_wc wc[SMC_WR_MAX_POLL_CQE];
+ int i = 0, rc;
+ int polled = 0;
+
+again:
+ polled++;
+ do {
+ rc = ib_poll_cq(dev->roce_cq_send, SMC_WR_MAX_POLL_CQE, wc);
+ if (polled == 1) {
+ ib_req_notify_cq(dev->roce_cq_send,
+ IB_CQ_NEXT_COMP |
+ IB_CQ_REPORT_MISSED_EVENTS);
+ }
+ if (!rc)
+ break;
+ for (i = 0; i < rc; i++)
+ smc_wr_tx_process_cqe(&wc[i]);
+ } while (rc > 0);
+ if (polled == 1)
+ goto again;
+}
+
+void smc_wr_tx_cq_handler(struct ib_cq *ib_cq, void *cq_context)
+{
+ struct smc_ib_device *dev = (struct smc_ib_device *)cq_context;
+
+ tasklet_schedule(&dev->send_tasklet);
+}
+
+/*---------------------------- request submission ---------------------------*/
+
+static inline int smc_wr_tx_get_free_slot_index(struct smc_link *link, u32 *idx)
+{
+ *idx = link->wr_tx_cnt;
+ for_each_clear_bit(*idx, link->wr_tx_mask, link->wr_tx_cnt) {
+ if (!test_and_set_bit(*idx, link->wr_tx_mask))
+ return 0;
+ }
+ *idx = link->wr_tx_cnt;
+ return -EBUSY;
+}
+
+/**
+ * smc_wr_tx_get_free_slot() - returns buffer for message assembly,
+ * and sets info for pending transmit tracking
+ * @link: Pointer to smc_link used to later send the message.
+ * @handler: Send completion handler function pointer.
+ * @wr_buf: Out value returns pointer to message buffer.
+ * @wr_pend_priv: Out value returns pointer serving as handler context.
+ *
+ * Return: 0 on success, or -errno on error.
+ */
+int smc_wr_tx_get_free_slot(struct smc_link *link,
+ smc_wr_tx_handler handler,
+ struct smc_wr_buf **wr_buf,
+ struct smc_wr_tx_pend_priv **wr_pend_priv)
+{
+ struct smc_wr_tx_pend *wr_pend;
+ struct ib_send_wr *wr_ib;
+ u64 wr_id;
+ u32 idx;
+ int rc;
+
+ *wr_buf = NULL;
+ *wr_pend_priv = NULL;
+ if (in_softirq()) {
+ rc = smc_wr_tx_get_free_slot_index(link, &idx);
+ if (rc)
+ return rc;
+ } else {
+ rc = wait_event_interruptible_timeout(
+ link->wr_tx_wait,
+ (smc_wr_tx_get_free_slot_index(link, &idx) != -EBUSY),
+ SMC_WR_TX_WAIT_FREE_SLOT_TIME);
+ if (!rc) {
+ /* tbd in future patch: timeout - terminate connections
+ * of this link group abnormally
+ */
+ return -EPIPE;
+ }
+ if (rc == -ERESTARTSYS)
+ return -EINTR;
+ if (idx == link->wr_tx_cnt)
+ return -EPIPE;
+ }
+ wr_id = smc_wr_tx_get_next_wr_id(link);
+ wr_pend = &link->wr_tx_pends[idx];
+ wr_pend->wr_id = wr_id;
+ wr_pend->handler = handler;
+ wr_pend->link = link;
+ wr_pend->idx = idx;
+ wr_ib = &link->wr_tx_ibs[idx];
+ wr_ib->wr_id = wr_id;
+ *wr_buf = &link->wr_tx_bufs[idx];
+ *wr_pend_priv = &wr_pend->priv;
+ return 0;
+}
+
+int smc_wr_tx_put_slot(struct smc_link *link,
+ struct smc_wr_tx_pend_priv *wr_pend_priv)
+{
+ struct smc_wr_tx_pend *pend;
+
+ pend = container_of(wr_pend_priv, struct smc_wr_tx_pend, priv);
+ if (pend->idx < link->wr_tx_cnt) {
+ /* clear the full struct smc_wr_tx_pend including .priv */
+ memset(&link->wr_tx_pends[pend->idx], 0,
+ sizeof(link->wr_tx_pends[pend->idx]));
+ memset(&link->wr_tx_bufs[pend->idx], 0,
+ sizeof(link->wr_tx_bufs[pend->idx]));
+ test_and_clear_bit(pend->idx, link->wr_tx_mask);
+ return 1;
+ }
+
+ return 0;
+}
+
+/* Send prepared WR slot via ib_post_send.
+ * @priv: pointer to smc_wr_tx_pend_priv identifying prepared message buffer
+ */
+int smc_wr_tx_send(struct smc_link *link, struct smc_wr_tx_pend_priv *priv)
+{
+ struct ib_send_wr *failed_wr = NULL;
+ struct smc_wr_tx_pend *pend;
+ int rc;
+
+ ib_req_notify_cq(link->smcibdev->roce_cq_send,
+ IB_CQ_SOLICITED_MASK | IB_CQ_REPORT_MISSED_EVENTS);
+ pend = container_of(priv, struct smc_wr_tx_pend, priv);
+ rc = ib_post_send(link->roce_qp, &link->wr_tx_ibs[pend->idx],
+ &failed_wr);
+ if (rc)
+ smc_wr_tx_put_slot(link, priv);
+ return rc;
+}
+
+/****************************** receive queue ********************************/
+
+int smc_wr_rx_register_handler(struct smc_wr_rx_handler *handler)
+{
+ struct smc_wr_rx_handler *h_iter;
+ int rc = 0;
+
+ spin_lock(&smc_wr_rx_hash_lock);
+ hash_for_each_possible(smc_wr_rx_hash, h_iter, list, handler->type) {
+ if (h_iter->type == handler->type) {
+ rc = -EEXIST;
+ goto out_unlock;
+ }
+ }
+ hash_add(smc_wr_rx_hash, &handler->list, handler->type);
+out_unlock:
+ spin_unlock(&smc_wr_rx_hash_lock);
+ return rc;
+}
+
+/* Demultiplex a received work request based on the message type to its handler.
+ * Relies on smc_wr_rx_hash having been completely filled before any IB WRs,
+ * and not being modified any more afterwards so we don't need to lock it.
+ */
+static inline void smc_wr_rx_demultiplex(struct ib_wc *wc)
+{
+ struct smc_link *link = (struct smc_link *)wc->qp->qp_context;
+ struct smc_wr_rx_handler *handler;
+ struct smc_wr_rx_hdr *wr_rx;
+ u64 temp_wr_id;
+ u32 index;
+
+ if (wc->byte_len < sizeof(*wr_rx))
+ return; /* short message */
+ temp_wr_id = wc->wr_id;
+ index = do_div(temp_wr_id, link->wr_rx_cnt);
+ wr_rx = (struct smc_wr_rx_hdr *)&link->wr_rx_bufs[index];
+ hash_for_each_possible(smc_wr_rx_hash, handler, list, wr_rx->type) {
+ if (handler->type == wr_rx->type)
+ handler->handler(wc, wr_rx);
+ }
+}
+
+static inline void smc_wr_rx_process_cqes(struct ib_wc wc[], int num)
+{
+ struct smc_link *link;
+ int i;
+
+ for (i = 0; i < num; i++) {
+ link = wc[i].qp->qp_context;
+ if (wc[i].status == IB_WC_SUCCESS) {
+ smc_wr_rx_demultiplex(&wc[i]);
+ smc_wr_rx_post(link); /* refill WR RX */
+ } else {
+ /* handle status errors */
+ switch (wc[i].status) {
+ case IB_WC_RETRY_EXC_ERR:
+ case IB_WC_RNR_RETRY_EXC_ERR:
+ case IB_WC_WR_FLUSH_ERR:
+ /* tbd in future patch: terminate connections of this
+ * link group abnormally
+ */
+ break;
+ default:
+ smc_wr_rx_post(link); /* refill WR RX */
+ break;
+ }
+ }
+ }
+}
+
+static void smc_wr_rx_tasklet_fn(unsigned long data)
+{
+ struct smc_ib_device *dev = (struct smc_ib_device *)data;
+ struct ib_wc wc[SMC_WR_MAX_POLL_CQE];
+ int polled = 0;
+ int rc;
+
+again:
+ polled++;
+ do {
+ memset(&wc, 0, sizeof(wc));
+ rc = ib_poll_cq(dev->roce_cq_recv, SMC_WR_MAX_POLL_CQE, wc);
+ if (polled == 1) {
+ ib_req_notify_cq(dev->roce_cq_recv,
+ IB_CQ_SOLICITED_MASK
+ | IB_CQ_REPORT_MISSED_EVENTS);
+ }
+ if (!rc)
+ break;
+ smc_wr_rx_process_cqes(&wc[0], rc);
+ } while (rc > 0);
+ if (polled == 1)
+ goto again;
+}
+
+void smc_wr_rx_cq_handler(struct ib_cq *ib_cq, void *cq_context)
+{
+ struct smc_ib_device *dev = (struct smc_ib_device *)cq_context;
+
+ tasklet_schedule(&dev->recv_tasklet);
+}
+
+int smc_wr_rx_post_init(struct smc_link *link)
+{
+ u32 i;
+ int rc = 0;
+
+ for (i = 0; i < link->wr_rx_cnt; i++)
+ rc = smc_wr_rx_post(link);
+ return rc;
+}
+
+/***************************** init, exit, misc ******************************/
+
+void smc_wr_remember_qp_attr(struct smc_link *lnk)
+{
+ struct ib_qp_attr *attr = &lnk->qp_attr;
+ struct ib_qp_init_attr init_attr;
+
+ memset(attr, 0, sizeof(*attr));
+ memset(&init_attr, 0, sizeof(init_attr));
+ ib_query_qp(lnk->roce_qp, attr,
+ IB_QP_STATE |
+ IB_QP_CUR_STATE |
+ IB_QP_PKEY_INDEX |
+ IB_QP_PORT |
+ IB_QP_QKEY |
+ IB_QP_AV |
+ IB_QP_PATH_MTU |
+ IB_QP_TIMEOUT |
+ IB_QP_RETRY_CNT |
+ IB_QP_RNR_RETRY |
+ IB_QP_RQ_PSN |
+ IB_QP_ALT_PATH |
+ IB_QP_MIN_RNR_TIMER |
+ IB_QP_SQ_PSN |
+ IB_QP_PATH_MIG_STATE |
+ IB_QP_CAP |
+ IB_QP_DEST_QPN,
+ &init_attr);
+
+ lnk->wr_tx_cnt = min_t(size_t, SMC_WR_BUF_CNT,
+ lnk->qp_attr.cap.max_send_wr);
+ lnk->wr_rx_cnt = min_t(size_t, SMC_WR_BUF_CNT * 3,
+ lnk->qp_attr.cap.max_recv_wr);
+}
+
+static void smc_wr_init_sge(struct smc_link *lnk)
+{
+ u32 i;
+
+ for (i = 0; i < lnk->wr_tx_cnt; i++) {
+ lnk->wr_tx_sges[i].addr =
+ lnk->wr_tx_dma_addr + i * SMC_WR_BUF_SIZE;
+ lnk->wr_tx_sges[i].length = SMC_WR_TX_SIZE;
+ lnk->wr_tx_ibs[i].next = NULL;
+ lnk->wr_tx_ibs[i].sg_list = &lnk->wr_tx_sges[i];
+ lnk->wr_tx_ibs[i].num_sge = 1;
+ lnk->wr_tx_ibs[i].opcode = IB_WR_SEND;
+ lnk->wr_tx_ibs[i].send_flags =
+ IB_SEND_SIGNALED | IB_SEND_SOLICITED | IB_SEND_INLINE;
+ }
+ for (i = 0; i < lnk->wr_rx_cnt; i++) {
+ lnk->wr_rx_sges[i].addr =
+ lnk->wr_rx_dma_addr + i * SMC_WR_BUF_SIZE;
+ lnk->wr_rx_sges[i].length = SMC_WR_BUF_SIZE;
+ lnk->wr_rx_ibs[i].next = NULL;
+ lnk->wr_rx_ibs[i].sg_list = &lnk->wr_rx_sges[i];
+ lnk->wr_rx_ibs[i].num_sge = 1;
+ }
+}
+
+void smc_wr_free_link(struct smc_link *lnk)
+{
+ struct ib_device *ibdev;
+
+ memset(lnk->wr_tx_mask, 0,
+ BITS_TO_LONGS(SMC_WR_BUF_CNT) * sizeof(*lnk->wr_tx_mask));
+
+ if (!lnk->smcibdev)
+ return;
+ ibdev = lnk->smcibdev->ibdev;
+
+ if (lnk->wr_rx_dma_addr) {
+ ib_dma_unmap_single(ibdev, lnk->wr_rx_dma_addr,
+ SMC_WR_BUF_SIZE * lnk->wr_rx_cnt,
+ DMA_FROM_DEVICE);
+ lnk->wr_rx_dma_addr = 0;
+ }
+ if (lnk->wr_tx_dma_addr) {
+ ib_dma_unmap_single(ibdev, lnk->wr_tx_dma_addr,
+ SMC_WR_BUF_SIZE * lnk->wr_tx_cnt,
+ DMA_TO_DEVICE);
+ lnk->wr_tx_dma_addr = 0;
+ }
+}
+
+void smc_wr_free_link_mem(struct smc_link *lnk)
+{
+ kfree(lnk->wr_tx_pends);
+ lnk->wr_tx_pends = NULL;
+ kfree(lnk->wr_tx_mask);
+ lnk->wr_tx_mask = NULL;
+ kfree(lnk->wr_tx_sges);
+ lnk->wr_tx_sges = NULL;
+ kfree(lnk->wr_rx_sges);
+ lnk->wr_rx_sges = NULL;
+ kfree(lnk->wr_rx_ibs);
+ lnk->wr_rx_ibs = NULL;
+ kfree(lnk->wr_tx_ibs);
+ lnk->wr_tx_ibs = NULL;
+ kfree(lnk->wr_tx_bufs);
+ lnk->wr_tx_bufs = NULL;
+ kfree(lnk->wr_rx_bufs);
+ lnk->wr_rx_bufs = NULL;
+}
+
+int smc_wr_alloc_link_mem(struct smc_link *link)
+{
+ /* allocate link related memory */
+ link->wr_tx_bufs = kcalloc(SMC_WR_BUF_CNT, SMC_WR_BUF_SIZE, GFP_KERNEL);
+ if (!link->wr_tx_bufs)
+ goto no_mem;
+ link->wr_rx_bufs = kcalloc(SMC_WR_BUF_CNT * 3, SMC_WR_BUF_SIZE,
+ GFP_KERNEL);
+ if (!link->wr_rx_bufs)
+ goto no_mem_wr_tx_bufs;
+ link->wr_tx_ibs = kcalloc(SMC_WR_BUF_CNT, sizeof(link->wr_tx_ibs[0]),
+ GFP_KERNEL);
+ if (!link->wr_tx_ibs)
+ goto no_mem_wr_rx_bufs;
+ link->wr_rx_ibs = kcalloc(SMC_WR_BUF_CNT * 3,
+ sizeof(link->wr_rx_ibs[0]),
+ GFP_KERNEL);
+ if (!link->wr_rx_ibs)
+ goto no_mem_wr_tx_ibs;
+ link->wr_tx_sges = kcalloc(SMC_WR_BUF_CNT, sizeof(link->wr_tx_sges[0]),
+ GFP_KERNEL);
+ if (!link->wr_tx_sges)
+ goto no_mem_wr_rx_ibs;
+ link->wr_rx_sges = kcalloc(SMC_WR_BUF_CNT * 3,
+ sizeof(link->wr_rx_sges[0]),
+ GFP_KERNEL);
+ if (!link->wr_rx_sges)
+ goto no_mem_wr_tx_sges;
+ link->wr_tx_mask = kzalloc(
+ BITS_TO_LONGS(SMC_WR_BUF_CNT) * sizeof(*link->wr_tx_mask),
+ GFP_KERNEL);
+ if (!link->wr_tx_mask)
+ goto no_mem_wr_rx_sges;
+ link->wr_tx_pends = kcalloc(SMC_WR_BUF_CNT,
+ sizeof(link->wr_tx_pends[0]),
+ GFP_KERNEL);
+ if (!link->wr_tx_pends)
+ goto no_mem_wr_tx_mask;
+ return 0;
+
+no_mem_wr_tx_mask:
+ kfree(link->wr_tx_mask);
+no_mem_wr_rx_sges:
+ kfree(link->wr_rx_sges);
+no_mem_wr_tx_sges:
+ kfree(link->wr_tx_sges);
+no_mem_wr_rx_ibs:
+ kfree(link->wr_rx_ibs);
+no_mem_wr_tx_ibs:
+ kfree(link->wr_tx_ibs);
+no_mem_wr_rx_bufs:
+ kfree(link->wr_rx_bufs);
+no_mem_wr_tx_bufs:
+ kfree(link->wr_tx_bufs);
+no_mem:
+ return -ENOMEM;
+}
+
+void smc_wr_remove_dev(struct smc_ib_device *smcibdev)
+{
+ tasklet_kill(&smcibdev->recv_tasklet);
+ tasklet_kill(&smcibdev->send_tasklet);
+}
+
+void smc_wr_add_dev(struct smc_ib_device *smcibdev)
+{
+ tasklet_init(&smcibdev->recv_tasklet, smc_wr_rx_tasklet_fn,
+ (unsigned long)smcibdev);
+ tasklet_init(&smcibdev->send_tasklet, smc_wr_tx_tasklet_fn,
+ (unsigned long)smcibdev);
+}
+
+int smc_wr_create_link(struct smc_link *lnk)
+{
+ struct ib_device *ibdev = lnk->smcibdev->ibdev;
+ int rc = 0;
+
+ smc_wr_tx_set_wr_id(&lnk->wr_tx_id, 0);
+ lnk->wr_rx_id = 0;
+ lnk->wr_rx_dma_addr = ib_dma_map_single(
+ ibdev, lnk->wr_rx_bufs, SMC_WR_BUF_SIZE * lnk->wr_rx_cnt,
+ DMA_FROM_DEVICE);
+ if (ib_dma_mapping_error(ibdev, lnk->wr_rx_dma_addr)) {
+ lnk->wr_rx_dma_addr = 0;
+ rc = -EIO;
+ goto out;
+ }
+ lnk->wr_tx_dma_addr = ib_dma_map_single(
+ ibdev, lnk->wr_tx_bufs, SMC_WR_BUF_SIZE * lnk->wr_tx_cnt,
+ DMA_TO_DEVICE);
+ if (ib_dma_mapping_error(ibdev, lnk->wr_tx_dma_addr)) {
+ rc = -EIO;
+ goto dma_unmap;
+ }
+ smc_wr_init_sge(lnk);
+ memset(lnk->wr_tx_mask, 0,
+ BITS_TO_LONGS(SMC_WR_BUF_CNT) * sizeof(*lnk->wr_tx_mask));
+ return rc;
+
+dma_unmap:
+ ib_dma_unmap_single(ibdev, lnk->wr_rx_dma_addr,
+ SMC_WR_BUF_SIZE * lnk->wr_rx_cnt,
+ DMA_FROM_DEVICE);
+ lnk->wr_rx_dma_addr = 0;
+out:
+ return rc;
+}
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