Introduce Virtio-loopback epsilon release:

Epsilon release introduces a new compatibility layer which make virtio-loopback
design to work with QEMU and rust-vmm vhost-user backend without require any
changes.

Signed-off-by: Timos Ampelikiotis <t.ampelikiotis@virtualopensystems.com>
Change-Id: I52e57563e08a7d0bdc002f8e928ee61ba0c53dd9

1 files changed, 1401 insertions, 0 deletions

diff --git a/hw/rdma/rdma_backend.c b/hw/rdma/rdma_backend.c
new file mode 100644
index 000000000..6dcdfbbbe
--- /dev/null
+++ b/hw/rdma/rdma_backend.c
@@ -0,0 +1,1401 @@
+/*
+ * QEMU paravirtual RDMA - Generic RDMA backend
+ *
+ * Copyright (C) 2018 Oracle
+ * Copyright (C) 2018 Red Hat Inc
+ *
+ * Authors:
+ *     Yuval Shaia <yuval.shaia@oracle.com>
+ *     Marcel Apfelbaum <marcel@redhat.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ *
+ */
+
+#include "qemu/osdep.h"
+#include "qapi/qapi-events-rdma.h"
+
+#include <infiniband/verbs.h>
+
+#include "contrib/rdmacm-mux/rdmacm-mux.h"
+#include "trace.h"
+#include "rdma_utils.h"
+#include "rdma_rm.h"
+#include "rdma_backend.h"
+
+#define THR_NAME_LEN 16
+#define THR_POLL_TO  5000
+
+#define MAD_HDR_SIZE sizeof(struct ibv_grh)
+
+typedef struct BackendCtx {
+    void *up_ctx;
+    struct ibv_sge sge; /* Used to save MAD recv buffer */
+    RdmaBackendQP *backend_qp; /* To maintain recv buffers */
+    RdmaBackendSRQ *backend_srq;
+} BackendCtx;
+
+struct backend_umad {
+    struct ib_user_mad hdr;
+    char mad[RDMA_MAX_PRIVATE_DATA];
+};
+
+static void (*comp_handler)(void *ctx, struct ibv_wc *wc);
+
+static void dummy_comp_handler(void *ctx, struct ibv_wc *wc)
+{
+    rdma_error_report("No completion handler is registered");
+}
+
+static inline void complete_work(enum ibv_wc_status status, uint32_t vendor_err,
+                                 void *ctx)
+{
+    struct ibv_wc wc = {};
+
+    wc.status = status;
+    wc.vendor_err = vendor_err;
+
+    comp_handler(ctx, &wc);
+}
+
+static void free_cqe_ctx(gpointer data, gpointer user_data)
+{
+    BackendCtx *bctx;
+    RdmaDeviceResources *rdma_dev_res = user_data;
+    unsigned long cqe_ctx_id = GPOINTER_TO_INT(data);
+
+    bctx = rdma_rm_get_cqe_ctx(rdma_dev_res, cqe_ctx_id);
+    if (bctx) {
+        rdma_rm_dealloc_cqe_ctx(rdma_dev_res, cqe_ctx_id);
+        qatomic_dec(&rdma_dev_res->stats.missing_cqe);
+    }
+    g_free(bctx);
+}
+
+static void clean_recv_mads(RdmaBackendDev *backend_dev)
+{
+    unsigned long cqe_ctx_id;
+
+    do {
+        cqe_ctx_id = rdma_protected_gqueue_pop_int64(&backend_dev->
+                                                    recv_mads_list);
+        if (cqe_ctx_id != -ENOENT) {
+            qatomic_inc(&backend_dev->rdma_dev_res->stats.missing_cqe);
+            free_cqe_ctx(GINT_TO_POINTER(cqe_ctx_id),
+                         backend_dev->rdma_dev_res);
+        }
+    } while (cqe_ctx_id != -ENOENT);
+}
+
+static int rdma_poll_cq(RdmaDeviceResources *rdma_dev_res, struct ibv_cq *ibcq)
+{
+    int i, ne, total_ne = 0;
+    BackendCtx *bctx;
+    struct ibv_wc wc[2];
+    RdmaProtectedGSList *cqe_ctx_list;
+
+    WITH_QEMU_LOCK_GUARD(&rdma_dev_res->lock) {
+        do {
+            ne = ibv_poll_cq(ibcq, ARRAY_SIZE(wc), wc);
+
+            trace_rdma_poll_cq(ne, ibcq);
+
+            for (i = 0; i < ne; i++) {
+                bctx = rdma_rm_get_cqe_ctx(rdma_dev_res, wc[i].wr_id);
+                if (unlikely(!bctx)) {
+                    rdma_error_report("No matching ctx for req %"PRId64,
+                                      wc[i].wr_id);
+                    continue;
+                }
+
+                comp_handler(bctx->up_ctx, &wc[i]);
+
+                if (bctx->backend_qp) {
+                    cqe_ctx_list = &bctx->backend_qp->cqe_ctx_list;
+                } else {
+                    cqe_ctx_list = &bctx->backend_srq->cqe_ctx_list;
+                }
+
+                rdma_protected_gslist_remove_int32(cqe_ctx_list, wc[i].wr_id);
+                rdma_rm_dealloc_cqe_ctx(rdma_dev_res, wc[i].wr_id);
+                g_free(bctx);
+            }
+            total_ne += ne;
+        } while (ne > 0);
+        qatomic_sub(&rdma_dev_res->stats.missing_cqe, total_ne);
+    }
+
+    if (ne < 0) {
+        rdma_error_report("ibv_poll_cq fail, rc=%d, errno=%d", ne, errno);
+    }
+
+    rdma_dev_res->stats.completions += total_ne;
+
+    return total_ne;
+}
+
+static void *comp_handler_thread(void *arg)
+{
+    RdmaBackendDev *backend_dev = (RdmaBackendDev *)arg;
+    int rc;
+    struct ibv_cq *ev_cq;
+    void *ev_ctx;
+    int flags;
+    GPollFD pfds[1];
+
+    /* Change to non-blocking mode */
+    flags = fcntl(backend_dev->channel->fd, F_GETFL);
+    rc = fcntl(backend_dev->channel->fd, F_SETFL, flags | O_NONBLOCK);
+    if (rc < 0) {
+        rdma_error_report("Failed to change backend channel FD to non-blocking");
+        return NULL;
+    }
+
+    pfds[0].fd = backend_dev->channel->fd;
+    pfds[0].events = G_IO_IN | G_IO_HUP | G_IO_ERR;
+
+    backend_dev->comp_thread.is_running = true;
+
+    while (backend_dev->comp_thread.run) {
+        do {
+            rc = qemu_poll_ns(pfds, 1, THR_POLL_TO * (int64_t)SCALE_MS);
+            if (!rc) {
+                backend_dev->rdma_dev_res->stats.poll_cq_ppoll_to++;
+            }
+        } while (!rc && backend_dev->comp_thread.run);
+
+        if (backend_dev->comp_thread.run) {
+            rc = ibv_get_cq_event(backend_dev->channel, &ev_cq, &ev_ctx);
+            if (unlikely(rc)) {
+                rdma_error_report("ibv_get_cq_event fail, rc=%d, errno=%d", rc,
+                                  errno);
+                continue;
+            }
+
+            rc = ibv_req_notify_cq(ev_cq, 0);
+            if (unlikely(rc)) {
+                rdma_error_report("ibv_req_notify_cq fail, rc=%d, errno=%d", rc,
+                                  errno);
+            }
+
+            backend_dev->rdma_dev_res->stats.poll_cq_from_bk++;
+            rdma_poll_cq(backend_dev->rdma_dev_res, ev_cq);
+
+            ibv_ack_cq_events(ev_cq, 1);
+        }
+    }
+
+    backend_dev->comp_thread.is_running = false;
+
+    qemu_thread_exit(0);
+
+    return NULL;
+}
+
+static inline void disable_rdmacm_mux_async(RdmaBackendDev *backend_dev)
+{
+    qatomic_set(&backend_dev->rdmacm_mux.can_receive, 0);
+}
+
+static inline void enable_rdmacm_mux_async(RdmaBackendDev *backend_dev)
+{
+    qatomic_set(&backend_dev->rdmacm_mux.can_receive, sizeof(RdmaCmMuxMsg));
+}
+
+static inline int rdmacm_mux_can_process_async(RdmaBackendDev *backend_dev)
+{
+    return qatomic_read(&backend_dev->rdmacm_mux.can_receive);
+}
+
+static int rdmacm_mux_check_op_status(CharBackend *mad_chr_be)
+{
+    RdmaCmMuxMsg msg = {};
+    int ret;
+
+    ret = qemu_chr_fe_read_all(mad_chr_be, (uint8_t *)&msg, sizeof(msg));
+    if (ret != sizeof(msg)) {
+        rdma_error_report("Got invalid message from mux: size %d, expecting %d",
+                          ret, (int)sizeof(msg));
+        return -EIO;
+    }
+
+    trace_rdmacm_mux_check_op_status(msg.hdr.msg_type, msg.hdr.op_code,
+                                     msg.hdr.err_code);
+
+    if (msg.hdr.msg_type != RDMACM_MUX_MSG_TYPE_RESP) {
+        rdma_error_report("Got invalid message type %d", msg.hdr.msg_type);
+        return -EIO;
+    }
+
+    if (msg.hdr.err_code != RDMACM_MUX_ERR_CODE_OK) {
+        rdma_error_report("Operation failed in mux, error code %d",
+                          msg.hdr.err_code);
+        return -EIO;
+    }
+
+    return 0;
+}
+
+static int rdmacm_mux_send(RdmaBackendDev *backend_dev, RdmaCmMuxMsg *msg)
+{
+    int rc = 0;
+
+    msg->hdr.msg_type = RDMACM_MUX_MSG_TYPE_REQ;
+    trace_rdmacm_mux("send", msg->hdr.msg_type, msg->hdr.op_code);
+    disable_rdmacm_mux_async(backend_dev);
+    rc = qemu_chr_fe_write(backend_dev->rdmacm_mux.chr_be,
+                           (const uint8_t *)msg, sizeof(*msg));
+    if (rc != sizeof(*msg)) {
+        enable_rdmacm_mux_async(backend_dev);
+        rdma_error_report("Failed to send request to rdmacm_mux (rc=%d)", rc);
+        return -EIO;
+    }
+
+    rc = rdmacm_mux_check_op_status(backend_dev->rdmacm_mux.chr_be);
+    if (rc) {
+        rdma_error_report("Failed to execute rdmacm_mux request %d (rc=%d)",
+                          msg->hdr.op_code, rc);
+    }
+
+    enable_rdmacm_mux_async(backend_dev);
+
+    return 0;
+}
+
+static void stop_backend_thread(RdmaBackendThread *thread)
+{
+    thread->run = false;
+    while (thread->is_running) {
+        sleep(THR_POLL_TO / SCALE_US / 2);
+    }
+}
+
+static void start_comp_thread(RdmaBackendDev *backend_dev)
+{
+    char thread_name[THR_NAME_LEN] = {};
+
+    stop_backend_thread(&backend_dev->comp_thread);
+
+    snprintf(thread_name, sizeof(thread_name), "rdma_comp_%s",
+             ibv_get_device_name(backend_dev->ib_dev));
+    backend_dev->comp_thread.run = true;
+    qemu_thread_create(&backend_dev->comp_thread.thread, thread_name,
+                       comp_handler_thread, backend_dev, QEMU_THREAD_DETACHED);
+}
+
+void rdma_backend_register_comp_handler(void (*handler)(void *ctx,
+                                                         struct ibv_wc *wc))
+{
+    comp_handler = handler;
+}
+
+void rdma_backend_unregister_comp_handler(void)
+{
+    rdma_backend_register_comp_handler(dummy_comp_handler);
+}
+
+int rdma_backend_query_port(RdmaBackendDev *backend_dev,
+                            struct ibv_port_attr *port_attr)
+{
+    int rc;
+
+    rc = ibv_query_port(backend_dev->context, backend_dev->port_num, port_attr);
+    if (rc) {
+        rdma_error_report("ibv_query_port fail, rc=%d, errno=%d", rc, errno);
+        return -EIO;
+    }
+
+    return 0;
+}
+
+void rdma_backend_poll_cq(RdmaDeviceResources *rdma_dev_res, RdmaBackendCQ *cq)
+{
+    int polled;
+
+    rdma_dev_res->stats.poll_cq_from_guest++;
+    polled = rdma_poll_cq(rdma_dev_res, cq->ibcq);
+    if (!polled) {
+        rdma_dev_res->stats.poll_cq_from_guest_empty++;
+    }
+}
+
+static GHashTable *ah_hash;
+
+static struct ibv_ah *create_ah(RdmaBackendDev *backend_dev, struct ibv_pd *pd,
+                                uint8_t sgid_idx, union ibv_gid *dgid)
+{
+    GBytes *ah_key = g_bytes_new(dgid, sizeof(*dgid));
+    struct ibv_ah *ah = g_hash_table_lookup(ah_hash, ah_key);
+
+    if (ah) {
+        trace_rdma_create_ah_cache_hit(be64_to_cpu(dgid->global.subnet_prefix),
+                                       be64_to_cpu(dgid->global.interface_id));
+        g_bytes_unref(ah_key);
+    } else {
+        struct ibv_ah_attr ah_attr = {
+            .is_global     = 1,
+            .port_num      = backend_dev->port_num,
+            .grh.hop_limit = 1,
+        };
+
+        ah_attr.grh.dgid = *dgid;
+        ah_attr.grh.sgid_index = sgid_idx;
+
+        ah = ibv_create_ah(pd, &ah_attr);
+        if (ah) {
+            g_hash_table_insert(ah_hash, ah_key, ah);
+        } else {
+            g_bytes_unref(ah_key);
+            rdma_error_report("Failed to create AH for gid <0x%" PRIx64", 0x%"PRIx64">",
+                              be64_to_cpu(dgid->global.subnet_prefix),
+                              be64_to_cpu(dgid->global.interface_id));
+        }
+
+        trace_rdma_create_ah_cache_miss(be64_to_cpu(dgid->global.subnet_prefix),
+                                        be64_to_cpu(dgid->global.interface_id));
+    }
+
+    return ah;
+}
+
+static void destroy_ah_hash_key(gpointer data)
+{
+    g_bytes_unref(data);
+}
+
+static void destroy_ah_hast_data(gpointer data)
+{
+    struct ibv_ah *ah = data;
+
+    ibv_destroy_ah(ah);
+}
+
+static void ah_cache_init(void)
+{
+    ah_hash = g_hash_table_new_full(g_bytes_hash, g_bytes_equal,
+                                    destroy_ah_hash_key, destroy_ah_hast_data);
+}
+
+#ifdef LEGACY_RDMA_REG_MR
+static int build_host_sge_array(RdmaDeviceResources *rdma_dev_res,
+                                struct ibv_sge *sge, uint8_t num_sge,
+                                uint64_t *total_length)
+{
+    RdmaRmMR *mr;
+    int idx;
+
+    for (idx = 0; idx < num_sge; idx++) {
+        mr = rdma_rm_get_mr(rdma_dev_res, sge[idx].lkey);
+        if (unlikely(!mr)) {
+            rdma_error_report("Invalid lkey 0x%x", sge[idx].lkey);
+            return VENDOR_ERR_INVLKEY | sge[idx].lkey;
+        }
+
+        sge[idx].addr = (uintptr_t)mr->virt + sge[idx].addr - mr->start;
+        sge[idx].lkey = rdma_backend_mr_lkey(&mr->backend_mr);
+
+        *total_length += sge[idx].length;
+    }
+
+    return 0;
+}
+#else
+static inline int build_host_sge_array(RdmaDeviceResources *rdma_dev_res,
+                                       struct ibv_sge *sge, uint8_t num_sge,
+                                       uint64_t *total_length)
+{
+    int idx;
+
+    for (idx = 0; idx < num_sge; idx++) {
+        *total_length += sge[idx].length;
+    }
+    return 0;
+}
+#endif
+
+static void trace_mad_message(const char *title, char *buf, int len)
+{
+    int i;
+    char *b = g_malloc0(len * 3 + 1);
+    char b1[4];
+
+    for (i = 0; i < len; i++) {
+        sprintf(b1, "%.2X ", buf[i] & 0x000000FF);
+        strcat(b, b1);
+    }
+
+    trace_rdma_mad_message(title, len, b);
+
+    g_free(b);
+}
+
+static int mad_send(RdmaBackendDev *backend_dev, uint8_t sgid_idx,
+                    union ibv_gid *sgid, struct ibv_sge *sge, uint32_t num_sge)
+{
+    RdmaCmMuxMsg msg = {};
+    char *hdr, *data;
+    int ret;
+
+    if (num_sge != 2) {
+        return -EINVAL;
+    }
+
+    msg.hdr.op_code = RDMACM_MUX_OP_CODE_MAD;
+    memcpy(msg.hdr.sgid.raw, sgid->raw, sizeof(msg.hdr.sgid));
+
+    msg.umad_len = sge[0].length + sge[1].length;
+
+    if (msg.umad_len > sizeof(msg.umad.mad)) {
+        return -ENOMEM;
+    }
+
+    msg.umad.hdr.addr.qpn = htobe32(1);
+    msg.umad.hdr.addr.grh_present = 1;
+    msg.umad.hdr.addr.gid_index = sgid_idx;
+    memcpy(msg.umad.hdr.addr.gid, sgid->raw, sizeof(msg.umad.hdr.addr.gid));
+    msg.umad.hdr.addr.hop_limit = 0xFF;
+
+    hdr = rdma_pci_dma_map(backend_dev->dev, sge[0].addr, sge[0].length);
+    if (!hdr) {
+        return -ENOMEM;
+    }
+    data = rdma_pci_dma_map(backend_dev->dev, sge[1].addr, sge[1].length);
+    if (!data) {
+        rdma_pci_dma_unmap(backend_dev->dev, hdr, sge[0].length);
+        return -ENOMEM;
+    }
+
+    memcpy(&msg.umad.mad[0], hdr, sge[0].length);
+    memcpy(&msg.umad.mad[sge[0].length], data, sge[1].length);
+
+    rdma_pci_dma_unmap(backend_dev->dev, data, sge[1].length);
+    rdma_pci_dma_unmap(backend_dev->dev, hdr, sge[0].length);
+
+    trace_mad_message("send", msg.umad.mad, msg.umad_len);
+
+    ret = rdmacm_mux_send(backend_dev, &msg);
+    if (ret) {
+        rdma_error_report("Failed to send MAD to rdma_umadmux (%d)", ret);
+        return -EIO;
+    }
+
+    return 0;
+}
+
+void rdma_backend_post_send(RdmaBackendDev *backend_dev,
+                            RdmaBackendQP *qp, uint8_t qp_type,
+                            struct ibv_sge *sge, uint32_t num_sge,
+                            uint8_t sgid_idx, union ibv_gid *sgid,
+                            union ibv_gid *dgid, uint32_t dqpn, uint32_t dqkey,
+                            void *ctx)
+{
+    BackendCtx *bctx;
+    uint32_t bctx_id;
+    int rc;
+    struct ibv_send_wr wr = {}, *bad_wr;
+
+    if (!qp->ibqp) { /* This field is not initialized for QP0 and QP1 */
+        if (qp_type == IBV_QPT_SMI) {
+            rdma_error_report("Got QP0 request");
+            complete_work(IBV_WC_GENERAL_ERR, VENDOR_ERR_QP0, ctx);
+        } else if (qp_type == IBV_QPT_GSI) {
+            rc = mad_send(backend_dev, sgid_idx, sgid, sge, num_sge);
+            if (rc) {
+                complete_work(IBV_WC_GENERAL_ERR, VENDOR_ERR_MAD_SEND, ctx);
+                backend_dev->rdma_dev_res->stats.mad_tx_err++;
+            } else {
+                complete_work(IBV_WC_SUCCESS, 0, ctx);
+                backend_dev->rdma_dev_res->stats.mad_tx++;
+            }
+        }
+        return;
+    }
+
+    bctx = g_malloc0(sizeof(*bctx));
+    bctx->up_ctx = ctx;
+    bctx->backend_qp = qp;
+
+    rc = rdma_rm_alloc_cqe_ctx(backend_dev->rdma_dev_res, &bctx_id, bctx);
+    if (unlikely(rc)) {
+        complete_work(IBV_WC_GENERAL_ERR, VENDOR_ERR_NOMEM, ctx);
+        goto err_free_bctx;
+    }
+
+    rdma_protected_gslist_append_int32(&qp->cqe_ctx_list, bctx_id);
+
+    rc = build_host_sge_array(backend_dev->rdma_dev_res, sge, num_sge,
+                              &backend_dev->rdma_dev_res->stats.tx_len);
+    if (rc) {
+        complete_work(IBV_WC_GENERAL_ERR, rc, ctx);
+        goto err_dealloc_cqe_ctx;
+    }
+
+    if (qp_type == IBV_QPT_UD) {
+        wr.wr.ud.ah = create_ah(backend_dev, qp->ibpd, sgid_idx, dgid);
+        if (!wr.wr.ud.ah) {
+            complete_work(IBV_WC_GENERAL_ERR, VENDOR_ERR_FAIL_BACKEND, ctx);
+            goto err_dealloc_cqe_ctx;
+        }
+        wr.wr.ud.remote_qpn = dqpn;
+        wr.wr.ud.remote_qkey = dqkey;
+    }
+
+    wr.num_sge = num_sge;
+    wr.opcode = IBV_WR_SEND;
+    wr.send_flags = IBV_SEND_SIGNALED;
+    wr.sg_list = sge;
+    wr.wr_id = bctx_id;
+
+    rc = ibv_post_send(qp->ibqp, &wr, &bad_wr);
+    if (rc) {
+        rdma_error_report("ibv_post_send fail, qpn=0x%x, rc=%d, errno=%d",
+                          qp->ibqp->qp_num, rc, errno);
+        complete_work(IBV_WC_GENERAL_ERR, VENDOR_ERR_FAIL_BACKEND, ctx);
+        goto err_dealloc_cqe_ctx;
+    }
+
+    qatomic_inc(&backend_dev->rdma_dev_res->stats.missing_cqe);
+    backend_dev->rdma_dev_res->stats.tx++;
+
+    return;
+
+err_dealloc_cqe_ctx:
+    backend_dev->rdma_dev_res->stats.tx_err++;
+    rdma_rm_dealloc_cqe_ctx(backend_dev->rdma_dev_res, bctx_id);
+
+err_free_bctx:
+    g_free(bctx);
+}
+
+static unsigned int save_mad_recv_buffer(RdmaBackendDev *backend_dev,
+                                         struct ibv_sge *sge, uint32_t num_sge,
+                                         void *ctx)
+{
+    BackendCtx *bctx;
+    int rc;
+    uint32_t bctx_id;
+
+    if (num_sge != 1) {
+        rdma_error_report("Invalid num_sge (%d), expecting 1", num_sge);
+        return VENDOR_ERR_INV_NUM_SGE;
+    }
+
+    if (sge[0].length < RDMA_MAX_PRIVATE_DATA + sizeof(struct ibv_grh)) {
+        rdma_error_report("Too small buffer for MAD");
+        return VENDOR_ERR_INV_MAD_BUFF;
+    }
+
+    bctx = g_malloc0(sizeof(*bctx));
+
+    rc = rdma_rm_alloc_cqe_ctx(backend_dev->rdma_dev_res, &bctx_id, bctx);
+    if (unlikely(rc)) {
+        g_free(bctx);
+        return VENDOR_ERR_NOMEM;
+    }
+
+    bctx->up_ctx = ctx;
+    bctx->sge = *sge;
+
+    rdma_protected_gqueue_append_int64(&backend_dev->recv_mads_list, bctx_id);
+
+    return 0;
+}
+
+void rdma_backend_post_recv(RdmaBackendDev *backend_dev,
+                            RdmaBackendQP *qp, uint8_t qp_type,
+                            struct ibv_sge *sge, uint32_t num_sge, void *ctx)
+{
+    BackendCtx *bctx;
+    uint32_t bctx_id;
+    int rc;
+    struct ibv_recv_wr wr = {}, *bad_wr;
+
+    if (!qp->ibqp) { /* This field does not get initialized for QP0 and QP1 */
+        if (qp_type == IBV_QPT_SMI) {
+            rdma_error_report("Got QP0 request");
+            complete_work(IBV_WC_GENERAL_ERR, VENDOR_ERR_QP0, ctx);
+        }
+        if (qp_type == IBV_QPT_GSI) {
+            rc = save_mad_recv_buffer(backend_dev, sge, num_sge, ctx);
+            if (rc) {
+                complete_work(IBV_WC_GENERAL_ERR, rc, ctx);
+                backend_dev->rdma_dev_res->stats.mad_rx_bufs_err++;
+            } else {
+                backend_dev->rdma_dev_res->stats.mad_rx_bufs++;
+            }
+        }
+        return;
+    }
+
+    bctx = g_malloc0(sizeof(*bctx));
+    bctx->up_ctx = ctx;
+    bctx->backend_qp = qp;
+
+    rc = rdma_rm_alloc_cqe_ctx(backend_dev->rdma_dev_res, &bctx_id, bctx);
+    if (unlikely(rc)) {
+        complete_work(IBV_WC_GENERAL_ERR, VENDOR_ERR_NOMEM, ctx);
+        goto err_free_bctx;
+    }
+
+    rdma_protected_gslist_append_int32(&qp->cqe_ctx_list, bctx_id);
+
+    rc = build_host_sge_array(backend_dev->rdma_dev_res, sge, num_sge,
+                              &backend_dev->rdma_dev_res->stats.rx_bufs_len);
+    if (rc) {
+        complete_work(IBV_WC_GENERAL_ERR, rc, ctx);
+        goto err_dealloc_cqe_ctx;
+    }
+
+    wr.num_sge = num_sge;
+    wr.sg_list = sge;
+    wr.wr_id = bctx_id;
+    rc = ibv_post_recv(qp->ibqp, &wr, &bad_wr);
+    if (rc) {
+        rdma_error_report("ibv_post_recv fail, qpn=0x%x, rc=%d, errno=%d",
+                          qp->ibqp->qp_num, rc, errno);
+        complete_work(IBV_WC_GENERAL_ERR, VENDOR_ERR_FAIL_BACKEND, ctx);
+        goto err_dealloc_cqe_ctx;
+    }
+
+    qatomic_inc(&backend_dev->rdma_dev_res->stats.missing_cqe);
+    backend_dev->rdma_dev_res->stats.rx_bufs++;
+
+    return;
+
+err_dealloc_cqe_ctx:
+    backend_dev->rdma_dev_res->stats.rx_bufs_err++;
+    rdma_rm_dealloc_cqe_ctx(backend_dev->rdma_dev_res, bctx_id);
+
+err_free_bctx:
+    g_free(bctx);
+}
+
+void rdma_backend_post_srq_recv(RdmaBackendDev *backend_dev,
+                                RdmaBackendSRQ *srq, struct ibv_sge *sge,
+                                uint32_t num_sge, void *ctx)
+{
+    BackendCtx *bctx;
+    uint32_t bctx_id;
+    int rc;
+    struct ibv_recv_wr wr = {}, *bad_wr;
+
+    bctx = g_malloc0(sizeof(*bctx));
+    bctx->up_ctx = ctx;
+    bctx->backend_srq = srq;
+
+    rc = rdma_rm_alloc_cqe_ctx(backend_dev->rdma_dev_res, &bctx_id, bctx);
+    if (unlikely(rc)) {
+        complete_work(IBV_WC_GENERAL_ERR, VENDOR_ERR_NOMEM, ctx);
+        goto err_free_bctx;
+    }
+
+    rdma_protected_gslist_append_int32(&srq->cqe_ctx_list, bctx_id);
+
+    rc = build_host_sge_array(backend_dev->rdma_dev_res, sge, num_sge,
+                              &backend_dev->rdma_dev_res->stats.rx_bufs_len);
+    if (rc) {
+        complete_work(IBV_WC_GENERAL_ERR, rc, ctx);
+        goto err_dealloc_cqe_ctx;
+    }
+
+    wr.num_sge = num_sge;
+    wr.sg_list = sge;
+    wr.wr_id = bctx_id;
+    rc = ibv_post_srq_recv(srq->ibsrq, &wr, &bad_wr);
+    if (rc) {
+        rdma_error_report("ibv_post_srq_recv fail, srqn=0x%x, rc=%d, errno=%d",
+                          srq->ibsrq->handle, rc, errno);
+        complete_work(IBV_WC_GENERAL_ERR, VENDOR_ERR_FAIL_BACKEND, ctx);
+        goto err_dealloc_cqe_ctx;
+    }
+
+    qatomic_inc(&backend_dev->rdma_dev_res->stats.missing_cqe);
+    backend_dev->rdma_dev_res->stats.rx_bufs++;
+    backend_dev->rdma_dev_res->stats.rx_srq++;
+
+    return;
+
+err_dealloc_cqe_ctx:
+    backend_dev->rdma_dev_res->stats.rx_bufs_err++;
+    rdma_rm_dealloc_cqe_ctx(backend_dev->rdma_dev_res, bctx_id);
+
+err_free_bctx:
+    g_free(bctx);
+}
+
+int rdma_backend_create_pd(RdmaBackendDev *backend_dev, RdmaBackendPD *pd)
+{
+    pd->ibpd = ibv_alloc_pd(backend_dev->context);
+
+    if (!pd->ibpd) {
+        rdma_error_report("ibv_alloc_pd fail, errno=%d", errno);
+        return -EIO;
+    }
+
+    return 0;
+}
+
+void rdma_backend_destroy_pd(RdmaBackendPD *pd)
+{
+    if (pd->ibpd) {
+        ibv_dealloc_pd(pd->ibpd);
+    }
+}
+
+int rdma_backend_create_mr(RdmaBackendMR *mr, RdmaBackendPD *pd, void *addr,
+                           size_t length, uint64_t guest_start, int access)
+{
+#ifdef LEGACY_RDMA_REG_MR
+    mr->ibmr = ibv_reg_mr(pd->ibpd, addr, length, access);
+#else
+    mr->ibmr = ibv_reg_mr_iova(pd->ibpd, addr, length, guest_start, access);
+#endif
+    if (!mr->ibmr) {
+        rdma_error_report("ibv_reg_mr fail, errno=%d", errno);
+        return -EIO;
+    }
+
+    mr->ibpd = pd->ibpd;
+
+    return 0;
+}
+
+void rdma_backend_destroy_mr(RdmaBackendMR *mr)
+{
+    if (mr->ibmr) {
+        ibv_dereg_mr(mr->ibmr);
+    }
+}
+
+int rdma_backend_create_cq(RdmaBackendDev *backend_dev, RdmaBackendCQ *cq,
+                           int cqe)
+{
+    int rc;
+
+    cq->ibcq = ibv_create_cq(backend_dev->context, cqe + 1, NULL,
+                             backend_dev->channel, 0);
+    if (!cq->ibcq) {
+        rdma_error_report("ibv_create_cq fail, errno=%d", errno);
+        return -EIO;
+    }
+
+    rc = ibv_req_notify_cq(cq->ibcq, 0);
+    if (rc) {
+        rdma_warn_report("ibv_req_notify_cq fail, rc=%d, errno=%d", rc, errno);
+    }
+
+    cq->backend_dev = backend_dev;
+
+    return 0;
+}
+
+void rdma_backend_destroy_cq(RdmaBackendCQ *cq)
+{
+    if (cq->ibcq) {
+        ibv_destroy_cq(cq->ibcq);
+    }
+}
+
+int rdma_backend_create_qp(RdmaBackendQP *qp, uint8_t qp_type,
+                           RdmaBackendPD *pd, RdmaBackendCQ *scq,
+                           RdmaBackendCQ *rcq, RdmaBackendSRQ *srq,
+                           uint32_t max_send_wr, uint32_t max_recv_wr,
+                           uint32_t max_send_sge, uint32_t max_recv_sge)
+{
+    struct ibv_qp_init_attr attr = {};
+
+    qp->ibqp = 0;
+
+    switch (qp_type) {
+    case IBV_QPT_GSI:
+        return 0;
+
+    case IBV_QPT_RC:
+        /* fall through */
+    case IBV_QPT_UD:
+        /* do nothing */
+        break;
+
+    default:
+        rdma_error_report("Unsupported QP type %d", qp_type);
+        return -EIO;
+    }
+
+    attr.qp_type = qp_type;
+    attr.send_cq = scq->ibcq;
+    attr.recv_cq = rcq->ibcq;
+    attr.cap.max_send_wr = max_send_wr;
+    attr.cap.max_recv_wr = max_recv_wr;
+    attr.cap.max_send_sge = max_send_sge;
+    attr.cap.max_recv_sge = max_recv_sge;
+    if (srq) {
+        attr.srq = srq->ibsrq;
+    }
+
+    qp->ibqp = ibv_create_qp(pd->ibpd, &attr);
+    if (!qp->ibqp) {
+        rdma_error_report("ibv_create_qp fail, errno=%d", errno);
+        return -EIO;
+    }
+
+    rdma_protected_gslist_init(&qp->cqe_ctx_list);
+
+    qp->ibpd = pd->ibpd;
+
+    /* TODO: Query QP to get max_inline_data and save it to be used in send */
+
+    return 0;
+}
+
+int rdma_backend_qp_state_init(RdmaBackendDev *backend_dev, RdmaBackendQP *qp,
+                               uint8_t qp_type, uint32_t qkey)
+{
+    struct ibv_qp_attr attr = {};
+    int rc, attr_mask;
+
+    attr_mask = IBV_QP_STATE | IBV_QP_PKEY_INDEX | IBV_QP_PORT;
+    attr.qp_state        = IBV_QPS_INIT;
+    attr.pkey_index      = 0;
+    attr.port_num        = backend_dev->port_num;
+
+    switch (qp_type) {
+    case IBV_QPT_RC:
+        attr_mask |= IBV_QP_ACCESS_FLAGS;
+        trace_rdma_backend_rc_qp_state_init(qp->ibqp->qp_num);
+        break;
+
+    case IBV_QPT_UD:
+        attr.qkey = qkey;
+        attr_mask |= IBV_QP_QKEY;
+        trace_rdma_backend_ud_qp_state_init(qp->ibqp->qp_num, qkey);
+        break;
+
+    default:
+        rdma_error_report("Unsupported QP type %d", qp_type);
+        return -EIO;
+    }
+
+    rc = ibv_modify_qp(qp->ibqp, &attr, attr_mask);
+    if (rc) {
+        rdma_error_report("ibv_modify_qp fail, rc=%d, errno=%d", rc, errno);
+        return -EIO;
+    }
+
+    return 0;
+}
+
+int rdma_backend_qp_state_rtr(RdmaBackendDev *backend_dev, RdmaBackendQP *qp,
+                              uint8_t qp_type, uint8_t sgid_idx,
+                              union ibv_gid *dgid, uint32_t dqpn,
+                              uint32_t rq_psn, uint32_t qkey, bool use_qkey)
+{
+    struct ibv_qp_attr attr = {};
+    union ibv_gid ibv_gid = {
+        .global.interface_id = dgid->global.interface_id,
+        .global.subnet_prefix = dgid->global.subnet_prefix
+    };
+    int rc, attr_mask;
+
+    attr.qp_state = IBV_QPS_RTR;
+    attr_mask = IBV_QP_STATE;
+
+    qp->sgid_idx = sgid_idx;
+
+    switch (qp_type) {
+    case IBV_QPT_RC:
+        attr.path_mtu               = IBV_MTU_1024;
+        attr.dest_qp_num            = dqpn;
+        attr.max_dest_rd_atomic     = 1;
+        attr.min_rnr_timer          = 12;
+        attr.ah_attr.port_num       = backend_dev->port_num;
+        attr.ah_attr.is_global      = 1;
+        attr.ah_attr.grh.hop_limit  = 1;
+        attr.ah_attr.grh.dgid       = ibv_gid;
+        attr.ah_attr.grh.sgid_index = qp->sgid_idx;
+        attr.rq_psn                 = rq_psn;
+
+        attr_mask |= IBV_QP_AV | IBV_QP_PATH_MTU | IBV_QP_DEST_QPN |
+                     IBV_QP_RQ_PSN | IBV_QP_MAX_DEST_RD_ATOMIC |
+                     IBV_QP_MIN_RNR_TIMER;
+
+        trace_rdma_backend_rc_qp_state_rtr(qp->ibqp->qp_num,
+                                           be64_to_cpu(ibv_gid.global.
+                                                       subnet_prefix),
+                                           be64_to_cpu(ibv_gid.global.
+                                                       interface_id),
+                                           qp->sgid_idx, dqpn, rq_psn);
+        break;
+
+    case IBV_QPT_UD:
+        if (use_qkey) {
+            attr.qkey = qkey;
+            attr_mask |= IBV_QP_QKEY;
+        }
+        trace_rdma_backend_ud_qp_state_rtr(qp->ibqp->qp_num, use_qkey ? qkey :
+                                           0);
+        break;
+    }
+
+    rc = ibv_modify_qp(qp->ibqp, &attr, attr_mask);
+    if (rc) {
+        rdma_error_report("ibv_modify_qp fail, rc=%d, errno=%d", rc, errno);
+        return -EIO;
+    }
+
+    return 0;
+}
+
+int rdma_backend_qp_state_rts(RdmaBackendQP *qp, uint8_t qp_type,
+                              uint32_t sq_psn, uint32_t qkey, bool use_qkey)
+{
+    struct ibv_qp_attr attr = {};
+    int rc, attr_mask;
+
+    attr.qp_state = IBV_QPS_RTS;
+    attr.sq_psn = sq_psn;
+    attr_mask = IBV_QP_STATE | IBV_QP_SQ_PSN;
+
+    switch (qp_type) {
+    case IBV_QPT_RC:
+        attr.timeout       = 14;
+        attr.retry_cnt     = 7;
+        attr.rnr_retry     = 7;
+        attr.max_rd_atomic = 1;
+
+        attr_mask |= IBV_QP_TIMEOUT | IBV_QP_RETRY_CNT | IBV_QP_RNR_RETRY |
+                     IBV_QP_MAX_QP_RD_ATOMIC;
+        trace_rdma_backend_rc_qp_state_rts(qp->ibqp->qp_num, sq_psn);
+        break;
+
+    case IBV_QPT_UD:
+        if (use_qkey) {
+            attr.qkey = qkey;
+            attr_mask |= IBV_QP_QKEY;
+        }
+        trace_rdma_backend_ud_qp_state_rts(qp->ibqp->qp_num, sq_psn,
+                                           use_qkey ? qkey : 0);
+        break;
+    }
+
+    rc = ibv_modify_qp(qp->ibqp, &attr, attr_mask);
+    if (rc) {
+        rdma_error_report("ibv_modify_qp fail, rc=%d, errno=%d", rc, errno);
+        return -EIO;
+    }
+
+    return 0;
+}
+
+int rdma_backend_query_qp(RdmaBackendQP *qp, struct ibv_qp_attr *attr,
+                          int attr_mask, struct ibv_qp_init_attr *init_attr)
+{
+    if (!qp->ibqp) {
+        attr->qp_state = IBV_QPS_RTS;
+        return 0;
+    }
+
+    return ibv_query_qp(qp->ibqp, attr, attr_mask, init_attr);
+}
+
+void rdma_backend_destroy_qp(RdmaBackendQP *qp, RdmaDeviceResources *dev_res)
+{
+    if (qp->ibqp) {
+        ibv_destroy_qp(qp->ibqp);
+    }
+    g_slist_foreach(qp->cqe_ctx_list.list, free_cqe_ctx, dev_res);
+    rdma_protected_gslist_destroy(&qp->cqe_ctx_list);
+}
+
+int rdma_backend_create_srq(RdmaBackendSRQ *srq, RdmaBackendPD *pd,
+                            uint32_t max_wr, uint32_t max_sge,
+                            uint32_t srq_limit)
+{
+    struct ibv_srq_init_attr srq_init_attr = {};
+
+    srq_init_attr.attr.max_wr = max_wr;
+    srq_init_attr.attr.max_sge = max_sge;
+    srq_init_attr.attr.srq_limit = srq_limit;
+
+    srq->ibsrq = ibv_create_srq(pd->ibpd, &srq_init_attr);
+    if (!srq->ibsrq) {
+        rdma_error_report("ibv_create_srq failed, errno=%d", errno);
+        return -EIO;
+    }
+
+    rdma_protected_gslist_init(&srq->cqe_ctx_list);
+
+    return 0;
+}
+
+int rdma_backend_query_srq(RdmaBackendSRQ *srq, struct ibv_srq_attr *srq_attr)
+{
+    if (!srq->ibsrq) {
+        return -EINVAL;
+    }
+
+    return ibv_query_srq(srq->ibsrq, srq_attr);
+}
+
+int rdma_backend_modify_srq(RdmaBackendSRQ *srq, struct ibv_srq_attr *srq_attr,
+                int srq_attr_mask)
+{
+    if (!srq->ibsrq) {
+        return -EINVAL;
+    }
+
+    return ibv_modify_srq(srq->ibsrq, srq_attr, srq_attr_mask);
+}
+
+void rdma_backend_destroy_srq(RdmaBackendSRQ *srq, RdmaDeviceResources *dev_res)
+{
+    if (srq->ibsrq) {
+        ibv_destroy_srq(srq->ibsrq);
+    }
+    g_slist_foreach(srq->cqe_ctx_list.list, free_cqe_ctx, dev_res);
+    rdma_protected_gslist_destroy(&srq->cqe_ctx_list);
+}
+
+#define CHK_ATTR(req, dev, member, fmt) ({ \
+    trace_rdma_check_dev_attr(#member, dev.member, req->member); \
+    if (req->member > dev.member) { \
+        rdma_warn_report("%s = "fmt" is higher than host device capability "fmt, \
+                         #member, req->member, dev.member); \
+        req->member = dev.member; \
+    } \
+})
+
+static int init_device_caps(RdmaBackendDev *backend_dev,
+                            struct ibv_device_attr *dev_attr)
+{
+    struct ibv_device_attr bk_dev_attr;
+    int rc;
+
+    rc = ibv_query_device(backend_dev->context, &bk_dev_attr);
+    if (rc) {
+        rdma_error_report("ibv_query_device fail, rc=%d, errno=%d", rc, errno);
+        return -EIO;
+    }
+
+    dev_attr->max_sge = MAX_SGE;
+    dev_attr->max_srq_sge = MAX_SGE;
+
+    CHK_ATTR(dev_attr, bk_dev_attr, max_mr_size, "%" PRId64);
+    CHK_ATTR(dev_attr, bk_dev_attr, max_qp, "%d");
+    CHK_ATTR(dev_attr, bk_dev_attr, max_sge, "%d");
+    CHK_ATTR(dev_attr, bk_dev_attr, max_cq, "%d");
+    CHK_ATTR(dev_attr, bk_dev_attr, max_mr, "%d");
+    CHK_ATTR(dev_attr, bk_dev_attr, max_pd, "%d");
+    CHK_ATTR(dev_attr, bk_dev_attr, max_qp_rd_atom, "%d");
+    CHK_ATTR(dev_attr, bk_dev_attr, max_qp_init_rd_atom, "%d");
+    CHK_ATTR(dev_attr, bk_dev_attr, max_ah, "%d");
+    CHK_ATTR(dev_attr, bk_dev_attr, max_srq, "%d");
+
+    return 0;
+}
+
+static inline void build_mad_hdr(struct ibv_grh *grh, union ibv_gid *sgid,
+                                 union ibv_gid *my_gid, int paylen)
+{
+    grh->paylen = htons(paylen);
+    grh->sgid = *sgid;
+    grh->dgid = *my_gid;
+}
+
+static void process_incoming_mad_req(RdmaBackendDev *backend_dev,
+                                     RdmaCmMuxMsg *msg)
+{
+    unsigned long cqe_ctx_id;
+    BackendCtx *bctx;
+    char *mad;
+
+    trace_mad_message("recv", msg->umad.mad, msg->umad_len);
+
+    cqe_ctx_id = rdma_protected_gqueue_pop_int64(&backend_dev->recv_mads_list);
+    if (cqe_ctx_id == -ENOENT) {
+        rdma_warn_report("No more free MADs buffers, waiting for a while");
+        sleep(THR_POLL_TO);
+        return;
+    }
+
+    bctx = rdma_rm_get_cqe_ctx(backend_dev->rdma_dev_res, cqe_ctx_id);
+    if (unlikely(!bctx)) {
+        rdma_error_report("No matching ctx for req %ld", cqe_ctx_id);
+        backend_dev->rdma_dev_res->stats.mad_rx_err++;
+        return;
+    }
+
+    mad = rdma_pci_dma_map(backend_dev->dev, bctx->sge.addr,
+                           bctx->sge.length);
+    if (!mad || bctx->sge.length < msg->umad_len + MAD_HDR_SIZE) {
+        backend_dev->rdma_dev_res->stats.mad_rx_err++;
+        complete_work(IBV_WC_GENERAL_ERR, VENDOR_ERR_INV_MAD_BUFF,
+                      bctx->up_ctx);
+    } else {
+        struct ibv_wc wc = {};
+        memset(mad, 0, bctx->sge.length);
+        build_mad_hdr((struct ibv_grh *)mad,
+                      (union ibv_gid *)&msg->umad.hdr.addr.gid, &msg->hdr.sgid,
+                      msg->umad_len);
+        memcpy(&mad[MAD_HDR_SIZE], msg->umad.mad, msg->umad_len);
+        rdma_pci_dma_unmap(backend_dev->dev, mad, bctx->sge.length);
+
+        wc.byte_len = msg->umad_len;
+        wc.status = IBV_WC_SUCCESS;
+        wc.wc_flags = IBV_WC_GRH;
+        backend_dev->rdma_dev_res->stats.mad_rx++;
+        comp_handler(bctx->up_ctx, &wc);
+    }
+
+    g_free(bctx);
+    rdma_rm_dealloc_cqe_ctx(backend_dev->rdma_dev_res, cqe_ctx_id);
+}
+
+static inline int rdmacm_mux_can_receive(void *opaque)
+{
+    RdmaBackendDev *backend_dev = (RdmaBackendDev *)opaque;
+
+    return rdmacm_mux_can_process_async(backend_dev);
+}
+
+static void rdmacm_mux_read(void *opaque, const uint8_t *buf, int size)
+{
+    RdmaBackendDev *backend_dev = (RdmaBackendDev *)opaque;
+    RdmaCmMuxMsg *msg = (RdmaCmMuxMsg *)buf;
+
+    trace_rdmacm_mux("read", msg->hdr.msg_type, msg->hdr.op_code);
+
+    if (msg->hdr.msg_type != RDMACM_MUX_MSG_TYPE_REQ &&
+        msg->hdr.op_code != RDMACM_MUX_OP_CODE_MAD) {
+            rdma_error_report("Error: Not a MAD request, skipping");
+            return;
+    }
+    process_incoming_mad_req(backend_dev, msg);
+}
+
+static int mad_init(RdmaBackendDev *backend_dev, CharBackend *mad_chr_be)
+{
+    int ret;
+
+    backend_dev->rdmacm_mux.chr_be = mad_chr_be;
+
+    ret = qemu_chr_fe_backend_connected(backend_dev->rdmacm_mux.chr_be);
+    if (!ret) {
+        rdma_error_report("Missing chardev for MAD multiplexer");
+        return -EIO;
+    }
+
+    rdma_protected_gqueue_init(&backend_dev->recv_mads_list);
+
+    enable_rdmacm_mux_async(backend_dev);
+
+    qemu_chr_fe_set_handlers(backend_dev->rdmacm_mux.chr_be,
+                             rdmacm_mux_can_receive, rdmacm_mux_read, NULL,
+                             NULL, backend_dev, NULL, true);
+
+    return 0;
+}
+
+static void mad_stop(RdmaBackendDev *backend_dev)
+{
+    clean_recv_mads(backend_dev);
+}
+
+static void mad_fini(RdmaBackendDev *backend_dev)
+{
+    disable_rdmacm_mux_async(backend_dev);
+    qemu_chr_fe_disconnect(backend_dev->rdmacm_mux.chr_be);
+    rdma_protected_gqueue_destroy(&backend_dev->recv_mads_list);
+}
+
+int rdma_backend_get_gid_index(RdmaBackendDev *backend_dev,
+                               union ibv_gid *gid)
+{
+    union ibv_gid sgid;
+    int ret;
+    int i = 0;
+
+    do {
+        ret = ibv_query_gid(backend_dev->context, backend_dev->port_num, i,
+                            &sgid);
+        i++;
+    } while (!ret && (memcmp(&sgid, gid, sizeof(*gid))));
+
+    trace_rdma_backend_get_gid_index(be64_to_cpu(gid->global.subnet_prefix),
+                                     be64_to_cpu(gid->global.interface_id),
+                                     i - 1);
+
+    return ret ? ret : i - 1;
+}
+
+int rdma_backend_add_gid(RdmaBackendDev *backend_dev, const char *ifname,
+                         union ibv_gid *gid)
+{
+    RdmaCmMuxMsg msg = {};
+    int ret;
+
+    trace_rdma_backend_gid_change("add", be64_to_cpu(gid->global.subnet_prefix),
+                                  be64_to_cpu(gid->global.interface_id));
+
+    msg.hdr.op_code = RDMACM_MUX_OP_CODE_REG;
+    memcpy(msg.hdr.sgid.raw, gid->raw, sizeof(msg.hdr.sgid));
+
+    ret = rdmacm_mux_send(backend_dev, &msg);
+    if (ret) {
+        rdma_error_report("Failed to register GID to rdma_umadmux (%d)", ret);
+        return -EIO;
+    }
+
+    qapi_event_send_rdma_gid_status_changed(ifname, true,
+                                            gid->global.subnet_prefix,
+                                            gid->global.interface_id);
+
+    return ret;
+}
+
+int rdma_backend_del_gid(RdmaBackendDev *backend_dev, const char *ifname,
+                         union ibv_gid *gid)
+{
+    RdmaCmMuxMsg msg = {};
+    int ret;
+
+    trace_rdma_backend_gid_change("del", be64_to_cpu(gid->global.subnet_prefix),
+                                  be64_to_cpu(gid->global.interface_id));
+
+    msg.hdr.op_code = RDMACM_MUX_OP_CODE_UNREG;
+    memcpy(msg.hdr.sgid.raw, gid->raw, sizeof(msg.hdr.sgid));
+
+    ret = rdmacm_mux_send(backend_dev, &msg);
+    if (ret) {
+        rdma_error_report("Failed to unregister GID from rdma_umadmux (%d)",
+                          ret);
+        return -EIO;
+    }
+
+    qapi_event_send_rdma_gid_status_changed(ifname, false,
+                                            gid->global.subnet_prefix,
+                                            gid->global.interface_id);
+
+    return 0;
+}
+
+int rdma_backend_init(RdmaBackendDev *backend_dev, PCIDevice *pdev,
+                      RdmaDeviceResources *rdma_dev_res,
+                      const char *backend_device_name, uint8_t port_num,
+                      struct ibv_device_attr *dev_attr, CharBackend *mad_chr_be)
+{
+    int i;
+    int ret = 0;
+    int num_ibv_devices;
+    struct ibv_device **dev_list;
+
+    memset(backend_dev, 0, sizeof(*backend_dev));
+
+    backend_dev->dev = pdev;
+    backend_dev->port_num = port_num;
+    backend_dev->rdma_dev_res = rdma_dev_res;
+
+    rdma_backend_register_comp_handler(dummy_comp_handler);
+
+    dev_list = ibv_get_device_list(&num_ibv_devices);
+    if (!dev_list) {
+        rdma_error_report("Failed to get IB devices list");
+        return -EIO;
+    }
+
+    if (num_ibv_devices == 0) {
+        rdma_error_report("No IB devices were found");
+        ret = -ENXIO;
+        goto out_free_dev_list;
+    }
+
+    if (backend_device_name) {
+        for (i = 0; dev_list[i]; ++i) {
+            if (!strcmp(ibv_get_device_name(dev_list[i]),
+                        backend_device_name)) {
+                break;
+            }
+        }
+
+        backend_dev->ib_dev = dev_list[i];
+        if (!backend_dev->ib_dev) {
+            rdma_error_report("Failed to find IB device %s",
+                              backend_device_name);
+            ret = -EIO;
+            goto out_free_dev_list;
+        }
+    } else {
+        backend_dev->ib_dev = *dev_list;
+    }
+
+    rdma_info_report("uverb device %s", backend_dev->ib_dev->dev_name);
+
+    backend_dev->context = ibv_open_device(backend_dev->ib_dev);
+    if (!backend_dev->context) {
+        rdma_error_report("Failed to open IB device %s",
+                          ibv_get_device_name(backend_dev->ib_dev));
+        ret = -EIO;
+        goto out;
+    }
+
+    backend_dev->channel = ibv_create_comp_channel(backend_dev->context);
+    if (!backend_dev->channel) {
+        rdma_error_report("Failed to create IB communication channel");
+        ret = -EIO;
+        goto out_close_device;
+    }
+
+    ret = init_device_caps(backend_dev, dev_attr);
+    if (ret) {
+        rdma_error_report("Failed to initialize device capabilities");
+        ret = -EIO;
+        goto out_destroy_comm_channel;
+    }
+
+
+    ret = mad_init(backend_dev, mad_chr_be);
+    if (ret) {
+        rdma_error_report("Failed to initialize mad");
+        ret = -EIO;
+        goto out_destroy_comm_channel;
+    }
+
+    backend_dev->comp_thread.run = false;
+    backend_dev->comp_thread.is_running = false;
+
+    ah_cache_init();
+
+    goto out_free_dev_list;
+
+out_destroy_comm_channel:
+    ibv_destroy_comp_channel(backend_dev->channel);
+
+out_close_device:
+    ibv_close_device(backend_dev->context);
+
+out_free_dev_list:
+    ibv_free_device_list(dev_list);
+
+out:
+    return ret;
+}
+
+
+void rdma_backend_start(RdmaBackendDev *backend_dev)
+{
+    start_comp_thread(backend_dev);
+}
+
+void rdma_backend_stop(RdmaBackendDev *backend_dev)
+{
+    mad_stop(backend_dev);
+    stop_backend_thread(&backend_dev->comp_thread);
+}
+
+void rdma_backend_fini(RdmaBackendDev *backend_dev)
+{
+    mad_fini(backend_dev);
+    g_hash_table_destroy(ah_hash);
+    ibv_destroy_comp_channel(backend_dev->channel);
+    ibv_close_device(backend_dev->context);
+}