new file mode 100644
@@ -0,0 +1,65 @@
+/*
+ * Sharing QEMU devices via vhost-user protocol
+ *
+ * Copyright (c) Coiby Xu <coiby.xu@gmail.com>.
+ * Copyright (c) 2020 Red Hat, Inc.
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or
+ * later. See the COPYING file in the top-level directory.
+ */
+
+#ifndef VHOST_USER_SERVER_H
+#define VHOST_USER_SERVER_H
+
+#include "contrib/libvhost-user/libvhost-user.h"
+#include "io/channel-socket.h"
+#include "io/channel-file.h"
+#include "io/net-listener.h"
+#include "qemu/error-report.h"
+#include "qapi/error.h"
+#include "standard-headers/linux/virtio_blk.h"
+
+typedef struct VuFdWatch {
+ VuDev *vu_dev;
+ int fd; /*kick fd*/
+ void *pvt;
+ vu_watch_cb cb;
+ bool processing;
+ QTAILQ_ENTRY(VuFdWatch) next;
+} VuFdWatch;
+
+typedef struct VuServer VuServer;
+typedef void DevicePanicNotifierFn(VuServer *server);
+
+struct VuServer {
+ QIONetListener *listener;
+ AioContext *ctx;
+ DevicePanicNotifierFn *device_panic_notifier;
+ int max_queues;
+ const VuDevIface *vu_iface;
+ VuDev vu_dev;
+ QIOChannel *ioc; /* The I/O channel with the client */
+ QIOChannelSocket *sioc; /* The underlying data channel with the client */
+ /* IOChannel for fd provided via VHOST_USER_SET_SLAVE_REQ_FD */
+ QIOChannel *ioc_slave;
+ QIOChannelSocket *sioc_slave;
+ Coroutine *co_trip; /* coroutine for processing VhostUserMsg */
+ QTAILQ_HEAD(, VuFdWatch) vu_fd_watches;
+ /* restart coroutine co_trip if AIOContext is changed */
+ bool aio_context_changed;
+ bool processing_msg;
+};
+
+bool vhost_user_server_start(VuServer *server,
+ SocketAddress *unix_socket,
+ AioContext *ctx,
+ uint16_t max_queues,
+ DevicePanicNotifierFn *device_panic_notifier,
+ const VuDevIface *vu_iface,
+ Error **errp);
+
+void vhost_user_server_stop(VuServer *server);
+
+void vhost_user_server_set_aio_context(VuServer *server, AioContext *ctx);
+
+#endif /* VHOST_USER_SERVER_H */
new file mode 100644
@@ -0,0 +1,428 @@
+/*
+ * Sharing QEMU devices via vhost-user protocol
+ *
+ * Copyright (c) Coiby Xu <coiby.xu@gmail.com>.
+ * Copyright (c) 2020 Red Hat, Inc.
+ *
+ * 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 "qemu/main-loop.h"
+#include "vhost-user-server.h"
+
+static void vmsg_close_fds(VhostUserMsg *vmsg)
+{
+ int i;
+ for (i = 0; i < vmsg->fd_num; i++) {
+ close(vmsg->fds[i]);
+ }
+}
+
+static void vmsg_unblock_fds(VhostUserMsg *vmsg)
+{
+ int i;
+ for (i = 0; i < vmsg->fd_num; i++) {
+ qemu_set_nonblock(vmsg->fds[i]);
+ }
+}
+
+static void vu_accept(QIONetListener *listener, QIOChannelSocket *sioc,
+ gpointer opaque);
+
+static void close_client(VuServer *server)
+{
+ /*
+ * Before closing the client
+ *
+ * 1. Let vu_client_trip stop processing new vhost-user msg
+ *
+ * 2. remove kick_handler
+ *
+ * 3. wait for the kick handler to be finished
+ *
+ * 4. wait for the current vhost-user msg to be finished processing
+ */
+
+ QIOChannelSocket *sioc = server->sioc;
+ /* When this is set vu_client_trip will stop new processing vhost-user message */
+ server->sioc = NULL;
+
+ VuFdWatch *vu_fd_watch, *next;
+ QTAILQ_FOREACH_SAFE(vu_fd_watch, &server->vu_fd_watches, next, next) {
+ aio_set_fd_handler(server->ioc->ctx, vu_fd_watch->fd, true, NULL,
+ NULL, NULL, NULL);
+ }
+
+ while (!QTAILQ_EMPTY(&server->vu_fd_watches)) {
+ QTAILQ_FOREACH_SAFE(vu_fd_watch, &server->vu_fd_watches, next, next) {
+ if (!vu_fd_watch->processing) {
+ QTAILQ_REMOVE(&server->vu_fd_watches, vu_fd_watch, next);
+ g_free(vu_fd_watch);
+ }
+ }
+ }
+
+ while (server->processing_msg) {
+ if (server->ioc->read_coroutine) {
+ server->ioc->read_coroutine = NULL;
+ qio_channel_set_aio_fd_handler(server->ioc, server->ioc->ctx, NULL,
+ NULL, server->ioc);
+ server->processing_msg = false;
+ }
+ }
+
+ vu_deinit(&server->vu_dev);
+ object_unref(OBJECT(sioc));
+ object_unref(OBJECT(server->ioc));
+}
+
+static void panic_cb(VuDev *vu_dev, const char *buf)
+{
+ VuServer *server = container_of(vu_dev, VuServer, vu_dev);
+
+ /* avoid while loop in close_client */
+ server->processing_msg = false;
+
+ if (buf) {
+ error_report("vu_panic: %s", buf);
+ }
+
+ if (server->sioc) {
+ close_client(server);
+ }
+
+ if (server->device_panic_notifier) {
+ server->device_panic_notifier(server);
+ }
+
+ /*
+ * Set the callback function for network listener so another
+ * vhost-user client can connect to this server
+ */
+ qio_net_listener_set_client_func(server->listener,
+ vu_accept,
+ server,
+ NULL);
+}
+
+static bool coroutine_fn
+vu_message_read(VuDev *vu_dev, int conn_fd, VhostUserMsg *vmsg)
+{
+ struct iovec iov = {
+ .iov_base = (char *)vmsg,
+ .iov_len = VHOST_USER_HDR_SIZE,
+ };
+ int rc, read_bytes = 0;
+ Error *local_err = NULL;
+ /*
+ * Store fds/nfds returned from qio_channel_readv_full into
+ * temporary variables.
+ *
+ * VhostUserMsg is a packed structure, gcc will complain about passing
+ * pointer to a packed structure member if we pass &VhostUserMsg.fd_num
+ * and &VhostUserMsg.fds directly when calling qio_channel_readv_full,
+ * thus two temporary variables nfds and fds are used here.
+ */
+ size_t nfds = 0, nfds_t = 0;
+ const size_t max_fds = G_N_ELEMENTS(vmsg->fds);
+ int *fds_t = NULL;
+ VuServer *server = container_of(vu_dev, VuServer, vu_dev);
+ QIOChannel *ioc = server->ioc;
+
+ if (!ioc) {
+ error_report_err(local_err);
+ goto fail;
+ }
+
+ assert(qemu_in_coroutine());
+ do {
+ /*
+ * qio_channel_readv_full may have short reads, keeping calling it
+ * until getting VHOST_USER_HDR_SIZE or 0 bytes in total
+ */
+ rc = qio_channel_readv_full(ioc, &iov, 1, &fds_t, &nfds_t, &local_err);
+ if (rc < 0) {
+ if (rc == QIO_CHANNEL_ERR_BLOCK) {
+ qio_channel_yield(ioc, G_IO_IN);
+ continue;
+ } else {
+ error_report_err(local_err);
+ return false;
+ }
+ }
+ read_bytes += rc;
+ if (nfds_t > 0) {
+ if (nfds + nfds_t > max_fds) {
+ error_report("A maximum of %zu fds are allowed, "
+ "however got %zu fds now",
+ max_fds, nfds + nfds_t);
+ goto fail;
+ }
+ memcpy(vmsg->fds + nfds, fds_t,
+ nfds_t *sizeof(vmsg->fds[0]));
+ nfds += nfds_t;
+ g_free(fds_t);
+ }
+ if (read_bytes == VHOST_USER_HDR_SIZE || rc == 0) {
+ break;
+ }
+ iov.iov_base = (char *)vmsg + read_bytes;
+ iov.iov_len = VHOST_USER_HDR_SIZE - read_bytes;
+ } while (true);
+
+ vmsg->fd_num = nfds;
+ /* qio_channel_readv_full will make socket fds blocking, unblock them */
+ vmsg_unblock_fds(vmsg);
+ if (vmsg->size > sizeof(vmsg->payload)) {
+ error_report("Error: too big message request: %d, "
+ "size: vmsg->size: %u, "
+ "while sizeof(vmsg->payload) = %zu",
+ vmsg->request, vmsg->size, sizeof(vmsg->payload));
+ goto fail;
+ }
+
+ struct iovec iov_payload = {
+ .iov_base = (char *)&vmsg->payload,
+ .iov_len = vmsg->size,
+ };
+ if (vmsg->size) {
+ rc = qio_channel_readv_all_eof(ioc, &iov_payload, 1, &local_err);
+ if (rc == -1) {
+ error_report_err(local_err);
+ goto fail;
+ }
+ }
+
+ return true;
+
+fail:
+ vmsg_close_fds(vmsg);
+
+ return false;
+}
+
+
+static void vu_client_start(VuServer *server);
+static coroutine_fn void vu_client_trip(void *opaque)
+{
+ VuServer *server = opaque;
+
+ while (!server->aio_context_changed && server->sioc) {
+ server->processing_msg = true;
+ vu_dispatch(&server->vu_dev);
+ server->processing_msg = false;
+ }
+
+ if (server->aio_context_changed && server->sioc) {
+ server->aio_context_changed = false;
+ vu_client_start(server);
+ }
+}
+
+static void vu_client_start(VuServer *server)
+{
+ server->co_trip = qemu_coroutine_create(vu_client_trip, server);
+ aio_co_enter(server->ctx, server->co_trip);
+}
+
+/*
+ * a wrapper for vu_kick_cb
+ *
+ * since aio_dispatch can only pass one user data pointer to the
+ * callback function, pack VuDev and pvt into a struct. Then unpack it
+ * and pass them to vu_kick_cb
+ */
+static void kick_handler(void *opaque)
+{
+ VuFdWatch *vu_fd_watch = opaque;
+ vu_fd_watch->processing = true;
+ vu_fd_watch->cb(vu_fd_watch->vu_dev, 0, vu_fd_watch->pvt);
+ vu_fd_watch->processing = false;
+}
+
+
+static VuFdWatch *find_vu_fd_watch(VuServer *server, int fd)
+{
+
+ VuFdWatch *vu_fd_watch, *next;
+ QTAILQ_FOREACH_SAFE(vu_fd_watch, &server->vu_fd_watches, next, next) {
+ if (vu_fd_watch->fd == fd) {
+ return vu_fd_watch;
+ }
+ }
+ return NULL;
+}
+
+static void
+set_watch(VuDev *vu_dev, int fd, int vu_evt,
+ vu_watch_cb cb, void *pvt)
+{
+
+ VuServer *server = container_of(vu_dev, VuServer, vu_dev);
+ g_assert(vu_dev);
+ g_assert(fd >= 0);
+ g_assert(cb);
+
+ VuFdWatch *vu_fd_watch = find_vu_fd_watch(server, fd);
+
+ if (!vu_fd_watch) {
+ VuFdWatch *vu_fd_watch = g_new0(VuFdWatch, 1);
+
+ QTAILQ_INSERT_TAIL(&server->vu_fd_watches, vu_fd_watch, next);
+
+ vu_fd_watch->fd = fd;
+ vu_fd_watch->cb = cb;
+ qemu_set_nonblock(fd);
+ aio_set_fd_handler(server->ioc->ctx, fd, true, kick_handler,
+ NULL, NULL, vu_fd_watch);
+ vu_fd_watch->vu_dev = vu_dev;
+ vu_fd_watch->pvt = pvt;
+ }
+}
+
+
+static void remove_watch(VuDev *vu_dev, int fd)
+{
+ VuServer *server;
+ g_assert(vu_dev);
+ g_assert(fd >= 0);
+
+ server = container_of(vu_dev, VuServer, vu_dev);
+
+ VuFdWatch *vu_fd_watch = find_vu_fd_watch(server, fd);
+
+ if (!vu_fd_watch) {
+ return;
+ }
+ aio_set_fd_handler(server->ioc->ctx, fd, true, NULL, NULL, NULL, NULL);
+
+ QTAILQ_REMOVE(&server->vu_fd_watches, vu_fd_watch, next);
+ g_free(vu_fd_watch);
+}
+
+
+static void vu_accept(QIONetListener *listener, QIOChannelSocket *sioc,
+ gpointer opaque)
+{
+ VuServer *server = opaque;
+
+ if (server->sioc) {
+ warn_report("Only one vhost-user client is allowed to "
+ "connect the server one time");
+ return;
+ }
+
+ if (!vu_init(&server->vu_dev, server->max_queues, sioc->fd, panic_cb,
+ vu_message_read, set_watch, remove_watch, server->vu_iface)) {
+ error_report("Failed to initialize libvhost-user");
+ return;
+ }
+
+ /*
+ * Unset the callback function for network listener to make another
+ * vhost-user client keeping waiting until this client disconnects
+ */
+ qio_net_listener_set_client_func(server->listener,
+ NULL,
+ NULL,
+ NULL);
+ server->sioc = sioc;
+ /*
+ * Increase the object reference, so sioc will not freed by
+ * qio_net_listener_channel_func which will call object_unref(OBJECT(sioc))
+ */
+ object_ref(OBJECT(server->sioc));
+ qio_channel_set_name(QIO_CHANNEL(sioc), "vhost-user client");
+ server->ioc = QIO_CHANNEL(sioc);
+ object_ref(OBJECT(server->ioc));
+ qio_channel_attach_aio_context(server->ioc, server->ctx);
+ qio_channel_set_blocking(QIO_CHANNEL(server->sioc), false, NULL);
+ vu_client_start(server);
+}
+
+
+void vhost_user_server_stop(VuServer *server)
+{
+ if (server->sioc) {
+ close_client(server);
+ }
+
+ if (server->listener) {
+ qio_net_listener_disconnect(server->listener);
+ object_unref(OBJECT(server->listener));
+ }
+
+}
+
+void vhost_user_server_set_aio_context(VuServer *server, AioContext *ctx)
+{
+ VuFdWatch *vu_fd_watch, *next;
+ void *opaque = NULL;
+ IOHandler *io_read = NULL;
+ bool attach;
+
+ server->ctx = ctx ? ctx : qemu_get_aio_context();
+
+ if (!server->sioc) {
+ /* not yet serving any client*/
+ return;
+ }
+
+ if (ctx) {
+ qio_channel_attach_aio_context(server->ioc, ctx);
+ server->aio_context_changed = true;
+ io_read = kick_handler;
+ attach = true;
+ } else {
+ qio_channel_detach_aio_context(server->ioc);
+ /* server->ioc->ctx keeps the old AioConext */
+ ctx = server->ioc->ctx;
+ attach = false;
+ }
+
+ QTAILQ_FOREACH_SAFE(vu_fd_watch, &server->vu_fd_watches, next, next) {
+ if (vu_fd_watch->cb) {
+ opaque = attach ? vu_fd_watch : NULL;
+ aio_set_fd_handler(ctx, vu_fd_watch->fd, true,
+ io_read, NULL, NULL,
+ opaque);
+ }
+ }
+}
+
+
+bool vhost_user_server_start(VuServer *server,
+ SocketAddress *socket_addr,
+ AioContext *ctx,
+ uint16_t max_queues,
+ DevicePanicNotifierFn *device_panic_notifier,
+ const VuDevIface *vu_iface,
+ Error **errp)
+{
+ QIONetListener *listener = qio_net_listener_new();
+ if (qio_net_listener_open_sync(listener, socket_addr, 1,
+ errp) < 0) {
+ object_unref(OBJECT(listener));
+ return false;
+ }
+
+ /* zero out unspecified fileds */
+ *server = (VuServer) {
+ .listener = listener,
+ .vu_iface = vu_iface,
+ .max_queues = max_queues,
+ .ctx = ctx,
+ .device_panic_notifier = device_panic_notifier,
+ };
+
+ qio_net_listener_set_name(server->listener, "vhost-user-backend-listener");
+
+ qio_net_listener_set_client_func(server->listener,
+ vu_accept,
+ server,
+ NULL);
+
+ QTAILQ_INIT(&server->vu_fd_watches);
+ return true;
+}
@@ -66,6 +66,7 @@ if have_block
util_ss.add(files('main-loop.c'))
util_ss.add(files('nvdimm-utils.c'))
util_ss.add(files('qemu-coroutine.c', 'qemu-coroutine-lock.c', 'qemu-coroutine-io.c'))
+ util_ss.add(when: 'CONFIG_LINUX', if_true: files('vhost-user-server.c'))
util_ss.add(files('qemu-coroutine-sleep.c'))
util_ss.add(files('qemu-co-shared-resource.c'))
util_ss.add(files('thread-pool.c', 'qemu-timer.c'))