Sharing QEMU devices via vhost-user protocol
Signed-off-by: Coiby Xu <coiby...@gmail.com>
---
util/Makefile.objs | 3 +
util/vhost-user-server.c | 429 +++++++++++++++++++++++++++++++++++++++
util/vhost-user-server.h | 56 +++++
3 files changed, 489 insertions(+)
create mode 100644 util/vhost-user-server.c
create mode 100644 util/vhost-user-server.h
diff --git a/util/Makefile.objs b/util/Makefile.objs
index 11262aafaf..5e450e501c 100644
--- a/util/Makefile.objs
+++ b/util/Makefile.objs
@@ -36,6 +36,9 @@ util-obj-y += readline.o
util-obj-y += rcu.o
util-obj-$(CONFIG_MEMBARRIER) += sys_membarrier.o
util-obj-y += qemu-coroutine.o qemu-coroutine-lock.o qemu-coroutine-io.o
+ifdef CONFIG_LINUX
+util-obj-y += vhost-user-server.o
+endif
util-obj-y += qemu-coroutine-sleep.o
util-obj-y += qemu-co-shared-resource.o
util-obj-y += coroutine-$(CONFIG_COROUTINE_BACKEND).o
diff --git a/util/vhost-user-server.c b/util/vhost-user-server.c
new file mode 100644
index 0000000000..0766b414c3
--- /dev/null
+++ b/util/vhost-user-server.c
@@ -0,0 +1,429 @@
+/*
+ * Sharing QEMU devices via vhost-user protocol
+ *
+ * Author: Coiby Xu <coiby...@gmail.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 <sys/eventfd.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 close_client(VuClient *client)
+{
+ vu_deinit(&client->parent);
+ client->sioc = NULL;
+ object_unref(OBJECT(client->ioc));
+ client->closed = true;
+
+}
+
+static void panic_cb(VuDev *vu_dev, const char *buf)
+{
+ if (buf) {
+ error_report("vu_panic: %s", buf);
+ }
+
+ VuClient *client = container_of(vu_dev, VuClient, parent);
+ VuServer *server = client->server;
+ if (!client->closed) {
+ close_client(client);
+ QTAILQ_REMOVE(&server->clients, client, next);
+ }
+
+ if (server->device_panic_notifier) {
+ server->device_panic_notifier(client);
+ }
+}
+
+
+
+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;
+ /*
+ * 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;
+ int *fds = NULL, *fds_t = NULL;
+ VuClient *client = container_of(vu_dev, VuClient, parent);
+ QIOChannel *ioc = client->ioc;
+
+ Error *erp;
+ 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, &erp);
+ if (rc < 0) {
+ if (rc == QIO_CHANNEL_ERR_BLOCK) {
+ qio_channel_yield(ioc, G_IO_IN);
+ continue;
+ } else {
+ error_report("Error while recvmsg: %s", strerror(errno));
+ return false;
+ }
+ }
+ read_bytes += rc;
+ fds = g_renew(int, fds_t, nfds + nfds_t);
+ memcpy(fds + nfds, fds_t, nfds_t);
+ nfds += nfds_t;
+ if (read_bytes == VHOST_USER_HDR_SIZE || rc == 0) {
+ break;
+ }
+ } while (true);
+
+ vmsg->fd_num = nfds;
+ memcpy(vmsg->fds, fds, nfds * sizeof(int));
+ g_free(fds);
+ /* 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, &erp);
+ if (rc == -1) {
+ error_report("Error while reading: %s", strerror(errno));
+ goto fail;
+ }
+ }
+
+ return true;
+
+fail:
+ vmsg_close_fds(vmsg);
+
+ return false;
+}
+
+
+static coroutine_fn void vu_client_next_trip(VuClient *client);
+
+static coroutine_fn void vu_client_trip(void *opaque)
+{
+ VuClient *client = opaque;
+
+ vu_dispatch(&client->parent);
+ client->co_trip = NULL;
+ if (!client->closed) {
+ vu_client_next_trip(client);
+ }
+}
+
+static coroutine_fn void vu_client_next_trip(VuClient *client)
+{
+ if (!client->co_trip) {
+ client->co_trip = qemu_coroutine_create(vu_client_trip, client);
+ aio_co_schedule(client->ioc->ctx, client->co_trip);
+ }
+}
+
+static void vu_client_start(VuClient *client)
+{
+ client->co_trip = qemu_coroutine_create(vu_client_trip, client);
+ aio_co_enter(client->ioc->ctx, client->co_trip);
+}
+
+static void coroutine_fn vu_kick_cb_next(VuClient *client,
+ kick_info *data);
+
+static void coroutine_fn vu_kick_cb(void *opaque)
+{
+ kick_info *data = (kick_info *) opaque;
+ int index = data->index;
+ VuDev *dev = data->vu_dev;
+ VuClient *client;
+ client = container_of(dev, VuClient, parent);
+ VuVirtq *vq = &dev->vq[index];
+ int sock = vq->kick_fd;
+ if (sock == -1) {
+ return;
+ }
+ assert(sock == data->fd);
+ eventfd_t kick_data;
+ ssize_t rc;
+ /*
+ * When eventfd is closed, the revent is POLLNVAL (=G_IO_NVAL) and
+ * reading eventfd will return errno=EBADF (Bad file number).
+ * Calling qio_channel_yield(ioc, G_IO_IN) will set reading handler
+ * for QIOChannel, but aio_dispatch_handlers will only dispatch
+ * G_IO_IN | G_IO_HUP | G_IO_ERR revents while ignoring
+ * G_IO_NVAL (POLLNVAL) revents.
+ *
+ * Thus when eventfd is closed by vhost-user client, QEMU will ignore
+ * G_IO_NVAL and keeping polling by repeatedly calling qemu_poll_ns which
+ * will lead to 100% CPU usage.
+ *
+ * To aovid this issue, make sure set_watch and remove_watch use the same
+ * AIOContext for QIOChannel. Thus remove_watch will eventually succefully
+ * remove eventfd from the set of file descriptors polled for
+ * corresponding GSource.
+ */
+ rc = read(sock, &kick_data, sizeof(eventfd_t));
+ if (rc != sizeof(eventfd_t)) {
+ if (errno == EAGAIN) {
+ qio_channel_yield(data->ioc, G_IO_IN);
+ } else if (errno != EINTR) {
+ data->co = NULL;
+ return;
+ }
+ } else {
+ vq->handler(dev, index);
+ }
+ data->co = NULL;
+ vu_kick_cb_next(client, data);
+
+}
+
+static void coroutine_fn vu_kick_cb_next(VuClient *client,
+ kick_info *cb_data)
+{
+ if (!cb_data->co) {
+ cb_data->co = qemu_coroutine_create(vu_kick_cb, cb_data);
+ aio_co_schedule(client->ioc->ctx, cb_data->co);
+ }
+}
+static const CoIface co_iface = {
+ .read_msg = vu_message_read,
+ .kick_callback = vu_kick_cb,
+};
+
+
+static void
+set_watch(VuDev *vu_dev, int fd, int vu_evt,
+ vu_watch_cb_packed_data cb, void *pvt)
+{
+ /*
+ * since aio_dispatch can only pass one user data pointer to the
+ * callback function, pack VuDev, pvt into a struct
+ */
+
+ VuClient *client;
+
+ client = container_of(vu_dev, VuClient, parent);
+ g_assert(vu_dev);
+ g_assert(fd >= 0);
+ long index = (intptr_t) pvt;
+ g_assert(cb);
+ kick_info *kick_info = &client->kick_info[index];
+ if (!kick_info->co) {
+ kick_info->fd = fd;
+ QIOChannelFile *fioc = qio_channel_file_new_fd(fd);
+ QIOChannel *ioc = QIO_CHANNEL(fioc);
+ ioc->ctx = client->ioc->ctx;
+ qio_channel_set_blocking(QIO_CHANNEL(ioc), false, NULL);
+ kick_info->fioc = fioc;
+ kick_info->ioc = ioc;
+ kick_info->vu_dev = vu_dev;
+ kick_info->co = qemu_coroutine_create(cb, kick_info);
+ aio_co_enter(client->ioc->ctx, kick_info->co);
+ }
+}
+
+
+static void remove_watch(VuDev *vu_dev, int fd)
+{
+ VuClient *client;
+ int i;
+ int index = -1;
+ g_assert(vu_dev);
+ g_assert(fd >= 0);
+
+ client = container_of(vu_dev, VuClient, parent);
+ for (i = 0; i < vu_dev->max_queues; i++) {
+ if (client->kick_info[i].fd == fd) {
+ index = i;
+ break;
+ }
+ }
+
+ if (index == -1) {
+ return;
+ }
+
+ kick_info *kick_info = &client->kick_info[index];
+ if (kick_info->ioc) {
+ aio_set_fd_handler(client->ioc->ctx, fd, false, NULL,
+ NULL, NULL, NULL);
+ kick_info->ioc = NULL;
+ g_free(kick_info->fioc);
+ kick_info->co = NULL;
+ kick_info->fioc = NULL;
+ }
+}
+
+
+static void vu_accept(QIONetListener *listener, QIOChannelSocket *sioc,
+ gpointer opaque)
+{
+ VuClient *client;
+ VuServer *server = opaque;
+ client = g_new0(VuClient, 1);
+
+ if (!vu_init_packed_data(&client->parent, server->max_queues,
+ sioc->fd, panic_cb,
+ set_watch, remove_watch,
+ server->vu_iface, &co_iface)) {
+ error_report("Failed to initialized libvhost-user");
+ g_free(client);
+ return;
+ }
+
+ client->server = server;
+ client->sioc = sioc;
+ client->kick_info = g_new0(struct kick_info, server->max_queues);
+ /*
+ * increase the object reference, so cioc will not freed by
+ * qio_net_listener_channel_func which will call object_unref(OBJECT(sioc))
+ */
+ object_ref(OBJECT(client->sioc));
+ qio_channel_set_name(QIO_CHANNEL(sioc), "vhost-user client");
+ client->ioc = QIO_CHANNEL(sioc);
+ object_ref(OBJECT(client->ioc));
+ object_ref(OBJECT(sioc));
+ qio_channel_attach_aio_context(client->ioc, server->ctx);
+ qio_channel_set_blocking(QIO_CHANNEL(client->sioc), false, NULL);
+ client->closed = false;
+ QTAILQ_INSERT_TAIL(&server->clients, client, next);
+ vu_client_start(client);
+}
+
+
+void vhost_user_server_stop(VuServer *server)
+{
+ if (!server) {
+ return;
+ }
+
+ VuClient *client, *next;
+ QTAILQ_FOREACH_SAFE(client, &server->clients, next, next) {
+ if (!client->closed) {
+ close_client(client);
+ QTAILQ_REMOVE(&server->clients, client, next);
+ }
+ }
+
+ if (server->listener) {
+ qio_net_listener_disconnect(server->listener);
+ object_unref(OBJECT(server->listener));
+ }
+}
+
+static void detach_context(VuServer *server)
+{
+ VuClient *client;
+ int i;
+ QTAILQ_FOREACH(client, &server->clients, next) {
+ qio_channel_detach_aio_context(client->ioc);
+ for (i = 0; i < client->parent.max_queues; i++) {
+ if (client->kick_info[i].ioc) {
+ qio_channel_detach_aio_context(client->kick_info[i].ioc);
+ }
+ }
+ }
+}
+
+static void attach_context(VuServer *server, AioContext *ctx)
+{
+ VuClient *client;
+ int i;
+ QTAILQ_FOREACH(client, &server->clients, next) {
+ qio_channel_attach_aio_context(client->ioc, ctx);
+ if (client->co_trip) {
+ aio_co_schedule(ctx, client->co_trip);
+ }
+ for (i = 0; i < client->parent.max_queues; i++) {
+ if (client->kick_info[i].co) {
+ qio_channel_attach_aio_context(client->kick_info[i].ioc, ctx);
+ aio_co_schedule(ctx, client->kick_info[i].co);
+ }
+ }
+ }
+}
+void change_vu_context(AioContext *ctx, VuServer *server)
+{
+ AioContext *acquire_ctx = ctx ? ctx : server->ctx;
+ aio_context_acquire(acquire_ctx);
+ server->ctx = ctx ? ctx : qemu_get_aio_context();
+ if (ctx) {
+ attach_context(server, ctx);
+ } else {
+ detach_context(server);
+ }
+ aio_context_release(acquire_ctx);
+}
+
+
+VuServer *vhost_user_server_start(uint16_t max_queues,
+ char *unix_socket,
+ AioContext *ctx,
+ void *server_ptr,
+ void *device_panic_notifier,
+ const VuDevIface *vu_iface,
+ Error **errp)
+{
+ VuServer *server = g_new0(VuServer, 1);
+ server->ptr_in_device = server_ptr;
+ server->listener = qio_net_listener_new();
+ SocketAddress addr = {};
+ addr.u.q_unix.path = (char *) unix_socket;
+ addr.type = SOCKET_ADDRESS_TYPE_UNIX;
+ if (qio_net_listener_open_sync(server->listener, &addr, 1, errp) < 0) {
+ goto error;
+ }
+
+ qio_net_listener_set_name(server->listener, "vhost-user-backend-listener");
+
+ server->vu_iface = vu_iface;
+ server->max_queues = max_queues;
+ server->ctx = ctx;
+ qio_net_listener_set_client_func(server->listener,
+ vu_accept,
+ server,
+ NULL);
+
+ QTAILQ_INIT(&server->clients);
+ return server;
+error:
+ g_free(server);
+ return NULL;
+}
diff --git a/util/vhost-user-server.h b/util/vhost-user-server.h
new file mode 100644
index 0000000000..2172d67937
--- /dev/null
+++ b/util/vhost-user-server.h
@@ -0,0 +1,56 @@
+#include "io/channel-socket.h"
+#include "io/channel-file.h"
+#include "io/net-listener.h"
+#include "contrib/libvhost-user/libvhost-user.h"
+#include "standard-headers/linux/virtio_blk.h"
+#include "qemu/error-report.h"
+
+typedef struct VuClient VuClient;
+
+typedef struct VuServer {
+ QIONetListener *listener;
+ AioContext *ctx;
+ QTAILQ_HEAD(, VuClient) clients;
+ void (*device_panic_notifier)(struct VuClient *client) ;
+ int max_queues;
+ const VuDevIface *vu_iface;
+ /*
+ * @ptr_in_device: VuServer pointer memory location in vhost-user device
+ * struct, so later container_of can be used to get device destruct
+ */
+ void *ptr_in_device;
+ bool close;
+} VuServer;
+
+typedef struct kick_info {
+ VuDev *vu_dev;
+ int fd; /*kick fd*/
+ long index; /*queue index*/
+ QIOChannel *ioc; /*I/O channel for kick fd*/
+ QIOChannelFile *fioc; /*underlying data channel for kick fd*/
+ Coroutine *co;
+} kick_info;
+
+struct VuClient {
+ VuDev parent;
+ VuServer *server;
+ QIOChannel *ioc; /* The current I/O channel */
+ QIOChannelSocket *sioc; /* The underlying data channel */
+ Coroutine *co_trip;
+ struct kick_info *kick_info;
+ QTAILQ_ENTRY(VuClient) next;
+ bool closed;
+};
+
+
+VuServer *vhost_user_server_start(uint16_t max_queues,
+ char *unix_socket,
+ AioContext *ctx,
+ void *server_ptr,
+ void *device_panic_notifier,
+ const VuDevIface *vu_iface,
+ Error **errp);
+
+void vhost_user_server_stop(VuServer *server);
+
+void change_vu_context(AioContext *ctx, VuServer *server);
--
2.25.0
