util/vhost-user-server: generic vhost user server

Sharing QEMU devices via vhost-user protocol.

Only one vhost-user client can connect to the server one time.

Suggested-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Coiby Xu <coiby.xu@gmail.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-id: 20200918080912.321299-4-coiby.xu@gmail.com
[Fixed size_t %lu -> %zu format string compiler error.
--Stefan]
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
This commit is contained in:
Coiby Xu 2020-09-18 16:09:08 +08:00 committed by Stefan Hajnoczi
parent f1baeee9ff
commit 70eb2c079c
3 changed files with 494 additions and 0 deletions

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@ -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'))

428
util/vhost-user-server.c Normal file
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@ -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;
}

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util/vhost-user-server.h Normal file
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/*
* 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 */