Message ID | 20200218050711.8133-3-coiby.xu@gmail.com (mailing list archive) |
---|---|
State | New, archived |
Headers | show |
Series | vhost-user block device backend implementation | expand |
Am 18.02.2020 um 06:07 hat Coiby Xu geschrieben: > Sharing QEMU devices via vhost-user protocol > > Signed-off-by: Coiby Xu <coiby.xu@gmail.com> > --- > util/Makefile.objs | 3 + > util/vhost-user-server.c | 427 +++++++++++++++++++++++++++++++++++++++ > util/vhost-user-server.h | 56 +++++ > 3 files changed, 486 insertions(+) > create mode 100644 util/vhost-user-server.c > create mode 100644 util/vhost-user-server.h > > diff --git a/util/vhost-user-server.h b/util/vhost-user-server.h > new file mode 100644 > index 0000000000..ff6d3145cd > --- /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; I find the terminology a bit confusing here: VuClient is really the connection to a single client, but it's part of the server. The name gives the impression as if this were client-side code. (This is something that already tends to confuse me in the NBD code.) I'm not sure what a better name could be, though. Maybe VuServerConnevtion or VuExportClient or VuExportConnection? > +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; I suppose this could specifically be VuClient? > + 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; If each struct kick_info (btw, QEMU coding style requires CamelCase) has exactly one VuClient and each VuClient has exactly on kick_info, should this be a single struct containing both? [ Coming back from reading the code below - it's because this is in fact an array. This should be made clear in the definition. ] > + QTAILQ_ENTRY(VuClient) next; > + bool closed; > +}; > + > + > +VuServer *vhost_user_server_start(uint16_t max_queues, > + SocketAddress *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); Let's call this vhost_user_server_set_aio_context() for consistency. > 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..70ff6d6701 > --- /dev/null > +++ b/util/vhost-user-server.c > @@ -0,0 +1,427 @@ > +/* > + * Sharing QEMU devices via vhost-user protocol > + * > + * Author: Coiby Xu <coiby.xu@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; Please put declarations at the start of the block. > + 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; The convention is to call this local_err. It should be initialised as NULL. > + 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)); I don't think, qio_channel_*() promise anything about the value in errno. (They also don't promise to use recvmsg().) Instead, use error_report_err() because erp contains the real error message. > + 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)); error_report_err() again. > + 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); > + } > +} The last part is very untypical coroutine code: It says that we want to spawn a new coroutine with vu_client_trip() as its entry point, and then terminates the current one. Why don't we just put the whole thing in a while (!client->closed) loop and stay in the same coroutine instead of terminating the old one and starting a new one all the time? > +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); > +} This is essentially a duplicate of vu_client_next_trip(). The only place where it is called (vu_accept()) knows that client->co_trip is already NULL, so it could just call vu_client_next_trip(). Or in fact, if vu_client_trip() gets turned into a loop, it's vu_client_next_trip() that becomes unnecessary. > +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 s/aovid/avoid/ > + * 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)); Why not a QIOChannel function like for vu_message_read() above? > + 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); This can be a loop, too, instead of terminating the coroutine and starting a new one for the same function. > +} > + > +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); > + } > +} Kevin
> > +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); > > + } > > +} > > The last part is very untypical coroutine code: It says that we want to spawn a new coroutine with vu_client_trip() as its entry point, and then terminates the current one. > > Why don't we just put the whole thing in a while (!client->closed) loop and stay in the same coroutine instead of terminating the old one and starting a new one all the time? > > +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); > > +} > This is essentially a duplicate of vu_client_next_trip(). The only place where it is called (vu_accept()) knows that client->co_trip is already NULL, so it could just call vu_client_next_trip(). > Or in fact, if vu_client_trip() gets turned into a loop, it's > vu_client_next_trip() that becomes unnecessary. This part of code is an imitation of nbd_client_trip in nbd/server.c. I think the reason to repeatedly create/start/terminate vu_client_trip is to support BlockBackendAioNotifier. In v5, I will keep running the spawned coroutine in a loop until being informed of the change of AioContext of the block device backend, i.e. vu_client_trip will only be restarted when the block device backend is attached to a different AiOContext. > > + 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); > This can be a loop, too, instead of terminating the coroutine and starting a new one for the same function. In v5, I plan to use aio_set_fd_handler to set a read hander which is a wrapper for vu_kick_cb to deal with kick events since eventfd doesn't have the short read issue like socket. Thus vu_kick_cb in libvhost-user can be re-used. My only concern is if this could lead to worse performance in comparison to keep reading from eventfd until getting EAGAIN errno. On Tue, Feb 25, 2020 at 11:44 PM Kevin Wolf <kwolf@redhat.com> wrote: > > Am 18.02.2020 um 06:07 hat Coiby Xu geschrieben: > > Sharing QEMU devices via vhost-user protocol > > > > Signed-off-by: Coiby Xu <coiby.xu@gmail.com> > > --- > > util/Makefile.objs | 3 + > > util/vhost-user-server.c | 427 +++++++++++++++++++++++++++++++++++++++ > > util/vhost-user-server.h | 56 +++++ > > 3 files changed, 486 insertions(+) > > create mode 100644 util/vhost-user-server.c > > create mode 100644 util/vhost-user-server.h > > > > diff --git a/util/vhost-user-server.h b/util/vhost-user-server.h > > new file mode 100644 > > index 0000000000..ff6d3145cd > > --- /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; > > I find the terminology a bit confusing here: VuClient is really the > connection to a single client, but it's part of the server. The name > gives the impression as if this were client-side code. (This is > something that already tends to confuse me in the NBD code.) > > I'm not sure what a better name could be, though. Maybe > VuServerConnevtion or VuExportClient or VuExportConnection? > > > +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; > > I suppose this could specifically be VuClient? > > > + 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; > > If each struct kick_info (btw, QEMU coding style requires CamelCase) has > exactly one VuClient and each VuClient has exactly on kick_info, should > this be a single struct containing both? > > [ Coming back from reading the code below - it's because this is in > fact an array. This should be made clear in the definition. ] > > > + QTAILQ_ENTRY(VuClient) next; > > + bool closed; > > +}; > > + > > + > > +VuServer *vhost_user_server_start(uint16_t max_queues, > > + SocketAddress *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); > > Let's call this vhost_user_server_set_aio_context() for consistency. > > > 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..70ff6d6701 > > --- /dev/null > > +++ b/util/vhost-user-server.c > > @@ -0,0 +1,427 @@ > > +/* > > + * Sharing QEMU devices via vhost-user protocol > > + * > > + * Author: Coiby Xu <coiby.xu@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; > > Please put declarations at the start of the block. > > > + 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; > > The convention is to call this local_err. It should be initialised as > NULL. > > > + 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)); > > I don't think, qio_channel_*() promise anything about the value in > errno. (They also don't promise to use recvmsg().) > > Instead, use error_report_err() because erp contains the real error > message. > > > + 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)); > > error_report_err() again. > > > + 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); > > + } > > +} > > The last part is very untypical coroutine code: It says that we want to > spawn a new coroutine with vu_client_trip() as its entry point, and then > terminates the current one. > > Why don't we just put the whole thing in a while (!client->closed) loop > and stay in the same coroutine instead of terminating the old one and > starting a new one all the time? > > > +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); > > +} > > This is essentially a duplicate of vu_client_next_trip(). The only > place where it is called (vu_accept()) knows that client->co_trip is > already NULL, so it could just call vu_client_next_trip(). > > Or in fact, if vu_client_trip() gets turned into a loop, it's > vu_client_next_trip() that becomes unnecessary. > > > +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 > > s/aovid/avoid/ > > > + * 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)); > > Why not a QIOChannel function like for vu_message_read() above? > > > + 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); > > This can be a loop, too, instead of terminating the coroutine and > starting a new one for the same function. > > > +} > > + > > +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); > > + } > > +} > > Kevin >
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..70ff6d6701 --- /dev/null +++ b/util/vhost-user-server.c @@ -0,0 +1,427 @@ +/* + * Sharing QEMU devices via vhost-user protocol + * + * Author: Coiby Xu <coiby.xu@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, + SocketAddress *socket_addr, + 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(); + if (qio_net_listener_open_sync(server->listener, socket_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; + server->device_panic_notifier = device_panic_notifier; + 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..ff6d3145cd --- /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, + SocketAddress *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);
Sharing QEMU devices via vhost-user protocol Signed-off-by: Coiby Xu <coiby.xu@gmail.com> --- util/Makefile.objs | 3 + util/vhost-user-server.c | 427 +++++++++++++++++++++++++++++++++++++++ util/vhost-user-server.h | 56 +++++ 3 files changed, 486 insertions(+) create mode 100644 util/vhost-user-server.c create mode 100644 util/vhost-user-server.h