From ff1320050a3a7af8b094020c5e4bb6ad736421a8 Mon Sep 17 00:00:00 2001 From: Johannes Berg Date: Thu, 23 Jan 2020 09:17:08 +0100 Subject: [PATCH] libvhost-user: implement in-band notifications Add support for VHOST_USER_PROTOCOL_F_IN_BAND_NOTIFICATIONS, but as it's not desired by default, don't enable it unless the device implementation opts in by returning it from its protocol features callback. Note that I updated vu_set_vring_err_exec(), but didn't add any sending of the VHOST_USER_SLAVE_VRING_ERR message as there's no write to the err_fd today either. This also adds vu_queue_notify_sync() which can be used to force a synchronous notification if inband notifications are supported. Previously, I had left out the slave->master direction handling of F_REPLY_ACK, this now adds some code to support it as well. Signed-off-by: Johannes Berg Message-Id: <20200123081708.7817-7-johannes@sipsolutions.net> Reviewed-by: Michael S. Tsirkin Signed-off-by: Michael S. Tsirkin --- contrib/libvhost-user/libvhost-user.c | 103 +++++++++++++++++++++++++- contrib/libvhost-user/libvhost-user.h | 14 ++++ 2 files changed, 114 insertions(+), 3 deletions(-) diff --git a/contrib/libvhost-user/libvhost-user.c b/contrib/libvhost-user/libvhost-user.c index 3abc9689e5..3bca996c62 100644 --- a/contrib/libvhost-user/libvhost-user.c +++ b/contrib/libvhost-user/libvhost-user.c @@ -136,6 +136,7 @@ vu_request_to_string(unsigned int req) REQ(VHOST_USER_GET_INFLIGHT_FD), REQ(VHOST_USER_SET_INFLIGHT_FD), REQ(VHOST_USER_GPU_SET_SOCKET), + REQ(VHOST_USER_VRING_KICK), REQ(VHOST_USER_MAX), }; #undef REQ @@ -163,7 +164,10 @@ vu_panic(VuDev *dev, const char *msg, ...) dev->panic(dev, buf); free(buf); - /* FIXME: find a way to call virtio_error? */ + /* + * FIXME: + * find a way to call virtio_error, or perhaps close the connection? + */ } /* Translate guest physical address to our virtual address. */ @@ -1203,6 +1207,14 @@ vu_set_vring_err_exec(VuDev *dev, VhostUserMsg *vmsg) static bool vu_get_protocol_features_exec(VuDev *dev, VhostUserMsg *vmsg) { + /* + * Note that we support, but intentionally do not set, + * VHOST_USER_PROTOCOL_F_INBAND_NOTIFICATIONS. This means that + * a device implementation can return it in its callback + * (get_protocol_features) if it wants to use this for + * simulation, but it is otherwise not desirable (if even + * implemented by the master.) + */ uint64_t features = 1ULL << VHOST_USER_PROTOCOL_F_MQ | 1ULL << VHOST_USER_PROTOCOL_F_LOG_SHMFD | 1ULL << VHOST_USER_PROTOCOL_F_SLAVE_REQ | @@ -1235,6 +1247,25 @@ vu_set_protocol_features_exec(VuDev *dev, VhostUserMsg *vmsg) dev->protocol_features = vmsg->payload.u64; + if (vu_has_protocol_feature(dev, + VHOST_USER_PROTOCOL_F_INBAND_NOTIFICATIONS) && + (!vu_has_protocol_feature(dev, VHOST_USER_PROTOCOL_F_SLAVE_REQ) || + !vu_has_protocol_feature(dev, VHOST_USER_PROTOCOL_F_REPLY_ACK))) { + /* + * The use case for using messages for kick/call is simulation, to make + * the kick and call synchronous. To actually get that behaviour, both + * of the other features are required. + * Theoretically, one could use only kick messages, or do them without + * having F_REPLY_ACK, but too many (possibly pending) messages on the + * socket will eventually cause the master to hang, to avoid this in + * scenarios where not desired enforce that the settings are in a way + * that actually enables the simulation case. + */ + vu_panic(dev, + "F_IN_BAND_NOTIFICATIONS requires F_SLAVE_REQ && F_REPLY_ACK"); + return false; + } + if (dev->iface->set_protocol_features) { dev->iface->set_protocol_features(dev, features); } @@ -1495,6 +1526,34 @@ vu_set_inflight_fd(VuDev *dev, VhostUserMsg *vmsg) return false; } +static bool +vu_handle_vring_kick(VuDev *dev, VhostUserMsg *vmsg) +{ + unsigned int index = vmsg->payload.state.index; + + if (index >= dev->max_queues) { + vu_panic(dev, "Invalid queue index: %u", index); + return false; + } + + DPRINT("Got kick message: handler:%p idx:%d\n", + dev->vq[index].handler, index); + + if (!dev->vq[index].started) { + dev->vq[index].started = true; + + if (dev->iface->queue_set_started) { + dev->iface->queue_set_started(dev, index, true); + } + } + + if (dev->vq[index].handler) { + dev->vq[index].handler(dev, index); + } + + return false; +} + static bool vu_process_message(VuDev *dev, VhostUserMsg *vmsg) { @@ -1577,6 +1636,8 @@ vu_process_message(VuDev *dev, VhostUserMsg *vmsg) return vu_get_inflight_fd(dev, vmsg); case VHOST_USER_SET_INFLIGHT_FD: return vu_set_inflight_fd(dev, vmsg); + case VHOST_USER_VRING_KICK: + return vu_handle_vring_kick(dev, vmsg); default: vmsg_close_fds(vmsg); vu_panic(dev, "Unhandled request: %d", vmsg->request); @@ -2038,8 +2099,7 @@ vring_notify(VuDev *dev, VuVirtq *vq) return !v || vring_need_event(vring_get_used_event(vq), new, old); } -void -vu_queue_notify(VuDev *dev, VuVirtq *vq) +static void _vu_queue_notify(VuDev *dev, VuVirtq *vq, bool sync) { if (unlikely(dev->broken) || unlikely(!vq->vring.avail)) { @@ -2051,11 +2111,48 @@ vu_queue_notify(VuDev *dev, VuVirtq *vq) return; } + if (vq->call_fd < 0 && + vu_has_protocol_feature(dev, + VHOST_USER_PROTOCOL_F_INBAND_NOTIFICATIONS) && + vu_has_protocol_feature(dev, VHOST_USER_PROTOCOL_F_SLAVE_REQ)) { + VhostUserMsg vmsg = { + .request = VHOST_USER_SLAVE_VRING_CALL, + .flags = VHOST_USER_VERSION, + .size = sizeof(vmsg.payload.state), + .payload.state = { + .index = vq - dev->vq, + }, + }; + bool ack = sync && + vu_has_protocol_feature(dev, + VHOST_USER_PROTOCOL_F_REPLY_ACK); + + if (ack) { + vmsg.flags |= VHOST_USER_NEED_REPLY_MASK; + } + + vu_message_write(dev, dev->slave_fd, &vmsg); + if (ack) { + vu_message_read(dev, dev->slave_fd, &vmsg); + } + return; + } + if (eventfd_write(vq->call_fd, 1) < 0) { vu_panic(dev, "Error writing eventfd: %s", strerror(errno)); } } +void vu_queue_notify(VuDev *dev, VuVirtq *vq) +{ + _vu_queue_notify(dev, vq, false); +} + +void vu_queue_notify_sync(VuDev *dev, VuVirtq *vq) +{ + _vu_queue_notify(dev, vq, true); +} + static inline void vring_used_flags_set_bit(VuVirtq *vq, int mask) { diff --git a/contrib/libvhost-user/libvhost-user.h b/contrib/libvhost-user/libvhost-user.h index 5cb7708559..6fc8000e99 100644 --- a/contrib/libvhost-user/libvhost-user.h +++ b/contrib/libvhost-user/libvhost-user.h @@ -54,6 +54,7 @@ enum VhostUserProtocolFeature { VHOST_USER_PROTOCOL_F_SLAVE_SEND_FD = 10, VHOST_USER_PROTOCOL_F_HOST_NOTIFIER = 11, VHOST_USER_PROTOCOL_F_INFLIGHT_SHMFD = 12, + VHOST_USER_PROTOCOL_F_INBAND_NOTIFICATIONS = 14, VHOST_USER_PROTOCOL_F_MAX }; @@ -95,6 +96,7 @@ typedef enum VhostUserRequest { VHOST_USER_GET_INFLIGHT_FD = 31, VHOST_USER_SET_INFLIGHT_FD = 32, VHOST_USER_GPU_SET_SOCKET = 33, + VHOST_USER_VRING_KICK = 35, VHOST_USER_MAX } VhostUserRequest; @@ -103,6 +105,8 @@ typedef enum VhostUserSlaveRequest { VHOST_USER_SLAVE_IOTLB_MSG = 1, VHOST_USER_SLAVE_CONFIG_CHANGE_MSG = 2, VHOST_USER_SLAVE_VRING_HOST_NOTIFIER_MSG = 3, + VHOST_USER_SLAVE_VRING_CALL = 4, + VHOST_USER_SLAVE_VRING_ERR = 5, VHOST_USER_SLAVE_MAX } VhostUserSlaveRequest; @@ -528,6 +532,16 @@ bool vu_queue_empty(VuDev *dev, VuVirtq *vq); */ void vu_queue_notify(VuDev *dev, VuVirtq *vq); +/** + * vu_queue_notify_sync: + * @dev: a VuDev context + * @vq: a VuVirtq queue + * + * Request to notify the queue via callfd (skipped if unnecessary) + * or sync message if possible. + */ +void vu_queue_notify_sync(VuDev *dev, VuVirtq *vq); + /** * vu_queue_pop: * @dev: a VuDev context