VSOCK: Introduce virtio_transport.ko

VM sockets virtio transport implementation.  This driver runs in the
guest.

Signed-off-by: Asias He <asias@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

1 files changed, 624 insertions, 0 deletions

diff --git a/net/vmw_vsock/virtio_transport.c b/net/vmw_vsock/virtio_transport.c
new file mode 100644
index 000000000000..699dfabdbccd
--- /dev/null
+++ b/net/vmw_vsock/virtio_transport.c
@@ -0,0 +1,624 @@
+/*
+ * virtio transport for vsock
+ *
+ * Copyright (C) 2013-2015 Red Hat, Inc.
+ * Author: Asias He <asias@redhat.com>
+ *         Stefan Hajnoczi <stefanha@redhat.com>
+ *
+ * Some of the code is take from Gerd Hoffmann <kraxel@redhat.com>'s
+ * early virtio-vsock proof-of-concept bits.
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2.
+ */
+#include <linux/spinlock.h>
+#include <linux/module.h>
+#include <linux/list.h>
+#include <linux/atomic.h>
+#include <linux/virtio.h>
+#include <linux/virtio_ids.h>
+#include <linux/virtio_config.h>
+#include <linux/virtio_vsock.h>
+#include <net/sock.h>
+#include <linux/mutex.h>
+#include <net/af_vsock.h>
+
+static struct workqueue_struct *virtio_vsock_workqueue;
+static struct virtio_vsock *the_virtio_vsock;
+static DEFINE_MUTEX(the_virtio_vsock_mutex); /* protects the_virtio_vsock */
+
+struct virtio_vsock {
+        struct virtio_device *vdev;
+        struct virtqueue *vqs[VSOCK_VQ_MAX];
+
+        /* Virtqueue processing is deferred to a workqueue */
+        struct work_struct tx_work;
+        struct work_struct rx_work;
+        struct work_struct event_work;
+
+        /* The following fields are protected by tx_lock.  vqs[VSOCK_VQ_TX]
+         * must be accessed with tx_lock held.
+         */
+        struct mutex tx_lock;
+
+        struct work_struct send_pkt_work;
+        spinlock_t send_pkt_list_lock;
+        struct list_head send_pkt_list;
+
+        atomic_t queued_replies;
+
+        /* The following fields are protected by rx_lock.  vqs[VSOCK_VQ_RX]
+         * must be accessed with rx_lock held.
+         */
+        struct mutex rx_lock;
+        int rx_buf_nr;
+        int rx_buf_max_nr;
+
+        /* The following fields are protected by event_lock.
+         * vqs[VSOCK_VQ_EVENT] must be accessed with event_lock held.
+         */
+        struct mutex event_lock;
+        struct virtio_vsock_event event_list[8];
+
+        u32 guest_cid;
+};
+
+static struct virtio_vsock *virtio_vsock_get(void)
+{
+        return the_virtio_vsock;
+}
+
+static u32 virtio_transport_get_local_cid(void)
+{
+        struct virtio_vsock *vsock = virtio_vsock_get();
+
+        return vsock->guest_cid;
+}
+
+static void
+virtio_transport_send_pkt_work(struct work_struct *work)
+{
+        struct virtio_vsock *vsock =
+                container_of(work, struct virtio_vsock, send_pkt_work);
+        struct virtqueue *vq;
+        bool added = false;
+        bool restart_rx = false;
+
+        mutex_lock(&vsock->tx_lock);
+
+        vq = vsock->vqs[VSOCK_VQ_TX];
+
+        /* Avoid unnecessary interrupts while we're processing the ring */
+        virtqueue_disable_cb(vq);
+
+        for (;;) {
+                struct virtio_vsock_pkt *pkt;
+                struct scatterlist hdr, buf, *sgs[2];
+                int ret, in_sg = 0, out_sg = 0;
+                bool reply;
+
+                spin_lock_bh(&vsock->send_pkt_list_lock);
+                if (list_empty(&vsock->send_pkt_list)) {
+                        spin_unlock_bh(&vsock->send_pkt_list_lock);
+                        virtqueue_enable_cb(vq);
+                        break;
+                }
+
+                pkt = list_first_entry(&vsock->send_pkt_list,
+                                       struct virtio_vsock_pkt, list);
+                list_del_init(&pkt->list);
+                spin_unlock_bh(&vsock->send_pkt_list_lock);
+
+                reply = pkt->reply;
+
+                sg_init_one(&hdr, &pkt->hdr, sizeof(pkt->hdr));
+                sgs[out_sg++] = &hdr;
+                if (pkt->buf) {
+                        sg_init_one(&buf, pkt->buf, pkt->len);
+                        sgs[out_sg++] = &buf;
+                }
+
+                ret = virtqueue_add_sgs(vq, sgs, out_sg, in_sg, pkt, GFP_KERNEL);
+                if (ret < 0) {
+                        spin_lock_bh(&vsock->send_pkt_list_lock);
+                        list_add(&pkt->list, &vsock->send_pkt_list);
+                        spin_unlock_bh(&vsock->send_pkt_list_lock);
+
+                        if (!virtqueue_enable_cb(vq) && ret == -ENOSPC)
+                                continue; /* retry now that we have more space */
+                        break;
+                }
+
+                if (reply) {
+                        struct virtqueue *rx_vq = vsock->vqs[VSOCK_VQ_RX];
+                        int val;
+
+                        val = atomic_dec_return(&vsock->queued_replies);
+
+                        /* Do we now have resources to resume rx processing? */
+                        if (val + 1 == virtqueue_get_vring_size(rx_vq))
+                                restart_rx = true;
+                }
+
+                added = true;
+        }
+
+        if (added)
+                virtqueue_kick(vq);
+
+        mutex_unlock(&vsock->tx_lock);
+
+        if (restart_rx)
+                queue_work(virtio_vsock_workqueue, &vsock->rx_work);
+}
+
+static int
+virtio_transport_send_pkt(struct virtio_vsock_pkt *pkt)
+{
+        struct virtio_vsock *vsock;
+        int len = pkt->len;
+
+        vsock = virtio_vsock_get();
+        if (!vsock) {
+                virtio_transport_free_pkt(pkt);
+                return -ENODEV;
+        }
+
+        if (pkt->reply)
+                atomic_inc(&vsock->queued_replies);
+
+        spin_lock_bh(&vsock->send_pkt_list_lock);
+        list_add_tail(&pkt->list, &vsock->send_pkt_list);
+        spin_unlock_bh(&vsock->send_pkt_list_lock);
+
+        queue_work(virtio_vsock_workqueue, &vsock->send_pkt_work);
+        return len;
+}
+
+static void virtio_vsock_rx_fill(struct virtio_vsock *vsock)
+{
+        int buf_len = VIRTIO_VSOCK_DEFAULT_RX_BUF_SIZE;
+        struct virtio_vsock_pkt *pkt;
+        struct scatterlist hdr, buf, *sgs[2];
+        struct virtqueue *vq;
+        int ret;
+
+        vq = vsock->vqs[VSOCK_VQ_RX];
+
+        do {
+                pkt = kzalloc(sizeof(*pkt), GFP_KERNEL);
+                if (!pkt)
+                        break;
+
+                pkt->buf = kmalloc(buf_len, GFP_KERNEL);
+                if (!pkt->buf) {
+                        virtio_transport_free_pkt(pkt);
+                        break;
+                }
+
+                pkt->len = buf_len;
+
+                sg_init_one(&hdr, &pkt->hdr, sizeof(pkt->hdr));
+                sgs[0] = &hdr;
+
+                sg_init_one(&buf, pkt->buf, buf_len);
+                sgs[1] = &buf;
+                ret = virtqueue_add_sgs(vq, sgs, 0, 2, pkt, GFP_KERNEL);
+                if (ret) {
+                        virtio_transport_free_pkt(pkt);
+                        break;
+                }
+                vsock->rx_buf_nr++;
+        } while (vq->num_free);
+        if (vsock->rx_buf_nr > vsock->rx_buf_max_nr)
+                vsock->rx_buf_max_nr = vsock->rx_buf_nr;
+        virtqueue_kick(vq);
+}
+
+static void virtio_transport_tx_work(struct work_struct *work)
+{
+        struct virtio_vsock *vsock =
+                container_of(work, struct virtio_vsock, tx_work);
+        struct virtqueue *vq;
+        bool added = false;
+
+        vq = vsock->vqs[VSOCK_VQ_TX];
+        mutex_lock(&vsock->tx_lock);
+        do {
+                struct virtio_vsock_pkt *pkt;
+                unsigned int len;
+
+                virtqueue_disable_cb(vq);
+                while ((pkt = virtqueue_get_buf(vq, &len)) != NULL) {
+                        virtio_transport_free_pkt(pkt);
+                        added = true;
+                }
+        } while (!virtqueue_enable_cb(vq));
+        mutex_unlock(&vsock->tx_lock);
+
+        if (added)
+                queue_work(virtio_vsock_workqueue, &vsock->send_pkt_work);
+}
+
+/* Is there space left for replies to rx packets? */
+static bool virtio_transport_more_replies(struct virtio_vsock *vsock)
+{
+        struct virtqueue *vq = vsock->vqs[VSOCK_VQ_RX];
+        int val;
+
+        smp_rmb(); /* paired with atomic_inc() and atomic_dec_return() */
+        val = atomic_read(&vsock->queued_replies);
+
+        return val < virtqueue_get_vring_size(vq);
+}
+
+static void virtio_transport_rx_work(struct work_struct *work)
+{
+        struct virtio_vsock *vsock =
+                container_of(work, struct virtio_vsock, rx_work);
+        struct virtqueue *vq;
+
+        vq = vsock->vqs[VSOCK_VQ_RX];
+
+        mutex_lock(&vsock->rx_lock);
+
+        do {
+                virtqueue_disable_cb(vq);
+                for (;;) {
+                        struct virtio_vsock_pkt *pkt;
+                        unsigned int len;
+
+                        if (!virtio_transport_more_replies(vsock)) {
+                                /* Stop rx until the device processes already
+                                 * pending replies.  Leave rx virtqueue
+                                 * callbacks disabled.
+                                 */
+                                goto out;
+                        }
+
+                        pkt = virtqueue_get_buf(vq, &len);
+                        if (!pkt) {
+                                break;
+                        }
+
+                        vsock->rx_buf_nr--;
+
+                        /* Drop short/long packets */
+                        if (unlikely(len < sizeof(pkt->hdr) ||
+                                     len > sizeof(pkt->hdr) + pkt->len)) {
+                                virtio_transport_free_pkt(pkt);
+                                continue;
+                        }
+
+                        pkt->len = len - sizeof(pkt->hdr);
+                        virtio_transport_recv_pkt(pkt);
+                }
+        } while (!virtqueue_enable_cb(vq));
+
+out:
+        if (vsock->rx_buf_nr < vsock->rx_buf_max_nr / 2)
+                virtio_vsock_rx_fill(vsock);
+        mutex_unlock(&vsock->rx_lock);
+}
+
+/* event_lock must be held */
+static int virtio_vsock_event_fill_one(struct virtio_vsock *vsock,
+                                       struct virtio_vsock_event *event)
+{
+        struct scatterlist sg;
+        struct virtqueue *vq;
+
+        vq = vsock->vqs[VSOCK_VQ_EVENT];
+
+        sg_init_one(&sg, event, sizeof(*event));
+
+        return virtqueue_add_inbuf(vq, &sg, 1, event, GFP_KERNEL);
+}
+
+/* event_lock must be held */
+static void virtio_vsock_event_fill(struct virtio_vsock *vsock)
+{
+        size_t i;
+
+        for (i = 0; i < ARRAY_SIZE(vsock->event_list); i++) {
+                struct virtio_vsock_event *event = &vsock->event_list[i];
+
+                virtio_vsock_event_fill_one(vsock, event);
+        }
+
+        virtqueue_kick(vsock->vqs[VSOCK_VQ_EVENT]);
+}
+
+static void virtio_vsock_reset_sock(struct sock *sk)
+{
+        lock_sock(sk);
+        sk->sk_state = SS_UNCONNECTED;
+        sk->sk_err = ECONNRESET;
+        sk->sk_error_report(sk);
+        release_sock(sk);
+}
+
+static void virtio_vsock_update_guest_cid(struct virtio_vsock *vsock)
+{
+        struct virtio_device *vdev = vsock->vdev;
+        u64 guest_cid;
+
+        vdev->config->get(vdev, offsetof(struct virtio_vsock_config, guest_cid),
+                          &guest_cid, sizeof(guest_cid));
+        vsock->guest_cid = le64_to_cpu(guest_cid);
+}
+
+/* event_lock must be held */
+static void virtio_vsock_event_handle(struct virtio_vsock *vsock,
+                                      struct virtio_vsock_event *event)
+{
+        switch (le32_to_cpu(event->id)) {
+        case VIRTIO_VSOCK_EVENT_TRANSPORT_RESET:
+                virtio_vsock_update_guest_cid(vsock);
+                vsock_for_each_connected_socket(virtio_vsock_reset_sock);
+                break;
+        }
+}
+
+static void virtio_transport_event_work(struct work_struct *work)
+{
+        struct virtio_vsock *vsock =
+                container_of(work, struct virtio_vsock, event_work);
+        struct virtqueue *vq;
+
+        vq = vsock->vqs[VSOCK_VQ_EVENT];
+
+        mutex_lock(&vsock->event_lock);
+
+        do {
+                struct virtio_vsock_event *event;
+                unsigned int len;
+
+                virtqueue_disable_cb(vq);
+                while ((event = virtqueue_get_buf(vq, &len)) != NULL) {
+                        if (len == sizeof(*event))
+                                virtio_vsock_event_handle(vsock, event);
+
+                        virtio_vsock_event_fill_one(vsock, event);
+                }
+        } while (!virtqueue_enable_cb(vq));
+
+        virtqueue_kick(vsock->vqs[VSOCK_VQ_EVENT]);
+
+        mutex_unlock(&vsock->event_lock);
+}
+
+static void virtio_vsock_event_done(struct virtqueue *vq)
+{
+        struct virtio_vsock *vsock = vq->vdev->priv;
+
+        if (!vsock)
+                return;
+        queue_work(virtio_vsock_workqueue, &vsock->event_work);
+}
+
+static void virtio_vsock_tx_done(struct virtqueue *vq)
+{
+        struct virtio_vsock *vsock = vq->vdev->priv;
+
+        if (!vsock)
+                return;
+        queue_work(virtio_vsock_workqueue, &vsock->tx_work);
+}
+
+static void virtio_vsock_rx_done(struct virtqueue *vq)
+{
+        struct virtio_vsock *vsock = vq->vdev->priv;
+
+        if (!vsock)
+                return;
+        queue_work(virtio_vsock_workqueue, &vsock->rx_work);
+}
+
+static struct virtio_transport virtio_transport = {
+        .transport = {
+                .get_local_cid            = virtio_transport_get_local_cid,
+
+                .init                     = virtio_transport_do_socket_init,
+                .destruct                 = virtio_transport_destruct,
+                .release                  = virtio_transport_release,
+                .connect                  = virtio_transport_connect,
+                .shutdown                 = virtio_transport_shutdown,
+
+                .dgram_bind               = virtio_transport_dgram_bind,
+                .dgram_dequeue            = virtio_transport_dgram_dequeue,
+                .dgram_enqueue            = virtio_transport_dgram_enqueue,
+                .dgram_allow              = virtio_transport_dgram_allow,
+
+                .stream_dequeue           = virtio_transport_stream_dequeue,
+                .stream_enqueue           = virtio_transport_stream_enqueue,
+                .stream_has_data          = virtio_transport_stream_has_data,
+                .stream_has_space         = virtio_transport_stream_has_space,
+                .stream_rcvhiwat          = virtio_transport_stream_rcvhiwat,
+                .stream_is_active         = virtio_transport_stream_is_active,
+                .stream_allow             = virtio_transport_stream_allow,
+
+                .notify_poll_in           = virtio_transport_notify_poll_in,
+                .notify_poll_out          = virtio_transport_notify_poll_out,
+                .notify_recv_init         = virtio_transport_notify_recv_init,
+                .notify_recv_pre_block    = virtio_transport_notify_recv_pre_block,
+                .notify_recv_pre_dequeue  = virtio_transport_notify_recv_pre_dequeue,
+                .notify_recv_post_dequeue = virtio_transport_notify_recv_post_dequeue,
+                .notify_send_init         = virtio_transport_notify_send_init,
+                .notify_send_pre_block    = virtio_transport_notify_send_pre_block,
+                .notify_send_pre_enqueue  = virtio_transport_notify_send_pre_enqueue,
+                .notify_send_post_enqueue = virtio_transport_notify_send_post_enqueue,
+
+                .set_buffer_size          = virtio_transport_set_buffer_size,
+                .set_min_buffer_size      = virtio_transport_set_min_buffer_size,
+                .set_max_buffer_size      = virtio_transport_set_max_buffer_size,
+                .get_buffer_size          = virtio_transport_get_buffer_size,
+                .get_min_buffer_size      = virtio_transport_get_min_buffer_size,
+                .get_max_buffer_size      = virtio_transport_get_max_buffer_size,
+        },
+
+        .send_pkt = virtio_transport_send_pkt,
+};
+
+static int virtio_vsock_probe(struct virtio_device *vdev)
+{
+        vq_callback_t *callbacks[] = {
+                virtio_vsock_rx_done,
+                virtio_vsock_tx_done,
+                virtio_vsock_event_done,
+        };
+        static const char * const names[] = {
+                "rx",
+                "tx",
+                "event",
+        };
+        struct virtio_vsock *vsock = NULL;
+        int ret;
+
+        ret = mutex_lock_interruptible(&the_virtio_vsock_mutex);
+        if (ret)
+                return ret;
+
+        /* Only one virtio-vsock device per guest is supported */
+        if (the_virtio_vsock) {
+                ret = -EBUSY;
+                goto out;
+        }
+
+        vsock = kzalloc(sizeof(*vsock), GFP_KERNEL);
+        if (!vsock) {
+                ret = -ENOMEM;
+                goto out;
+        }
+
+        vsock->vdev = vdev;
+
+        ret = vsock->vdev->config->find_vqs(vsock->vdev, VSOCK_VQ_MAX,
+                                            vsock->vqs, callbacks, names);
+        if (ret < 0)
+                goto out;
+
+        virtio_vsock_update_guest_cid(vsock);
+
+        ret = vsock_core_init(&virtio_transport.transport);
+        if (ret < 0)
+                goto out_vqs;
+
+        vsock->rx_buf_nr = 0;
+        vsock->rx_buf_max_nr = 0;
+        atomic_set(&vsock->queued_replies, 0);
+
+        vdev->priv = vsock;
+        the_virtio_vsock = vsock;
+        mutex_init(&vsock->tx_lock);
+        mutex_init(&vsock->rx_lock);
+        mutex_init(&vsock->event_lock);
+        spin_lock_init(&vsock->send_pkt_list_lock);
+        INIT_LIST_HEAD(&vsock->send_pkt_list);
+        INIT_WORK(&vsock->rx_work, virtio_transport_rx_work);
+        INIT_WORK(&vsock->tx_work, virtio_transport_tx_work);
+        INIT_WORK(&vsock->event_work, virtio_transport_event_work);
+        INIT_WORK(&vsock->send_pkt_work, virtio_transport_send_pkt_work);
+
+        mutex_lock(&vsock->rx_lock);
+        virtio_vsock_rx_fill(vsock);
+        mutex_unlock(&vsock->rx_lock);
+
+        mutex_lock(&vsock->event_lock);
+        virtio_vsock_event_fill(vsock);
+        mutex_unlock(&vsock->event_lock);
+
+        mutex_unlock(&the_virtio_vsock_mutex);
+        return 0;
+
+out_vqs:
+        vsock->vdev->config->del_vqs(vsock->vdev);
+out:
+        kfree(vsock);
+        mutex_unlock(&the_virtio_vsock_mutex);
+        return ret;
+}
+
+static void virtio_vsock_remove(struct virtio_device *vdev)
+{
+        struct virtio_vsock *vsock = vdev->priv;
+        struct virtio_vsock_pkt *pkt;
+
+        flush_work(&vsock->rx_work);
+        flush_work(&vsock->tx_work);
+        flush_work(&vsock->event_work);
+        flush_work(&vsock->send_pkt_work);
+
+        vdev->config->reset(vdev);
+
+        mutex_lock(&vsock->rx_lock);
+        while ((pkt = virtqueue_detach_unused_buf(vsock->vqs[VSOCK_VQ_RX])))
+                virtio_transport_free_pkt(pkt);
+        mutex_unlock(&vsock->rx_lock);
+
+        mutex_lock(&vsock->tx_lock);
+        while ((pkt = virtqueue_detach_unused_buf(vsock->vqs[VSOCK_VQ_TX])))
+                virtio_transport_free_pkt(pkt);
+        mutex_unlock(&vsock->tx_lock);
+
+        spin_lock_bh(&vsock->send_pkt_list_lock);
+        while (!list_empty(&vsock->send_pkt_list)) {
+                pkt = list_first_entry(&vsock->send_pkt_list,
+                                       struct virtio_vsock_pkt, list);
+                list_del(&pkt->list);
+                virtio_transport_free_pkt(pkt);
+        }
+        spin_unlock_bh(&vsock->send_pkt_list_lock);
+
+        mutex_lock(&the_virtio_vsock_mutex);
+        the_virtio_vsock = NULL;
+        vsock_core_exit();
+        mutex_unlock(&the_virtio_vsock_mutex);
+
+        vdev->config->del_vqs(vdev);
+
+        kfree(vsock);
+}
+
+static struct virtio_device_id id_table[] = {
+        { VIRTIO_ID_VSOCK, VIRTIO_DEV_ANY_ID },
+        { 0 },
+};
+
+static unsigned int features[] = {
+};
+
+static struct virtio_driver virtio_vsock_driver = {
+        .feature_table = features,
+        .feature_table_size = ARRAY_SIZE(features),
+        .driver.name = KBUILD_MODNAME,
+        .driver.owner = THIS_MODULE,
+        .id_table = id_table,
+        .probe = virtio_vsock_probe,
+        .remove = virtio_vsock_remove,
+};
+
+static int __init virtio_vsock_init(void)
+{
+        int ret;
+
+        virtio_vsock_workqueue = alloc_workqueue("virtio_vsock", 0, 0);
+        if (!virtio_vsock_workqueue)
+                return -ENOMEM;
+        ret = register_virtio_driver(&virtio_vsock_driver);
+        if (ret)
+                destroy_workqueue(virtio_vsock_workqueue);
+        return ret;
+}
+
+static void __exit virtio_vsock_exit(void)
+{
+        unregister_virtio_driver(&virtio_vsock_driver);
+        destroy_workqueue(virtio_vsock_workqueue);
+}
+
+module_init(virtio_vsock_init);
+module_exit(virtio_vsock_exit);
+MODULE_LICENSE("GPL v2");
+MODULE_AUTHOR("Asias He");
+MODULE_DESCRIPTION("virtio transport for vsock");
+MODULE_DEVICE_TABLE(virtio, id_table);