vhost-vsock: add virtio sockets device

Implement the new virtio sockets device for host<->guest communication
using the Sockets API.  Most of the work is done in a vhost kernel
driver so that virtio-vsock can hook into the AF_VSOCK address family.
The QEMU vhost-vsock device handles configuration and live migration
while the rx/tx happens in the vhost_vsock.ko Linux kernel driver.

The vsock device must be given a CID (host-wide unique address):

  # qemu -device vhost-vsock-pci,id=vhost-vsock-pci0,guest-cid=3 ...

For more information see:
http://qemu-project.org/Features/VirtioVsock

[Endianness fixes and virtio-ccw support by Claudio Imbrenda
<imbrenda@linux.vnet.ibm.com>]

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
[mst: rebase to master]
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

1 files changed, 417 insertions, 0 deletions

diff --git a/hw/virtio/vhost-vsock.c b/hw/virtio/vhost-vsock.c
new file mode 100644
index 0000000000..bde2456621
--- /dev/null
+++ b/hw/virtio/vhost-vsock.c
@@ -0,0 +1,417 @@
+/*
+ * Virtio vsock device
+ *
+ * Copyright 2015 Red Hat, Inc.
+ *
+ * Authors:
+ *  Stefan Hajnoczi <stefanha@redhat.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or
+ * (at your option) any later version.  See the COPYING file in the
+ * top-level directory.
+ */
+
+#include <sys/ioctl.h>
+#include "qemu/osdep.h"
+#include "standard-headers/linux/virtio_vsock.h"
+#include "qapi/error.h"
+#include "hw/virtio/virtio-bus.h"
+#include "hw/virtio/virtio-access.h"
+#include "migration/migration.h"
+#include "qemu/error-report.h"
+#include "hw/virtio/vhost-vsock.h"
+#include "qemu/iov.h"
+#include "monitor/monitor.h"
+
+enum {
+    VHOST_VSOCK_SAVEVM_VERSION = 0,
+
+    VHOST_VSOCK_QUEUE_SIZE = 128,
+};
+
+static void vhost_vsock_get_config(VirtIODevice *vdev, uint8_t *config)
+{
+    VHostVSock *vsock = VHOST_VSOCK(vdev);
+    struct virtio_vsock_config vsockcfg = {};
+
+    virtio_stq_p(vdev, &vsockcfg.guest_cid, vsock->conf.guest_cid);
+    memcpy(config, &vsockcfg, sizeof(vsockcfg));
+}
+
+static int vhost_vsock_set_guest_cid(VHostVSock *vsock)
+{
+    const VhostOps *vhost_ops = vsock->vhost_dev.vhost_ops;
+    int ret;
+
+    if (!vhost_ops->vhost_vsock_set_guest_cid) {
+        return -ENOSYS;
+    }
+
+    ret = vhost_ops->vhost_vsock_set_guest_cid(&vsock->vhost_dev,
+                                               vsock->conf.guest_cid);
+    if (ret < 0) {
+        return -errno;
+    }
+    return 0;
+}
+
+static int vhost_vsock_set_running(VHostVSock *vsock, int start)
+{
+    const VhostOps *vhost_ops = vsock->vhost_dev.vhost_ops;
+    int ret;
+
+    if (!vhost_ops->vhost_vsock_set_running) {
+        return -ENOSYS;
+    }
+
+    ret = vhost_ops->vhost_vsock_set_running(&vsock->vhost_dev, start);
+    if (ret < 0) {
+        return -errno;
+    }
+    return 0;
+}
+
+static void vhost_vsock_start(VirtIODevice *vdev)
+{
+    VHostVSock *vsock = VHOST_VSOCK(vdev);
+    BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(vdev)));
+    VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
+    int ret;
+    int i;
+
+    if (!k->set_guest_notifiers) {
+        error_report("binding does not support guest notifiers");
+        return;
+    }
+
+    ret = vhost_dev_enable_notifiers(&vsock->vhost_dev, vdev);
+    if (ret < 0) {
+        error_report("Error enabling host notifiers: %d", -ret);
+        return;
+    }
+
+    ret = k->set_guest_notifiers(qbus->parent, vsock->vhost_dev.nvqs, true);
+    if (ret < 0) {
+        error_report("Error binding guest notifier: %d", -ret);
+        goto err_host_notifiers;
+    }
+
+    vsock->vhost_dev.acked_features = vdev->guest_features;
+    ret = vhost_dev_start(&vsock->vhost_dev, vdev);
+    if (ret < 0) {
+        error_report("Error starting vhost: %d", -ret);
+        goto err_guest_notifiers;
+    }
+
+    ret = vhost_vsock_set_running(vsock, 1);
+    if (ret < 0) {
+        error_report("Error starting vhost vsock: %d", -ret);
+        goto err_dev_start;
+    }
+
+    /* guest_notifier_mask/pending not used yet, so just unmask
+     * everything here.  virtio-pci will do the right thing by
+     * enabling/disabling irqfd.
+     */
+    for (i = 0; i < vsock->vhost_dev.nvqs; i++) {
+        vhost_virtqueue_mask(&vsock->vhost_dev, vdev, i, false);
+    }
+
+    return;
+
+err_dev_start:
+    vhost_dev_stop(&vsock->vhost_dev, vdev);
+err_guest_notifiers:
+    k->set_guest_notifiers(qbus->parent, vsock->vhost_dev.nvqs, false);
+err_host_notifiers:
+    vhost_dev_disable_notifiers(&vsock->vhost_dev, vdev);
+}
+
+static void vhost_vsock_stop(VirtIODevice *vdev)
+{
+    VHostVSock *vsock = VHOST_VSOCK(vdev);
+    BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(vdev)));
+    VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
+    int ret;
+
+    if (!k->set_guest_notifiers) {
+        return;
+    }
+
+    ret = vhost_vsock_set_running(vsock, 0);
+    if (ret < 0) {
+        error_report("vhost vsock set running failed: %d", ret);
+        return;
+    }
+
+    vhost_dev_stop(&vsock->vhost_dev, vdev);
+
+    ret = k->set_guest_notifiers(qbus->parent, vsock->vhost_dev.nvqs, false);
+    if (ret < 0) {
+        error_report("vhost guest notifier cleanup failed: %d", ret);
+        return;
+    }
+
+    vhost_dev_disable_notifiers(&vsock->vhost_dev, vdev);
+}
+
+static void vhost_vsock_set_status(VirtIODevice *vdev, uint8_t status)
+{
+    VHostVSock *vsock = VHOST_VSOCK(vdev);
+    bool should_start = status & VIRTIO_CONFIG_S_DRIVER_OK;
+
+    if (!vdev->vm_running) {
+        should_start = false;
+    }
+
+    if (vsock->vhost_dev.started == should_start) {
+        return;
+    }
+
+    if (should_start) {
+        vhost_vsock_start(vdev);
+    } else {
+        vhost_vsock_stop(vdev);
+    }
+}
+
+static uint64_t vhost_vsock_get_features(VirtIODevice *vdev,
+                                         uint64_t requested_features,
+                                         Error **errp)
+{
+    /* No feature bits used yet */
+    return requested_features;
+}
+
+static void vhost_vsock_handle_output(VirtIODevice *vdev, VirtQueue *vq)
+{
+    /* Do nothing */
+}
+
+static void vhost_vsock_guest_notifier_mask(VirtIODevice *vdev, int idx,
+                                            bool mask)
+{
+    VHostVSock *vsock = VHOST_VSOCK(vdev);
+
+    vhost_virtqueue_mask(&vsock->vhost_dev, vdev, idx, mask);
+}
+
+static bool vhost_vsock_guest_notifier_pending(VirtIODevice *vdev, int idx)
+{
+    VHostVSock *vsock = VHOST_VSOCK(vdev);
+
+    return vhost_virtqueue_pending(&vsock->vhost_dev, idx);
+}
+
+static void vhost_vsock_send_transport_reset(VHostVSock *vsock)
+{
+    VirtQueueElement *elem;
+    VirtQueue *vq = vsock->event_vq;
+    struct virtio_vsock_event event = {
+        .id = cpu_to_le32(VIRTIO_VSOCK_EVENT_TRANSPORT_RESET),
+    };
+
+    elem = virtqueue_pop(vq, sizeof(VirtQueueElement));
+    if (!elem) {
+        error_report("vhost-vsock missed transport reset event");
+        return;
+    }
+
+    if (elem->out_num) {
+        error_report("invalid vhost-vsock event virtqueue element with "
+                     "out buffers");
+        goto out;
+    }
+
+    if (iov_from_buf(elem->in_sg, elem->in_num, 0,
+                     &event, sizeof(event)) != sizeof(event)) {
+        error_report("vhost-vsock event virtqueue element is too short");
+        goto out;
+    }
+
+    virtqueue_push(vq, elem, sizeof(event));
+    virtio_notify(VIRTIO_DEVICE(vsock), vq);
+
+out:
+    g_free(elem);
+}
+
+static void vhost_vsock_save(QEMUFile *f, void *opaque, size_t size)
+{
+    VHostVSock *vsock = opaque;
+    VirtIODevice *vdev = VIRTIO_DEVICE(vsock);
+
+    /* At this point, backend must be stopped, otherwise
+     * it might keep writing to memory. */
+    assert(!vsock->vhost_dev.started);
+    virtio_save(vdev, f);
+}
+
+static void vhost_vsock_post_load_timer_cleanup(VHostVSock *vsock)
+{
+    if (!vsock->post_load_timer) {
+        return;
+    }
+
+    timer_del(vsock->post_load_timer);
+    timer_free(vsock->post_load_timer);
+    vsock->post_load_timer = NULL;
+}
+
+static void vhost_vsock_post_load_timer_cb(void *opaque)
+{
+    VHostVSock *vsock = opaque;
+
+    vhost_vsock_post_load_timer_cleanup(vsock);
+    vhost_vsock_send_transport_reset(vsock);
+}
+
+static int vhost_vsock_load(QEMUFile *f, void *opaque, size_t size)
+{
+    VHostVSock *vsock = opaque;
+    VirtIODevice *vdev = VIRTIO_DEVICE(vsock);
+    int ret;
+
+    ret = virtio_load(vdev, f, VHOST_VSOCK_SAVEVM_VERSION);
+    if (ret) {
+        return ret;
+    }
+
+    if (virtio_queue_get_addr(vdev, 2)) {
+        /* Defer transport reset event to a vm clock timer so that virtqueue
+         * changes happen after migration has completed.
+         */
+        assert(!vsock->post_load_timer);
+        vsock->post_load_timer =
+            timer_new_ns(QEMU_CLOCK_VIRTUAL,
+                         vhost_vsock_post_load_timer_cb,
+                         vsock);
+        timer_mod(vsock->post_load_timer, 1);
+    }
+
+    return 0;
+}
+
+VMSTATE_VIRTIO_DEVICE(vhost_vsock, VHOST_VSOCK_SAVEVM_VERSION,
+                      vhost_vsock_load, vhost_vsock_save);
+
+static void vhost_vsock_device_realize(DeviceState *dev, Error **errp)
+{
+    VirtIODevice *vdev = VIRTIO_DEVICE(dev);
+    VHostVSock *vsock = VHOST_VSOCK(dev);
+    int vhostfd;
+    int ret;
+
+    /* Refuse to use reserved CID numbers */
+    if (vsock->conf.guest_cid <= 2) {
+        error_setg(errp, "guest-cid property must be greater than 2");
+        return;
+    }
+
+    if (vsock->conf.guest_cid > UINT32_MAX) {
+        error_setg(errp, "guest-cid property must be a 32-bit number");
+        return;
+    }
+
+    if (vsock->conf.vhostfd) {
+        vhostfd = monitor_fd_param(cur_mon, vsock->conf.vhostfd, errp);
+        if (vhostfd == -1) {
+            error_prepend(errp, "vhost-vsock: unable to parse vhostfd: ");
+            return;
+        }
+    } else {
+        vhostfd = open("/dev/vhost-vsock", O_RDWR);
+        if (vhostfd < 0) {
+            error_setg_errno(errp, -errno,
+                             "vhost-vsock: failed to open vhost device");
+            return;
+        }
+    }
+
+    virtio_init(vdev, "vhost-vsock", VIRTIO_ID_VSOCK,
+                sizeof(struct virtio_vsock_config));
+
+    /* Receive and transmit queues belong to vhost */
+    virtio_add_queue(vdev, VHOST_VSOCK_QUEUE_SIZE, vhost_vsock_handle_output);
+    virtio_add_queue(vdev, VHOST_VSOCK_QUEUE_SIZE, vhost_vsock_handle_output);
+
+    /* The event queue belongs to QEMU */
+    vsock->event_vq = virtio_add_queue(vdev, VHOST_VSOCK_QUEUE_SIZE,
+                                       vhost_vsock_handle_output);
+
+    vsock->vhost_dev.nvqs = ARRAY_SIZE(vsock->vhost_vqs);
+    vsock->vhost_dev.vqs = vsock->vhost_vqs;
+    ret = vhost_dev_init(&vsock->vhost_dev, (void *)(uintptr_t)vhostfd,
+                         VHOST_BACKEND_TYPE_KERNEL, 0);
+    if (ret < 0) {
+        error_setg_errno(errp, -ret, "vhost-vsock: vhost_dev_init failed");
+        goto err_virtio;
+    }
+
+    ret = vhost_vsock_set_guest_cid(vsock);
+    if (ret < 0) {
+        error_setg_errno(errp, -ret, "vhost-vsock: unable to set guest cid");
+        goto err_vhost_dev;
+    }
+
+    vsock->post_load_timer = NULL;
+    return;
+
+err_vhost_dev:
+    vhost_dev_cleanup(&vsock->vhost_dev);
+err_virtio:
+    virtio_cleanup(vdev);
+    close(vhostfd);
+    return;
+}
+
+static void vhost_vsock_device_unrealize(DeviceState *dev, Error **errp)
+{
+    VirtIODevice *vdev = VIRTIO_DEVICE(dev);
+    VHostVSock *vsock = VHOST_VSOCK(dev);
+
+    vhost_vsock_post_load_timer_cleanup(vsock);
+
+    /* This will stop vhost backend if appropriate. */
+    vhost_vsock_set_status(vdev, 0);
+
+    vhost_dev_cleanup(&vsock->vhost_dev);
+    virtio_cleanup(vdev);
+}
+
+static Property vhost_vsock_properties[] = {
+    DEFINE_PROP_UINT64("guest-cid", VHostVSock, conf.guest_cid, 0),
+    DEFINE_PROP_STRING("vhostfd", VHostVSock, conf.vhostfd),
+    DEFINE_PROP_END_OF_LIST(),
+};
+
+static void vhost_vsock_class_init(ObjectClass *klass, void *data)
+{
+    DeviceClass *dc = DEVICE_CLASS(klass);
+    VirtioDeviceClass *vdc = VIRTIO_DEVICE_CLASS(klass);
+
+    dc->props = vhost_vsock_properties;
+    dc->vmsd = &vmstate_virtio_vhost_vsock;
+    set_bit(DEVICE_CATEGORY_MISC, dc->categories);
+    vdc->realize = vhost_vsock_device_realize;
+    vdc->unrealize = vhost_vsock_device_unrealize;
+    vdc->get_features = vhost_vsock_get_features;
+    vdc->get_config = vhost_vsock_get_config;
+    vdc->set_status = vhost_vsock_set_status;
+    vdc->guest_notifier_mask = vhost_vsock_guest_notifier_mask;
+    vdc->guest_notifier_pending = vhost_vsock_guest_notifier_pending;
+}
+
+static const TypeInfo vhost_vsock_info = {
+    .name = TYPE_VHOST_VSOCK,
+    .parent = TYPE_VIRTIO_DEVICE,
+    .instance_size = sizeof(VHostVSock),
+    .class_init = vhost_vsock_class_init,
+};
+
+static void vhost_vsock_register_types(void)
+{
+    type_register_static(&vhost_vsock_info);
+}
+
+type_init(vhost_vsock_register_types)