backends/vhost-user.c

   1 /*
   2  * QEMU vhost-user backend
   3  *
   4  * Copyright (C) 2018 Red Hat Inc
   5  *
   6  * Authors:
   7  *  Marc-André Lureau <marcandre.lureau@redhat.com>
   8  *
   9  * This work is licensed under the terms of the GNU GPL, version 2 or later.
  10  * See the COPYING file in the top-level directory.
  11  */
  12
  13
  14 #include "qemu/osdep.h"
  15 #include "qapi/error.h"
  16 #include "qapi/qmp/qerror.h"
  17 #include "qemu/error-report.h"
  18 #include "qom/object_interfaces.h"
  19 #include "sysemu/vhost-user-backend.h"
  20 #include "sysemu/kvm.h"
  21 #include "io/channel-command.h"
  22 #include "hw/virtio/virtio-bus.h"
  23
  24 static bool
  25 ioeventfd_enabled(void)
  26 {
  27     return kvm_enabled() && kvm_eventfds_enabled();
  28 }
  29
  30 int
  31 vhost_user_backend_dev_init(VhostUserBackend *b, VirtIODevice *vdev,
  32                             unsigned nvqs, Error **errp)
  33 {
  34     int ret;
  35
  36     assert(!b->vdev && vdev);
  37
  38     if (!ioeventfd_enabled()) {
  39         error_setg(errp, "vhost initialization failed: requires kvm");
  40         return -1;
  41     }
  42
  43     if (!vhost_user_init(&b->vhost_user, &b->chr, errp)) {
  44         return -1;
  45     }
  46
  47     b->vdev = vdev;
  48     b->dev.nvqs = nvqs;
  49     b->dev.vqs = g_new0(struct vhost_virtqueue, nvqs);
  50
  51     ret = vhost_dev_init(&b->dev, &b->vhost_user, VHOST_BACKEND_TYPE_USER, 0);
  52     if (ret < 0) {
  53         error_setg_errno(errp, -ret, "vhost initialization failed");
  54         return -1;
  55     }
  56
  57     return 0;
  58 }
  59
  60 void
  61 vhost_user_backend_start(VhostUserBackend *b)
  62 {
  63     BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(b->vdev)));
  64     VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
  65     int ret, i ;
  66
  67     if (b->started) {
  68         return;
  69     }
  70
  71     if (!k->set_guest_notifiers) {
  72         error_report("binding does not support guest notifiers");
  73         return;
  74     }
  75
  76     ret = vhost_dev_enable_notifiers(&b->dev, b->vdev);
  77     if (ret < 0) {
  78         return;
  79     }
  80
  81     ret = k->set_guest_notifiers(qbus->parent, b->dev.nvqs, true);
  82     if (ret < 0) {
  83         error_report("Error binding guest notifier");
  84         goto err_host_notifiers;
  85     }
  86
  87     b->dev.acked_features = b->vdev->guest_features;
  88     ret = vhost_dev_start(&b->dev, b->vdev);
  89     if (ret < 0) {
  90         error_report("Error start vhost dev");
  91         goto err_guest_notifiers;
  92     }
  93
  94     /* guest_notifier_mask/pending not used yet, so just unmask
  95      * everything here.  virtio-pci will do the right thing by
  96      * enabling/disabling irqfd.
  97      */
  98     for (i = 0; i < b->dev.nvqs; i++) {
  99         vhost_virtqueue_mask(&b->dev, b->vdev,
 100                              b->dev.vq_index + i, false);
 101     }
 102
 103     b->started = true;
 104     return;
 105
 106 err_guest_notifiers:
 107     k->set_guest_notifiers(qbus->parent, b->dev.nvqs, false);
 108 err_host_notifiers:
 109     vhost_dev_disable_notifiers(&b->dev, b->vdev);
 110 }
 111
 112 void
 113 vhost_user_backend_stop(VhostUserBackend *b)
 114 {
 115     BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(b->vdev)));
 116     VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
 117     int ret = 0;
 118
 119     if (!b->started) {
 120         return;
 121     }
 122
 123     vhost_dev_stop(&b->dev, b->vdev);
 124
 125     if (k->set_guest_notifiers) {
 126         ret = k->set_guest_notifiers(qbus->parent,
 127                                      b->dev.nvqs, false);
 128         if (ret < 0) {
 129             error_report("vhost guest notifier cleanup failed: %d", ret);
 130         }
 131     }
 132     assert(ret >= 0);
 133
 134     vhost_dev_disable_notifiers(&b->dev, b->vdev);
 135     b->started = false;
 136 }
 137
 138 static void set_chardev(Object *obj, const char *value, Error **errp)
 139 {
 140     VhostUserBackend *b = VHOST_USER_BACKEND(obj);
 141     Chardev *chr;
 142
 143     if (b->completed) {
 144         error_setg(errp, QERR_PERMISSION_DENIED);
 145         return;
 146     }
 147
 148     g_free(b->chr_name);
 149     b->chr_name = g_strdup(value);
 150
 151     chr = qemu_chr_find(b->chr_name);
 152     if (chr == NULL) {
 153         error_set(errp, ERROR_CLASS_DEVICE_NOT_FOUND,
 154                   "Chardev '%s' not found", b->chr_name);
 155         return;
 156     }
 157
 158     if (!qemu_chr_fe_init(&b->chr, chr, errp)) {
 159         return;
 160     }
 161
 162     b->completed = true;
 163     /* could call vhost_dev_init() so early message can be exchanged */
 164 }
 165
 166 static char *get_chardev(Object *obj, Error **errp)
 167 {
 168     VhostUserBackend *b = VHOST_USER_BACKEND(obj);
 169     Chardev *chr = qemu_chr_fe_get_driver(&b->chr);
 170
 171     if (chr && chr->label) {
 172         return g_strdup(chr->label);
 173     }
 174
 175     return NULL;
 176 }
 177
 178 static void vhost_user_backend_class_init(ObjectClass *oc, void *data)
 179 {
 180     object_class_property_add_str(oc, "chardev", get_chardev, set_chardev);
 181 }
 182
 183 static void vhost_user_backend_finalize(Object *obj)
 184 {
 185     VhostUserBackend *b = VHOST_USER_BACKEND(obj);
 186
 187     g_free(b->dev.vqs);
 188     g_free(b->chr_name);
 189
 190     vhost_user_cleanup(&b->vhost_user);
 191     qemu_chr_fe_deinit(&b->chr, true);
 192 }
 193
 194 static const TypeInfo vhost_user_backend_info = {
 195     .name = TYPE_VHOST_USER_BACKEND,
 196     .parent = TYPE_OBJECT,
 197     .instance_size = sizeof(VhostUserBackend),
 198     .class_init = vhost_user_backend_class_init,
 199     .instance_finalize = vhost_user_backend_finalize,
 200 };
 201
 202 static void register_types(void)
 203 {
 204     type_register_static(&vhost_user_backend_info);
 205 }
 206
 207 type_init(register_types);