hw/scsi/virtio-scsi-dataplane.c

   1 /*
   2  * Virtio SCSI dataplane
   3  *
   4  * Copyright Red Hat, Inc. 2014
   5  *
   6  * Authors:
   7  *   Fam Zheng <famz@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 "hw/virtio/virtio-scsi.h"
  17 #include "qemu/error-report.h"
  18 #include "sysemu/block-backend.h"
  19 #include "hw/scsi/scsi.h"
  20 #include "block/scsi.h"
  21 #include "hw/virtio/virtio-bus.h"
  22 #include "hw/virtio/virtio-access.h"
  23
  24 /* Context: QEMU global mutex held */
  25 void virtio_scsi_dataplane_setup(VirtIOSCSI *s, Error **errp)
  26 {
  27     VirtIOSCSICommon *vs = VIRTIO_SCSI_COMMON(s);
  28     VirtIODevice *vdev = VIRTIO_DEVICE(s);
  29     BusState *qbus = qdev_get_parent_bus(DEVICE(vdev));
  30     VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
  31
  32     if (vs->conf.iothread) {
  33         if (!k->set_guest_notifiers || !k->ioeventfd_assign) {
  34             error_setg(errp,
  35                        "device is incompatible with iothread "
  36                        "(transport does not support notifiers)");
  37             return;
  38         }
  39         if (!virtio_device_ioeventfd_enabled(vdev)) {
  40             error_setg(errp, "ioeventfd is required for iothread");
  41             return;
  42         }
  43         s->ctx = iothread_get_aio_context(vs->conf.iothread);
  44     } else {
  45         if (!virtio_device_ioeventfd_enabled(vdev)) {
  46             return;
  47         }
  48         s->ctx = qemu_get_aio_context();
  49     }
  50 }
  51
  52 static bool virtio_scsi_data_plane_handle_cmd(VirtIODevice *vdev,
  53                                               VirtQueue *vq)
  54 {
  55     VirtIOSCSI *s = (VirtIOSCSI *)vdev;
  56
  57     assert(s->ctx && s->dataplane_started);
  58     return virtio_scsi_handle_cmd_vq(s, vq);
  59 }
  60
  61 static bool virtio_scsi_data_plane_handle_ctrl(VirtIODevice *vdev,
  62                                                VirtQueue *vq)
  63 {
  64     VirtIOSCSI *s = VIRTIO_SCSI(vdev);
  65
  66     assert(s->ctx && s->dataplane_started);
  67     return virtio_scsi_handle_ctrl_vq(s, vq);
  68 }
  69
  70 static bool virtio_scsi_data_plane_handle_event(VirtIODevice *vdev,
  71                                                 VirtQueue *vq)
  72 {
  73     VirtIOSCSI *s = VIRTIO_SCSI(vdev);
  74
  75     assert(s->ctx && s->dataplane_started);
  76     return virtio_scsi_handle_event_vq(s, vq);
  77 }
  78
  79 static int virtio_scsi_vring_init(VirtIOSCSI *s, VirtQueue *vq, int n,
  80                                   VirtIOHandleAIOOutput fn)
  81 {
  82     BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(s)));
  83     int rc;
  84
  85     /* Set up virtqueue notify */
  86     rc = virtio_bus_set_host_notifier(VIRTIO_BUS(qbus), n, true);
  87     if (rc != 0) {
  88         fprintf(stderr, "virtio-scsi: Failed to set host notifier (%d)\n",
  89                 rc);
  90         s->dataplane_fenced = true;
  91         return rc;
  92     }
  93
  94     virtio_queue_aio_set_host_notifier_handler(vq, s->ctx, fn);
  95     return 0;
  96 }
  97
  98 /* assumes s->ctx held */
  99 static void virtio_scsi_clear_aio(VirtIOSCSI *s)
 100 {
 101     VirtIOSCSICommon *vs = VIRTIO_SCSI_COMMON(s);
 102     int i;
 103
 104     virtio_queue_aio_set_host_notifier_handler(vs->ctrl_vq, s->ctx, NULL);
 105     virtio_queue_aio_set_host_notifier_handler(vs->event_vq, s->ctx, NULL);
 106     for (i = 0; i < vs->conf.num_queues; i++) {
 107         virtio_queue_aio_set_host_notifier_handler(vs->cmd_vqs[i], s->ctx, NULL);
 108     }
 109 }
 110
 111 /* Context: QEMU global mutex held */
 112 int virtio_scsi_dataplane_start(VirtIODevice *vdev)
 113 {
 114     int i;
 115     int rc;
 116     BusState *qbus = qdev_get_parent_bus(DEVICE(vdev));
 117     VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
 118     VirtIOSCSICommon *vs = VIRTIO_SCSI_COMMON(vdev);
 119     VirtIOSCSI *s = VIRTIO_SCSI(vdev);
 120
 121     if (s->dataplane_started ||
 122         s->dataplane_starting ||
 123         s->dataplane_fenced) {
 124         return 0;
 125     }
 126
 127     s->dataplane_starting = true;
 128
 129     /* Set up guest notifier (irq) */
 130     rc = k->set_guest_notifiers(qbus->parent, vs->conf.num_queues + 2, true);
 131     if (rc != 0) {
 132         fprintf(stderr, "virtio-scsi: Failed to set guest notifiers (%d), "
 133                 "ensure -enable-kvm is set\n", rc);
 134         goto fail_guest_notifiers;
 135     }
 136
 137     aio_context_acquire(s->ctx);
 138     rc = virtio_scsi_vring_init(s, vs->ctrl_vq, 0,
 139                                 virtio_scsi_data_plane_handle_ctrl);
 140     if (rc) {
 141         goto fail_vrings;
 142     }
 143     rc = virtio_scsi_vring_init(s, vs->event_vq, 1,
 144                                 virtio_scsi_data_plane_handle_event);
 145     if (rc) {
 146         goto fail_vrings;
 147     }
 148     for (i = 0; i < vs->conf.num_queues; i++) {
 149         rc = virtio_scsi_vring_init(s, vs->cmd_vqs[i], i + 2,
 150                                     virtio_scsi_data_plane_handle_cmd);
 151         if (rc) {
 152             goto fail_vrings;
 153         }
 154     }
 155
 156     s->dataplane_starting = false;
 157     s->dataplane_started = true;
 158     aio_context_release(s->ctx);
 159     return 0;
 160
 161 fail_vrings:
 162     virtio_scsi_clear_aio(s);
 163     aio_context_release(s->ctx);
 164     for (i = 0; i < vs->conf.num_queues + 2; i++) {
 165         virtio_bus_set_host_notifier(VIRTIO_BUS(qbus), i, false);
 166     }
 167     k->set_guest_notifiers(qbus->parent, vs->conf.num_queues + 2, false);
 168 fail_guest_notifiers:
 169     s->dataplane_fenced = true;
 170     s->dataplane_starting = false;
 171     s->dataplane_started = true;
 172     return -ENOSYS;
 173 }
 174
 175 /* Context: QEMU global mutex held */
 176 void virtio_scsi_dataplane_stop(VirtIODevice *vdev)
 177 {
 178     BusState *qbus = qdev_get_parent_bus(DEVICE(vdev));
 179     VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
 180     VirtIOSCSICommon *vs = VIRTIO_SCSI_COMMON(vdev);
 181     VirtIOSCSI *s = VIRTIO_SCSI(vdev);
 182     int i;
 183
 184     if (!s->dataplane_started || s->dataplane_stopping) {
 185         return;
 186     }
 187
 188     /* Better luck next time. */
 189     if (s->dataplane_fenced) {
 190         s->dataplane_fenced = false;
 191         s->dataplane_started = false;
 192         return;
 193     }
 194     s->dataplane_stopping = true;
 195
 196     aio_context_acquire(s->ctx);
 197     virtio_scsi_clear_aio(s);
 198     aio_context_release(s->ctx);
 199
 200     blk_drain_all(); /* ensure there are no in-flight requests */
 201
 202     for (i = 0; i < vs->conf.num_queues + 2; i++) {
 203         virtio_bus_set_host_notifier(VIRTIO_BUS(qbus), i, false);
 204     }
 205
 206     /* Clean up guest notifier (irq) */
 207     k->set_guest_notifiers(qbus->parent, vs->conf.num_queues + 2, false);
 208     s->dataplane_stopping = false;
 209     s->dataplane_started = false;
 210 }