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 "scsi/constants.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     bool progress;
  56     VirtIOSCSI *s = VIRTIO_SCSI(vdev);
  57
  58     virtio_scsi_acquire(s);
  59     assert(s->ctx && s->dataplane_started);
  60     progress = virtio_scsi_handle_cmd_vq(s, vq);
  61     virtio_scsi_release(s);
  62     return progress;
  63 }
  64
  65 static bool virtio_scsi_data_plane_handle_ctrl(VirtIODevice *vdev,
  66                                                VirtQueue *vq)
  67 {
  68     bool progress;
  69     VirtIOSCSI *s = VIRTIO_SCSI(vdev);
  70
  71     virtio_scsi_acquire(s);
  72     assert(s->ctx && s->dataplane_started);
  73     progress = virtio_scsi_handle_ctrl_vq(s, vq);
  74     virtio_scsi_release(s);
  75     return progress;
  76 }
  77
  78 static bool virtio_scsi_data_plane_handle_event(VirtIODevice *vdev,
  79                                                 VirtQueue *vq)
  80 {
  81     bool progress;
  82     VirtIOSCSI *s = VIRTIO_SCSI(vdev);
  83
  84     virtio_scsi_acquire(s);
  85     assert(s->ctx && s->dataplane_started);
  86     progress = virtio_scsi_handle_event_vq(s, vq);
  87     virtio_scsi_release(s);
  88     return progress;
  89 }
  90
  91 static int virtio_scsi_vring_init(VirtIOSCSI *s, VirtQueue *vq, int n,
  92                                   VirtIOHandleAIOOutput fn)
  93 {
  94     BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(s)));
  95     int rc;
  96
  97     /* Set up virtqueue notify */
  98     rc = virtio_bus_set_host_notifier(VIRTIO_BUS(qbus), n, true);
  99     if (rc != 0) {
 100         fprintf(stderr, "virtio-scsi: Failed to set host notifier (%d)\n",
 101                 rc);
 102         s->dataplane_fenced = true;
 103         return rc;
 104     }
 105
 106     virtio_queue_aio_set_host_notifier_handler(vq, s->ctx, fn);
 107     return 0;
 108 }
 109
 110 /* Context: BH in IOThread */
 111 static void virtio_scsi_dataplane_stop_bh(void *opaque)
 112 {
 113     VirtIOSCSI *s = opaque;
 114     VirtIOSCSICommon *vs = VIRTIO_SCSI_COMMON(s);
 115     int i;
 116
 117     virtio_queue_aio_set_host_notifier_handler(vs->ctrl_vq, s->ctx, NULL);
 118     virtio_queue_aio_set_host_notifier_handler(vs->event_vq, s->ctx, NULL);
 119     for (i = 0; i < vs->conf.num_queues; i++) {
 120         virtio_queue_aio_set_host_notifier_handler(vs->cmd_vqs[i], s->ctx, NULL);
 121     }
 122 }
 123
 124 /* Context: QEMU global mutex held */
 125 int virtio_scsi_dataplane_start(VirtIODevice *vdev)
 126 {
 127     int i;
 128     int rc;
 129     BusState *qbus = qdev_get_parent_bus(DEVICE(vdev));
 130     VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
 131     VirtIOSCSICommon *vs = VIRTIO_SCSI_COMMON(vdev);
 132     VirtIOSCSI *s = VIRTIO_SCSI(vdev);
 133
 134     if (s->dataplane_started ||
 135         s->dataplane_starting ||
 136         s->dataplane_fenced) {
 137         return 0;
 138     }
 139
 140     s->dataplane_starting = true;
 141
 142     /* Set up guest notifier (irq) */
 143     rc = k->set_guest_notifiers(qbus->parent, vs->conf.num_queues + 2, true);
 144     if (rc != 0) {
 145         error_report("virtio-scsi: Failed to set guest notifiers (%d), "
 146                      "ensure -accel kvm is set.", rc);
 147         goto fail_guest_notifiers;
 148     }
 149
 150     aio_context_acquire(s->ctx);
 151     rc = virtio_scsi_vring_init(s, vs->ctrl_vq, 0,
 152                                 virtio_scsi_data_plane_handle_ctrl);
 153     if (rc) {
 154         goto fail_vrings;
 155     }
 156     rc = virtio_scsi_vring_init(s, vs->event_vq, 1,
 157                                 virtio_scsi_data_plane_handle_event);
 158     if (rc) {
 159         goto fail_vrings;
 160     }
 161     for (i = 0; i < vs->conf.num_queues; i++) {
 162         rc = virtio_scsi_vring_init(s, vs->cmd_vqs[i], i + 2,
 163                                     virtio_scsi_data_plane_handle_cmd);
 164         if (rc) {
 165             goto fail_vrings;
 166         }
 167     }
 168
 169     s->dataplane_starting = false;
 170     s->dataplane_started = true;
 171     aio_context_release(s->ctx);
 172     return 0;
 173
 174 fail_vrings:
 175     aio_wait_bh_oneshot(s->ctx, virtio_scsi_dataplane_stop_bh, s);
 176     aio_context_release(s->ctx);
 177     for (i = 0; i < vs->conf.num_queues + 2; i++) {
 178         virtio_bus_set_host_notifier(VIRTIO_BUS(qbus), i, false);
 179         virtio_bus_cleanup_host_notifier(VIRTIO_BUS(qbus), i);
 180     }
 181     k->set_guest_notifiers(qbus->parent, vs->conf.num_queues + 2, false);
 182 fail_guest_notifiers:
 183     s->dataplane_fenced = true;
 184     s->dataplane_starting = false;
 185     s->dataplane_started = true;
 186     return -ENOSYS;
 187 }
 188
 189 /* Context: QEMU global mutex held */
 190 void virtio_scsi_dataplane_stop(VirtIODevice *vdev)
 191 {
 192     BusState *qbus = qdev_get_parent_bus(DEVICE(vdev));
 193     VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
 194     VirtIOSCSICommon *vs = VIRTIO_SCSI_COMMON(vdev);
 195     VirtIOSCSI *s = VIRTIO_SCSI(vdev);
 196     int i;
 197
 198     if (!s->dataplane_started || s->dataplane_stopping) {
 199         return;
 200     }
 201
 202     /* Better luck next time. */
 203     if (s->dataplane_fenced) {
 204         s->dataplane_fenced = false;
 205         s->dataplane_started = false;
 206         return;
 207     }
 208     s->dataplane_stopping = true;
 209
 210     aio_context_acquire(s->ctx);
 211     aio_wait_bh_oneshot(s->ctx, virtio_scsi_dataplane_stop_bh, s);
 212     aio_context_release(s->ctx);
 213
 214     blk_drain_all(); /* ensure there are no in-flight requests */
 215
 216     for (i = 0; i < vs->conf.num_queues + 2; i++) {
 217         virtio_bus_set_host_notifier(VIRTIO_BUS(qbus), i, false);
 218         virtio_bus_cleanup_host_notifier(VIRTIO_BUS(qbus), i);
 219     }
 220
 221     /* Clean up guest notifier (irq) */
 222     k->set_guest_notifiers(qbus->parent, vs->conf.num_queues + 2, false);
 223     s->dataplane_stopping = false;
 224     s->dataplane_started = false;
 225 }