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 void 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     virtio_scsi_handle_cmd_vq(s, vq);
  59 }
  60
  61 static void 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     virtio_scsi_handle_ctrl_vq(s, vq);
  68 }
  69
  70 static void 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     virtio_scsi_handle_event_vq(s, vq);
  77 }
  78
  79 static int virtio_scsi_vring_init(VirtIOSCSI *s, VirtQueue *vq, int n,
  80                                   void (*fn)(VirtIODevice *vdev, VirtQueue *vq))
  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 void virtio_scsi_dataplane_notify(VirtIODevice *vdev, VirtIOSCSIReq *req)
  99 {
 100     if (virtio_should_notify(vdev, req->vq)) {
 101         event_notifier_set(virtio_queue_get_guest_notifier(req->vq));
 102     }
 103 }
 104
 105 /* assumes s->ctx held */
 106 static void virtio_scsi_clear_aio(VirtIOSCSI *s)
 107 {
 108     VirtIOSCSICommon *vs = VIRTIO_SCSI_COMMON(s);
 109     int i;
 110
 111     virtio_queue_aio_set_host_notifier_handler(vs->ctrl_vq, s->ctx, NULL);
 112     virtio_queue_aio_set_host_notifier_handler(vs->event_vq, s->ctx, NULL);
 113     for (i = 0; i < vs->conf.num_queues; i++) {
 114         virtio_queue_aio_set_host_notifier_handler(vs->cmd_vqs[i], s->ctx, NULL);
 115     }
 116 }
 117
 118 /* Context: QEMU global mutex held */
 119 int virtio_scsi_dataplane_start(VirtIODevice *vdev)
 120 {
 121     int i;
 122     int rc;
 123     BusState *qbus = qdev_get_parent_bus(DEVICE(vdev));
 124     VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
 125     VirtIOSCSICommon *vs = VIRTIO_SCSI_COMMON(vdev);
 126     VirtIOSCSI *s = VIRTIO_SCSI(vdev);
 127
 128     if (s->dataplane_started ||
 129         s->dataplane_starting ||
 130         s->dataplane_fenced) {
 131         return 0;
 132     }
 133
 134     s->dataplane_starting = true;
 135
 136     /* Set up guest notifier (irq) */
 137     rc = k->set_guest_notifiers(qbus->parent, vs->conf.num_queues + 2, true);
 138     if (rc != 0) {
 139         fprintf(stderr, "virtio-scsi: Failed to set guest notifiers (%d), "
 140                 "ensure -enable-kvm is set\n", rc);
 141         goto fail_guest_notifiers;
 142     }
 143
 144     aio_context_acquire(s->ctx);
 145     rc = virtio_scsi_vring_init(s, vs->ctrl_vq, 0,
 146                                 virtio_scsi_data_plane_handle_ctrl);
 147     if (rc) {
 148         goto fail_vrings;
 149     }
 150     rc = virtio_scsi_vring_init(s, vs->event_vq, 1,
 151                                 virtio_scsi_data_plane_handle_event);
 152     if (rc) {
 153         goto fail_vrings;
 154     }
 155     for (i = 0; i < vs->conf.num_queues; i++) {
 156         rc = virtio_scsi_vring_init(s, vs->cmd_vqs[i], i + 2,
 157                                     virtio_scsi_data_plane_handle_cmd);
 158         if (rc) {
 159             goto fail_vrings;
 160         }
 161     }
 162
 163     s->dataplane_starting = false;
 164     s->dataplane_started = true;
 165     aio_context_release(s->ctx);
 166     return 0;
 167
 168 fail_vrings:
 169     virtio_scsi_clear_aio(s);
 170     aio_context_release(s->ctx);
 171     for (i = 0; i < vs->conf.num_queues + 2; i++) {
 172         virtio_bus_set_host_notifier(VIRTIO_BUS(qbus), i, false);
 173     }
 174     k->set_guest_notifiers(qbus->parent, vs->conf.num_queues + 2, false);
 175 fail_guest_notifiers:
 176     s->dataplane_fenced = true;
 177     s->dataplane_starting = false;
 178     s->dataplane_started = true;
 179     return -ENOSYS;
 180 }
 181
 182 /* Context: QEMU global mutex held */
 183 void virtio_scsi_dataplane_stop(VirtIODevice *vdev)
 184 {
 185     BusState *qbus = qdev_get_parent_bus(DEVICE(vdev));
 186     VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
 187     VirtIOSCSICommon *vs = VIRTIO_SCSI_COMMON(vdev);
 188     VirtIOSCSI *s = VIRTIO_SCSI(vdev);
 189     int i;
 190
 191     if (!s->dataplane_started || s->dataplane_stopping) {
 192         return;
 193     }
 194
 195     /* Better luck next time. */
 196     if (s->dataplane_fenced) {
 197         s->dataplane_fenced = false;
 198         s->dataplane_started = false;
 199         return;
 200     }
 201     s->dataplane_stopping = true;
 202
 203     aio_context_acquire(s->ctx);
 204
 205     virtio_scsi_clear_aio(s);
 206
 207     blk_drain_all(); /* ensure there are no in-flight requests */
 208
 209     aio_context_release(s->ctx);
 210
 211     for (i = 0; i < vs->conf.num_queues + 2; i++) {
 212         virtio_bus_set_host_notifier(VIRTIO_BUS(qbus), i, false);
 213     }
 214
 215     /* Clean up guest notifier (irq) */
 216     k->set_guest_notifiers(qbus->parent, vs->conf.num_queues + 2, false);
 217     s->dataplane_stopping = false;
 218     s->dataplane_started = false;
 219 }