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