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 = false;
  56     VirtIOSCSI *s = VIRTIO_SCSI(vdev);
  57
  58     virtio_scsi_acquire(s);
  59     if (!s->dataplane_fenced) {
  60         assert(s->ctx && s->dataplane_started);
  61         progress = virtio_scsi_handle_cmd_vq(s, vq);
  62     }
  63     virtio_scsi_release(s);
  64     return progress;
  65 }
  66
  67 static bool virtio_scsi_data_plane_handle_ctrl(VirtIODevice *vdev,
  68                                                VirtQueue *vq)
  69 {
  70     bool progress = false;
  71     VirtIOSCSI *s = VIRTIO_SCSI(vdev);
  72
  73     virtio_scsi_acquire(s);
  74     if (!s->dataplane_fenced) {
  75         assert(s->ctx && s->dataplane_started);
  76         progress = virtio_scsi_handle_ctrl_vq(s, vq);
  77     }
  78     virtio_scsi_release(s);
  79     return progress;
  80 }
  81
  82 static bool virtio_scsi_data_plane_handle_event(VirtIODevice *vdev,
  83                                                 VirtQueue *vq)
  84 {
  85     bool progress = false;
  86     VirtIOSCSI *s = VIRTIO_SCSI(vdev);
  87
  88     virtio_scsi_acquire(s);
  89     if (!s->dataplane_fenced) {
  90         assert(s->ctx && s->dataplane_started);
  91         progress = virtio_scsi_handle_event_vq(s, vq);
  92     }
  93     virtio_scsi_release(s);
  94     return progress;
  95 }
  96
  97 static int virtio_scsi_set_host_notifier(VirtIOSCSI *s, VirtQueue *vq, int n)
  98 {
  99     BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(s)));
 100     int rc;
 101
 102     /* Set up virtqueue notify */
 103     rc = virtio_bus_set_host_notifier(VIRTIO_BUS(qbus), n, true);
 104     if (rc != 0) {
 105         fprintf(stderr, "virtio-scsi: Failed to set host notifier (%d)\n",
 106                 rc);
 107         s->dataplane_fenced = true;
 108         return rc;
 109     }
 110
 111     return 0;
 112 }
 113
 114 /* Context: BH in IOThread */
 115 static void virtio_scsi_dataplane_stop_bh(void *opaque)
 116 {
 117     VirtIOSCSI *s = opaque;
 118     VirtIOSCSICommon *vs = VIRTIO_SCSI_COMMON(s);
 119     int i;
 120
 121     virtio_queue_aio_set_host_notifier_handler(vs->ctrl_vq, s->ctx, NULL);
 122     virtio_queue_aio_set_host_notifier_handler(vs->event_vq, s->ctx, NULL);
 123     for (i = 0; i < vs->conf.num_queues; i++) {
 124         virtio_queue_aio_set_host_notifier_handler(vs->cmd_vqs[i], s->ctx, NULL);
 125     }
 126 }
 127
 128 /* Context: QEMU global mutex held */
 129 int virtio_scsi_dataplane_start(VirtIODevice *vdev)
 130 {
 131     int i;
 132     int rc;
 133     int vq_init_count = 0;
 134     BusState *qbus = qdev_get_parent_bus(DEVICE(vdev));
 135     VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
 136     VirtIOSCSICommon *vs = VIRTIO_SCSI_COMMON(vdev);
 137     VirtIOSCSI *s = VIRTIO_SCSI(vdev);
 138
 139     if (s->dataplane_started ||
 140         s->dataplane_starting ||
 141         s->dataplane_fenced) {
 142         return 0;
 143     }
 144
 145     s->dataplane_starting = true;
 146
 147     /* Set up guest notifier (irq) */
 148     rc = k->set_guest_notifiers(qbus->parent, vs->conf.num_queues + 2, true);
 149     if (rc != 0) {
 150         error_report("virtio-scsi: Failed to set guest notifiers (%d), "
 151                      "ensure -accel kvm is set.", rc);
 152         goto fail_guest_notifiers;
 153     }
 154
 155     memory_region_transaction_begin();
 156
 157     rc = virtio_scsi_set_host_notifier(s, vs->ctrl_vq, 0);
 158     if (rc != 0) {
 159         goto fail_host_notifiers;
 160     }
 161
 162     vq_init_count++;
 163     rc = virtio_scsi_set_host_notifier(s, vs->event_vq, 1);
 164     if (rc != 0) {
 165         goto fail_host_notifiers;
 166     }
 167
 168     vq_init_count++;
 169
 170     for (i = 0; i < vs->conf.num_queues; i++) {
 171         rc = virtio_scsi_set_host_notifier(s, vs->cmd_vqs[i], i + 2);
 172         if (rc) {
 173             goto fail_host_notifiers;
 174         }
 175         vq_init_count++;
 176     }
 177
 178     memory_region_transaction_commit();
 179
 180     aio_context_acquire(s->ctx);
 181     virtio_queue_aio_set_host_notifier_handler(vs->ctrl_vq, s->ctx,
 182                                             virtio_scsi_data_plane_handle_ctrl);
 183     virtio_queue_aio_set_host_notifier_handler(vs->event_vq, s->ctx,
 184                                            virtio_scsi_data_plane_handle_event);
 185
 186     for (i = 0; i < vs->conf.num_queues; i++) {
 187         virtio_queue_aio_set_host_notifier_handler(vs->cmd_vqs[i], s->ctx,
 188                                              virtio_scsi_data_plane_handle_cmd);
 189     }
 190
 191     s->dataplane_starting = false;
 192     s->dataplane_started = true;
 193     aio_context_release(s->ctx);
 194     return 0;
 195
 196 fail_host_notifiers:
 197     for (i = 0; i < vq_init_count; i++) {
 198         virtio_bus_set_host_notifier(VIRTIO_BUS(qbus), i, false);
 199     }
 200
 201     memory_region_transaction_commit();
 202
 203     for (i = 0; i < vq_init_count; i++) {
 204         virtio_bus_cleanup_host_notifier(VIRTIO_BUS(qbus), i);
 205     }
 206     k->set_guest_notifiers(qbus->parent, vs->conf.num_queues + 2, false);
 207 fail_guest_notifiers:
 208     s->dataplane_fenced = true;
 209     s->dataplane_starting = false;
 210     s->dataplane_started = true;
 211     return -ENOSYS;
 212 }
 213
 214 /* Context: QEMU global mutex held */
 215 void virtio_scsi_dataplane_stop(VirtIODevice *vdev)
 216 {
 217     BusState *qbus = qdev_get_parent_bus(DEVICE(vdev));
 218     VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
 219     VirtIOSCSICommon *vs = VIRTIO_SCSI_COMMON(vdev);
 220     VirtIOSCSI *s = VIRTIO_SCSI(vdev);
 221     int i;
 222
 223     if (!s->dataplane_started || s->dataplane_stopping) {
 224         return;
 225     }
 226
 227     /* Better luck next time. */
 228     if (s->dataplane_fenced) {
 229         s->dataplane_fenced = false;
 230         s->dataplane_started = false;
 231         return;
 232     }
 233     s->dataplane_stopping = true;
 234
 235     aio_context_acquire(s->ctx);
 236     aio_wait_bh_oneshot(s->ctx, virtio_scsi_dataplane_stop_bh, s);
 237     aio_context_release(s->ctx);
 238
 239     blk_drain_all(); /* ensure there are no in-flight requests */
 240
 241     memory_region_transaction_begin();
 242
 243     for (i = 0; i < vs->conf.num_queues + 2; i++) {
 244         virtio_bus_set_host_notifier(VIRTIO_BUS(qbus), i, false);
 245     }
 246
 247     memory_region_transaction_commit();
 248
 249     for (i = 0; i < vs->conf.num_queues + 2; i++) {
 250         virtio_bus_cleanup_host_notifier(VIRTIO_BUS(qbus), i);
 251     }
 252
 253     /* Clean up guest notifier (irq) */
 254     k->set_guest_notifiers(qbus->parent, vs->conf.num_queues + 2, false);
 255     s->dataplane_stopping = false;
 256     s->dataplane_started = false;
 257 }