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_vring_init(VirtIOSCSI *s, VirtQueue *vq, int n,
  98                                   VirtIOHandleAIOOutput fn)
  99 {
 100     BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(s)));
 101     int rc;
 102
 103     /* Set up virtqueue notify */
 104     rc = virtio_bus_set_host_notifier(VIRTIO_BUS(qbus), n, true);
 105     if (rc != 0) {
 106         fprintf(stderr, "virtio-scsi: Failed to set host notifier (%d)\n",
 107                 rc);
 108         s->dataplane_fenced = true;
 109         return rc;
 110     }
 111
 112     virtio_queue_aio_set_host_notifier_handler(vq, s->ctx, fn);
 113     return 0;
 114 }
 115
 116 /* Context: BH in IOThread */
 117 static void virtio_scsi_dataplane_stop_bh(void *opaque)
 118 {
 119     VirtIOSCSI *s = opaque;
 120     VirtIOSCSICommon *vs = VIRTIO_SCSI_COMMON(s);
 121     int i;
 122
 123     virtio_queue_aio_set_host_notifier_handler(vs->ctrl_vq, s->ctx, NULL);
 124     virtio_queue_aio_set_host_notifier_handler(vs->event_vq, s->ctx, NULL);
 125     for (i = 0; i < vs->conf.num_queues; i++) {
 126         virtio_queue_aio_set_host_notifier_handler(vs->cmd_vqs[i], s->ctx, NULL);
 127     }
 128 }
 129
 130 /* Context: QEMU global mutex held */
 131 int virtio_scsi_dataplane_start(VirtIODevice *vdev)
 132 {
 133     int i;
 134     int rc;
 135     int vq_init_count = 0;
 136     BusState *qbus = qdev_get_parent_bus(DEVICE(vdev));
 137     VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
 138     VirtIOSCSICommon *vs = VIRTIO_SCSI_COMMON(vdev);
 139     VirtIOSCSI *s = VIRTIO_SCSI(vdev);
 140
 141     if (s->dataplane_started ||
 142         s->dataplane_starting ||
 143         s->dataplane_fenced) {
 144         return 0;
 145     }
 146
 147     s->dataplane_starting = true;
 148
 149     /* Set up guest notifier (irq) */
 150     rc = k->set_guest_notifiers(qbus->parent, vs->conf.num_queues + 2, true);
 151     if (rc != 0) {
 152         error_report("virtio-scsi: Failed to set guest notifiers (%d), "
 153                      "ensure -accel kvm is set.", rc);
 154         goto fail_guest_notifiers;
 155     }
 156
 157     aio_context_acquire(s->ctx);
 158     rc = virtio_scsi_vring_init(s, vs->ctrl_vq, 0,
 159                                 virtio_scsi_data_plane_handle_ctrl);
 160     if (rc) {
 161         goto fail_vrings;
 162     }
 163
 164     vq_init_count++;
 165     rc = virtio_scsi_vring_init(s, vs->event_vq, 1,
 166                                 virtio_scsi_data_plane_handle_event);
 167     if (rc) {
 168         goto fail_vrings;
 169     }
 170
 171     vq_init_count++;
 172     for (i = 0; i < vs->conf.num_queues; i++) {
 173         rc = virtio_scsi_vring_init(s, vs->cmd_vqs[i], i + 2,
 174                                     virtio_scsi_data_plane_handle_cmd);
 175         if (rc) {
 176             goto fail_vrings;
 177         }
 178         vq_init_count++;
 179     }
 180
 181     s->dataplane_starting = false;
 182     s->dataplane_started = true;
 183     aio_context_release(s->ctx);
 184     return 0;
 185
 186 fail_vrings:
 187     aio_wait_bh_oneshot(s->ctx, virtio_scsi_dataplane_stop_bh, s);
 188     aio_context_release(s->ctx);
 189     for (i = 0; i < vq_init_count; i++) {
 190         virtio_bus_set_host_notifier(VIRTIO_BUS(qbus), i, false);
 191         virtio_bus_cleanup_host_notifier(VIRTIO_BUS(qbus), i);
 192     }
 193     k->set_guest_notifiers(qbus->parent, vs->conf.num_queues + 2, false);
 194 fail_guest_notifiers:
 195     s->dataplane_fenced = true;
 196     s->dataplane_starting = false;
 197     s->dataplane_started = true;
 198     return -ENOSYS;
 199 }
 200
 201 /* Context: QEMU global mutex held */
 202 void virtio_scsi_dataplane_stop(VirtIODevice *vdev)
 203 {
 204     BusState *qbus = qdev_get_parent_bus(DEVICE(vdev));
 205     VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
 206     VirtIOSCSICommon *vs = VIRTIO_SCSI_COMMON(vdev);
 207     VirtIOSCSI *s = VIRTIO_SCSI(vdev);
 208     int i;
 209
 210     if (!s->dataplane_started || s->dataplane_stopping) {
 211         return;
 212     }
 213
 214     /* Better luck next time. */
 215     if (s->dataplane_fenced) {
 216         s->dataplane_fenced = false;
 217         s->dataplane_started = false;
 218         return;
 219     }
 220     s->dataplane_stopping = true;
 221
 222     aio_context_acquire(s->ctx);
 223     aio_wait_bh_oneshot(s->ctx, virtio_scsi_dataplane_stop_bh, s);
 224     aio_context_release(s->ctx);
 225
 226     blk_drain_all(); /* ensure there are no in-flight requests */
 227
 228     for (i = 0; i < vs->conf.num_queues + 2; i++) {
 229         virtio_bus_set_host_notifier(VIRTIO_BUS(qbus), i, false);
 230         virtio_bus_cleanup_host_notifier(VIRTIO_BUS(qbus), i);
 231     }
 232
 233     /* Clean up guest notifier (irq) */
 234     k->set_guest_notifiers(qbus->parent, vs->conf.num_queues + 2, false);
 235     s->dataplane_stopping = false;
 236     s->dataplane_started = false;
 237 }