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 "hw/virtio/virtio-scsi.h"
  15 #include "qemu/error-report.h"
  16 #include "sysemu/block-backend.h"
  17 #include <hw/scsi/scsi.h>
  18 #include <block/scsi.h>
  19 #include <hw/virtio/virtio-bus.h>
  20 #include "hw/virtio/virtio-access.h"
  21 #include "stdio.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->set_host_notifier) {
  35         fprintf(stderr, "virtio-scsi: Failed to set iothread "
  36                    "(transport does not support notifiers)");
  37         exit(1);
  38     }
  39 }
  40
  41 static VirtIOSCSIVring *virtio_scsi_vring_init(VirtIOSCSI *s,
  42                                                VirtQueue *vq,
  43                                                EventNotifierHandler *handler,
  44                                                int n)
  45 {
  46     BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(s)));
  47     VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
  48     VirtIOSCSIVring *r = g_slice_new(VirtIOSCSIVring);
  49     int rc;
  50
  51     /* Set up virtqueue notify */
  52     rc = k->set_host_notifier(qbus->parent, n, true);
  53     if (rc != 0) {
  54         fprintf(stderr, "virtio-scsi: Failed to set host notifier (%d)\n",
  55                 rc);
  56         s->dataplane_fenced = true;
  57         return NULL;
  58     }
  59     r->host_notifier = *virtio_queue_get_host_notifier(vq);
  60     r->guest_notifier = *virtio_queue_get_guest_notifier(vq);
  61     aio_set_event_notifier(s->ctx, &r->host_notifier, handler);
  62
  63     r->parent = s;
  64
  65     if (!vring_setup(&r->vring, VIRTIO_DEVICE(s), n)) {
  66         fprintf(stderr, "virtio-scsi: VRing setup failed\n");
  67         goto fail_vring;
  68     }
  69     return r;
  70
  71 fail_vring:
  72     aio_set_event_notifier(s->ctx, &r->host_notifier, NULL);
  73     k->set_host_notifier(qbus->parent, n, false);
  74     g_slice_free(VirtIOSCSIVring, r);
  75     return NULL;
  76 }
  77
  78 VirtIOSCSIReq *virtio_scsi_pop_req_vring(VirtIOSCSI *s,
  79                                          VirtIOSCSIVring *vring)
  80 {
  81     VirtIOSCSIReq *req = virtio_scsi_init_req(s, NULL);
  82     int r;
  83
  84     req->vring = vring;
  85     r = vring_pop((VirtIODevice *)s, &vring->vring, &req->elem);
  86     if (r < 0) {
  87         virtio_scsi_free_req(req);
  88         req = NULL;
  89     }
  90     return req;
  91 }
  92
  93 void virtio_scsi_vring_push_notify(VirtIOSCSIReq *req)
  94 {
  95     VirtIODevice *vdev = VIRTIO_DEVICE(req->vring->parent);
  96
  97     vring_push(&req->vring->vring, &req->elem,
  98                req->qsgl.size + req->resp_iov.size);
  99
 100     if (vring_should_notify(vdev, &req->vring->vring)) {
 101         event_notifier_set(&req->vring->guest_notifier);
 102     }
 103 }
 104
 105 static void virtio_scsi_iothread_handle_ctrl(EventNotifier *notifier)
 106 {
 107     VirtIOSCSIVring *vring = container_of(notifier,
 108                                           VirtIOSCSIVring, host_notifier);
 109     VirtIOSCSI *s = VIRTIO_SCSI(vring->parent);
 110     VirtIOSCSIReq *req;
 111
 112     event_notifier_test_and_clear(notifier);
 113     while ((req = virtio_scsi_pop_req_vring(s, vring))) {
 114         virtio_scsi_handle_ctrl_req(s, req);
 115     }
 116 }
 117
 118 static void virtio_scsi_iothread_handle_event(EventNotifier *notifier)
 119 {
 120     VirtIOSCSIVring *vring = container_of(notifier,
 121                                           VirtIOSCSIVring, host_notifier);
 122     VirtIOSCSI *s = vring->parent;
 123     VirtIODevice *vdev = VIRTIO_DEVICE(s);
 124
 125     event_notifier_test_and_clear(notifier);
 126
 127     if (!(vdev->status & VIRTIO_CONFIG_S_DRIVER_OK)) {
 128         return;
 129     }
 130
 131     if (s->events_dropped) {
 132         virtio_scsi_push_event(s, NULL, VIRTIO_SCSI_T_NO_EVENT, 0);
 133     }
 134 }
 135
 136 static void virtio_scsi_iothread_handle_cmd(EventNotifier *notifier)
 137 {
 138     VirtIOSCSIVring *vring = container_of(notifier,
 139                                           VirtIOSCSIVring, host_notifier);
 140     VirtIOSCSI *s = (VirtIOSCSI *)vring->parent;
 141     VirtIOSCSIReq *req, *next;
 142     QTAILQ_HEAD(, VirtIOSCSIReq) reqs = QTAILQ_HEAD_INITIALIZER(reqs);
 143
 144     event_notifier_test_and_clear(notifier);
 145     while ((req = virtio_scsi_pop_req_vring(s, vring))) {
 146         if (virtio_scsi_handle_cmd_req_prepare(s, req)) {
 147             QTAILQ_INSERT_TAIL(&reqs, req, next);
 148         }
 149     }
 150
 151     QTAILQ_FOREACH_SAFE(req, &reqs, next, next) {
 152         virtio_scsi_handle_cmd_req_submit(s, req);
 153     }
 154 }
 155
 156 /* assumes s->ctx held */
 157 static void virtio_scsi_clear_aio(VirtIOSCSI *s)
 158 {
 159     VirtIOSCSICommon *vs = VIRTIO_SCSI_COMMON(s);
 160     int i;
 161
 162     if (s->ctrl_vring) {
 163         aio_set_event_notifier(s->ctx, &s->ctrl_vring->host_notifier, NULL);
 164     }
 165     if (s->event_vring) {
 166         aio_set_event_notifier(s->ctx, &s->event_vring->host_notifier, NULL);
 167     }
 168     if (s->cmd_vrings) {
 169         for (i = 0; i < vs->conf.num_queues && s->cmd_vrings[i]; i++) {
 170             aio_set_event_notifier(s->ctx, &s->cmd_vrings[i]->host_notifier, NULL);
 171         }
 172     }
 173 }
 174
 175 static void virtio_scsi_vring_teardown(VirtIOSCSI *s)
 176 {
 177     VirtIODevice *vdev = VIRTIO_DEVICE(s);
 178     VirtIOSCSICommon *vs = VIRTIO_SCSI_COMMON(s);
 179     int i;
 180
 181     if (s->ctrl_vring) {
 182         vring_teardown(&s->ctrl_vring->vring, vdev, 0);
 183     }
 184     if (s->event_vring) {
 185         vring_teardown(&s->event_vring->vring, vdev, 1);
 186     }
 187     if (s->cmd_vrings) {
 188         for (i = 0; i < vs->conf.num_queues && s->cmd_vrings[i]; i++) {
 189             vring_teardown(&s->cmd_vrings[i]->vring, vdev, 2 + i);
 190         }
 191         free(s->cmd_vrings);
 192         s->cmd_vrings = NULL;
 193     }
 194 }
 195
 196 /* Context: QEMU global mutex held */
 197 void virtio_scsi_dataplane_start(VirtIOSCSI *s)
 198 {
 199     int i;
 200     int rc;
 201     BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(s)));
 202     VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
 203     VirtIOSCSICommon *vs = VIRTIO_SCSI_COMMON(s);
 204
 205     if (s->dataplane_started ||
 206         s->dataplane_starting ||
 207         s->dataplane_fenced ||
 208         s->ctx != iothread_get_aio_context(vs->conf.iothread)) {
 209         return;
 210     }
 211
 212     s->dataplane_starting = true;
 213
 214     assert(!s->blocker);
 215     error_setg(&s->blocker, "block device is in use by data plane");
 216     /* Set up guest notifier (irq) */
 217     rc = k->set_guest_notifiers(qbus->parent, vs->conf.num_queues + 2, true);
 218     if (rc != 0) {
 219         fprintf(stderr, "virtio-scsi: Failed to set guest notifiers (%d), "
 220                 "ensure -enable-kvm is set\n", rc);
 221         s->dataplane_fenced = true;
 222         goto fail_guest_notifiers;
 223     }
 224
 225     aio_context_acquire(s->ctx);
 226     s->ctrl_vring = virtio_scsi_vring_init(s, vs->ctrl_vq,
 227                                            virtio_scsi_iothread_handle_ctrl,
 228                                            0);
 229     if (!s->ctrl_vring) {
 230         goto fail_vrings;
 231     }
 232     s->event_vring = virtio_scsi_vring_init(s, vs->event_vq,
 233                                             virtio_scsi_iothread_handle_event,
 234                                             1);
 235     if (!s->event_vring) {
 236         goto fail_vrings;
 237     }
 238     s->cmd_vrings = g_new(VirtIOSCSIVring *, vs->conf.num_queues);
 239     for (i = 0; i < vs->conf.num_queues; i++) {
 240         s->cmd_vrings[i] =
 241             virtio_scsi_vring_init(s, vs->cmd_vqs[i],
 242                                    virtio_scsi_iothread_handle_cmd,
 243                                    i + 2);
 244         if (!s->cmd_vrings[i]) {
 245             goto fail_vrings;
 246         }
 247     }
 248
 249     s->dataplane_starting = false;
 250     s->dataplane_started = true;
 251     aio_context_release(s->ctx);
 252     return;
 253
 254 fail_vrings:
 255     virtio_scsi_clear_aio(s);
 256     aio_context_release(s->ctx);
 257     virtio_scsi_vring_teardown(s);
 258     for (i = 0; i < vs->conf.num_queues + 2; i++) {
 259         k->set_host_notifier(qbus->parent, i, false);
 260     }
 261     k->set_guest_notifiers(qbus->parent, vs->conf.num_queues + 2, false);
 262 fail_guest_notifiers:
 263     s->dataplane_starting = false;
 264 }
 265
 266 /* Context: QEMU global mutex held */
 267 void virtio_scsi_dataplane_stop(VirtIOSCSI *s)
 268 {
 269     BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(s)));
 270     VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
 271     VirtIOSCSICommon *vs = VIRTIO_SCSI_COMMON(s);
 272     int i;
 273
 274     /* Better luck next time. */
 275     if (s->dataplane_fenced) {
 276         s->dataplane_fenced = false;
 277         return;
 278     }
 279     if (!s->dataplane_started || s->dataplane_stopping) {
 280         return;
 281     }
 282     error_free(s->blocker);
 283     s->blocker = NULL;
 284     s->dataplane_stopping = true;
 285     assert(s->ctx == iothread_get_aio_context(vs->conf.iothread));
 286
 287     aio_context_acquire(s->ctx);
 288
 289     aio_set_event_notifier(s->ctx, &s->ctrl_vring->host_notifier, NULL);
 290     aio_set_event_notifier(s->ctx, &s->event_vring->host_notifier, NULL);
 291     for (i = 0; i < vs->conf.num_queues; i++) {
 292         aio_set_event_notifier(s->ctx, &s->cmd_vrings[i]->host_notifier, NULL);
 293     }
 294
 295     blk_drain_all(); /* ensure there are no in-flight requests */
 296
 297     aio_context_release(s->ctx);
 298
 299     /* Sync vring state back to virtqueue so that non-dataplane request
 300      * processing can continue when we disable the host notifier below.
 301      */
 302     virtio_scsi_vring_teardown(s);
 303
 304     for (i = 0; i < vs->conf.num_queues + 2; i++) {
 305         k->set_host_notifier(qbus->parent, i, false);
 306     }
 307
 308     /* Clean up guest notifier (irq) */
 309     k->set_guest_notifiers(qbus->parent, vs->conf.num_queues + 2, false);
 310     s->dataplane_stopping = false;
 311     s->dataplane_started = false;
 312 }