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;
  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
  60     r = g_slice_new(VirtIOSCSIVring);
  61     r->host_notifier = *virtio_queue_get_host_notifier(vq);
  62     r->guest_notifier = *virtio_queue_get_guest_notifier(vq);
  63     aio_set_event_notifier(s->ctx, &r->host_notifier, handler);
  64
  65     r->parent = s;
  66
  67     if (!vring_setup(&r->vring, VIRTIO_DEVICE(s), n)) {
  68         fprintf(stderr, "virtio-scsi: VRing setup failed\n");
  69         goto fail_vring;
  70     }
  71     return r;
  72
  73 fail_vring:
  74     aio_set_event_notifier(s->ctx, &r->host_notifier, NULL);
  75     k->set_host_notifier(qbus->parent, n, false);
  76     g_slice_free(VirtIOSCSIVring, r);
  77     return NULL;
  78 }
  79
  80 VirtIOSCSIReq *virtio_scsi_pop_req_vring(VirtIOSCSI *s,
  81                                          VirtIOSCSIVring *vring)
  82 {
  83     VirtIOSCSIReq *req = virtio_scsi_init_req(s, NULL);
  84     int r;
  85
  86     req->vring = vring;
  87     r = vring_pop((VirtIODevice *)s, &vring->vring, &req->elem);
  88     if (r < 0) {
  89         virtio_scsi_free_req(req);
  90         req = NULL;
  91     }
  92     return req;
  93 }
  94
  95 void virtio_scsi_vring_push_notify(VirtIOSCSIReq *req)
  96 {
  97     VirtIODevice *vdev = VIRTIO_DEVICE(req->vring->parent);
  98
  99     vring_push(vdev, &req->vring->vring, &req->elem,
 100                req->qsgl.size + req->resp_iov.size);
 101
 102     if (vring_should_notify(vdev, &req->vring->vring)) {
 103         event_notifier_set(&req->vring->guest_notifier);
 104     }
 105 }
 106
 107 static void virtio_scsi_iothread_handle_ctrl(EventNotifier *notifier)
 108 {
 109     VirtIOSCSIVring *vring = container_of(notifier,
 110                                           VirtIOSCSIVring, host_notifier);
 111     VirtIOSCSI *s = VIRTIO_SCSI(vring->parent);
 112     VirtIOSCSIReq *req;
 113
 114     event_notifier_test_and_clear(notifier);
 115     while ((req = virtio_scsi_pop_req_vring(s, vring))) {
 116         virtio_scsi_handle_ctrl_req(s, req);
 117     }
 118 }
 119
 120 static void virtio_scsi_iothread_handle_event(EventNotifier *notifier)
 121 {
 122     VirtIOSCSIVring *vring = container_of(notifier,
 123                                           VirtIOSCSIVring, host_notifier);
 124     VirtIOSCSI *s = vring->parent;
 125     VirtIODevice *vdev = VIRTIO_DEVICE(s);
 126
 127     event_notifier_test_and_clear(notifier);
 128
 129     if (!(vdev->status & VIRTIO_CONFIG_S_DRIVER_OK)) {
 130         return;
 131     }
 132
 133     if (s->events_dropped) {
 134         virtio_scsi_push_event(s, NULL, VIRTIO_SCSI_T_NO_EVENT, 0);
 135     }
 136 }
 137
 138 static void virtio_scsi_iothread_handle_cmd(EventNotifier *notifier)
 139 {
 140     VirtIOSCSIVring *vring = container_of(notifier,
 141                                           VirtIOSCSIVring, host_notifier);
 142     VirtIOSCSI *s = (VirtIOSCSI *)vring->parent;
 143     VirtIOSCSIReq *req, *next;
 144     QTAILQ_HEAD(, VirtIOSCSIReq) reqs = QTAILQ_HEAD_INITIALIZER(reqs);
 145
 146     event_notifier_test_and_clear(notifier);
 147     while ((req = virtio_scsi_pop_req_vring(s, vring))) {
 148         if (virtio_scsi_handle_cmd_req_prepare(s, req)) {
 149             QTAILQ_INSERT_TAIL(&reqs, req, next);
 150         }
 151     }
 152
 153     QTAILQ_FOREACH_SAFE(req, &reqs, next, next) {
 154         virtio_scsi_handle_cmd_req_submit(s, req);
 155     }
 156 }
 157
 158 /* assumes s->ctx held */
 159 static void virtio_scsi_clear_aio(VirtIOSCSI *s)
 160 {
 161     VirtIOSCSICommon *vs = VIRTIO_SCSI_COMMON(s);
 162     int i;
 163
 164     if (s->ctrl_vring) {
 165         aio_set_event_notifier(s->ctx, &s->ctrl_vring->host_notifier, NULL);
 166     }
 167     if (s->event_vring) {
 168         aio_set_event_notifier(s->ctx, &s->event_vring->host_notifier, NULL);
 169     }
 170     if (s->cmd_vrings) {
 171         for (i = 0; i < vs->conf.num_queues && s->cmd_vrings[i]; i++) {
 172             aio_set_event_notifier(s->ctx, &s->cmd_vrings[i]->host_notifier, NULL);
 173         }
 174     }
 175 }
 176
 177 static void virtio_scsi_vring_teardown(VirtIOSCSI *s)
 178 {
 179     VirtIODevice *vdev = VIRTIO_DEVICE(s);
 180     VirtIOSCSICommon *vs = VIRTIO_SCSI_COMMON(s);
 181     int i;
 182
 183     if (s->ctrl_vring) {
 184         vring_teardown(&s->ctrl_vring->vring, vdev, 0);
 185         g_slice_free(VirtIOSCSIVring, s->ctrl_vring);
 186         s->ctrl_vring = NULL;
 187     }
 188     if (s->event_vring) {
 189         vring_teardown(&s->event_vring->vring, vdev, 1);
 190         g_slice_free(VirtIOSCSIVring, s->event_vring);
 191         s->event_vring = NULL;
 192     }
 193     if (s->cmd_vrings) {
 194         for (i = 0; i < vs->conf.num_queues && s->cmd_vrings[i]; i++) {
 195             vring_teardown(&s->cmd_vrings[i]->vring, vdev, 2 + i);
 196             g_slice_free(VirtIOSCSIVring, s->cmd_vrings[i]);
 197             s->cmd_vrings[i] = NULL;
 198         }
 199         free(s->cmd_vrings);
 200         s->cmd_vrings = NULL;
 201     }
 202 }
 203
 204 /* Context: QEMU global mutex held */
 205 void virtio_scsi_dataplane_start(VirtIOSCSI *s)
 206 {
 207     int i;
 208     int rc;
 209     BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(s)));
 210     VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
 211     VirtIOSCSICommon *vs = VIRTIO_SCSI_COMMON(s);
 212
 213     if (s->dataplane_started ||
 214         s->dataplane_starting ||
 215         s->dataplane_fenced ||
 216         s->ctx != iothread_get_aio_context(vs->conf.iothread)) {
 217         return;
 218     }
 219
 220     s->dataplane_starting = true;
 221
 222     /* Set up guest notifier (irq) */
 223     rc = k->set_guest_notifiers(qbus->parent, vs->conf.num_queues + 2, true);
 224     if (rc != 0) {
 225         fprintf(stderr, "virtio-scsi: Failed to set guest notifiers (%d), "
 226                 "ensure -enable-kvm is set\n", rc);
 227         s->dataplane_fenced = true;
 228         goto fail_guest_notifiers;
 229     }
 230
 231     aio_context_acquire(s->ctx);
 232     s->ctrl_vring = virtio_scsi_vring_init(s, vs->ctrl_vq,
 233                                            virtio_scsi_iothread_handle_ctrl,
 234                                            0);
 235     if (!s->ctrl_vring) {
 236         goto fail_vrings;
 237     }
 238     s->event_vring = virtio_scsi_vring_init(s, vs->event_vq,
 239                                             virtio_scsi_iothread_handle_event,
 240                                             1);
 241     if (!s->event_vring) {
 242         goto fail_vrings;
 243     }
 244     s->cmd_vrings = g_new(VirtIOSCSIVring *, vs->conf.num_queues);
 245     for (i = 0; i < vs->conf.num_queues; i++) {
 246         s->cmd_vrings[i] =
 247             virtio_scsi_vring_init(s, vs->cmd_vqs[i],
 248                                    virtio_scsi_iothread_handle_cmd,
 249                                    i + 2);
 250         if (!s->cmd_vrings[i]) {
 251             goto fail_vrings;
 252         }
 253     }
 254
 255     s->dataplane_starting = false;
 256     s->dataplane_started = true;
 257     aio_context_release(s->ctx);
 258     return;
 259
 260 fail_vrings:
 261     virtio_scsi_clear_aio(s);
 262     aio_context_release(s->ctx);
 263     virtio_scsi_vring_teardown(s);
 264     for (i = 0; i < vs->conf.num_queues + 2; i++) {
 265         k->set_host_notifier(qbus->parent, i, false);
 266     }
 267     k->set_guest_notifiers(qbus->parent, vs->conf.num_queues + 2, false);
 268 fail_guest_notifiers:
 269     s->dataplane_starting = false;
 270 }
 271
 272 /* Context: QEMU global mutex held */
 273 void virtio_scsi_dataplane_stop(VirtIOSCSI *s)
 274 {
 275     BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(s)));
 276     VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
 277     VirtIOSCSICommon *vs = VIRTIO_SCSI_COMMON(s);
 278     int i;
 279
 280     /* Better luck next time. */
 281     if (s->dataplane_fenced) {
 282         s->dataplane_fenced = false;
 283         return;
 284     }
 285     if (!s->dataplane_started || s->dataplane_stopping) {
 286         return;
 287     }
 288     s->dataplane_stopping = true;
 289     assert(s->ctx == iothread_get_aio_context(vs->conf.iothread));
 290
 291     aio_context_acquire(s->ctx);
 292
 293     aio_set_event_notifier(s->ctx, &s->ctrl_vring->host_notifier, NULL);
 294     aio_set_event_notifier(s->ctx, &s->event_vring->host_notifier, NULL);
 295     for (i = 0; i < vs->conf.num_queues; i++) {
 296         aio_set_event_notifier(s->ctx, &s->cmd_vrings[i]->host_notifier, NULL);
 297     }
 298
 299     blk_drain_all(); /* ensure there are no in-flight requests */
 300
 301     aio_context_release(s->ctx);
 302
 303     /* Sync vring state back to virtqueue so that non-dataplane request
 304      * processing can continue when we disable the host notifier below.
 305      */
 306     virtio_scsi_vring_teardown(s);
 307
 308     for (i = 0; i < vs->conf.num_queues + 2; i++) {
 309         k->set_host_notifier(qbus->parent, i, false);
 310     }
 311
 312     /* Clean up guest notifier (irq) */
 313     k->set_guest_notifiers(qbus->parent, vs->conf.num_queues + 2, false);
 314     s->dataplane_stopping = false;
 315     s->dataplane_started = false;
 316 }