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_new(VirtIOSCSIVring, 1);
  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, true, 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, true, NULL);
  75     k->set_host_notifier(qbus->parent, n, false);
  76     g_free(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,
 166                                true, NULL);
 167     }
 168     if (s->event_vring) {
 169         aio_set_event_notifier(s->ctx, &s->event_vring->host_notifier,
 170                                true, NULL);
 171     }
 172     if (s->cmd_vrings) {
 173         for (i = 0; i < vs->conf.num_queues && s->cmd_vrings[i]; i++) {
 174             aio_set_event_notifier(s->ctx, &s->cmd_vrings[i]->host_notifier,
 175                                    true, NULL);
 176         }
 177     }
 178 }
 179
 180 static void virtio_scsi_vring_teardown(VirtIOSCSI *s)
 181 {
 182     VirtIODevice *vdev = VIRTIO_DEVICE(s);
 183     VirtIOSCSICommon *vs = VIRTIO_SCSI_COMMON(s);
 184     int i;
 185
 186     if (s->ctrl_vring) {
 187         vring_teardown(&s->ctrl_vring->vring, vdev, 0);
 188         g_free(s->ctrl_vring);
 189         s->ctrl_vring = NULL;
 190     }
 191     if (s->event_vring) {
 192         vring_teardown(&s->event_vring->vring, vdev, 1);
 193         g_free(s->event_vring);
 194         s->event_vring = NULL;
 195     }
 196     if (s->cmd_vrings) {
 197         for (i = 0; i < vs->conf.num_queues && s->cmd_vrings[i]; i++) {
 198             vring_teardown(&s->cmd_vrings[i]->vring, vdev, 2 + i);
 199             g_free(s->cmd_vrings[i]);
 200             s->cmd_vrings[i] = NULL;
 201         }
 202         free(s->cmd_vrings);
 203         s->cmd_vrings = NULL;
 204     }
 205 }
 206
 207 /* Context: QEMU global mutex held */
 208 void virtio_scsi_dataplane_start(VirtIOSCSI *s)
 209 {
 210     int i;
 211     int rc;
 212     BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(s)));
 213     VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
 214     VirtIOSCSICommon *vs = VIRTIO_SCSI_COMMON(s);
 215
 216     if (s->dataplane_started ||
 217         s->dataplane_starting ||
 218         s->dataplane_fenced ||
 219         s->ctx != iothread_get_aio_context(vs->conf.iothread)) {
 220         return;
 221     }
 222
 223     s->dataplane_starting = true;
 224
 225     /* Set up guest notifier (irq) */
 226     rc = k->set_guest_notifiers(qbus->parent, vs->conf.num_queues + 2, true);
 227     if (rc != 0) {
 228         fprintf(stderr, "virtio-scsi: Failed to set guest notifiers (%d), "
 229                 "ensure -enable-kvm is set\n", rc);
 230         s->dataplane_fenced = true;
 231         goto fail_guest_notifiers;
 232     }
 233
 234     aio_context_acquire(s->ctx);
 235     s->ctrl_vring = virtio_scsi_vring_init(s, vs->ctrl_vq,
 236                                            virtio_scsi_iothread_handle_ctrl,
 237                                            0);
 238     if (!s->ctrl_vring) {
 239         goto fail_vrings;
 240     }
 241     s->event_vring = virtio_scsi_vring_init(s, vs->event_vq,
 242                                             virtio_scsi_iothread_handle_event,
 243                                             1);
 244     if (!s->event_vring) {
 245         goto fail_vrings;
 246     }
 247     s->cmd_vrings = g_new(VirtIOSCSIVring *, vs->conf.num_queues);
 248     for (i = 0; i < vs->conf.num_queues; i++) {
 249         s->cmd_vrings[i] =
 250             virtio_scsi_vring_init(s, vs->cmd_vqs[i],
 251                                    virtio_scsi_iothread_handle_cmd,
 252                                    i + 2);
 253         if (!s->cmd_vrings[i]) {
 254             goto fail_vrings;
 255         }
 256     }
 257
 258     s->dataplane_starting = false;
 259     s->dataplane_started = true;
 260     aio_context_release(s->ctx);
 261     return;
 262
 263 fail_vrings:
 264     virtio_scsi_clear_aio(s);
 265     aio_context_release(s->ctx);
 266     virtio_scsi_vring_teardown(s);
 267     for (i = 0; i < vs->conf.num_queues + 2; i++) {
 268         k->set_host_notifier(qbus->parent, i, false);
 269     }
 270     k->set_guest_notifiers(qbus->parent, vs->conf.num_queues + 2, false);
 271 fail_guest_notifiers:
 272     s->dataplane_starting = false;
 273 }
 274
 275 /* Context: QEMU global mutex held */
 276 void virtio_scsi_dataplane_stop(VirtIOSCSI *s)
 277 {
 278     BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(s)));
 279     VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
 280     VirtIOSCSICommon *vs = VIRTIO_SCSI_COMMON(s);
 281     int i;
 282
 283     /* Better luck next time. */
 284     if (s->dataplane_fenced) {
 285         s->dataplane_fenced = false;
 286         return;
 287     }
 288     if (!s->dataplane_started || s->dataplane_stopping) {
 289         return;
 290     }
 291     s->dataplane_stopping = true;
 292     assert(s->ctx == iothread_get_aio_context(vs->conf.iothread));
 293
 294     aio_context_acquire(s->ctx);
 295
 296     aio_set_event_notifier(s->ctx, &s->ctrl_vring->host_notifier,
 297                            true, NULL);
 298     aio_set_event_notifier(s->ctx, &s->event_vring->host_notifier,
 299                            true, NULL);
 300     for (i = 0; i < vs->conf.num_queues; i++) {
 301         aio_set_event_notifier(s->ctx, &s->cmd_vrings[i]->host_notifier,
 302                                true, NULL);
 303     }
 304
 305     blk_drain_all(); /* ensure there are no in-flight requests */
 306
 307     aio_context_release(s->ctx);
 308
 309     /* Sync vring state back to virtqueue so that non-dataplane request
 310      * processing can continue when we disable the host notifier below.
 311      */
 312     virtio_scsi_vring_teardown(s);
 313
 314     for (i = 0; i < vs->conf.num_queues + 2; i++) {
 315         k->set_host_notifier(qbus->parent, i, false);
 316     }
 317
 318     /* Clean up guest notifier (irq) */
 319     k->set_guest_notifiers(qbus->parent, vs->conf.num_queues + 2, false);
 320     s->dataplane_stopping = false;
 321     s->dataplane_started = false;
 322 }