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         return NULL;
  57     }
  58     r->host_notifier = *virtio_queue_get_host_notifier(vq);
  59     r->guest_notifier = *virtio_queue_get_guest_notifier(vq);
  60     aio_set_event_notifier(s->ctx, &r->host_notifier, handler);
  61
  62     r->parent = s;
  63
  64     if (!vring_setup(&r->vring, VIRTIO_DEVICE(s), n)) {
  65         fprintf(stderr, "virtio-scsi: VRing setup failed\n");
  66         goto fail_vring;
  67     }
  68     return r;
  69
  70 fail_vring:
  71     aio_set_event_notifier(s->ctx, &r->host_notifier, NULL);
  72     k->set_host_notifier(qbus->parent, n, false);
  73     g_slice_free(VirtIOSCSIVring, r);
  74     return NULL;
  75 }
  76
  77 VirtIOSCSIReq *virtio_scsi_pop_req_vring(VirtIOSCSI *s,
  78                                          VirtIOSCSIVring *vring)
  79 {
  80     VirtIOSCSIReq *req = virtio_scsi_init_req(s, NULL);
  81     int r;
  82
  83     req->vring = vring;
  84     r = vring_pop((VirtIODevice *)s, &vring->vring, &req->elem);
  85     if (r < 0) {
  86         virtio_scsi_free_req(req);
  87         req = NULL;
  88     }
  89     return req;
  90 }
  91
  92 void virtio_scsi_vring_push_notify(VirtIOSCSIReq *req)
  93 {
  94     vring_push(&req->vring->vring, &req->elem,
  95                req->qsgl.size + req->resp_iov.size);
  96     event_notifier_set(&req->vring->guest_notifier);
  97 }
  98
  99 static void virtio_scsi_iothread_handle_ctrl(EventNotifier *notifier)
 100 {
 101     VirtIOSCSIVring *vring = container_of(notifier,
 102                                           VirtIOSCSIVring, host_notifier);
 103     VirtIOSCSI *s = VIRTIO_SCSI(vring->parent);
 104     VirtIOSCSIReq *req;
 105
 106     event_notifier_test_and_clear(notifier);
 107     while ((req = virtio_scsi_pop_req_vring(s, vring))) {
 108         virtio_scsi_handle_ctrl_req(s, req);
 109     }
 110 }
 111
 112 static void virtio_scsi_iothread_handle_event(EventNotifier *notifier)
 113 {
 114     VirtIOSCSIVring *vring = container_of(notifier,
 115                                           VirtIOSCSIVring, host_notifier);
 116     VirtIOSCSI *s = vring->parent;
 117     VirtIODevice *vdev = VIRTIO_DEVICE(s);
 118
 119     event_notifier_test_and_clear(notifier);
 120
 121     if (!(vdev->status & VIRTIO_CONFIG_S_DRIVER_OK)) {
 122         return;
 123     }
 124
 125     if (s->events_dropped) {
 126         virtio_scsi_push_event(s, NULL, VIRTIO_SCSI_T_NO_EVENT, 0);
 127     }
 128 }
 129
 130 static void virtio_scsi_iothread_handle_cmd(EventNotifier *notifier)
 131 {
 132     VirtIOSCSIVring *vring = container_of(notifier,
 133                                           VirtIOSCSIVring, host_notifier);
 134     VirtIOSCSI *s = (VirtIOSCSI *)vring->parent;
 135     VirtIOSCSIReq *req, *next;
 136     QTAILQ_HEAD(, VirtIOSCSIReq) reqs = QTAILQ_HEAD_INITIALIZER(reqs);
 137
 138     event_notifier_test_and_clear(notifier);
 139     while ((req = virtio_scsi_pop_req_vring(s, vring))) {
 140         if (virtio_scsi_handle_cmd_req_prepare(s, req)) {
 141             QTAILQ_INSERT_TAIL(&reqs, req, next);
 142         }
 143     }
 144
 145     QTAILQ_FOREACH_SAFE(req, &reqs, next, next) {
 146         virtio_scsi_handle_cmd_req_submit(s, req);
 147     }
 148 }
 149
 150 /* assumes s->ctx held */
 151 static void virtio_scsi_clear_aio(VirtIOSCSI *s)
 152 {
 153     VirtIOSCSICommon *vs = VIRTIO_SCSI_COMMON(s);
 154     int i;
 155
 156     if (s->ctrl_vring) {
 157         aio_set_event_notifier(s->ctx, &s->ctrl_vring->host_notifier, NULL);
 158     }
 159     if (s->event_vring) {
 160         aio_set_event_notifier(s->ctx, &s->event_vring->host_notifier, NULL);
 161     }
 162     if (s->cmd_vrings) {
 163         for (i = 0; i < vs->conf.num_queues && s->cmd_vrings[i]; i++) {
 164             aio_set_event_notifier(s->ctx, &s->cmd_vrings[i]->host_notifier, NULL);
 165         }
 166     }
 167 }
 168
 169 static void virtio_scsi_vring_teardown(VirtIOSCSI *s)
 170 {
 171     VirtIODevice *vdev = VIRTIO_DEVICE(s);
 172     VirtIOSCSICommon *vs = VIRTIO_SCSI_COMMON(s);
 173     int i;
 174
 175     if (s->ctrl_vring) {
 176         vring_teardown(&s->ctrl_vring->vring, vdev, 0);
 177     }
 178     if (s->event_vring) {
 179         vring_teardown(&s->event_vring->vring, vdev, 1);
 180     }
 181     if (s->cmd_vrings) {
 182         for (i = 0; i < vs->conf.num_queues && s->cmd_vrings[i]; i++) {
 183             vring_teardown(&s->cmd_vrings[i]->vring, vdev, 2 + i);
 184         }
 185         free(s->cmd_vrings);
 186         s->cmd_vrings = NULL;
 187     }
 188 }
 189
 190 /* Context: QEMU global mutex held */
 191 void virtio_scsi_dataplane_start(VirtIOSCSI *s)
 192 {
 193     int i;
 194     int rc;
 195     BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(s)));
 196     VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
 197     VirtIOSCSICommon *vs = VIRTIO_SCSI_COMMON(s);
 198
 199     if (s->dataplane_started ||
 200         s->dataplane_starting ||
 201         s->ctx != iothread_get_aio_context(vs->conf.iothread)) {
 202         return;
 203     }
 204
 205     s->dataplane_starting = true;
 206
 207     assert(!s->blocker);
 208     error_setg(&s->blocker, "block device is in use by data plane");
 209     /* Set up guest notifier (irq) */
 210     rc = k->set_guest_notifiers(qbus->parent, vs->conf.num_queues + 2, true);
 211     if (rc != 0) {
 212         fprintf(stderr, "virtio-scsi: Failed to set guest notifiers (%d), "
 213                 "ensure -enable-kvm is set\n", rc);
 214         goto fail_guest_notifiers;
 215     }
 216
 217     aio_context_acquire(s->ctx);
 218     s->ctrl_vring = virtio_scsi_vring_init(s, vs->ctrl_vq,
 219                                            virtio_scsi_iothread_handle_ctrl,
 220                                            0);
 221     if (!s->ctrl_vring) {
 222         goto fail_vrings;
 223     }
 224     s->event_vring = virtio_scsi_vring_init(s, vs->event_vq,
 225                                             virtio_scsi_iothread_handle_event,
 226                                             1);
 227     if (!s->event_vring) {
 228         goto fail_vrings;
 229     }
 230     s->cmd_vrings = g_malloc0(sizeof(VirtIOSCSIVring) * vs->conf.num_queues);
 231     for (i = 0; i < vs->conf.num_queues; i++) {
 232         s->cmd_vrings[i] =
 233             virtio_scsi_vring_init(s, vs->cmd_vqs[i],
 234                                    virtio_scsi_iothread_handle_cmd,
 235                                    i + 2);
 236         if (!s->cmd_vrings[i]) {
 237             goto fail_vrings;
 238         }
 239     }
 240
 241     aio_context_release(s->ctx);
 242     s->dataplane_starting = false;
 243     s->dataplane_started = true;
 244
 245 fail_vrings:
 246     virtio_scsi_clear_aio(s);
 247     aio_context_release(s->ctx);
 248     virtio_scsi_vring_teardown(s);
 249     for (i = 0; i < vs->conf.num_queues + 2; i++) {
 250         k->set_host_notifier(qbus->parent, i, false);
 251     }
 252     k->set_guest_notifiers(qbus->parent, vs->conf.num_queues + 2, false);
 253 fail_guest_notifiers:
 254     s->dataplane_starting = false;
 255 }
 256
 257 /* Context: QEMU global mutex held */
 258 void virtio_scsi_dataplane_stop(VirtIOSCSI *s)
 259 {
 260     BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(s)));
 261     VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
 262     VirtIOSCSICommon *vs = VIRTIO_SCSI_COMMON(s);
 263     int i;
 264
 265     if (!s->dataplane_started || s->dataplane_stopping) {
 266         return;
 267     }
 268     error_free(s->blocker);
 269     s->blocker = NULL;
 270     s->dataplane_stopping = true;
 271     assert(s->ctx == iothread_get_aio_context(vs->conf.iothread));
 272
 273     aio_context_acquire(s->ctx);
 274
 275     aio_set_event_notifier(s->ctx, &s->ctrl_vring->host_notifier, NULL);
 276     aio_set_event_notifier(s->ctx, &s->event_vring->host_notifier, NULL);
 277     for (i = 0; i < vs->conf.num_queues; i++) {
 278         aio_set_event_notifier(s->ctx, &s->cmd_vrings[i]->host_notifier, NULL);
 279     }
 280
 281     blk_drain_all(); /* ensure there are no in-flight requests */
 282
 283     aio_context_release(s->ctx);
 284
 285     /* Sync vring state back to virtqueue so that non-dataplane request
 286      * processing can continue when we disable the host notifier below.
 287      */
 288     virtio_scsi_vring_teardown(s);
 289
 290     for (i = 0; i < vs->conf.num_queues + 2; i++) {
 291         k->set_host_notifier(qbus->parent, i, false);
 292     }
 293
 294     /* Clean up guest notifier (irq) */
 295     k->set_guest_notifiers(qbus->parent, vs->conf.num_queues + 2, false);
 296     s->dataplane_stopping = false;
 297     s->dataplane_started = false;
 298 }