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         exit(1);
  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         exit(1);
  67     }
  68     return r;
  69 }
  70
  71 VirtIOSCSIReq *virtio_scsi_pop_req_vring(VirtIOSCSI *s,
  72                                          VirtIOSCSIVring *vring)
  73 {
  74     VirtIOSCSIReq *req = virtio_scsi_init_req(s, NULL);
  75     int r;
  76
  77     req->vring = vring;
  78     r = vring_pop((VirtIODevice *)s, &vring->vring, &req->elem);
  79     if (r < 0) {
  80         virtio_scsi_free_req(req);
  81         req = NULL;
  82     }
  83     return req;
  84 }
  85
  86 void virtio_scsi_vring_push_notify(VirtIOSCSIReq *req)
  87 {
  88     vring_push(&req->vring->vring, &req->elem,
  89                req->qsgl.size + req->resp_iov.size);
  90     event_notifier_set(&req->vring->guest_notifier);
  91 }
  92
  93 static void virtio_scsi_iothread_handle_ctrl(EventNotifier *notifier)
  94 {
  95     VirtIOSCSIVring *vring = container_of(notifier,
  96                                           VirtIOSCSIVring, host_notifier);
  97     VirtIOSCSI *s = VIRTIO_SCSI(vring->parent);
  98     VirtIOSCSIReq *req;
  99
 100     event_notifier_test_and_clear(notifier);
 101     while ((req = virtio_scsi_pop_req_vring(s, vring))) {
 102         virtio_scsi_handle_ctrl_req(s, req);
 103     }
 104 }
 105
 106 static void virtio_scsi_iothread_handle_event(EventNotifier *notifier)
 107 {
 108     VirtIOSCSIVring *vring = container_of(notifier,
 109                                           VirtIOSCSIVring, host_notifier);
 110     VirtIOSCSI *s = vring->parent;
 111     VirtIODevice *vdev = VIRTIO_DEVICE(s);
 112
 113     event_notifier_test_and_clear(notifier);
 114
 115     if (!(vdev->status & VIRTIO_CONFIG_S_DRIVER_OK)) {
 116         return;
 117     }
 118
 119     if (s->events_dropped) {
 120         virtio_scsi_push_event(s, NULL, VIRTIO_SCSI_T_NO_EVENT, 0);
 121     }
 122 }
 123
 124 static void virtio_scsi_iothread_handle_cmd(EventNotifier *notifier)
 125 {
 126     VirtIOSCSIVring *vring = container_of(notifier,
 127                                           VirtIOSCSIVring, host_notifier);
 128     VirtIOSCSI *s = (VirtIOSCSI *)vring->parent;
 129     VirtIOSCSIReq *req, *next;
 130     QTAILQ_HEAD(, VirtIOSCSIReq) reqs = QTAILQ_HEAD_INITIALIZER(reqs);
 131
 132     event_notifier_test_and_clear(notifier);
 133     while ((req = virtio_scsi_pop_req_vring(s, vring))) {
 134         if (virtio_scsi_handle_cmd_req_prepare(s, req)) {
 135             QTAILQ_INSERT_TAIL(&reqs, req, next);
 136         }
 137     }
 138
 139     QTAILQ_FOREACH_SAFE(req, &reqs, next, next) {
 140         virtio_scsi_handle_cmd_req_submit(s, req);
 141     }
 142 }
 143
 144 /* Context: QEMU global mutex held */
 145 void virtio_scsi_dataplane_start(VirtIOSCSI *s)
 146 {
 147     int i;
 148     int rc;
 149     BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(s)));
 150     VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
 151     VirtIOSCSICommon *vs = VIRTIO_SCSI_COMMON(s);
 152
 153     if (s->dataplane_started ||
 154         s->dataplane_starting ||
 155         s->ctx != iothread_get_aio_context(vs->conf.iothread)) {
 156         return;
 157     }
 158
 159     s->dataplane_starting = true;
 160
 161     assert(!s->blocker);
 162     error_setg(&s->blocker, "block device is in use by data plane");
 163     /* Set up guest notifier (irq) */
 164     rc = k->set_guest_notifiers(qbus->parent, vs->conf.num_queues + 2, true);
 165     if (rc != 0) {
 166         fprintf(stderr, "virtio-scsi: Failed to set guest notifiers (%d), "
 167                 "ensure -enable-kvm is set\n", rc);
 168         exit(1);
 169     }
 170
 171     aio_context_acquire(s->ctx);
 172     s->ctrl_vring = virtio_scsi_vring_init(s, vs->ctrl_vq,
 173                                            virtio_scsi_iothread_handle_ctrl,
 174                                            0);
 175     s->event_vring = virtio_scsi_vring_init(s, vs->event_vq,
 176                                             virtio_scsi_iothread_handle_event,
 177                                             1);
 178     s->cmd_vrings = g_malloc0(sizeof(VirtIOSCSIVring) * vs->conf.num_queues);
 179     for (i = 0; i < vs->conf.num_queues; i++) {
 180         s->cmd_vrings[i] =
 181             virtio_scsi_vring_init(s, vs->cmd_vqs[i],
 182                                    virtio_scsi_iothread_handle_cmd,
 183                                    i + 2);
 184     }
 185
 186     aio_context_release(s->ctx);
 187     s->dataplane_starting = false;
 188     s->dataplane_started = true;
 189 }
 190
 191 /* Context: QEMU global mutex held */
 192 void virtio_scsi_dataplane_stop(VirtIOSCSI *s)
 193 {
 194     BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(s)));
 195     VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
 196     VirtIODevice *vdev = VIRTIO_DEVICE(s);
 197     VirtIOSCSICommon *vs = VIRTIO_SCSI_COMMON(s);
 198     int i;
 199
 200     if (!s->dataplane_started || s->dataplane_stopping) {
 201         return;
 202     }
 203     error_free(s->blocker);
 204     s->blocker = NULL;
 205     s->dataplane_stopping = true;
 206     assert(s->ctx == iothread_get_aio_context(vs->conf.iothread));
 207
 208     aio_context_acquire(s->ctx);
 209
 210     aio_set_event_notifier(s->ctx, &s->ctrl_vring->host_notifier, NULL);
 211     aio_set_event_notifier(s->ctx, &s->event_vring->host_notifier, NULL);
 212     for (i = 0; i < vs->conf.num_queues; i++) {
 213         aio_set_event_notifier(s->ctx, &s->cmd_vrings[i]->host_notifier, NULL);
 214     }
 215
 216     blk_drain_all(); /* ensure there are no in-flight requests */
 217
 218     aio_context_release(s->ctx);
 219
 220     /* Sync vring state back to virtqueue so that non-dataplane request
 221      * processing can continue when we disable the host notifier below.
 222      */
 223     vring_teardown(&s->ctrl_vring->vring, vdev, 0);
 224     vring_teardown(&s->event_vring->vring, vdev, 1);
 225     for (i = 0; i < vs->conf.num_queues; i++) {
 226         vring_teardown(&s->cmd_vrings[i]->vring, vdev, 2 + i);
 227     }
 228
 229     for (i = 0; i < vs->conf.num_queues + 2; i++) {
 230         k->set_host_notifier(qbus->parent, i, false);
 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 }