| 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 "qemu/osdep.h" |
| 15 | #include "qapi/error.h" |
| 16 | #include "hw/virtio/virtio-scsi.h" |
| 17 | #include "qemu/error-report.h" |
| 18 | #include "system/block-backend.h" |
| 19 | #include "hw/scsi/scsi.h" |
| 20 | #include "scsi/constants.h" |
| 21 | #include "hw/virtio/iothread-vq-mapping.h" |
| 22 | #include "hw/virtio/virtio-bus.h" |
| 23 | |
| 24 | /* Context: BQL held */ |
| 25 | void virtio_scsi_dataplane_setup(VirtIOSCSI *s, Error **errp) |
| 26 | { |
| 27 | VirtIOSCSICommon *vs = VIRTIO_SCSI_COMMON(s); |
| 28 | VirtIODevice *vdev = VIRTIO_DEVICE(s); |
| 29 | BusState *qbus = qdev_get_parent_bus(DEVICE(vdev)); |
| 30 | VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus); |
| 31 | |
| 32 | if (vs->conf.iothread && vs->conf.iothread_vq_mapping_list) { |
| 33 | error_setg(errp, |
| 34 | "iothread and iothread-vq-mapping properties cannot be set " |
| 35 | "at the same time"); |
| 36 | return; |
| 37 | } |
| 38 | |
| 39 | if (vs->conf.iothread || vs->conf.iothread_vq_mapping_list) { |
| 40 | if (!k->set_guest_notifiers || !k->ioeventfd_assign) { |
| 41 | error_setg(errp, |
| 42 | "device is incompatible with iothread " |
| 43 | "(transport does not support notifiers)"); |
| 44 | return; |
| 45 | } |
| 46 | if (!virtio_device_ioeventfd_enabled(vdev)) { |
| 47 | error_setg(errp, "ioeventfd is required for iothread"); |
| 48 | return; |
| 49 | } |
| 50 | } |
| 51 | |
| 52 | s->vq_aio_context = g_new(AioContext *, vs->conf.num_queues + |
| 53 | VIRTIO_SCSI_VQ_NUM_FIXED); |
| 54 | |
| 55 | /* |
| 56 | * Handle the ctrl virtqueue in the main loop thread where device resets |
| 57 | * can be performed. |
| 58 | */ |
| 59 | s->vq_aio_context[0] = qemu_get_aio_context(); |
| 60 | |
| 61 | /* |
| 62 | * Handle the event virtqueue in the main loop thread where its no_poll |
| 63 | * behavior won't stop IOThread polling. |
| 64 | */ |
| 65 | s->vq_aio_context[1] = qemu_get_aio_context(); |
| 66 | |
| 67 | if (vs->conf.iothread_vq_mapping_list) { |
| 68 | if (!iothread_vq_mapping_apply(vs->conf.iothread_vq_mapping_list, |
| 69 | &s->vq_aio_context[VIRTIO_SCSI_VQ_NUM_FIXED], |
| 70 | vs->conf.num_queues, errp)) { |
| 71 | g_free(s->vq_aio_context); |
| 72 | s->vq_aio_context = NULL; |
| 73 | return; |
| 74 | } |
| 75 | } else if (vs->conf.iothread) { |
| 76 | AioContext *ctx = iothread_get_aio_context(vs->conf.iothread); |
| 77 | for (uint16_t i = 0; i < vs->conf.num_queues; i++) { |
| 78 | s->vq_aio_context[VIRTIO_SCSI_VQ_NUM_FIXED + i] = ctx; |
| 79 | } |
| 80 | |
| 81 | /* Released in virtio_scsi_dataplane_cleanup() */ |
| 82 | object_ref(OBJECT(vs->conf.iothread)); |
| 83 | } else { |
| 84 | AioContext *ctx = qemu_get_aio_context(); |
| 85 | for (unsigned i = 0; i < vs->conf.num_queues; i++) { |
| 86 | s->vq_aio_context[VIRTIO_SCSI_VQ_NUM_FIXED + i] = ctx; |
| 87 | } |
| 88 | } |
| 89 | } |
| 90 | |
| 91 | /* Context: BQL held */ |
| 92 | void virtio_scsi_dataplane_cleanup(VirtIOSCSI *s) |
| 93 | { |
| 94 | VirtIOSCSICommon *vs = VIRTIO_SCSI_COMMON(s); |
| 95 | |
| 96 | if (vs->conf.iothread_vq_mapping_list) { |
| 97 | iothread_vq_mapping_cleanup(vs->conf.iothread_vq_mapping_list); |
| 98 | } |
| 99 | |
| 100 | if (vs->conf.iothread) { |
| 101 | object_unref(OBJECT(vs->conf.iothread)); |
| 102 | } |
| 103 | |
| 104 | g_free(s->vq_aio_context); |
| 105 | s->vq_aio_context = NULL; |
| 106 | } |
| 107 | |
| 108 | static int virtio_scsi_set_host_notifier(VirtIOSCSI *s, VirtQueue *vq, int n) |
| 109 | { |
| 110 | BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(s))); |
| 111 | int rc; |
| 112 | |
| 113 | /* Set up virtqueue notify */ |
| 114 | rc = virtio_bus_set_host_notifier(VIRTIO_BUS(qbus), n, true); |
| 115 | if (rc != 0) { |
| 116 | fprintf(stderr, "virtio-scsi: Failed to set host notifier (%d)\n", |
| 117 | rc); |
| 118 | s->dataplane_fenced = true; |
| 119 | return rc; |
| 120 | } |
| 121 | |
| 122 | return 0; |
| 123 | } |
| 124 | |
| 125 | /* Context: BH in IOThread */ |
| 126 | static void virtio_scsi_dataplane_stop_vq_bh(void *opaque) |
| 127 | { |
| 128 | AioContext *ctx = qemu_get_current_aio_context(); |
| 129 | VirtQueue *vq = opaque; |
| 130 | EventNotifier *host_notifier; |
| 131 | |
| 132 | virtio_queue_aio_detach_host_notifier(vq, ctx); |
| 133 | host_notifier = virtio_queue_get_host_notifier(vq); |
| 134 | |
| 135 | /* |
| 136 | * Test and clear notifier after disabling event, in case poll callback |
| 137 | * didn't have time to run. |
| 138 | */ |
| 139 | virtio_queue_host_notifier_read(host_notifier); |
| 140 | } |
| 141 | |
| 142 | /* Context: BQL held */ |
| 143 | int virtio_scsi_dataplane_start(VirtIODevice *vdev) |
| 144 | { |
| 145 | int i; |
| 146 | int rc; |
| 147 | int vq_init_count = 0; |
| 148 | BusState *qbus = qdev_get_parent_bus(DEVICE(vdev)); |
| 149 | VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus); |
| 150 | VirtIOSCSICommon *vs = VIRTIO_SCSI_COMMON(vdev); |
| 151 | VirtIOSCSI *s = VIRTIO_SCSI(vdev); |
| 152 | |
| 153 | if (s->dataplane_started || |
| 154 | s->dataplane_starting || |
| 155 | s->dataplane_fenced) { |
| 156 | return 0; |
| 157 | } |
| 158 | |
| 159 | s->dataplane_starting = true; |
| 160 | |
| 161 | /* Set up guest notifier (irq) */ |
| 162 | rc = k->set_guest_notifiers(qbus->parent, vs->conf.num_queues + 2, true); |
| 163 | if (rc != 0) { |
| 164 | error_report("virtio-scsi: Failed to set guest notifiers (%d), " |
| 165 | "ensure -accel kvm is set.", rc); |
| 166 | goto fail_guest_notifiers; |
| 167 | } |
| 168 | |
| 169 | /* |
| 170 | * Batch all the host notifiers in a single transaction to avoid |
| 171 | * quadratic time complexity in address_space_update_ioeventfds(). |
| 172 | */ |
| 173 | memory_region_transaction_begin(); |
| 174 | |
| 175 | rc = virtio_scsi_set_host_notifier(s, vs->ctrl_vq, 0); |
| 176 | if (rc != 0) { |
| 177 | goto fail_host_notifiers; |
| 178 | } |
| 179 | |
| 180 | vq_init_count++; |
| 181 | rc = virtio_scsi_set_host_notifier(s, vs->event_vq, 1); |
| 182 | if (rc != 0) { |
| 183 | goto fail_host_notifiers; |
| 184 | } |
| 185 | |
| 186 | vq_init_count++; |
| 187 | |
| 188 | for (i = 0; i < vs->conf.num_queues; i++) { |
| 189 | rc = virtio_scsi_set_host_notifier(s, vs->cmd_vqs[i], i + 2); |
| 190 | if (rc) { |
| 191 | goto fail_host_notifiers; |
| 192 | } |
| 193 | vq_init_count++; |
| 194 | } |
| 195 | |
| 196 | memory_region_transaction_commit(); |
| 197 | |
| 198 | s->dataplane_starting = false; |
| 199 | s->dataplane_started = true; |
| 200 | smp_wmb(); /* paired with aio_notify_accept() */ |
| 201 | |
| 202 | if (s->bus.drain_count == 0) { |
| 203 | virtio_queue_aio_attach_host_notifier(vs->ctrl_vq, |
| 204 | s->vq_aio_context[0]); |
| 205 | virtio_queue_aio_attach_host_notifier_no_poll(vs->event_vq, |
| 206 | s->vq_aio_context[1]); |
| 207 | |
| 208 | for (i = 0; i < vs->conf.num_queues; i++) { |
| 209 | AioContext *ctx = s->vq_aio_context[VIRTIO_SCSI_VQ_NUM_FIXED + i]; |
| 210 | virtio_queue_aio_attach_host_notifier(vs->cmd_vqs[i], ctx); |
| 211 | } |
| 212 | } |
| 213 | return 0; |
| 214 | |
| 215 | fail_host_notifiers: |
| 216 | for (i = 0; i < vq_init_count; i++) { |
| 217 | virtio_bus_set_host_notifier(VIRTIO_BUS(qbus), i, false); |
| 218 | } |
| 219 | |
| 220 | /* |
| 221 | * The transaction expects the ioeventfds to be open when it |
| 222 | * commits. Do it now, before the cleanup loop. |
| 223 | */ |
| 224 | memory_region_transaction_commit(); |
| 225 | |
| 226 | for (i = 0; i < vq_init_count; i++) { |
| 227 | virtio_bus_cleanup_host_notifier(VIRTIO_BUS(qbus), i); |
| 228 | } |
| 229 | k->set_guest_notifiers(qbus->parent, vs->conf.num_queues + 2, false); |
| 230 | fail_guest_notifiers: |
| 231 | s->dataplane_fenced = true; |
| 232 | s->dataplane_starting = false; |
| 233 | s->dataplane_started = true; |
| 234 | return -ENOSYS; |
| 235 | } |
| 236 | |
| 237 | /* Context: BQL held */ |
| 238 | void virtio_scsi_dataplane_stop(VirtIODevice *vdev) |
| 239 | { |
| 240 | BusState *qbus = qdev_get_parent_bus(DEVICE(vdev)); |
| 241 | VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus); |
| 242 | VirtIOSCSICommon *vs = VIRTIO_SCSI_COMMON(vdev); |
| 243 | VirtIOSCSI *s = VIRTIO_SCSI(vdev); |
| 244 | int i; |
| 245 | |
| 246 | if (!s->dataplane_started || s->dataplane_stopping) { |
| 247 | return; |
| 248 | } |
| 249 | |
| 250 | /* Better luck next time. */ |
| 251 | if (s->dataplane_fenced) { |
| 252 | s->dataplane_fenced = false; |
| 253 | s->dataplane_started = false; |
| 254 | return; |
| 255 | } |
| 256 | s->dataplane_stopping = true; |
| 257 | |
| 258 | if (s->bus.drain_count == 0) { |
| 259 | for (i = 0; i < vs->conf.num_queues + VIRTIO_SCSI_VQ_NUM_FIXED; i++) { |
| 260 | VirtQueue *vq = virtio_get_queue(&vs->parent_obj, i); |
| 261 | AioContext *ctx = s->vq_aio_context[i]; |
| 262 | aio_wait_bh_oneshot(ctx, virtio_scsi_dataplane_stop_vq_bh, vq); |
| 263 | } |
| 264 | } |
| 265 | |
| 266 | blk_drain_all(); /* ensure there are no in-flight requests */ |
| 267 | |
| 268 | /* |
| 269 | * Batch all the host notifiers in a single transaction to avoid |
| 270 | * quadratic time complexity in address_space_update_ioeventfds(). |
| 271 | */ |
| 272 | memory_region_transaction_begin(); |
| 273 | |
| 274 | for (i = 0; i < vs->conf.num_queues + 2; i++) { |
| 275 | virtio_bus_set_host_notifier(VIRTIO_BUS(qbus), i, false); |
| 276 | } |
| 277 | |
| 278 | /* |
| 279 | * The transaction expects the ioeventfds to be open when it |
| 280 | * commits. Do it now, before the cleanup loop. |
| 281 | */ |
| 282 | memory_region_transaction_commit(); |
| 283 | |
| 284 | for (i = 0; i < vs->conf.num_queues + 2; i++) { |
| 285 | virtio_bus_cleanup_host_notifier(VIRTIO_BUS(qbus), i); |
| 286 | } |
| 287 | |
| 288 | /* Clean up guest notifier (irq) */ |
| 289 | k->set_guest_notifiers(qbus->parent, vs->conf.num_queues + 2, false); |
| 290 | s->dataplane_stopping = false; |
| 291 | s->dataplane_started = false; |
| 292 | } |