vhost-user-blk-server.c (15926B)
1/* 2 * Sharing QEMU block devices via vhost-user protocal 3 * 4 * Parts of the code based on nbd/server.c. 5 * 6 * Copyright (c) Coiby Xu <coiby.xu@gmail.com>. 7 * Copyright (c) 2020 Red Hat, Inc. 8 * 9 * This work is licensed under the terms of the GNU GPL, version 2 or 10 * later. See the COPYING file in the top-level directory. 11 */ 12#include "qemu/osdep.h" 13#include "block/block.h" 14#include "subprojects/libvhost-user/libvhost-user.h" /* only for the type definitions */ 15#include "standard-headers/linux/virtio_blk.h" 16#include "qemu/vhost-user-server.h" 17#include "vhost-user-blk-server.h" 18#include "qapi/error.h" 19#include "qom/object_interfaces.h" 20#include "sysemu/block-backend.h" 21#include "util/block-helpers.h" 22 23/* 24 * Sector units are 512 bytes regardless of the 25 * virtio_blk_config->blk_size value. 26 */ 27#define VIRTIO_BLK_SECTOR_BITS 9 28#define VIRTIO_BLK_SECTOR_SIZE (1ull << VIRTIO_BLK_SECTOR_BITS) 29 30enum { 31 VHOST_USER_BLK_NUM_QUEUES_DEFAULT = 1, 32 VHOST_USER_BLK_MAX_DISCARD_SECTORS = 32768, 33 VHOST_USER_BLK_MAX_WRITE_ZEROES_SECTORS = 32768, 34}; 35struct virtio_blk_inhdr { 36 unsigned char status; 37}; 38 39typedef struct VuBlkReq { 40 VuVirtqElement elem; 41 int64_t sector_num; 42 size_t size; 43 struct virtio_blk_inhdr *in; 44 struct virtio_blk_outhdr out; 45 VuServer *server; 46 struct VuVirtq *vq; 47} VuBlkReq; 48 49/* vhost user block device */ 50typedef struct { 51 BlockExport export; 52 VuServer vu_server; 53 uint32_t blk_size; 54 QIOChannelSocket *sioc; 55 struct virtio_blk_config blkcfg; 56 bool writable; 57} VuBlkExport; 58 59static void vu_blk_req_complete(VuBlkReq *req) 60{ 61 VuDev *vu_dev = &req->server->vu_dev; 62 63 /* IO size with 1 extra status byte */ 64 vu_queue_push(vu_dev, req->vq, &req->elem, req->size + 1); 65 vu_queue_notify(vu_dev, req->vq); 66 67 free(req); 68} 69 70static bool vu_blk_sect_range_ok(VuBlkExport *vexp, uint64_t sector, 71 size_t size) 72{ 73 uint64_t nb_sectors; 74 uint64_t total_sectors; 75 76 if (size % VIRTIO_BLK_SECTOR_SIZE) { 77 return false; 78 } 79 80 nb_sectors = size >> VIRTIO_BLK_SECTOR_BITS; 81 82 QEMU_BUILD_BUG_ON(BDRV_SECTOR_SIZE != VIRTIO_BLK_SECTOR_SIZE); 83 if (nb_sectors > BDRV_REQUEST_MAX_SECTORS) { 84 return false; 85 } 86 if ((sector << VIRTIO_BLK_SECTOR_BITS) % vexp->blk_size) { 87 return false; 88 } 89 blk_get_geometry(vexp->export.blk, &total_sectors); 90 if (sector > total_sectors || nb_sectors > total_sectors - sector) { 91 return false; 92 } 93 return true; 94} 95 96static int coroutine_fn 97vu_blk_discard_write_zeroes(VuBlkExport *vexp, struct iovec *iov, 98 uint32_t iovcnt, uint32_t type) 99{ 100 BlockBackend *blk = vexp->export.blk; 101 struct virtio_blk_discard_write_zeroes desc; 102 ssize_t size; 103 uint64_t sector; 104 uint32_t num_sectors; 105 uint32_t max_sectors; 106 uint32_t flags; 107 int bytes; 108 109 /* Only one desc is currently supported */ 110 if (unlikely(iov_size(iov, iovcnt) > sizeof(desc))) { 111 return VIRTIO_BLK_S_UNSUPP; 112 } 113 114 size = iov_to_buf(iov, iovcnt, 0, &desc, sizeof(desc)); 115 if (unlikely(size != sizeof(desc))) { 116 error_report("Invalid size %zd, expected %zu", size, sizeof(desc)); 117 return VIRTIO_BLK_S_IOERR; 118 } 119 120 sector = le64_to_cpu(desc.sector); 121 num_sectors = le32_to_cpu(desc.num_sectors); 122 flags = le32_to_cpu(desc.flags); 123 max_sectors = (type == VIRTIO_BLK_T_WRITE_ZEROES) ? 124 VHOST_USER_BLK_MAX_WRITE_ZEROES_SECTORS : 125 VHOST_USER_BLK_MAX_DISCARD_SECTORS; 126 127 /* This check ensures that 'bytes' fits in an int */ 128 if (unlikely(num_sectors > max_sectors)) { 129 return VIRTIO_BLK_S_IOERR; 130 } 131 132 bytes = num_sectors << VIRTIO_BLK_SECTOR_BITS; 133 134 if (unlikely(!vu_blk_sect_range_ok(vexp, sector, bytes))) { 135 return VIRTIO_BLK_S_IOERR; 136 } 137 138 /* 139 * The device MUST set the status byte to VIRTIO_BLK_S_UNSUPP for discard 140 * and write zeroes commands if any unknown flag is set. 141 */ 142 if (unlikely(flags & ~VIRTIO_BLK_WRITE_ZEROES_FLAG_UNMAP)) { 143 return VIRTIO_BLK_S_UNSUPP; 144 } 145 146 if (type == VIRTIO_BLK_T_WRITE_ZEROES) { 147 int blk_flags = 0; 148 149 if (flags & VIRTIO_BLK_WRITE_ZEROES_FLAG_UNMAP) { 150 blk_flags |= BDRV_REQ_MAY_UNMAP; 151 } 152 153 if (blk_co_pwrite_zeroes(blk, sector << VIRTIO_BLK_SECTOR_BITS, 154 bytes, blk_flags) == 0) { 155 return VIRTIO_BLK_S_OK; 156 } 157 } else if (type == VIRTIO_BLK_T_DISCARD) { 158 /* 159 * The device MUST set the status byte to VIRTIO_BLK_S_UNSUPP for 160 * discard commands if the unmap flag is set. 161 */ 162 if (unlikely(flags & VIRTIO_BLK_WRITE_ZEROES_FLAG_UNMAP)) { 163 return VIRTIO_BLK_S_UNSUPP; 164 } 165 166 if (blk_co_pdiscard(blk, sector << VIRTIO_BLK_SECTOR_BITS, 167 bytes) == 0) { 168 return VIRTIO_BLK_S_OK; 169 } 170 } 171 172 return VIRTIO_BLK_S_IOERR; 173} 174 175static void coroutine_fn vu_blk_virtio_process_req(void *opaque) 176{ 177 VuBlkReq *req = opaque; 178 VuServer *server = req->server; 179 VuVirtqElement *elem = &req->elem; 180 uint32_t type; 181 182 VuBlkExport *vexp = container_of(server, VuBlkExport, vu_server); 183 BlockBackend *blk = vexp->export.blk; 184 185 struct iovec *in_iov = elem->in_sg; 186 struct iovec *out_iov = elem->out_sg; 187 unsigned in_num = elem->in_num; 188 unsigned out_num = elem->out_num; 189 190 /* refer to hw/block/virtio_blk.c */ 191 if (elem->out_num < 1 || elem->in_num < 1) { 192 error_report("virtio-blk request missing headers"); 193 goto err; 194 } 195 196 if (unlikely(iov_to_buf(out_iov, out_num, 0, &req->out, 197 sizeof(req->out)) != sizeof(req->out))) { 198 error_report("virtio-blk request outhdr too short"); 199 goto err; 200 } 201 202 iov_discard_front(&out_iov, &out_num, sizeof(req->out)); 203 204 if (in_iov[in_num - 1].iov_len < sizeof(struct virtio_blk_inhdr)) { 205 error_report("virtio-blk request inhdr too short"); 206 goto err; 207 } 208 209 /* We always touch the last byte, so just see how big in_iov is. */ 210 req->in = (void *)in_iov[in_num - 1].iov_base 211 + in_iov[in_num - 1].iov_len 212 - sizeof(struct virtio_blk_inhdr); 213 iov_discard_back(in_iov, &in_num, sizeof(struct virtio_blk_inhdr)); 214 215 type = le32_to_cpu(req->out.type); 216 switch (type & ~VIRTIO_BLK_T_BARRIER) { 217 case VIRTIO_BLK_T_IN: 218 case VIRTIO_BLK_T_OUT: { 219 QEMUIOVector qiov; 220 int64_t offset; 221 ssize_t ret = 0; 222 bool is_write = type & VIRTIO_BLK_T_OUT; 223 req->sector_num = le64_to_cpu(req->out.sector); 224 225 if (is_write && !vexp->writable) { 226 req->in->status = VIRTIO_BLK_S_IOERR; 227 break; 228 } 229 230 if (is_write) { 231 qemu_iovec_init_external(&qiov, out_iov, out_num); 232 } else { 233 qemu_iovec_init_external(&qiov, in_iov, in_num); 234 } 235 236 if (unlikely(!vu_blk_sect_range_ok(vexp, 237 req->sector_num, 238 qiov.size))) { 239 req->in->status = VIRTIO_BLK_S_IOERR; 240 break; 241 } 242 243 offset = req->sector_num << VIRTIO_BLK_SECTOR_BITS; 244 245 if (is_write) { 246 ret = blk_co_pwritev(blk, offset, qiov.size, &qiov, 0); 247 } else { 248 ret = blk_co_preadv(blk, offset, qiov.size, &qiov, 0); 249 } 250 if (ret >= 0) { 251 req->in->status = VIRTIO_BLK_S_OK; 252 } else { 253 req->in->status = VIRTIO_BLK_S_IOERR; 254 } 255 break; 256 } 257 case VIRTIO_BLK_T_FLUSH: 258 if (blk_co_flush(blk) == 0) { 259 req->in->status = VIRTIO_BLK_S_OK; 260 } else { 261 req->in->status = VIRTIO_BLK_S_IOERR; 262 } 263 break; 264 case VIRTIO_BLK_T_GET_ID: { 265 size_t size = MIN(iov_size(&elem->in_sg[0], in_num), 266 VIRTIO_BLK_ID_BYTES); 267 snprintf(elem->in_sg[0].iov_base, size, "%s", "vhost_user_blk"); 268 req->in->status = VIRTIO_BLK_S_OK; 269 req->size = elem->in_sg[0].iov_len; 270 break; 271 } 272 case VIRTIO_BLK_T_DISCARD: 273 case VIRTIO_BLK_T_WRITE_ZEROES: { 274 if (!vexp->writable) { 275 req->in->status = VIRTIO_BLK_S_IOERR; 276 break; 277 } 278 279 req->in->status = vu_blk_discard_write_zeroes(vexp, out_iov, out_num, 280 type); 281 break; 282 } 283 default: 284 req->in->status = VIRTIO_BLK_S_UNSUPP; 285 break; 286 } 287 288 vu_blk_req_complete(req); 289 return; 290 291err: 292 free(req); 293} 294 295static void vu_blk_process_vq(VuDev *vu_dev, int idx) 296{ 297 VuServer *server = container_of(vu_dev, VuServer, vu_dev); 298 VuVirtq *vq = vu_get_queue(vu_dev, idx); 299 300 while (1) { 301 VuBlkReq *req; 302 303 req = vu_queue_pop(vu_dev, vq, sizeof(VuBlkReq)); 304 if (!req) { 305 break; 306 } 307 308 req->server = server; 309 req->vq = vq; 310 311 Coroutine *co = 312 qemu_coroutine_create(vu_blk_virtio_process_req, req); 313 qemu_coroutine_enter(co); 314 } 315} 316 317static void vu_blk_queue_set_started(VuDev *vu_dev, int idx, bool started) 318{ 319 VuVirtq *vq; 320 321 assert(vu_dev); 322 323 vq = vu_get_queue(vu_dev, idx); 324 vu_set_queue_handler(vu_dev, vq, started ? vu_blk_process_vq : NULL); 325} 326 327static uint64_t vu_blk_get_features(VuDev *dev) 328{ 329 uint64_t features; 330 VuServer *server = container_of(dev, VuServer, vu_dev); 331 VuBlkExport *vexp = container_of(server, VuBlkExport, vu_server); 332 features = 1ull << VIRTIO_BLK_F_SIZE_MAX | 333 1ull << VIRTIO_BLK_F_SEG_MAX | 334 1ull << VIRTIO_BLK_F_TOPOLOGY | 335 1ull << VIRTIO_BLK_F_BLK_SIZE | 336 1ull << VIRTIO_BLK_F_FLUSH | 337 1ull << VIRTIO_BLK_F_DISCARD | 338 1ull << VIRTIO_BLK_F_WRITE_ZEROES | 339 1ull << VIRTIO_BLK_F_CONFIG_WCE | 340 1ull << VIRTIO_BLK_F_MQ | 341 1ull << VIRTIO_F_VERSION_1 | 342 1ull << VIRTIO_RING_F_INDIRECT_DESC | 343 1ull << VIRTIO_RING_F_EVENT_IDX | 344 1ull << VHOST_USER_F_PROTOCOL_FEATURES; 345 346 if (!vexp->writable) { 347 features |= 1ull << VIRTIO_BLK_F_RO; 348 } 349 350 return features; 351} 352 353static uint64_t vu_blk_get_protocol_features(VuDev *dev) 354{ 355 return 1ull << VHOST_USER_PROTOCOL_F_CONFIG; 356} 357 358static int 359vu_blk_get_config(VuDev *vu_dev, uint8_t *config, uint32_t len) 360{ 361 VuServer *server = container_of(vu_dev, VuServer, vu_dev); 362 VuBlkExport *vexp = container_of(server, VuBlkExport, vu_server); 363 364 if (len > sizeof(struct virtio_blk_config)) { 365 return -1; 366 } 367 368 memcpy(config, &vexp->blkcfg, len); 369 return 0; 370} 371 372static int 373vu_blk_set_config(VuDev *vu_dev, const uint8_t *data, 374 uint32_t offset, uint32_t size, uint32_t flags) 375{ 376 VuServer *server = container_of(vu_dev, VuServer, vu_dev); 377 VuBlkExport *vexp = container_of(server, VuBlkExport, vu_server); 378 uint8_t wce; 379 380 /* don't support live migration */ 381 if (flags != VHOST_SET_CONFIG_TYPE_MASTER) { 382 return -EINVAL; 383 } 384 385 if (offset != offsetof(struct virtio_blk_config, wce) || 386 size != 1) { 387 return -EINVAL; 388 } 389 390 wce = *data; 391 vexp->blkcfg.wce = wce; 392 blk_set_enable_write_cache(vexp->export.blk, wce); 393 return 0; 394} 395 396/* 397 * When the client disconnects, it sends a VHOST_USER_NONE request 398 * and vu_process_message will simple call exit which cause the VM 399 * to exit abruptly. 400 * To avoid this issue, process VHOST_USER_NONE request ahead 401 * of vu_process_message. 402 * 403 */ 404static int vu_blk_process_msg(VuDev *dev, VhostUserMsg *vmsg, int *do_reply) 405{ 406 if (vmsg->request == VHOST_USER_NONE) { 407 dev->panic(dev, "disconnect"); 408 return true; 409 } 410 return false; 411} 412 413static const VuDevIface vu_blk_iface = { 414 .get_features = vu_blk_get_features, 415 .queue_set_started = vu_blk_queue_set_started, 416 .get_protocol_features = vu_blk_get_protocol_features, 417 .get_config = vu_blk_get_config, 418 .set_config = vu_blk_set_config, 419 .process_msg = vu_blk_process_msg, 420}; 421 422static void blk_aio_attached(AioContext *ctx, void *opaque) 423{ 424 VuBlkExport *vexp = opaque; 425 426 vexp->export.ctx = ctx; 427 vhost_user_server_attach_aio_context(&vexp->vu_server, ctx); 428} 429 430static void blk_aio_detach(void *opaque) 431{ 432 VuBlkExport *vexp = opaque; 433 434 vhost_user_server_detach_aio_context(&vexp->vu_server); 435 vexp->export.ctx = NULL; 436} 437 438static void 439vu_blk_initialize_config(BlockDriverState *bs, 440 struct virtio_blk_config *config, 441 uint32_t blk_size, 442 uint16_t num_queues) 443{ 444 config->capacity = 445 cpu_to_le64(bdrv_getlength(bs) >> VIRTIO_BLK_SECTOR_BITS); 446 config->blk_size = cpu_to_le32(blk_size); 447 config->size_max = cpu_to_le32(0); 448 config->seg_max = cpu_to_le32(128 - 2); 449 config->min_io_size = cpu_to_le16(1); 450 config->opt_io_size = cpu_to_le32(1); 451 config->num_queues = cpu_to_le16(num_queues); 452 config->max_discard_sectors = 453 cpu_to_le32(VHOST_USER_BLK_MAX_DISCARD_SECTORS); 454 config->max_discard_seg = cpu_to_le32(1); 455 config->discard_sector_alignment = 456 cpu_to_le32(blk_size >> VIRTIO_BLK_SECTOR_BITS); 457 config->max_write_zeroes_sectors 458 = cpu_to_le32(VHOST_USER_BLK_MAX_WRITE_ZEROES_SECTORS); 459 config->max_write_zeroes_seg = cpu_to_le32(1); 460} 461 462static void vu_blk_exp_request_shutdown(BlockExport *exp) 463{ 464 VuBlkExport *vexp = container_of(exp, VuBlkExport, export); 465 466 vhost_user_server_stop(&vexp->vu_server); 467} 468 469static int vu_blk_exp_create(BlockExport *exp, BlockExportOptions *opts, 470 Error **errp) 471{ 472 VuBlkExport *vexp = container_of(exp, VuBlkExport, export); 473 BlockExportOptionsVhostUserBlk *vu_opts = &opts->u.vhost_user_blk; 474 Error *local_err = NULL; 475 uint64_t logical_block_size; 476 uint16_t num_queues = VHOST_USER_BLK_NUM_QUEUES_DEFAULT; 477 478 vexp->writable = opts->writable; 479 vexp->blkcfg.wce = 0; 480 481 if (vu_opts->has_logical_block_size) { 482 logical_block_size = vu_opts->logical_block_size; 483 } else { 484 logical_block_size = VIRTIO_BLK_SECTOR_SIZE; 485 } 486 check_block_size(exp->id, "logical-block-size", logical_block_size, 487 &local_err); 488 if (local_err) { 489 error_propagate(errp, local_err); 490 return -EINVAL; 491 } 492 vexp->blk_size = logical_block_size; 493 blk_set_guest_block_size(exp->blk, logical_block_size); 494 495 if (vu_opts->has_num_queues) { 496 num_queues = vu_opts->num_queues; 497 } 498 if (num_queues == 0) { 499 error_setg(errp, "num-queues must be greater than 0"); 500 return -EINVAL; 501 } 502 503 vu_blk_initialize_config(blk_bs(exp->blk), &vexp->blkcfg, 504 logical_block_size, num_queues); 505 506 blk_add_aio_context_notifier(exp->blk, blk_aio_attached, blk_aio_detach, 507 vexp); 508 509 if (!vhost_user_server_start(&vexp->vu_server, vu_opts->addr, exp->ctx, 510 num_queues, &vu_blk_iface, errp)) { 511 blk_remove_aio_context_notifier(exp->blk, blk_aio_attached, 512 blk_aio_detach, vexp); 513 return -EADDRNOTAVAIL; 514 } 515 516 return 0; 517} 518 519static void vu_blk_exp_delete(BlockExport *exp) 520{ 521 VuBlkExport *vexp = container_of(exp, VuBlkExport, export); 522 523 blk_remove_aio_context_notifier(exp->blk, blk_aio_attached, blk_aio_detach, 524 vexp); 525} 526 527const BlockExportDriver blk_exp_vhost_user_blk = { 528 .type = BLOCK_EXPORT_TYPE_VHOST_USER_BLK, 529 .instance_size = sizeof(VuBlkExport), 530 .create = vu_blk_exp_create, 531 .delete = vu_blk_exp_delete, 532 .request_shutdown = vu_blk_exp_request_shutdown, 533};