/* * Virtio Block Device * * Copyright IBM, Corp. 2007 * * Authors: * Anthony Liguori * * This work is licensed under the terms of the GNU GPL, version 2. See * the COPYING file in the top-level directory. * */ #include "qemu/osdep.h" #include "qapi/error.h" #include "qemu-common.h" #include "qemu/iov.h" #include "qemu/error-report.h" #include "trace.h" #include "hw/block/block.h" #include "sysemu/block-backend.h" #include "sysemu/blockdev.h" #include "hw/virtio/virtio-blk.h" #include "dataplane/virtio-blk.h" #include "block/scsi.h" #ifdef __linux__ # include #endif #include "hw/virtio/virtio-bus.h" #include "hw/virtio/virtio-access.h" void virtio_blk_init_request(VirtIOBlock *s, VirtIOBlockReq *req) { req->dev = s; req->qiov.size = 0; req->in_len = 0; req->next = NULL; req->mr_next = NULL; } void virtio_blk_free_request(VirtIOBlockReq *req) { if (req) { g_free(req); } } static void virtio_blk_req_complete(VirtIOBlockReq *req, unsigned char status) { VirtIOBlock *s = req->dev; VirtIODevice *vdev = VIRTIO_DEVICE(s); trace_virtio_blk_req_complete(req, status); stb_p(&req->in->status, status); virtqueue_push(s->vq, &req->elem, req->in_len); if (s->dataplane) { virtio_blk_data_plane_notify(s->dataplane); } else { virtio_notify(vdev, s->vq); } } static int virtio_blk_handle_rw_error(VirtIOBlockReq *req, int error, bool is_read) { BlockErrorAction action = blk_get_error_action(req->dev->blk, is_read, error); VirtIOBlock *s = req->dev; if (action == BLOCK_ERROR_ACTION_STOP) { /* Break the link as the next request is going to be parsed from the * ring again. Otherwise we may end up doing a double completion! */ req->mr_next = NULL; req->next = s->rq; s->rq = req; } else if (action == BLOCK_ERROR_ACTION_REPORT) { virtio_blk_req_complete(req, VIRTIO_BLK_S_IOERR); block_acct_failed(blk_get_stats(s->blk), &req->acct); virtio_blk_free_request(req); } blk_error_action(s->blk, action, is_read, error); return action != BLOCK_ERROR_ACTION_IGNORE; } static void virtio_blk_rw_complete(void *opaque, int ret) { VirtIOBlockReq *next = opaque; while (next) { VirtIOBlockReq *req = next; next = req->mr_next; trace_virtio_blk_rw_complete(req, ret); if (req->qiov.nalloc != -1) { /* If nalloc is != 1 req->qiov is a local copy of the original * external iovec. It was allocated in submit_merged_requests * to be able to merge requests. */ qemu_iovec_destroy(&req->qiov); } if (ret) { int p = virtio_ldl_p(VIRTIO_DEVICE(req->dev), &req->out.type); bool is_read = !(p & VIRTIO_BLK_T_OUT); /* Note that memory may be dirtied on read failure. If the * virtio request is not completed here, as is the case for * BLOCK_ERROR_ACTION_STOP, the memory may not be copied * correctly during live migration. While this is ugly, * it is acceptable because the device is free to write to * the memory until the request is completed (which will * happen on the other side of the migration). */ if (virtio_blk_handle_rw_error(req, -ret, is_read)) { continue; } } virtio_blk_req_complete(req, VIRTIO_BLK_S_OK); block_acct_done(blk_get_stats(req->dev->blk), &req->acct); virtio_blk_free_request(req); } } static void virtio_blk_flush_complete(void *opaque, int ret) { VirtIOBlockReq *req = opaque; if (ret) { if (virtio_blk_handle_rw_error(req, -ret, 0)) { return; } } virtio_blk_req_complete(req, VIRTIO_BLK_S_OK); block_acct_done(blk_get_stats(req->dev->blk), &req->acct); virtio_blk_free_request(req); } #ifdef __linux__ typedef struct { VirtIOBlockReq *req; struct sg_io_hdr hdr; } VirtIOBlockIoctlReq; static void virtio_blk_ioctl_complete(void *opaque, int status) { VirtIOBlockIoctlReq *ioctl_req = opaque; VirtIOBlockReq *req = ioctl_req->req; VirtIODevice *vdev = VIRTIO_DEVICE(req->dev); struct virtio_scsi_inhdr *scsi; struct sg_io_hdr *hdr; scsi = (void *)req->elem.in_sg[req->elem.in_num - 2].iov_base; if (status) { status = VIRTIO_BLK_S_UNSUPP; virtio_stl_p(vdev, &scsi->errors, 255); goto out; } hdr = &ioctl_req->hdr; /* * From SCSI-Generic-HOWTO: "Some lower level drivers (e.g. ide-scsi) * clear the masked_status field [hence status gets cleared too, see * block/scsi_ioctl.c] even when a CHECK_CONDITION or COMMAND_TERMINATED * status has occurred. However they do set DRIVER_SENSE in driver_status * field. Also a (sb_len_wr > 0) indicates there is a sense buffer. */ if (hdr->status == 0 && hdr->sb_len_wr > 0) { hdr->status = CHECK_CONDITION; } virtio_stl_p(vdev, &scsi->errors, hdr->status | (hdr->msg_status << 8) | (hdr->host_status << 16) | (hdr->driver_status << 24)); virtio_stl_p(vdev, &scsi->residual, hdr->resid); virtio_stl_p(vdev, &scsi->sense_len, hdr->sb_len_wr); virtio_stl_p(vdev, &scsi->data_len, hdr->dxfer_len); out: virtio_blk_req_complete(req, status); virtio_blk_free_request(req); g_free(ioctl_req); } #endif static VirtIOBlockReq *virtio_blk_get_request(VirtIOBlock *s) { VirtIOBlockReq *req = virtqueue_pop(s->vq, sizeof(VirtIOBlockReq)); if (req) { virtio_blk_init_request(s, req); } return req; } static int virtio_blk_handle_scsi_req(VirtIOBlockReq *req) { int status = VIRTIO_BLK_S_OK; struct virtio_scsi_inhdr *scsi = NULL; VirtIODevice *vdev = VIRTIO_DEVICE(req->dev); VirtQueueElement *elem = &req->elem; VirtIOBlock *blk = req->dev; #ifdef __linux__ int i; VirtIOBlockIoctlReq *ioctl_req; BlockAIOCB *acb; #endif /* * We require at least one output segment each for the virtio_blk_outhdr * and the SCSI command block. * * We also at least require the virtio_blk_inhdr, the virtio_scsi_inhdr * and the sense buffer pointer in the input segments. */ if (elem->out_num < 2 || elem->in_num < 3) { status = VIRTIO_BLK_S_IOERR; goto fail; } /* * The scsi inhdr is placed in the second-to-last input segment, just * before the regular inhdr. */ scsi = (void *)elem->in_sg[elem->in_num - 2].iov_base; if (!blk->conf.scsi) { status = VIRTIO_BLK_S_UNSUPP; goto fail; } /* * No support for bidirection commands yet. */ if (elem->out_num > 2 && elem->in_num > 3) { status = VIRTIO_BLK_S_UNSUPP; goto fail; } #ifdef __linux__ ioctl_req = g_new0(VirtIOBlockIoctlReq, 1); ioctl_req->req = req; ioctl_req->hdr.interface_id = 'S'; ioctl_req->hdr.cmd_len = elem->out_sg[1].iov_len; ioctl_req->hdr.cmdp = elem->out_sg[1].iov_base; ioctl_req->hdr.dxfer_len = 0; if (elem->out_num > 2) { /* * If there are more than the minimally required 2 output segments * there is write payload starting from the third iovec. */ ioctl_req->hdr.dxfer_direction = SG_DXFER_TO_DEV; ioctl_req->hdr.iovec_count = elem->out_num - 2; for (i = 0; i < ioctl_req->hdr.iovec_count; i++) { ioctl_req->hdr.dxfer_len += elem->out_sg[i + 2].iov_len; } ioctl_req->hdr.dxferp = elem->out_sg + 2; } else if (elem->in_num > 3) { /* * If we have more than 3 input segments the guest wants to actually * read data. */ ioctl_req->hdr.dxfer_direction = SG_DXFER_FROM_DEV; ioctl_req->hdr.iovec_count = elem->in_num - 3; for (i = 0; i < ioctl_req->hdr.iovec_count; i++) { ioctl_req->hdr.dxfer_len += elem->in_sg[i].iov_len; } ioctl_req->hdr.dxferp = elem->in_sg; } else { /* * Some SCSI commands don't actually transfer any data. */ ioctl_req->hdr.dxfer_direction = SG_DXFER_NONE; } ioctl_req->hdr.sbp = elem->in_sg[elem->in_num - 3].iov_base; ioctl_req->hdr.mx_sb_len = elem->in_sg[elem->in_num - 3].iov_len; acb = blk_aio_ioctl(blk->blk, SG_IO, &ioctl_req->hdr, virtio_blk_ioctl_complete, ioctl_req); if (!acb) { g_free(ioctl_req); status = VIRTIO_BLK_S_UNSUPP; goto fail; } return -EINPROGRESS; #else abort(); #endif fail: /* Just put anything nonzero so that the ioctl fails in the guest. */ if (scsi) { virtio_stl_p(vdev, &scsi->errors, 255); } return status; } static void virtio_blk_handle_scsi(VirtIOBlockReq *req) { int status; status = virtio_blk_handle_scsi_req(req); if (status != -EINPROGRESS) { virtio_blk_req_complete(req, status); virtio_blk_free_request(req); } } static inline void submit_requests(BlockBackend *blk, MultiReqBuffer *mrb, int start, int num_reqs, int niov) { QEMUIOVector *qiov = &mrb->reqs[start]->qiov; int64_t sector_num = mrb->reqs[start]->sector_num; int nb_sectors = mrb->reqs[start]->qiov.size / BDRV_SECTOR_SIZE; bool is_write = mrb->is_write; if (num_reqs > 1) { int i; struct iovec *tmp_iov = qiov->iov; int tmp_niov = qiov->niov; /* mrb->reqs[start]->qiov was initialized from external so we can't * modifiy it here. We need to initialize it locally and then add the * external iovecs. */ qemu_iovec_init(qiov, niov); for (i = 0; i < tmp_niov; i++) { qemu_iovec_add(qiov, tmp_iov[i].iov_base, tmp_iov[i].iov_len); } for (i = start + 1; i < start + num_reqs; i++) { qemu_iovec_concat(qiov, &mrb->reqs[i]->qiov, 0, mrb->reqs[i]->qiov.size); mrb->reqs[i - 1]->mr_next = mrb->reqs[i]; nb_sectors += mrb->reqs[i]->qiov.size / BDRV_SECTOR_SIZE; } assert(nb_sectors == qiov->size / BDRV_SECTOR_SIZE); trace_virtio_blk_submit_multireq(mrb, start, num_reqs, sector_num, nb_sectors, is_write); block_acct_merge_done(blk_get_stats(blk), is_write ? BLOCK_ACCT_WRITE : BLOCK_ACCT_READ, num_reqs - 1); } if (is_write) { blk_aio_writev(blk, sector_num, qiov, nb_sectors, virtio_blk_rw_complete, mrb->reqs[start]); } else { blk_aio_readv(blk, sector_num, qiov, nb_sectors, virtio_blk_rw_complete, mrb->reqs[start]); } } static int multireq_compare(const void *a, const void *b) { const VirtIOBlockReq *req1 = *(VirtIOBlockReq **)a, *req2 = *(VirtIOBlockReq **)b; /* * Note that we can't simply subtract sector_num1 from sector_num2 * here as that could overflow the return value. */ if (req1->sector_num > req2->sector_num) { return 1; } else if (req1->sector_num < req2->sector_num) { return -1; } else { return 0; } } void virtio_blk_submit_multireq(BlockBackend *blk, MultiReqBuffer *mrb) { int i = 0, start = 0, num_reqs = 0, niov = 0, nb_sectors = 0; int max_xfer_len = 0; int64_t sector_num = 0; if (mrb->num_reqs == 1) { submit_requests(blk, mrb, 0, 1, -1); mrb->num_reqs = 0; return; } max_xfer_len = blk_get_max_transfer_length(mrb->reqs[0]->dev->blk); max_xfer_len = MIN_NON_ZERO(max_xfer_len, BDRV_REQUEST_MAX_SECTORS); qsort(mrb->reqs, mrb->num_reqs, sizeof(*mrb->reqs), &multireq_compare); for (i = 0; i < mrb->num_reqs; i++) { VirtIOBlockReq *req = mrb->reqs[i]; if (num_reqs > 0) { /* * NOTE: We cannot merge the requests in below situations: * 1. requests are not sequential * 2. merge would exceed maximum number of IOVs * 3. merge would exceed maximum transfer length of backend device */ if (sector_num + nb_sectors != req->sector_num || niov > blk_get_max_iov(blk) - req->qiov.niov || req->qiov.size / BDRV_SECTOR_SIZE > max_xfer_len || nb_sectors > max_xfer_len - req->qiov.size / BDRV_SECTOR_SIZE) { submit_requests(blk, mrb, start, num_reqs, niov); num_reqs = 0; } } if (num_reqs == 0) { sector_num = req->sector_num; nb_sectors = niov = 0; start = i; } nb_sectors += req->qiov.size / BDRV_SECTOR_SIZE; niov += req->qiov.niov; num_reqs++; } submit_requests(blk, mrb, start, num_reqs, niov); mrb->num_reqs = 0; } static void virtio_blk_handle_flush(VirtIOBlockReq *req, MultiReqBuffer *mrb) { block_acct_start(blk_get_stats(req->dev->blk), &req->acct, 0, BLOCK_ACCT_FLUSH); /* * Make sure all outstanding writes are posted to the backing device. */ if (mrb->is_write && mrb->num_reqs > 0) { virtio_blk_submit_multireq(req->dev->blk, mrb); } blk_aio_flush(req->dev->blk, virtio_blk_flush_complete, req); } static bool virtio_blk_sect_range_ok(VirtIOBlock *dev, uint64_t sector, size_t size) { uint64_t nb_sectors = size >> BDRV_SECTOR_BITS; uint64_t total_sectors; if (nb_sectors > BDRV_REQUEST_MAX_SECTORS) { return false; } if (sector & dev->sector_mask) { return false; } if (size % dev->conf.conf.logical_block_size) { return false; } blk_get_geometry(dev->blk, &total_sectors); if (sector > total_sectors || nb_sectors > total_sectors - sector) { return false; } return true; } void virtio_blk_handle_request(VirtIOBlockReq *req, MultiReqBuffer *mrb) { uint32_t type; struct iovec *in_iov = req->elem.in_sg; struct iovec *iov = req->elem.out_sg; unsigned in_num = req->elem.in_num; unsigned out_num = req->elem.out_num; if (req->elem.out_num < 1 || req->elem.in_num < 1) { error_report("virtio-blk missing headers"); exit(1); } if (unlikely(iov_to_buf(iov, out_num, 0, &req->out, sizeof(req->out)) != sizeof(req->out))) { error_report("virtio-blk request outhdr too short"); exit(1); } iov_discard_front(&iov, &out_num, sizeof(req->out)); if (in_iov[in_num - 1].iov_len < sizeof(struct virtio_blk_inhdr)) { error_report("virtio-blk request inhdr too short"); exit(1); } /* We always touch the last byte, so just see how big in_iov is. */ req->in_len = iov_size(in_iov, in_num); req->in = (void *)in_iov[in_num - 1].iov_base + in_iov[in_num - 1].iov_len - sizeof(struct virtio_blk_inhdr); iov_discard_back(in_iov, &in_num, sizeof(struct virtio_blk_inhdr)); type = virtio_ldl_p(VIRTIO_DEVICE(req->dev), &req->out.type); /* VIRTIO_BLK_T_OUT defines the command direction. VIRTIO_BLK_T_BARRIER * is an optional flag. Although a guest should not send this flag if * not negotiated we ignored it in the past. So keep ignoring it. */ switch (type & ~(VIRTIO_BLK_T_OUT | VIRTIO_BLK_T_BARRIER)) { case VIRTIO_BLK_T_IN: { bool is_write = type & VIRTIO_BLK_T_OUT; req->sector_num = virtio_ldq_p(VIRTIO_DEVICE(req->dev), &req->out.sector); if (is_write) { qemu_iovec_init_external(&req->qiov, iov, out_num); trace_virtio_blk_handle_write(req, req->sector_num, req->qiov.size / BDRV_SECTOR_SIZE); } else { qemu_iovec_init_external(&req->qiov, in_iov, in_num); trace_virtio_blk_handle_read(req, req->sector_num, req->qiov.size / BDRV_SECTOR_SIZE); } if (!virtio_blk_sect_range_ok(req->dev, req->sector_num, req->qiov.size)) { virtio_blk_req_complete(req, VIRTIO_BLK_S_IOERR); block_acct_invalid(blk_get_stats(req->dev->blk), is_write ? BLOCK_ACCT_WRITE : BLOCK_ACCT_READ); virtio_blk_free_request(req); return; } block_acct_start(blk_get_stats(req->dev->blk), &req->acct, req->qiov.size, is_write ? BLOCK_ACCT_WRITE : BLOCK_ACCT_READ); /* merge would exceed maximum number of requests or IO direction * changes */ if (mrb->num_reqs > 0 && (mrb->num_reqs == VIRTIO_BLK_MAX_MERGE_REQS || is_write != mrb->is_write || !req->dev->conf.request_merging)) { virtio_blk_submit_multireq(req->dev->blk, mrb); } assert(mrb->num_reqs < VIRTIO_BLK_MAX_MERGE_REQS); mrb->reqs[mrb->num_reqs++] = req; mrb->is_write = is_write; break; } case VIRTIO_BLK_T_FLUSH: virtio_blk_handle_flush(req, mrb); break; case VIRTIO_BLK_T_SCSI_CMD: virtio_blk_handle_scsi(req); break; case VIRTIO_BLK_T_GET_ID: { VirtIOBlock *s = req->dev; /* * NB: per existing s/n string convention the string is * terminated by '\0' only when shorter than buffer. */ const char *serial = s->conf.serial ? s->conf.serial : ""; size_t size = MIN(strlen(serial) + 1, MIN(iov_size(in_iov, in_num), VIRTIO_BLK_ID_BYTES)); iov_from_buf(in_iov, in_num, 0, serial, size); virtio_blk_req_complete(req, VIRTIO_BLK_S_OK); virtio_blk_free_request(req); break; } default: virtio_blk_req_complete(req, VIRTIO_BLK_S_UNSUPP); virtio_blk_free_request(req); } } static void virtio_blk_handle_output(VirtIODevice *vdev, VirtQueue *vq) { VirtIOBlock *s = VIRTIO_BLK(vdev); VirtIOBlockReq *req; MultiReqBuffer mrb = {}; /* Some guests kick before setting VIRTIO_CONFIG_S_DRIVER_OK so start * dataplane here instead of waiting for .set_status(). */ if (s->dataplane && !s->dataplane_started) { virtio_blk_data_plane_start(s->dataplane); return; } blk_io_plug(s->blk); while ((req = virtio_blk_get_request(s))) { virtio_blk_handle_request(req, &mrb); } if (mrb.num_reqs) { virtio_blk_submit_multireq(s->blk, &mrb); } blk_io_unplug(s->blk); } static void virtio_blk_dma_restart_bh(void *opaque) { VirtIOBlock *s = opaque; VirtIOBlockReq *req = s->rq; MultiReqBuffer mrb = {}; qemu_bh_delete(s->bh); s->bh = NULL; s->rq = NULL; while (req) { VirtIOBlockReq *next = req->next; virtio_blk_handle_request(req, &mrb); req = next; } if (mrb.num_reqs) { virtio_blk_submit_multireq(s->blk, &mrb); } } static void virtio_blk_dma_restart_cb(void *opaque, int running, RunState state) { VirtIOBlock *s = opaque; if (!running) { return; } if (!s->bh) { s->bh = aio_bh_new(blk_get_aio_context(s->conf.conf.blk), virtio_blk_dma_restart_bh, s); qemu_bh_schedule(s->bh); } } static void virtio_blk_reset(VirtIODevice *vdev) { VirtIOBlock *s = VIRTIO_BLK(vdev); AioContext *ctx; /* * This should cancel pending requests, but can't do nicely until there * are per-device request lists. */ ctx = blk_get_aio_context(s->blk); aio_context_acquire(ctx); blk_drain(s->blk); if (s->dataplane) { virtio_blk_data_plane_stop(s->dataplane); } aio_context_release(ctx); blk_set_enable_write_cache(s->blk, s->original_wce); } /* coalesce internal state, copy to pci i/o region 0 */ static void virtio_blk_update_config(VirtIODevice *vdev, uint8_t *config) { VirtIOBlock *s = VIRTIO_BLK(vdev); BlockConf *conf = &s->conf.conf; struct virtio_blk_config blkcfg; uint64_t capacity; int blk_size = conf->logical_block_size; blk_get_geometry(s->blk, &capacity); memset(&blkcfg, 0, sizeof(blkcfg)); virtio_stq_p(vdev, &blkcfg.capacity, capacity); virtio_stl_p(vdev, &blkcfg.seg_max, 128 - 2); virtio_stw_p(vdev, &blkcfg.geometry.cylinders, conf->cyls); virtio_stl_p(vdev, &blkcfg.blk_size, blk_size); virtio_stw_p(vdev, &blkcfg.min_io_size, conf->min_io_size / blk_size); virtio_stw_p(vdev, &blkcfg.opt_io_size, conf->opt_io_size / blk_size); blkcfg.geometry.heads = conf->heads; /* * We must ensure that the block device capacity is a multiple of * the logical block size. If that is not the case, let's use * sector_mask to adopt the geometry to have a correct picture. * For those devices where the capacity is ok for the given geometry * we don't touch the sector value of the geometry, since some devices * (like s390 dasd) need a specific value. Here the capacity is already * cyls*heads*secs*blk_size and the sector value is not block size * divided by 512 - instead it is the amount of blk_size blocks * per track (cylinder). */ if (blk_getlength(s->blk) / conf->heads / conf->secs % blk_size) { blkcfg.geometry.sectors = conf->secs & ~s->sector_mask; } else { blkcfg.geometry.sectors = conf->secs; } blkcfg.size_max = 0; blkcfg.physical_block_exp = get_physical_block_exp(conf); blkcfg.alignment_offset = 0; blkcfg.wce = blk_enable_write_cache(s->blk); memcpy(config, &blkcfg, sizeof(struct virtio_blk_config)); } static void virtio_blk_set_config(VirtIODevice *vdev, const uint8_t *config) { VirtIOBlock *s = VIRTIO_BLK(vdev); struct virtio_blk_config blkcfg; memcpy(&blkcfg, config, sizeof(blkcfg)); aio_context_acquire(blk_get_aio_context(s->blk)); blk_set_enable_write_cache(s->blk, blkcfg.wce != 0); aio_context_release(blk_get_aio_context(s->blk)); } static uint64_t virtio_blk_get_features(VirtIODevice *vdev, uint64_t features, Error **errp) { VirtIOBlock *s = VIRTIO_BLK(vdev); virtio_add_feature(&features, VIRTIO_BLK_F_SEG_MAX); virtio_add_feature(&features, VIRTIO_BLK_F_GEOMETRY); virtio_add_feature(&features, VIRTIO_BLK_F_TOPOLOGY); virtio_add_feature(&features, VIRTIO_BLK_F_BLK_SIZE); if (virtio_has_feature(features, VIRTIO_F_VERSION_1)) { if (s->conf.scsi) { error_setg(errp, "Please set scsi=off for virtio-blk devices in order to use virtio 1.0"); return 0; } } else { virtio_clear_feature(&features, VIRTIO_F_ANY_LAYOUT); virtio_add_feature(&features, VIRTIO_BLK_F_SCSI); } if (s->conf.config_wce) { virtio_add_feature(&features, VIRTIO_BLK_F_CONFIG_WCE); } if (blk_enable_write_cache(s->blk)) { virtio_add_feature(&features, VIRTIO_BLK_F_WCE); } if (blk_is_read_only(s->blk)) { virtio_add_feature(&features, VIRTIO_BLK_F_RO); } return features; } static void virtio_blk_set_status(VirtIODevice *vdev, uint8_t status) { VirtIOBlock *s = VIRTIO_BLK(vdev); if (s->dataplane && !(status & (VIRTIO_CONFIG_S_DRIVER | VIRTIO_CONFIG_S_DRIVER_OK))) { virtio_blk_data_plane_stop(s->dataplane); } if (!(status & VIRTIO_CONFIG_S_DRIVER_OK)) { return; } /* A guest that supports VIRTIO_BLK_F_CONFIG_WCE must be able to send * cache flushes. Thus, the "auto writethrough" behavior is never * necessary for guests that support the VIRTIO_BLK_F_CONFIG_WCE feature. * Leaving it enabled would break the following sequence: * * Guest started with "-drive cache=writethrough" * Guest sets status to 0 * Guest sets DRIVER bit in status field * Guest reads host features (WCE=0, CONFIG_WCE=1) * Guest writes guest features (WCE=0, CONFIG_WCE=1) * Guest writes 1 to the WCE configuration field (writeback mode) * Guest sets DRIVER_OK bit in status field * * s->blk would erroneously be placed in writethrough mode. */ if (!virtio_vdev_has_feature(vdev, VIRTIO_BLK_F_CONFIG_WCE)) { aio_context_acquire(blk_get_aio_context(s->blk)); blk_set_enable_write_cache(s->blk, virtio_vdev_has_feature(vdev, VIRTIO_BLK_F_WCE)); aio_context_release(blk_get_aio_context(s->blk)); } } static void virtio_blk_save(QEMUFile *f, void *opaque) { VirtIODevice *vdev = VIRTIO_DEVICE(opaque); VirtIOBlock *s = VIRTIO_BLK(vdev); if (s->dataplane) { virtio_blk_data_plane_stop(s->dataplane); } virtio_save(vdev, f); } static void virtio_blk_save_device(VirtIODevice *vdev, QEMUFile *f) { VirtIOBlock *s = VIRTIO_BLK(vdev); VirtIOBlockReq *req = s->rq; while (req) { qemu_put_sbyte(f, 1); qemu_put_virtqueue_element(f, &req->elem); req = req->next; } qemu_put_sbyte(f, 0); } static int virtio_blk_load(QEMUFile *f, void *opaque, int version_id) { VirtIOBlock *s = opaque; VirtIODevice *vdev = VIRTIO_DEVICE(s); if (version_id != 2) return -EINVAL; return virtio_load(vdev, f, version_id); } static int virtio_blk_load_device(VirtIODevice *vdev, QEMUFile *f, int version_id) { VirtIOBlock *s = VIRTIO_BLK(vdev); while (qemu_get_sbyte(f)) { VirtIOBlockReq *req; req = qemu_get_virtqueue_element(f, sizeof(VirtIOBlockReq)); virtio_blk_init_request(s, req); req->next = s->rq; s->rq = req; } return 0; } static void virtio_blk_resize(void *opaque) { VirtIODevice *vdev = VIRTIO_DEVICE(opaque); virtio_notify_config(vdev); } static const BlockDevOps virtio_block_ops = { .resize_cb = virtio_blk_resize, }; static void virtio_blk_device_realize(DeviceState *dev, Error **errp) { VirtIODevice *vdev = VIRTIO_DEVICE(dev); VirtIOBlock *s = VIRTIO_BLK(dev); VirtIOBlkConf *conf = &s->conf; Error *err = NULL; static int virtio_blk_id; if (!conf->conf.blk) { error_setg(errp, "drive property not set"); return; } if (!blk_is_inserted(conf->conf.blk)) { error_setg(errp, "Device needs media, but drive is empty"); return; } blkconf_serial(&conf->conf, &conf->serial); s->original_wce = blk_enable_write_cache(conf->conf.blk); blkconf_geometry(&conf->conf, NULL, 65535, 255, 255, &err); if (err) { error_propagate(errp, err); return; } blkconf_blocksizes(&conf->conf); virtio_init(vdev, "virtio-blk", VIRTIO_ID_BLOCK, sizeof(struct virtio_blk_config)); s->blk = conf->conf.blk; s->rq = NULL; s->sector_mask = (s->conf.conf.logical_block_size / BDRV_SECTOR_SIZE) - 1; s->vq = virtio_add_queue(vdev, 128, virtio_blk_handle_output); virtio_blk_data_plane_create(vdev, conf, &s->dataplane, &err); if (err != NULL) { error_propagate(errp, err); virtio_cleanup(vdev); return; } s->change = qemu_add_vm_change_state_handler(virtio_blk_dma_restart_cb, s); register_savevm(dev, "virtio-blk", virtio_blk_id++, 2, virtio_blk_save, virtio_blk_load, s); blk_set_dev_ops(s->blk, &virtio_block_ops, s); blk_set_guest_block_size(s->blk, s->conf.conf.logical_block_size); blk_iostatus_enable(s->blk); } static void virtio_blk_device_unrealize(DeviceState *dev, Error **errp) { VirtIODevice *vdev = VIRTIO_DEVICE(dev); VirtIOBlock *s = VIRTIO_BLK(dev); virtio_blk_data_plane_destroy(s->dataplane); s->dataplane = NULL; qemu_del_vm_change_state_handler(s->change); unregister_savevm(dev, "virtio-blk", s); blockdev_mark_auto_del(s->blk); virtio_cleanup(vdev); } static void virtio_blk_instance_init(Object *obj) { VirtIOBlock *s = VIRTIO_BLK(obj); object_property_add_link(obj, "iothread", TYPE_IOTHREAD, (Object **)&s->conf.iothread, qdev_prop_allow_set_link_before_realize, OBJ_PROP_LINK_UNREF_ON_RELEASE, NULL); device_add_bootindex_property(obj, &s->conf.conf.bootindex, "bootindex", "/disk@0,0", DEVICE(obj), NULL); } static Property virtio_blk_properties[] = { DEFINE_BLOCK_PROPERTIES(VirtIOBlock, conf.conf), DEFINE_BLOCK_CHS_PROPERTIES(VirtIOBlock, conf.conf), DEFINE_PROP_STRING("serial", VirtIOBlock, conf.serial), DEFINE_PROP_BIT("config-wce", VirtIOBlock, conf.config_wce, 0, true), #ifdef __linux__ DEFINE_PROP_BIT("scsi", VirtIOBlock, conf.scsi, 0, false), #endif DEFINE_PROP_BIT("request-merging", VirtIOBlock, conf.request_merging, 0, true), DEFINE_PROP_END_OF_LIST(), }; static void virtio_blk_class_init(ObjectClass *klass, void *data) { DeviceClass *dc = DEVICE_CLASS(klass); VirtioDeviceClass *vdc = VIRTIO_DEVICE_CLASS(klass); dc->props = virtio_blk_properties; set_bit(DEVICE_CATEGORY_STORAGE, dc->categories); vdc->realize = virtio_blk_device_realize; vdc->unrealize = virtio_blk_device_unrealize; vdc->get_config = virtio_blk_update_config; vdc->set_config = virtio_blk_set_config; vdc->get_features = virtio_blk_get_features; vdc->set_status = virtio_blk_set_status; vdc->reset = virtio_blk_reset; vdc->save = virtio_blk_save_device; vdc->load = virtio_blk_load_device; } static const TypeInfo virtio_device_info = { .name = TYPE_VIRTIO_BLK, .parent = TYPE_VIRTIO_DEVICE, .instance_size = sizeof(VirtIOBlock), .instance_init = virtio_blk_instance_init, .class_init = virtio_blk_class_init, }; static void virtio_register_types(void) { type_register_static(&virtio_device_info); } type_init(virtio_register_types)