diff options
Diffstat (limited to 'block/export/virtio-blk-handler.c')
| -rw-r--r-- | block/export/virtio-blk-handler.c | 240 |
1 files changed, 240 insertions, 0 deletions
diff --git a/block/export/virtio-blk-handler.c b/block/export/virtio-blk-handler.c new file mode 100644 index 0000000..313666e --- /dev/null +++ b/block/export/virtio-blk-handler.c @@ -0,0 +1,240 @@ +/* + * Handler for virtio-blk I/O + * + * Copyright (c) 2020 Red Hat, Inc. + * Copyright (C) 2022 Bytedance Inc. and/or its affiliates. All rights reserved. + * + * Author: + * Coiby Xu <coiby.xu@gmail.com> + * Xie Yongji <xieyongji@bytedance.com> + * + * This work is licensed under the terms of the GNU GPL, version 2 or + * later. See the COPYING file in the top-level directory. + */ + +#include "qemu/osdep.h" +#include "qemu/error-report.h" +#include "virtio-blk-handler.h" + +#include "standard-headers/linux/virtio_blk.h" + +struct virtio_blk_inhdr { + unsigned char status; +}; + +static bool virtio_blk_sect_range_ok(BlockBackend *blk, uint32_t block_size, + uint64_t sector, size_t size) +{ + uint64_t nb_sectors; + uint64_t total_sectors; + + if (size % VIRTIO_BLK_SECTOR_SIZE) { + return false; + } + + nb_sectors = size >> VIRTIO_BLK_SECTOR_BITS; + + QEMU_BUILD_BUG_ON(BDRV_SECTOR_SIZE != VIRTIO_BLK_SECTOR_SIZE); + if (nb_sectors > BDRV_REQUEST_MAX_SECTORS) { + return false; + } + if ((sector << VIRTIO_BLK_SECTOR_BITS) % block_size) { + return false; + } + blk_get_geometry(blk, &total_sectors); + if (sector > total_sectors || nb_sectors > total_sectors - sector) { + return false; + } + return true; +} + +static int coroutine_fn +virtio_blk_discard_write_zeroes(VirtioBlkHandler *handler, struct iovec *iov, + uint32_t iovcnt, uint32_t type) +{ + BlockBackend *blk = handler->blk; + struct virtio_blk_discard_write_zeroes desc; + ssize_t size; + uint64_t sector; + uint32_t num_sectors; + uint32_t max_sectors; + uint32_t flags; + int bytes; + + /* Only one desc is currently supported */ + if (unlikely(iov_size(iov, iovcnt) > sizeof(desc))) { + return VIRTIO_BLK_S_UNSUPP; + } + + size = iov_to_buf(iov, iovcnt, 0, &desc, sizeof(desc)); + if (unlikely(size != sizeof(desc))) { + error_report("Invalid size %zd, expected %zu", size, sizeof(desc)); + return VIRTIO_BLK_S_IOERR; + } + + sector = le64_to_cpu(desc.sector); + num_sectors = le32_to_cpu(desc.num_sectors); + flags = le32_to_cpu(desc.flags); + max_sectors = (type == VIRTIO_BLK_T_WRITE_ZEROES) ? + VIRTIO_BLK_MAX_WRITE_ZEROES_SECTORS : + VIRTIO_BLK_MAX_DISCARD_SECTORS; + + /* This check ensures that 'bytes' fits in an int */ + if (unlikely(num_sectors > max_sectors)) { + return VIRTIO_BLK_S_IOERR; + } + + bytes = num_sectors << VIRTIO_BLK_SECTOR_BITS; + + if (unlikely(!virtio_blk_sect_range_ok(blk, handler->logical_block_size, + sector, bytes))) { + return VIRTIO_BLK_S_IOERR; + } + + /* + * The device MUST set the status byte to VIRTIO_BLK_S_UNSUPP for discard + * and write zeroes commands if any unknown flag is set. + */ + if (unlikely(flags & ~VIRTIO_BLK_WRITE_ZEROES_FLAG_UNMAP)) { + return VIRTIO_BLK_S_UNSUPP; + } + + if (type == VIRTIO_BLK_T_WRITE_ZEROES) { + int blk_flags = 0; + + if (flags & VIRTIO_BLK_WRITE_ZEROES_FLAG_UNMAP) { + blk_flags |= BDRV_REQ_MAY_UNMAP; + } + + if (blk_co_pwrite_zeroes(blk, sector << VIRTIO_BLK_SECTOR_BITS, + bytes, blk_flags) == 0) { + return VIRTIO_BLK_S_OK; + } + } else if (type == VIRTIO_BLK_T_DISCARD) { + /* + * The device MUST set the status byte to VIRTIO_BLK_S_UNSUPP for + * discard commands if the unmap flag is set. + */ + if (unlikely(flags & VIRTIO_BLK_WRITE_ZEROES_FLAG_UNMAP)) { + return VIRTIO_BLK_S_UNSUPP; + } + + if (blk_co_pdiscard(blk, sector << VIRTIO_BLK_SECTOR_BITS, + bytes) == 0) { + return VIRTIO_BLK_S_OK; + } + } + + return VIRTIO_BLK_S_IOERR; +} + +int coroutine_fn virtio_blk_process_req(VirtioBlkHandler *handler, + struct iovec *in_iov, + struct iovec *out_iov, + unsigned int in_num, + unsigned int out_num) +{ + BlockBackend *blk = handler->blk; + struct virtio_blk_inhdr *in; + struct virtio_blk_outhdr out; + uint32_t type; + int in_len; + + if (out_num < 1 || in_num < 1) { + error_report("virtio-blk request missing headers"); + return -EINVAL; + } + + if (unlikely(iov_to_buf(out_iov, out_num, 0, &out, + sizeof(out)) != sizeof(out))) { + error_report("virtio-blk request outhdr too short"); + return -EINVAL; + } + + iov_discard_front(&out_iov, &out_num, sizeof(out)); + + if (in_iov[in_num - 1].iov_len < sizeof(struct virtio_blk_inhdr)) { + error_report("virtio-blk request inhdr too short"); + return -EINVAL; + } + + /* We always touch the last byte, so just see how big in_iov is. */ + in_len = iov_size(in_iov, in_num); + 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 = le32_to_cpu(out.type); + switch (type & ~VIRTIO_BLK_T_BARRIER) { + case VIRTIO_BLK_T_IN: + case VIRTIO_BLK_T_OUT: { + QEMUIOVector qiov; + int64_t offset; + ssize_t ret = 0; + bool is_write = type & VIRTIO_BLK_T_OUT; + int64_t sector_num = le64_to_cpu(out.sector); + + if (is_write && !handler->writable) { + in->status = VIRTIO_BLK_S_IOERR; + break; + } + + if (is_write) { + qemu_iovec_init_external(&qiov, out_iov, out_num); + } else { + qemu_iovec_init_external(&qiov, in_iov, in_num); + } + + if (unlikely(!virtio_blk_sect_range_ok(blk, + handler->logical_block_size, + sector_num, qiov.size))) { + in->status = VIRTIO_BLK_S_IOERR; + break; + } + + offset = sector_num << VIRTIO_BLK_SECTOR_BITS; + + if (is_write) { + ret = blk_co_pwritev(blk, offset, qiov.size, &qiov, 0); + } else { + ret = blk_co_preadv(blk, offset, qiov.size, &qiov, 0); + } + if (ret >= 0) { + in->status = VIRTIO_BLK_S_OK; + } else { + in->status = VIRTIO_BLK_S_IOERR; + } + break; + } + case VIRTIO_BLK_T_FLUSH: + if (blk_co_flush(blk) == 0) { + in->status = VIRTIO_BLK_S_OK; + } else { + in->status = VIRTIO_BLK_S_IOERR; + } + break; + case VIRTIO_BLK_T_GET_ID: { + size_t size = MIN(strlen(handler->serial) + 1, + MIN(iov_size(in_iov, in_num), + VIRTIO_BLK_ID_BYTES)); + iov_from_buf(in_iov, in_num, 0, handler->serial, size); + in->status = VIRTIO_BLK_S_OK; + break; + } + case VIRTIO_BLK_T_DISCARD: + case VIRTIO_BLK_T_WRITE_ZEROES: + if (!handler->writable) { + in->status = VIRTIO_BLK_S_IOERR; + break; + } + in->status = virtio_blk_discard_write_zeroes(handler, out_iov, + out_num, type); + break; + default: + in->status = VIRTIO_BLK_S_UNSUPP; + break; + } + + return in_len; +} |