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/*
* 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 coroutine_fn
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_co_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;
}
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