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qemu/hw/block/virtio-blk.c
Hiroki Narukawa 4c41c69e05 util: adjust coroutine pool size to virtio block queue 
Coroutine pool size was 64 from long ago, and the basis was organized in the commit message in 4d68e86b.

At that time, virtio-blk queue-size and num-queue were not configuable, and equivalent values were 128 and 1.

Coroutine pool size 64 was fine then.

Later queue-size and num-queue got configuable, and default values were increased.

Coroutine pool with size 64 exhausts frequently with random disk IO in new size, and slows down.

This commit adjusts coroutine pool size adaptively with new values.

This commit adds 64 by default, but now coroutine is not only for block devices,

and is not too much burdon comparing with new default.

pool size of 128 * vCPUs.

Signed-off-by: Hiroki Narukawa <hnarukaw@yahoo-corp.jp>
Message-id: 20220214115302.13294-2-hnarukaw@yahoo-corp.jp
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2022-02-14 17:11:25 +00:00

1351 lines
44 KiB
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/*
* Virtio Block Device
*
* Copyright IBM, Corp. 2007
*
* Authors:
* Anthony Liguori <aliguori@us.ibm.com>
*
* 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/iov.h"
#include "qemu/module.h"
#include "qemu/error-report.h"
#include "qemu/main-loop.h"
#include "trace.h"
#include "hw/block/block.h"
#include "hw/qdev-properties.h"
#include "sysemu/blockdev.h"
#include "sysemu/sysemu.h"
#include "sysemu/runstate.h"
#include "hw/virtio/virtio-blk.h"
#include "dataplane/virtio-blk.h"
#include "scsi/constants.h"
#ifdef __linux__
# include <scsi/sg.h>
#endif
#include "hw/virtio/virtio-bus.h"
#include "migration/qemu-file-types.h"
#include "hw/virtio/virtio-access.h"
#include "qemu/coroutine.h"
/* Config size before the discard support (hide associated config fields) */
#define VIRTIO_BLK_CFG_SIZE offsetof(struct virtio_blk_config, \
max_discard_sectors)
/*
* Starting from the discard feature, we can use this array to properly
* set the config size depending on the features enabled.
*/
static const VirtIOFeature feature_sizes[] = {
{.flags = 1ULL << VIRTIO_BLK_F_DISCARD,
.end = endof(struct virtio_blk_config, discard_sector_alignment)},
{.flags = 1ULL << VIRTIO_BLK_F_WRITE_ZEROES,
.end = endof(struct virtio_blk_config, write_zeroes_may_unmap)},
{}
};
static void virtio_blk_set_config_size(VirtIOBlock *s, uint64_t host_features)
{
s->config_size = MAX(VIRTIO_BLK_CFG_SIZE,
virtio_feature_get_config_size(feature_sizes, host_features));
assert(s->config_size <= sizeof(struct virtio_blk_config));
}
static void virtio_blk_init_request(VirtIOBlock *s, VirtQueue *vq,
VirtIOBlockReq *req)
{
req->dev = s;
req->vq = vq;
req->qiov.size = 0;
req->in_len = 0;
req->next = NULL;
req->mr_next = NULL;
}
static void virtio_blk_free_request(VirtIOBlockReq *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(vdev, req, status);
stb_p(&req->in->status, status);
iov_discard_undo(&req->inhdr_undo);
iov_discard_undo(&req->outhdr_undo);
virtqueue_push(req->vq, &req->elem, req->in_len);
if (s->dataplane_started && !s->dataplane_disabled) {
virtio_blk_data_plane_notify(s->dataplane, req->vq);
} else {
virtio_notify(vdev, req->vq);
}
}
static int virtio_blk_handle_rw_error(VirtIOBlockReq *req, int error,
bool is_read, bool acct_failed)
{
VirtIOBlock *s = req->dev;
BlockErrorAction action = blk_get_error_action(s->blk, is_read, error);
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);
if (acct_failed) {
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;
VirtIOBlock *s = next->dev;
VirtIODevice *vdev = VIRTIO_DEVICE(s);
aio_context_acquire(blk_get_aio_context(s->conf.conf.blk));
while (next) {
VirtIOBlockReq *req = next;
next = req->mr_next;
trace_virtio_blk_rw_complete(vdev, 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_requests to be
* able to merge requests. */
qemu_iovec_destroy(&req->qiov);
}
if (ret) {
int p = virtio_ldl_p(VIRTIO_DEVICE(s), &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, true)) {
continue;
}
}
virtio_blk_req_complete(req, VIRTIO_BLK_S_OK);
block_acct_done(blk_get_stats(s->blk), &req->acct);
virtio_blk_free_request(req);
}
aio_context_release(blk_get_aio_context(s->conf.conf.blk));
}
static void virtio_blk_flush_complete(void *opaque, int ret)
{
VirtIOBlockReq *req = opaque;
VirtIOBlock *s = req->dev;
aio_context_acquire(blk_get_aio_context(s->conf.conf.blk));
if (ret) {
if (virtio_blk_handle_rw_error(req, -ret, 0, true)) {
goto out;
}
}
virtio_blk_req_complete(req, VIRTIO_BLK_S_OK);
block_acct_done(blk_get_stats(s->blk), &req->acct);
virtio_blk_free_request(req);
out:
aio_context_release(blk_get_aio_context(s->conf.conf.blk));
}
static void virtio_blk_discard_write_zeroes_complete(void *opaque, int ret)
{
VirtIOBlockReq *req = opaque;
VirtIOBlock *s = req->dev;
bool is_write_zeroes = (virtio_ldl_p(VIRTIO_DEVICE(s), &req->out.type) &
~VIRTIO_BLK_T_BARRIER) == VIRTIO_BLK_T_WRITE_ZEROES;
aio_context_acquire(blk_get_aio_context(s->conf.conf.blk));
if (ret) {
if (virtio_blk_handle_rw_error(req, -ret, false, is_write_zeroes)) {
goto out;
}
}
virtio_blk_req_complete(req, VIRTIO_BLK_S_OK);
if (is_write_zeroes) {
block_acct_done(blk_get_stats(s->blk), &req->acct);
}
virtio_blk_free_request(req);
out:
aio_context_release(blk_get_aio_context(s->conf.conf.blk));
}
#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;
VirtIOBlock *s = req->dev;
VirtIODevice *vdev = VIRTIO_DEVICE(s);
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:
aio_context_acquire(blk_get_aio_context(s->conf.conf.blk));
virtio_blk_req_complete(req, status);
virtio_blk_free_request(req);
aio_context_release(blk_get_aio_context(s->conf.conf.blk));
g_free(ioctl_req);
}
#endif
static VirtIOBlockReq *virtio_blk_get_request(VirtIOBlock *s, VirtQueue *vq)
{
VirtIOBlockReq *req = virtqueue_pop(vq, sizeof(VirtIOBlockReq));
if (req) {
virtio_blk_init_request(s, vq, req);
}
return req;
}
static int virtio_blk_handle_scsi_req(VirtIOBlockReq *req)
{
int status = VIRTIO_BLK_S_OK;
struct virtio_scsi_inhdr *scsi = NULL;
VirtIOBlock *blk = req->dev;
VirtIODevice *vdev = VIRTIO_DEVICE(blk);
VirtQueueElement *elem = &req->elem;
#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 (!virtio_has_feature(blk->host_features, VIRTIO_BLK_F_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;
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
* modify 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];
}
trace_virtio_blk_submit_multireq(VIRTIO_DEVICE(mrb->reqs[start]->dev),
mrb, start, num_reqs,
sector_num << BDRV_SECTOR_BITS,
qiov->size, 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_pwritev(blk, sector_num << BDRV_SECTOR_BITS, qiov, 0,
virtio_blk_rw_complete, mrb->reqs[start]);
} else {
blk_aio_preadv(blk, sector_num << BDRV_SECTOR_BITS, qiov, 0,
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;
}
}
static void virtio_blk_submit_multireq(BlockBackend *blk, MultiReqBuffer *mrb)
{
int i = 0, start = 0, num_reqs = 0, niov = 0, nb_sectors = 0;
uint32_t max_transfer;
int64_t sector_num = 0;
if (mrb->num_reqs == 1) {
submit_requests(blk, mrb, 0, 1, -1);
mrb->num_reqs = 0;
return;
}
max_transfer = blk_get_max_transfer(mrb->reqs[0]->dev->blk);
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 > max_transfer ||
nb_sectors > (max_transfer -
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)
{
VirtIOBlock *s = req->dev;
block_acct_start(blk_get_stats(s->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(s->blk, mrb);
}
blk_aio_flush(s->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;
}
static uint8_t virtio_blk_handle_discard_write_zeroes(VirtIOBlockReq *req,
struct virtio_blk_discard_write_zeroes *dwz_hdr, bool is_write_zeroes)
{
VirtIOBlock *s = req->dev;
VirtIODevice *vdev = VIRTIO_DEVICE(s);
uint64_t sector;
uint32_t num_sectors, flags, max_sectors;
uint8_t err_status;
int bytes;
sector = virtio_ldq_p(vdev, &dwz_hdr->sector);
num_sectors = virtio_ldl_p(vdev, &dwz_hdr->num_sectors);
flags = virtio_ldl_p(vdev, &dwz_hdr->flags);
max_sectors = is_write_zeroes ? s->conf.max_write_zeroes_sectors :
s->conf.max_discard_sectors;
/*
* max_sectors is at most BDRV_REQUEST_MAX_SECTORS, this check
* make us sure that "num_sectors << BDRV_SECTOR_BITS" can fit in
* the integer variable.
*/
if (unlikely(num_sectors > max_sectors)) {
err_status = VIRTIO_BLK_S_IOERR;
goto err;
}
bytes = num_sectors << BDRV_SECTOR_BITS;
if (unlikely(!virtio_blk_sect_range_ok(s, sector, bytes))) {
err_status = VIRTIO_BLK_S_IOERR;
goto err;
}
/*
* 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)) {
err_status = VIRTIO_BLK_S_UNSUPP;
goto err;
}
if (is_write_zeroes) { /* VIRTIO_BLK_T_WRITE_ZEROES */
int blk_aio_flags = 0;
if (flags & VIRTIO_BLK_WRITE_ZEROES_FLAG_UNMAP) {
blk_aio_flags |= BDRV_REQ_MAY_UNMAP;
}
block_acct_start(blk_get_stats(s->blk), &req->acct, bytes,
BLOCK_ACCT_WRITE);
blk_aio_pwrite_zeroes(s->blk, sector << BDRV_SECTOR_BITS,
bytes, blk_aio_flags,
virtio_blk_discard_write_zeroes_complete, req);
} else { /* 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)) {
err_status = VIRTIO_BLK_S_UNSUPP;
goto err;
}
blk_aio_pdiscard(s->blk, sector << BDRV_SECTOR_BITS, bytes,
virtio_blk_discard_write_zeroes_complete, req);
}
return VIRTIO_BLK_S_OK;
err:
if (is_write_zeroes) {
block_acct_invalid(blk_get_stats(s->blk), BLOCK_ACCT_WRITE);
}
return err_status;
}
static int virtio_blk_handle_request(VirtIOBlockReq *req, MultiReqBuffer *mrb)
{
uint32_t type;
struct iovec *in_iov = req->elem.in_sg;
struct iovec *out_iov = req->elem.out_sg;
unsigned in_num = req->elem.in_num;
unsigned out_num = req->elem.out_num;
VirtIOBlock *s = req->dev;
VirtIODevice *vdev = VIRTIO_DEVICE(s);
if (req->elem.out_num < 1 || req->elem.in_num < 1) {
virtio_error(vdev, "virtio-blk missing headers");
return -1;
}
if (unlikely(iov_to_buf(out_iov, out_num, 0, &req->out,
sizeof(req->out)) != sizeof(req->out))) {
virtio_error(vdev, "virtio-blk request outhdr too short");
return -1;
}
iov_discard_front_undoable(&out_iov, &out_num, sizeof(req->out),
&req->outhdr_undo);
if (in_iov[in_num - 1].iov_len < sizeof(struct virtio_blk_inhdr)) {
virtio_error(vdev, "virtio-blk request inhdr too short");
iov_discard_undo(&req->outhdr_undo);
return -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_undoable(in_iov, &in_num, sizeof(struct virtio_blk_inhdr),
&req->inhdr_undo);
type = virtio_ldl_p(vdev, &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(vdev, &req->out.sector);
if (is_write) {
qemu_iovec_init_external(&req->qiov, out_iov, out_num);
trace_virtio_blk_handle_write(vdev, 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(vdev, req, req->sector_num,
req->qiov.size / BDRV_SECTOR_SIZE);
}
if (!virtio_blk_sect_range_ok(s, req->sector_num, req->qiov.size)) {
virtio_blk_req_complete(req, VIRTIO_BLK_S_IOERR);
block_acct_invalid(blk_get_stats(s->blk),
is_write ? BLOCK_ACCT_WRITE : BLOCK_ACCT_READ);
virtio_blk_free_request(req);
return 0;
}
block_acct_start(blk_get_stats(s->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 ||
!s->conf.request_merging)) {
virtio_blk_submit_multireq(s->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:
{
/*
* 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;
}
/*
* VIRTIO_BLK_T_DISCARD and VIRTIO_BLK_T_WRITE_ZEROES are defined with
* VIRTIO_BLK_T_OUT flag set. We masked this flag in the switch statement,
* so we must mask it for these requests, then we will check if it is set.
*/
case VIRTIO_BLK_T_DISCARD & ~VIRTIO_BLK_T_OUT:
case VIRTIO_BLK_T_WRITE_ZEROES & ~VIRTIO_BLK_T_OUT:
{
struct virtio_blk_discard_write_zeroes dwz_hdr;
size_t out_len = iov_size(out_iov, out_num);
bool is_write_zeroes = (type & ~VIRTIO_BLK_T_BARRIER) ==
VIRTIO_BLK_T_WRITE_ZEROES;
uint8_t err_status;
/*
* Unsupported if VIRTIO_BLK_T_OUT is not set or the request contains
* more than one segment.
*/
if (unlikely(!(type & VIRTIO_BLK_T_OUT) ||
out_len > sizeof(dwz_hdr))) {
virtio_blk_req_complete(req, VIRTIO_BLK_S_UNSUPP);
virtio_blk_free_request(req);
return 0;
}
if (unlikely(iov_to_buf(out_iov, out_num, 0, &dwz_hdr,
sizeof(dwz_hdr)) != sizeof(dwz_hdr))) {
iov_discard_undo(&req->inhdr_undo);
iov_discard_undo(&req->outhdr_undo);
virtio_error(vdev, "virtio-blk discard/write_zeroes header"
" too short");
return -1;
}
err_status = virtio_blk_handle_discard_write_zeroes(req, &dwz_hdr,
is_write_zeroes);
if (err_status != VIRTIO_BLK_S_OK) {
virtio_blk_req_complete(req, err_status);
virtio_blk_free_request(req);
}
break;
}
default:
virtio_blk_req_complete(req, VIRTIO_BLK_S_UNSUPP);
virtio_blk_free_request(req);
}
return 0;
}
void virtio_blk_handle_vq(VirtIOBlock *s, VirtQueue *vq)
{
VirtIOBlockReq *req;
MultiReqBuffer mrb = {};
bool suppress_notifications = virtio_queue_get_notification(vq);
aio_context_acquire(blk_get_aio_context(s->blk));
blk_io_plug(s->blk);
do {
if (suppress_notifications) {
virtio_queue_set_notification(vq, 0);
}
while ((req = virtio_blk_get_request(s, vq))) {
if (virtio_blk_handle_request(req, &mrb)) {
virtqueue_detach_element(req->vq, &req->elem, 0);
virtio_blk_free_request(req);
break;
}
}
if (suppress_notifications) {
virtio_queue_set_notification(vq, 1);
}
} while (!virtio_queue_empty(vq));
if (mrb.num_reqs) {
virtio_blk_submit_multireq(s->blk, &mrb);
}
blk_io_unplug(s->blk);
aio_context_release(blk_get_aio_context(s->blk));
}
static void virtio_blk_handle_output(VirtIODevice *vdev, VirtQueue *vq)
{
VirtIOBlock *s = (VirtIOBlock *)vdev;
if (s->dataplane && !s->dataplane_started) {
/* Some guests kick before setting VIRTIO_CONFIG_S_DRIVER_OK so start
* dataplane here instead of waiting for .set_status().
*/
virtio_device_start_ioeventfd(vdev);
if (!s->dataplane_disabled) {
return;
}
}
virtio_blk_handle_vq(s, vq);
}
void virtio_blk_process_queued_requests(VirtIOBlock *s, bool is_bh)
{
VirtIOBlockReq *req = s->rq;
MultiReqBuffer mrb = {};
s->rq = NULL;
aio_context_acquire(blk_get_aio_context(s->conf.conf.blk));
while (req) {
VirtIOBlockReq *next = req->next;
if (virtio_blk_handle_request(req, &mrb)) {
/* Device is now broken and won't do any processing until it gets
* reset. Already queued requests will be lost: let's purge them.
*/
while (req) {
next = req->next;
virtqueue_detach_element(req->vq, &req->elem, 0);
virtio_blk_free_request(req);
req = next;
}
break;
}
req = next;
}
if (mrb.num_reqs) {
virtio_blk_submit_multireq(s->blk, &mrb);
}
if (is_bh) {
blk_dec_in_flight(s->conf.conf.blk);
}
aio_context_release(blk_get_aio_context(s->conf.conf.blk));
}
static void virtio_blk_dma_restart_bh(void *opaque)
{
VirtIOBlock *s = opaque;
qemu_bh_delete(s->bh);
s->bh = NULL;
virtio_blk_process_queued_requests(s, true);
}
static void virtio_blk_dma_restart_cb(void *opaque, bool running,
RunState state)
{
VirtIOBlock *s = opaque;
BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(s)));
VirtioBusState *bus = VIRTIO_BUS(qbus);
if (!running) {
return;
}
/*
* If ioeventfd is enabled, don't schedule the BH here as queued
* requests will be processed while starting the data plane.
*/
if (!s->bh && !virtio_bus_ioeventfd_enabled(bus)) {
s->bh = aio_bh_new(blk_get_aio_context(s->conf.conf.blk),
virtio_blk_dma_restart_bh, s);
blk_inc_in_flight(s->conf.conf.blk);
qemu_bh_schedule(s->bh);
}
}
static void virtio_blk_reset(VirtIODevice *vdev)
{
VirtIOBlock *s = VIRTIO_BLK(vdev);
AioContext *ctx;
VirtIOBlockReq *req;
ctx = blk_get_aio_context(s->blk);
aio_context_acquire(ctx);
blk_drain(s->blk);
/* We drop queued requests after blk_drain() because blk_drain() itself can
* produce them. */
while (s->rq) {
req = s->rq;
s->rq = req->next;
virtqueue_detach_element(req->vq, &req->elem, 0);
virtio_blk_free_request(req);
}
aio_context_release(ctx);
assert(!s->dataplane_started);
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;
int64_t length;
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,
s->conf.seg_max_adjust ? s->conf.queue_size - 2 : 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_stl_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).
*/
length = blk_getlength(s->blk);
if (length > 0 && length / 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);
virtio_stw_p(vdev, &blkcfg.num_queues, s->conf.num_queues);
if (virtio_has_feature(s->host_features, VIRTIO_BLK_F_DISCARD)) {
uint32_t discard_granularity = conf->discard_granularity;
if (discard_granularity == -1 || !s->conf.report_discard_granularity) {
discard_granularity = blk_size;
}
virtio_stl_p(vdev, &blkcfg.max_discard_sectors,
s->conf.max_discard_sectors);
virtio_stl_p(vdev, &blkcfg.discard_sector_alignment,
discard_granularity >> BDRV_SECTOR_BITS);
/*
* We support only one segment per request since multiple segments
* are not widely used and there are no userspace APIs that allow
* applications to submit multiple segments in a single call.
*/
virtio_stl_p(vdev, &blkcfg.max_discard_seg, 1);
}
if (virtio_has_feature(s->host_features, VIRTIO_BLK_F_WRITE_ZEROES)) {
virtio_stl_p(vdev, &blkcfg.max_write_zeroes_sectors,
s->conf.max_write_zeroes_sectors);
blkcfg.write_zeroes_may_unmap = 1;
virtio_stl_p(vdev, &blkcfg.max_write_zeroes_seg, 1);
}
memcpy(config, &blkcfg, s->config_size);
}
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, s->config_size);
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);
/* Firstly sync all virtio-blk possible supported features */
features |= s->host_features;
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 (virtio_has_feature(s->host_features, VIRTIO_BLK_F_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 (blk_enable_write_cache(s->blk) ||
(s->conf.x_enable_wce_if_config_wce &&
virtio_has_feature(features, VIRTIO_BLK_F_CONFIG_WCE))) {
virtio_add_feature(&features, VIRTIO_BLK_F_WCE);
}
if (!blk_is_writable(s->blk)) {
virtio_add_feature(&features, VIRTIO_BLK_F_RO);
}
if (s->conf.num_queues > 1) {
virtio_add_feature(&features, VIRTIO_BLK_F_MQ);
}
return features;
}
static void virtio_blk_set_status(VirtIODevice *vdev, uint8_t status)
{
VirtIOBlock *s = VIRTIO_BLK(vdev);
if (!(status & (VIRTIO_CONFIG_S_DRIVER | VIRTIO_CONFIG_S_DRIVER_OK))) {
assert(!s->dataplane_started);
}
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_device(VirtIODevice *vdev, QEMUFile *f)
{
VirtIOBlock *s = VIRTIO_BLK(vdev);
VirtIOBlockReq *req = s->rq;
while (req) {
qemu_put_sbyte(f, 1);
if (s->conf.num_queues > 1) {
qemu_put_be32(f, virtio_get_queue_index(req->vq));
}
qemu_put_virtqueue_element(vdev, f, &req->elem);
req = req->next;
}
qemu_put_sbyte(f, 0);
}
static int virtio_blk_load_device(VirtIODevice *vdev, QEMUFile *f,
int version_id)
{
VirtIOBlock *s = VIRTIO_BLK(vdev);
while (qemu_get_sbyte(f)) {
unsigned nvqs = s->conf.num_queues;
unsigned vq_idx = 0;
VirtIOBlockReq *req;
if (nvqs > 1) {
vq_idx = qemu_get_be32(f);
if (vq_idx >= nvqs) {
error_report("Invalid virtqueue index in request list: %#x",
vq_idx);
return -EINVAL;
}
}
req = qemu_get_virtqueue_element(vdev, f, sizeof(VirtIOBlockReq));
virtio_blk_init_request(s, virtio_get_queue(vdev, vq_idx), req);
req->next = s->rq;
s->rq = req;
}
return 0;
}
static void virtio_resize_cb(void *opaque)
{
VirtIODevice *vdev = opaque;
assert(qemu_get_current_aio_context() == qemu_get_aio_context());
virtio_notify_config(vdev);
}
static void virtio_blk_resize(void *opaque)
{
VirtIODevice *vdev = VIRTIO_DEVICE(opaque);
/*
* virtio_notify_config() needs to acquire the global mutex,
* so it can't be called from an iothread. Instead, schedule
* it to be run in the main context BH.
*/
aio_bh_schedule_oneshot(qemu_get_aio_context(), virtio_resize_cb, 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;
unsigned i;
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;
}
if (conf->num_queues == VIRTIO_BLK_AUTO_NUM_QUEUES) {
conf->num_queues = 1;
}
if (!conf->num_queues) {
error_setg(errp, "num-queues property must be larger than 0");
return;
}
if (conf->queue_size <= 2) {
error_setg(errp, "invalid queue-size property (%" PRIu16 "), "
"must be > 2", conf->queue_size);
return;
}
if (!is_power_of_2(conf->queue_size) ||
conf->queue_size > VIRTQUEUE_MAX_SIZE) {
error_setg(errp, "invalid queue-size property (%" PRIu16 "), "
"must be a power of 2 (max %d)",
conf->queue_size, VIRTQUEUE_MAX_SIZE);
return;
}
if (!blkconf_apply_backend_options(&conf->conf,
!blk_supports_write_perm(conf->conf.blk),
true, errp)) {
return;
}
s->original_wce = blk_enable_write_cache(conf->conf.blk);
if (!blkconf_geometry(&conf->conf, NULL, 65535, 255, 255, errp)) {
return;
}
if (!blkconf_blocksizes(&conf->conf, errp)) {
return;
}
if (virtio_has_feature(s->host_features, VIRTIO_BLK_F_DISCARD) &&
(!conf->max_discard_sectors ||
conf->max_discard_sectors > BDRV_REQUEST_MAX_SECTORS)) {
error_setg(errp, "invalid max-discard-sectors property (%" PRIu32 ")"
", must be between 1 and %d",
conf->max_discard_sectors, (int)BDRV_REQUEST_MAX_SECTORS);
return;
}
if (virtio_has_feature(s->host_features, VIRTIO_BLK_F_WRITE_ZEROES) &&
(!conf->max_write_zeroes_sectors ||
conf->max_write_zeroes_sectors > BDRV_REQUEST_MAX_SECTORS)) {
error_setg(errp, "invalid max-write-zeroes-sectors property (%" PRIu32
"), must be between 1 and %d",
conf->max_write_zeroes_sectors,
(int)BDRV_REQUEST_MAX_SECTORS);
return;
}
virtio_blk_set_config_size(s, s->host_features);
virtio_init(vdev, "virtio-blk", VIRTIO_ID_BLOCK, s->config_size);
s->blk = conf->conf.blk;
s->rq = NULL;
s->sector_mask = (s->conf.conf.logical_block_size / BDRV_SECTOR_SIZE) - 1;
for (i = 0; i < conf->num_queues; i++) {
virtio_add_queue(vdev, conf->queue_size, virtio_blk_handle_output);
}
qemu_coroutine_increase_pool_batch_size(conf->num_queues * conf->queue_size
/ 2);
virtio_blk_data_plane_create(vdev, conf, &s->dataplane, &err);
if (err != NULL) {
error_propagate(errp, err);
for (i = 0; i < conf->num_queues; i++) {
virtio_del_queue(vdev, i);
}
virtio_cleanup(vdev);
return;
}
s->change = qemu_add_vm_change_state_handler(virtio_blk_dma_restart_cb, 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);
add_boot_device_lchs(dev, "/disk@0,0",
conf->conf.lcyls,
conf->conf.lheads,
conf->conf.lsecs);
}
static void virtio_blk_device_unrealize(DeviceState *dev)
{
VirtIODevice *vdev = VIRTIO_DEVICE(dev);
VirtIOBlock *s = VIRTIO_BLK(dev);
VirtIOBlkConf *conf = &s->conf;
unsigned i;
blk_drain(s->blk);
del_boot_device_lchs(dev, "/disk@0,0");
virtio_blk_data_plane_destroy(s->dataplane);
s->dataplane = NULL;
for (i = 0; i < conf->num_queues; i++) {
virtio_del_queue(vdev, i);
}
qemu_coroutine_decrease_pool_batch_size(conf->num_queues * conf->queue_size
/ 2);
qemu_del_vm_change_state_handler(s->change);
blockdev_mark_auto_del(s->blk);
virtio_cleanup(vdev);
}
static void virtio_blk_instance_init(Object *obj)
{
VirtIOBlock *s = VIRTIO_BLK(obj);
device_add_bootindex_property(obj, &s->conf.conf.bootindex,
"bootindex", "/disk@0,0",
DEVICE(obj));
}
static const VMStateDescription vmstate_virtio_blk = {
.name = "virtio-blk",
.minimum_version_id = 2,
.version_id = 2,
.fields = (VMStateField[]) {
VMSTATE_VIRTIO_DEVICE,
VMSTATE_END_OF_LIST()
},
};
static Property virtio_blk_properties[] = {
DEFINE_BLOCK_PROPERTIES(VirtIOBlock, conf.conf),
DEFINE_BLOCK_ERROR_PROPERTIES(VirtIOBlock, conf.conf),
DEFINE_BLOCK_CHS_PROPERTIES(VirtIOBlock, conf.conf),
DEFINE_PROP_STRING("serial", VirtIOBlock, conf.serial),
DEFINE_PROP_BIT64("config-wce", VirtIOBlock, host_features,
VIRTIO_BLK_F_CONFIG_WCE, true),
#ifdef __linux__
DEFINE_PROP_BIT64("scsi", VirtIOBlock, host_features,
VIRTIO_BLK_F_SCSI, false),
#endif
DEFINE_PROP_BIT("request-merging", VirtIOBlock, conf.request_merging, 0,
true),
DEFINE_PROP_UINT16("num-queues", VirtIOBlock, conf.num_queues,
VIRTIO_BLK_AUTO_NUM_QUEUES),
DEFINE_PROP_UINT16("queue-size", VirtIOBlock, conf.queue_size, 256),
DEFINE_PROP_BOOL("seg-max-adjust", VirtIOBlock, conf.seg_max_adjust, true),
DEFINE_PROP_LINK("iothread", VirtIOBlock, conf.iothread, TYPE_IOTHREAD,
IOThread *),
DEFINE_PROP_BIT64("discard", VirtIOBlock, host_features,
VIRTIO_BLK_F_DISCARD, true),
DEFINE_PROP_BOOL("report-discard-granularity", VirtIOBlock,
conf.report_discard_granularity, true),
DEFINE_PROP_BIT64("write-zeroes", VirtIOBlock, host_features,
VIRTIO_BLK_F_WRITE_ZEROES, true),
DEFINE_PROP_UINT32("max-discard-sectors", VirtIOBlock,
conf.max_discard_sectors, BDRV_REQUEST_MAX_SECTORS),
DEFINE_PROP_UINT32("max-write-zeroes-sectors", VirtIOBlock,
conf.max_write_zeroes_sectors, BDRV_REQUEST_MAX_SECTORS),
DEFINE_PROP_BOOL("x-enable-wce-if-config-wce", VirtIOBlock,
conf.x_enable_wce_if_config_wce, 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);
device_class_set_props(dc, virtio_blk_properties);
dc->vmsd = &vmstate_virtio_blk;
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;
vdc->start_ioeventfd = virtio_blk_data_plane_start;
vdc->stop_ioeventfd = virtio_blk_data_plane_stop;
}
static const TypeInfo virtio_blk_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_blk_info);
}
type_init(virtio_register_types)
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