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vduse-blk: Implement vduse-blk export
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This implements a VDUSE block backends based on
the libvduse library. We can use it to export the BDSs
for both VM and container (host) usage.

The new command-line syntax is:

$ qemu-storage-daemon \
    --blockdev file,node-name=drive0,filename=test.img \
    --export vduse-blk,node-name=drive0,id=vduse-export0,writable=on

After the qemu-storage-daemon started, we need to use
the "vdpa" command to attach the device to vDPA bus:

$ vdpa dev add name vduse-export0 mgmtdev vduse

Also the device must be removed via the "vdpa" command
before we stop the qemu-storage-daemon.

Signed-off-by: Xie Yongji <xieyongji@bytedance.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-Id: <20220523084611.91-7-xieyongji@bytedance.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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@YongjiXie @kevmw
YongjiXie authored and kevmw committed Jun 24, 2022
1 parent a6caeee commit 2a2359b
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Showing 9 changed files with 407 additions and 4 deletions.
4 changes: 3 additions & 1 deletion MAINTAINERS
View file
Expand Up @@ -3594,10 +3594,12 @@ L: qemu-block@nongnu.org
S: Supported
F: block/export/fuse.c

VDUSE library
VDUSE library and block device exports
M: Xie Yongji <xieyongji@bytedance.com>
S: Maintained
F: subprojects/libvduse/
F: block/export/vduse-blk.c
F: block/export/vduse-blk.h

Replication
M: Wen Congyang <wencongyang2@huawei.com>
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6 changes: 6 additions & 0 deletions block/export/export.c
View file
Expand Up @@ -26,6 +26,9 @@
#ifdef CONFIG_VHOST_USER_BLK_SERVER
#include "vhost-user-blk-server.h"
#endif
#ifdef CONFIG_VDUSE_BLK_EXPORT
#include "vduse-blk.h"
#endif

static const BlockExportDriver *blk_exp_drivers[] = {
&blk_exp_nbd,
Expand All @@ -35,6 +38,9 @@ static const BlockExportDriver *blk_exp_drivers[] = {
#ifdef CONFIG_FUSE
&blk_exp_fuse,
#endif
#ifdef CONFIG_VDUSE_BLK_EXPORT
&blk_exp_vduse_blk,
#endif
};

/* Only accessed from the main thread */
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5 changes: 5 additions & 0 deletions block/export/meson.build
View file
Expand Up @@ -5,3 +5,8 @@ if have_vhost_user_blk_server
endif

blockdev_ss.add(when: fuse, if_true: files('fuse.c'))

if have_vduse_blk_export
blockdev_ss.add(files('vduse-blk.c', 'virtio-blk-handler.c'))
blockdev_ss.add(libvduse)
endif
329 changes: 329 additions & 0 deletions block/export/vduse-blk.c
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@@ -0,0 +1,329 @@
/*
* Export QEMU block device via VDUSE
*
* Copyright (C) 2022 Bytedance Inc. and/or its affiliates. All rights reserved.
*
* Author:
* 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 <sys/eventfd.h>

#include "qemu/osdep.h"
#include "qapi/error.h"
#include "block/export.h"
#include "qemu/error-report.h"
#include "util/block-helpers.h"
#include "subprojects/libvduse/libvduse.h"
#include "virtio-blk-handler.h"

#include "standard-headers/linux/virtio_blk.h"

#define VDUSE_DEFAULT_NUM_QUEUE 1
#define VDUSE_DEFAULT_QUEUE_SIZE 256

typedef struct VduseBlkExport {
BlockExport export;
VirtioBlkHandler handler;
VduseDev *dev;
uint16_t num_queues;
unsigned int inflight;
} VduseBlkExport;

typedef struct VduseBlkReq {
VduseVirtqElement elem;
VduseVirtq *vq;
} VduseBlkReq;

static void vduse_blk_inflight_inc(VduseBlkExport *vblk_exp)
{
vblk_exp->inflight++;
}

static void vduse_blk_inflight_dec(VduseBlkExport *vblk_exp)
{
if (--vblk_exp->inflight == 0) {
aio_wait_kick();
}
}

static void vduse_blk_req_complete(VduseBlkReq *req, size_t in_len)
{
vduse_queue_push(req->vq, &req->elem, in_len);
vduse_queue_notify(req->vq);

free(req);
}

static void coroutine_fn vduse_blk_virtio_process_req(void *opaque)
{
VduseBlkReq *req = opaque;
VduseVirtq *vq = req->vq;
VduseDev *dev = vduse_queue_get_dev(vq);
VduseBlkExport *vblk_exp = vduse_dev_get_priv(dev);
VirtioBlkHandler *handler = &vblk_exp->handler;
VduseVirtqElement *elem = &req->elem;
struct iovec *in_iov = elem->in_sg;
struct iovec *out_iov = elem->out_sg;
unsigned in_num = elem->in_num;
unsigned out_num = elem->out_num;
int in_len;

in_len = virtio_blk_process_req(handler, in_iov,
out_iov, in_num, out_num);
if (in_len < 0) {
free(req);
return;
}

vduse_blk_req_complete(req, in_len);
vduse_blk_inflight_dec(vblk_exp);
}

static void vduse_blk_vq_handler(VduseDev *dev, VduseVirtq *vq)
{
VduseBlkExport *vblk_exp = vduse_dev_get_priv(dev);

while (1) {
VduseBlkReq *req;

req = vduse_queue_pop(vq, sizeof(VduseBlkReq));
if (!req) {
break;
}
req->vq = vq;

Coroutine *co =
qemu_coroutine_create(vduse_blk_virtio_process_req, req);

vduse_blk_inflight_inc(vblk_exp);
qemu_coroutine_enter(co);
}
}

static void on_vduse_vq_kick(void *opaque)
{
VduseVirtq *vq = opaque;
VduseDev *dev = vduse_queue_get_dev(vq);
int fd = vduse_queue_get_fd(vq);
eventfd_t kick_data;

if (eventfd_read(fd, &kick_data) == -1) {
error_report("failed to read data from eventfd");
return;
}

vduse_blk_vq_handler(dev, vq);
}

static void vduse_blk_enable_queue(VduseDev *dev, VduseVirtq *vq)
{
VduseBlkExport *vblk_exp = vduse_dev_get_priv(dev);

aio_set_fd_handler(vblk_exp->export.ctx, vduse_queue_get_fd(vq),
true, on_vduse_vq_kick, NULL, NULL, NULL, vq);
}

static void vduse_blk_disable_queue(VduseDev *dev, VduseVirtq *vq)
{
VduseBlkExport *vblk_exp = vduse_dev_get_priv(dev);

aio_set_fd_handler(vblk_exp->export.ctx, vduse_queue_get_fd(vq),
true, NULL, NULL, NULL, NULL, NULL);
}

static const VduseOps vduse_blk_ops = {
.enable_queue = vduse_blk_enable_queue,
.disable_queue = vduse_blk_disable_queue,
};

static void on_vduse_dev_kick(void *opaque)
{
VduseDev *dev = opaque;

vduse_dev_handler(dev);
}

static void vduse_blk_attach_ctx(VduseBlkExport *vblk_exp, AioContext *ctx)
{
int i;

aio_set_fd_handler(vblk_exp->export.ctx, vduse_dev_get_fd(vblk_exp->dev),
true, on_vduse_dev_kick, NULL, NULL, NULL,
vblk_exp->dev);

for (i = 0; i < vblk_exp->num_queues; i++) {
VduseVirtq *vq = vduse_dev_get_queue(vblk_exp->dev, i);
int fd = vduse_queue_get_fd(vq);

if (fd < 0) {
continue;
}
aio_set_fd_handler(vblk_exp->export.ctx, fd, true,
on_vduse_vq_kick, NULL, NULL, NULL, vq);
}
}

static void vduse_blk_detach_ctx(VduseBlkExport *vblk_exp)
{
int i;

for (i = 0; i < vblk_exp->num_queues; i++) {
VduseVirtq *vq = vduse_dev_get_queue(vblk_exp->dev, i);
int fd = vduse_queue_get_fd(vq);

if (fd < 0) {
continue;
}
aio_set_fd_handler(vblk_exp->export.ctx, fd,
true, NULL, NULL, NULL, NULL, NULL);
}
aio_set_fd_handler(vblk_exp->export.ctx, vduse_dev_get_fd(vblk_exp->dev),
true, NULL, NULL, NULL, NULL, NULL);

AIO_WAIT_WHILE(vblk_exp->export.ctx, vblk_exp->inflight > 0);
}


static void blk_aio_attached(AioContext *ctx, void *opaque)
{
VduseBlkExport *vblk_exp = opaque;

vblk_exp->export.ctx = ctx;
vduse_blk_attach_ctx(vblk_exp, ctx);
}

static void blk_aio_detach(void *opaque)
{
VduseBlkExport *vblk_exp = opaque;

vduse_blk_detach_ctx(vblk_exp);
vblk_exp->export.ctx = NULL;
}

static int vduse_blk_exp_create(BlockExport *exp, BlockExportOptions *opts,
Error **errp)
{
VduseBlkExport *vblk_exp = container_of(exp, VduseBlkExport, export);
BlockExportOptionsVduseBlk *vblk_opts = &opts->u.vduse_blk;
uint64_t logical_block_size = VIRTIO_BLK_SECTOR_SIZE;
uint16_t num_queues = VDUSE_DEFAULT_NUM_QUEUE;
uint16_t queue_size = VDUSE_DEFAULT_QUEUE_SIZE;
Error *local_err = NULL;
struct virtio_blk_config config = { 0 };
uint64_t features;
int i;

if (vblk_opts->has_num_queues) {
num_queues = vblk_opts->num_queues;
if (num_queues == 0) {
error_setg(errp, "num-queues must be greater than 0");
return -EINVAL;
}
}

if (vblk_opts->has_queue_size) {
queue_size = vblk_opts->queue_size;
if (queue_size <= 2 || !is_power_of_2(queue_size) ||
queue_size > VIRTQUEUE_MAX_SIZE) {
error_setg(errp, "queue-size is invalid");
return -EINVAL;
}
}

if (vblk_opts->has_logical_block_size) {
logical_block_size = vblk_opts->logical_block_size;
check_block_size(exp->id, "logical-block-size", logical_block_size,
&local_err);
if (local_err) {
error_propagate(errp, local_err);
return -EINVAL;
}
}
vblk_exp->num_queues = num_queues;
vblk_exp->handler.blk = exp->blk;
vblk_exp->handler.serial = exp->id;
vblk_exp->handler.logical_block_size = logical_block_size;
vblk_exp->handler.writable = opts->writable;

config.capacity =
cpu_to_le64(blk_getlength(exp->blk) >> VIRTIO_BLK_SECTOR_BITS);
config.seg_max = cpu_to_le32(queue_size - 2);
config.min_io_size = cpu_to_le16(1);
config.opt_io_size = cpu_to_le32(1);
config.num_queues = cpu_to_le16(num_queues);
config.blk_size = cpu_to_le32(logical_block_size);
config.max_discard_sectors = cpu_to_le32(VIRTIO_BLK_MAX_DISCARD_SECTORS);
config.max_discard_seg = cpu_to_le32(1);
config.discard_sector_alignment =
cpu_to_le32(logical_block_size >> VIRTIO_BLK_SECTOR_BITS);
config.max_write_zeroes_sectors =
cpu_to_le32(VIRTIO_BLK_MAX_WRITE_ZEROES_SECTORS);
config.max_write_zeroes_seg = cpu_to_le32(1);

features = vduse_get_virtio_features() |
(1ULL << VIRTIO_BLK_F_SEG_MAX) |
(1ULL << VIRTIO_BLK_F_TOPOLOGY) |
(1ULL << VIRTIO_BLK_F_BLK_SIZE) |
(1ULL << VIRTIO_BLK_F_FLUSH) |
(1ULL << VIRTIO_BLK_F_DISCARD) |
(1ULL << VIRTIO_BLK_F_WRITE_ZEROES);

if (num_queues > 1) {
features |= 1ULL << VIRTIO_BLK_F_MQ;
}
if (!opts->writable) {
features |= 1ULL << VIRTIO_BLK_F_RO;
}

vblk_exp->dev = vduse_dev_create(exp->id, VIRTIO_ID_BLOCK, 0,
features, num_queues,
sizeof(struct virtio_blk_config),
(char *)&config, &vduse_blk_ops,
vblk_exp);
if (!vblk_exp->dev) {
error_setg(errp, "failed to create vduse device");
return -ENOMEM;
}

for (i = 0; i < num_queues; i++) {
vduse_dev_setup_queue(vblk_exp->dev, i, queue_size);
}

aio_set_fd_handler(exp->ctx, vduse_dev_get_fd(vblk_exp->dev), true,
on_vduse_dev_kick, NULL, NULL, NULL, vblk_exp->dev);

blk_add_aio_context_notifier(exp->blk, blk_aio_attached, blk_aio_detach,
vblk_exp);

return 0;
}

static void vduse_blk_exp_delete(BlockExport *exp)
{
VduseBlkExport *vblk_exp = container_of(exp, VduseBlkExport, export);

blk_remove_aio_context_notifier(exp->blk, blk_aio_attached, blk_aio_detach,
vblk_exp);
vduse_dev_destroy(vblk_exp->dev);
}

static void vduse_blk_exp_request_shutdown(BlockExport *exp)
{
VduseBlkExport *vblk_exp = container_of(exp, VduseBlkExport, export);

aio_context_acquire(vblk_exp->export.ctx);
vduse_blk_detach_ctx(vblk_exp);
aio_context_acquire(vblk_exp->export.ctx);
}

const BlockExportDriver blk_exp_vduse_blk = {
.type = BLOCK_EXPORT_TYPE_VDUSE_BLK,
.instance_size = sizeof(VduseBlkExport),
.create = vduse_blk_exp_create,
.delete = vduse_blk_exp_delete,
.request_shutdown = vduse_blk_exp_request_shutdown,
};
20 changes: 20 additions & 0 deletions block/export/vduse-blk.h
View file
@@ -0,0 +1,20 @@
/*
* Export QEMU block device via VDUSE
*
* Copyright (C) 2022 Bytedance Inc. and/or its affiliates. All rights reserved.
*
* Author:
* 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.
*/

#ifndef VDUSE_BLK_H
#define VDUSE_BLK_H

#include "block/export.h"

extern const BlockExportDriver blk_exp_vduse_blk;

#endif /* VDUSE_BLK_H */

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