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qemu/block/export/vhost-user-blk-server.c
Stefan Hajnoczi 1b0b2e6d06 block/export: improve vu_blk_sect_range_ok() 
The checks in vu_blk_sect_range_ok() assume VIRTIO_BLK_SECTOR_SIZE is
equal to BDRV_SECTOR_SIZE. This is true, but let's add a
QEMU_BUILD_BUG_ON() to make it explicit.

We might as well check that the request buffer size is a multiple of
VIRTIO_BLK_SECTOR_SIZE while we're at it.

Suggested-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-Id: <20210331142727.391465-1-stefanha@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2021-05-18 11:08:13 +02:00

534 lines
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/*
* Sharing QEMU block devices via vhost-user protocal
*
* Parts of the code based on nbd/server.c.
*
* Copyright (c) Coiby Xu <coiby.xu@gmail.com>.
* Copyright (c) 2020 Red Hat, Inc.
*
* 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 "block/block.h"
#include "subprojects/libvhost-user/libvhost-user.h" /* only for the type definitions */
#include "standard-headers/linux/virtio_blk.h"
#include "qemu/vhost-user-server.h"
#include "vhost-user-blk-server.h"
#include "qapi/error.h"
#include "qom/object_interfaces.h"
#include "sysemu/block-backend.h"
#include "util/block-helpers.h"
/*
* Sector units are 512 bytes regardless of the
* virtio_blk_config->blk_size value.
*/
#define VIRTIO_BLK_SECTOR_BITS 9
#define VIRTIO_BLK_SECTOR_SIZE (1ull << VIRTIO_BLK_SECTOR_BITS)
enum {
VHOST_USER_BLK_NUM_QUEUES_DEFAULT = 1,
VHOST_USER_BLK_MAX_DISCARD_SECTORS = 32768,
VHOST_USER_BLK_MAX_WRITE_ZEROES_SECTORS = 32768,
};
struct virtio_blk_inhdr {
unsigned char status;
};
typedef struct VuBlkReq {
VuVirtqElement elem;
int64_t sector_num;
size_t size;
struct virtio_blk_inhdr *in;
struct virtio_blk_outhdr out;
VuServer *server;
struct VuVirtq *vq;
} VuBlkReq;
/* vhost user block device */
typedef struct {
BlockExport export;
VuServer vu_server;
uint32_t blk_size;
QIOChannelSocket *sioc;
struct virtio_blk_config blkcfg;
bool writable;
} VuBlkExport;
static void vu_blk_req_complete(VuBlkReq *req)
{
VuDev *vu_dev = &req->server->vu_dev;
/* IO size with 1 extra status byte */
vu_queue_push(vu_dev, req->vq, &req->elem, req->size + 1);
vu_queue_notify(vu_dev, req->vq);
free(req);
}
static bool vu_blk_sect_range_ok(VuBlkExport *vexp, 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) % vexp->blk_size) {
return false;
}
blk_get_geometry(vexp->export.blk, &total_sectors);
if (sector > total_sectors || nb_sectors > total_sectors - sector) {
return false;
}
return true;
}
static int coroutine_fn
vu_blk_discard_write_zeroes(VuBlkExport *vexp, struct iovec *iov,
uint32_t iovcnt, uint32_t type)
{
BlockBackend *blk = vexp->export.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) ?
VHOST_USER_BLK_MAX_WRITE_ZEROES_SECTORS :
VHOST_USER_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(!vu_blk_sect_range_ok(vexp, 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;
}
static void coroutine_fn vu_blk_virtio_process_req(void *opaque)
{
VuBlkReq *req = opaque;
VuServer *server = req->server;
VuVirtqElement *elem = &req->elem;
uint32_t type;
VuBlkExport *vexp = container_of(server, VuBlkExport, vu_server);
BlockBackend *blk = vexp->export.blk;
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;
/* refer to hw/block/virtio_blk.c */
if (elem->out_num < 1 || elem->in_num < 1) {
error_report("virtio-blk request missing headers");
goto err;
}
if (unlikely(iov_to_buf(out_iov, out_num, 0, &req->out,
sizeof(req->out)) != sizeof(req->out))) {
error_report("virtio-blk request outhdr too short");
goto err;
}
iov_discard_front(&out_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");
goto err;
}
/* We always touch the last byte, so just see how big in_iov is. */
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 = le32_to_cpu(req->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;
req->sector_num = le64_to_cpu(req->out.sector);
if (is_write && !vexp->writable) {
req->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(!vu_blk_sect_range_ok(vexp,
req->sector_num,
qiov.size))) {
req->in->status = VIRTIO_BLK_S_IOERR;
break;
}
offset = req->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) {
req->in->status = VIRTIO_BLK_S_OK;
} else {
req->in->status = VIRTIO_BLK_S_IOERR;
}
break;
}
case VIRTIO_BLK_T_FLUSH:
if (blk_co_flush(blk) == 0) {
req->in->status = VIRTIO_BLK_S_OK;
} else {
req->in->status = VIRTIO_BLK_S_IOERR;
}
break;
case VIRTIO_BLK_T_GET_ID: {
size_t size = MIN(iov_size(&elem->in_sg[0], in_num),
VIRTIO_BLK_ID_BYTES);
snprintf(elem->in_sg[0].iov_base, size, "%s", "vhost_user_blk");
req->in->status = VIRTIO_BLK_S_OK;
req->size = elem->in_sg[0].iov_len;
break;
}
case VIRTIO_BLK_T_DISCARD:
case VIRTIO_BLK_T_WRITE_ZEROES: {
if (!vexp->writable) {
req->in->status = VIRTIO_BLK_S_IOERR;
break;
}
req->in->status = vu_blk_discard_write_zeroes(vexp, out_iov, out_num,
type);
break;
}
default:
req->in->status = VIRTIO_BLK_S_UNSUPP;
break;
}
vu_blk_req_complete(req);
return;
err:
free(req);
}
static void vu_blk_process_vq(VuDev *vu_dev, int idx)
{
VuServer *server = container_of(vu_dev, VuServer, vu_dev);
VuVirtq *vq = vu_get_queue(vu_dev, idx);
while (1) {
VuBlkReq *req;
req = vu_queue_pop(vu_dev, vq, sizeof(VuBlkReq));
if (!req) {
break;
}
req->server = server;
req->vq = vq;
Coroutine *co =
qemu_coroutine_create(vu_blk_virtio_process_req, req);
qemu_coroutine_enter(co);
}
}
static void vu_blk_queue_set_started(VuDev *vu_dev, int idx, bool started)
{
VuVirtq *vq;
assert(vu_dev);
vq = vu_get_queue(vu_dev, idx);
vu_set_queue_handler(vu_dev, vq, started ? vu_blk_process_vq : NULL);
}
static uint64_t vu_blk_get_features(VuDev *dev)
{
uint64_t features;
VuServer *server = container_of(dev, VuServer, vu_dev);
VuBlkExport *vexp = container_of(server, VuBlkExport, vu_server);
features = 1ull << VIRTIO_BLK_F_SIZE_MAX |
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 |
1ull << VIRTIO_BLK_F_CONFIG_WCE |
1ull << VIRTIO_BLK_F_MQ |
1ull << VIRTIO_F_VERSION_1 |
1ull << VIRTIO_RING_F_INDIRECT_DESC |
1ull << VIRTIO_RING_F_EVENT_IDX |
1ull << VHOST_USER_F_PROTOCOL_FEATURES;
if (!vexp->writable) {
features |= 1ull << VIRTIO_BLK_F_RO;
}
return features;
}
static uint64_t vu_blk_get_protocol_features(VuDev *dev)
{
return 1ull << VHOST_USER_PROTOCOL_F_CONFIG;
}
static int
vu_blk_get_config(VuDev *vu_dev, uint8_t *config, uint32_t len)
{
VuServer *server = container_of(vu_dev, VuServer, vu_dev);
VuBlkExport *vexp = container_of(server, VuBlkExport, vu_server);
if (len > sizeof(struct virtio_blk_config)) {
return -1;
}
memcpy(config, &vexp->blkcfg, len);
return 0;
}
static int
vu_blk_set_config(VuDev *vu_dev, const uint8_t *data,
uint32_t offset, uint32_t size, uint32_t flags)
{
VuServer *server = container_of(vu_dev, VuServer, vu_dev);
VuBlkExport *vexp = container_of(server, VuBlkExport, vu_server);
uint8_t wce;
/* don't support live migration */
if (flags != VHOST_SET_CONFIG_TYPE_MASTER) {
return -EINVAL;
}
if (offset != offsetof(struct virtio_blk_config, wce) ||
size != 1) {
return -EINVAL;
}
wce = *data;
vexp->blkcfg.wce = wce;
blk_set_enable_write_cache(vexp->export.blk, wce);
return 0;
}
/*
* When the client disconnects, it sends a VHOST_USER_NONE request
* and vu_process_message will simple call exit which cause the VM
* to exit abruptly.
* To avoid this issue, process VHOST_USER_NONE request ahead
* of vu_process_message.
*
*/
static int vu_blk_process_msg(VuDev *dev, VhostUserMsg *vmsg, int *do_reply)
{
if (vmsg->request == VHOST_USER_NONE) {
dev->panic(dev, "disconnect");
return true;
}
return false;
}
static const VuDevIface vu_blk_iface = {
.get_features = vu_blk_get_features,
.queue_set_started = vu_blk_queue_set_started,
.get_protocol_features = vu_blk_get_protocol_features,
.get_config = vu_blk_get_config,
.set_config = vu_blk_set_config,
.process_msg = vu_blk_process_msg,
};
static void blk_aio_attached(AioContext *ctx, void *opaque)
{
VuBlkExport *vexp = opaque;
vexp->export.ctx = ctx;
vhost_user_server_attach_aio_context(&vexp->vu_server, ctx);
}
static void blk_aio_detach(void *opaque)
{
VuBlkExport *vexp = opaque;
vhost_user_server_detach_aio_context(&vexp->vu_server);
vexp->export.ctx = NULL;
}
static void
vu_blk_initialize_config(BlockDriverState *bs,
struct virtio_blk_config *config,
uint32_t blk_size,
uint16_t num_queues)
{
config->capacity =
cpu_to_le64(bdrv_getlength(bs) >> VIRTIO_BLK_SECTOR_BITS);
config->blk_size = cpu_to_le32(blk_size);
config->size_max = cpu_to_le32(0);
config->seg_max = cpu_to_le32(128 - 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->max_discard_sectors =
cpu_to_le32(VHOST_USER_BLK_MAX_DISCARD_SECTORS);
config->max_discard_seg = cpu_to_le32(1);
config->discard_sector_alignment =
cpu_to_le32(blk_size >> VIRTIO_BLK_SECTOR_BITS);
config->max_write_zeroes_sectors
= cpu_to_le32(VHOST_USER_BLK_MAX_WRITE_ZEROES_SECTORS);
config->max_write_zeroes_seg = cpu_to_le32(1);
}
static void vu_blk_exp_request_shutdown(BlockExport *exp)
{
VuBlkExport *vexp = container_of(exp, VuBlkExport, export);
vhost_user_server_stop(&vexp->vu_server);
}
static int vu_blk_exp_create(BlockExport *exp, BlockExportOptions *opts,
Error **errp)
{
VuBlkExport *vexp = container_of(exp, VuBlkExport, export);
BlockExportOptionsVhostUserBlk *vu_opts = &opts->u.vhost_user_blk;
Error *local_err = NULL;
uint64_t logical_block_size;
uint16_t num_queues = VHOST_USER_BLK_NUM_QUEUES_DEFAULT;
vexp->writable = opts->writable;
vexp->blkcfg.wce = 0;
if (vu_opts->has_logical_block_size) {
logical_block_size = vu_opts->logical_block_size;
} else {
logical_block_size = VIRTIO_BLK_SECTOR_SIZE;
}
check_block_size(exp->id, "logical-block-size", logical_block_size,
&local_err);
if (local_err) {
error_propagate(errp, local_err);
return -EINVAL;
}
vexp->blk_size = logical_block_size;
blk_set_guest_block_size(exp->blk, logical_block_size);
if (vu_opts->has_num_queues) {
num_queues = vu_opts->num_queues;
}
if (num_queues == 0) {
error_setg(errp, "num-queues must be greater than 0");
return -EINVAL;
}
vu_blk_initialize_config(blk_bs(exp->blk), &vexp->blkcfg,
logical_block_size, num_queues);
blk_add_aio_context_notifier(exp->blk, blk_aio_attached, blk_aio_detach,
vexp);
if (!vhost_user_server_start(&vexp->vu_server, vu_opts->addr, exp->ctx,
num_queues, &vu_blk_iface, errp)) {
blk_remove_aio_context_notifier(exp->blk, blk_aio_attached,
blk_aio_detach, vexp);
return -EADDRNOTAVAIL;
}
return 0;
}
static void vu_blk_exp_delete(BlockExport *exp)
{
VuBlkExport *vexp = container_of(exp, VuBlkExport, export);
blk_remove_aio_context_notifier(exp->blk, blk_aio_attached, blk_aio_detach,
vexp);
}
const BlockExportDriver blk_exp_vhost_user_blk = {
.type = BLOCK_EXPORT_TYPE_VHOST_USER_BLK,
.instance_size = sizeof(VuBlkExport),
.create = vu_blk_exp_create,
.delete = vu_blk_exp_delete,
.request_shutdown = vu_blk_exp_request_shutdown,
};
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