qemu/block/export/vhost-user-blk-server.c
Stefan Hajnoczi e1054cd4aa block/export: stop using is_external in vhost-user-blk server
vhost-user activity must be suspended during bdrv_drained_begin/end().
This prevents new requests from interfering with whatever is happening
in the drained section.

Previously this was done using aio_set_fd_handler()'s is_external
argument. In a multi-queue block layer world the aio_disable_external()
API cannot be used since multiple AioContext may be processing I/O, not
just one.

Switch to BlockDevOps->drained_begin/end() callbacks.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Message-Id: <20230516190238.8401-8-stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2023-05-30 17:32:02 +02:00

386 lines
11 KiB
C

/*
* 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 "qemu/error-report.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 "util/block-helpers.h"
#include "virtio-blk-handler.h"
enum {
VHOST_USER_BLK_NUM_QUEUES_DEFAULT = 1,
};
typedef struct VuBlkReq {
VuVirtqElement elem;
VuServer *server;
struct VuVirtq *vq;
} VuBlkReq;
/* vhost user block device */
typedef struct {
BlockExport export;
VuServer vu_server;
VirtioBlkHandler handler;
QIOChannelSocket *sioc;
struct virtio_blk_config blkcfg;
} VuBlkExport;
static void vu_blk_req_complete(VuBlkReq *req, size_t in_len)
{
VuDev *vu_dev = &req->server->vu_dev;
vu_queue_push(vu_dev, req->vq, &req->elem, in_len);
vu_queue_notify(vu_dev, req->vq);
free(req);
}
/*
* Called with server in_flight counter increased, must decrease before
* returning.
*/
static void coroutine_fn vu_blk_virtio_process_req(void *opaque)
{
VuBlkReq *req = opaque;
VuServer *server = req->server;
VuVirtqElement *elem = &req->elem;
VuBlkExport *vexp = container_of(server, VuBlkExport, vu_server);
VirtioBlkHandler *handler = &vexp->handler;
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);
vhost_user_server_dec_in_flight(server);
return;
}
vu_blk_req_complete(req, in_len);
vhost_user_server_dec_in_flight(server);
}
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);
vhost_user_server_inc_in_flight(server);
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->handler.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;
/*
* The actual attach will happen in vu_blk_drained_end() and we just
* restore ctx here.
*/
vexp->export.ctx = ctx;
}
static void blk_aio_detach(void *opaque)
{
VuBlkExport *vexp = opaque;
/*
* The actual detach already happened in vu_blk_drained_begin() but from
* this point on we must not access ctx anymore.
*/
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(VIRTIO_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(VIRTIO_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 void vu_blk_exp_resize(void *opaque)
{
VuBlkExport *vexp = opaque;
BlockDriverState *bs = blk_bs(vexp->handler.blk);
int64_t new_size = bdrv_getlength(bs);
if (new_size < 0) {
error_printf("Failed to get length of block node '%s'",
bdrv_get_node_name(bs));
return;
}
vexp->blkcfg.capacity = cpu_to_le64(new_size >> VIRTIO_BLK_SECTOR_BITS);
vu_config_change_msg(&vexp->vu_server.vu_dev);
}
/* Called with vexp->export.ctx acquired */
static void vu_blk_drained_begin(void *opaque)
{
VuBlkExport *vexp = opaque;
vhost_user_server_detach_aio_context(&vexp->vu_server);
}
/* Called with vexp->export.blk AioContext acquired */
static void vu_blk_drained_end(void *opaque)
{
VuBlkExport *vexp = opaque;
vhost_user_server_attach_aio_context(&vexp->vu_server, vexp->export.ctx);
}
/*
* Ensures that bdrv_drained_begin() waits until in-flight requests complete.
*
* Called with vexp->export.ctx acquired.
*/
static bool vu_blk_drained_poll(void *opaque)
{
VuBlkExport *vexp = opaque;
return vhost_user_server_has_in_flight(&vexp->vu_server);
}
static const BlockDevOps vu_blk_dev_ops = {
.drained_begin = vu_blk_drained_begin,
.drained_end = vu_blk_drained_end,
.drained_poll = vu_blk_drained_poll,
.resize_cb = vu_blk_exp_resize,
};
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->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;
}
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;
}
vexp->handler.blk = exp->blk;
vexp->handler.serial = g_strdup("vhost_user_blk");
vexp->handler.logical_block_size = logical_block_size;
vexp->handler.writable = opts->writable;
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);
blk_set_dev_ops(exp->blk, &vu_blk_dev_ops, 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);
g_free(vexp->handler.serial);
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);
g_free(vexp->handler.serial);
}
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,
};