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| From: | Coiby Xu |
| Subject: | Re: [PATCH v9 4/5] vhost-user block device backend server |
| Date: | Mon, 17 Aug 2020 20:30:16 +0800 |
On Thu, Jun 18, 2020 at 05:57:40PM +0200, Kevin Wolf wrote:
Am 14.06.2020 um 20:39 hat Coiby Xu geschrieben:By making use of libvhost-user, block device drive can be shared to the connected vhost-user client. Only one client can connect to the server one time. Since vhost-user-server needs a block drive to be created first, delay the creation of this object. Signed-off-by: Coiby Xu <coiby.xu@gmail.com> --- block/Makefile.objs | 1 + block/export/vhost-user-blk-server.c | 669 +++++++++++++++++++++++++++ block/export/vhost-user-blk-server.h | 35 ++ softmmu/vl.c | 4 + 4 files changed, 709 insertions(+) create mode 100644 block/export/vhost-user-blk-server.c create mode 100644 block/export/vhost-user-blk-server.h diff --git a/block/Makefile.objs b/block/Makefile.objs index 3635b6b4c1..0eb7eff470 100644 --- a/block/Makefile.objs +++ b/block/Makefile.objs @@ -24,6 +24,7 @@ block-obj-y += throttle-groups.o block-obj-$(CONFIG_LINUX) += nvme.o block-obj-y += nbd.o +block-obj-$(CONFIG_LINUX) += export/vhost-user-blk-server.o ../contrib/libvhost-user/libvhost-user.o block-obj-$(CONFIG_SHEEPDOG) += sheepdog.o block-obj-$(CONFIG_LIBISCSI) += iscsi.o block-obj-$(if $(CONFIG_LIBISCSI),y,n) += iscsi-opts.o diff --git a/block/export/vhost-user-blk-server.c b/block/export/vhost-user-blk-server.c new file mode 100644 index 0000000000..bbf2ceaa9b --- /dev/null +++ b/block/export/vhost-user-blk-server.c @@ -0,0 +1,669 @@ +/* + * Sharing QEMU block devices via vhost-user protocal + * + * Author: Coiby Xu <coiby.xu@gmail.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 "block/block.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" + +enum { + VHOST_USER_BLK_MAX_QUEUES = 1, +}; +struct virtio_blk_inhdr { + unsigned char status; +}; + + +typedef struct VuBlockReq { + VuVirtqElement *elem; + int64_t sector_num; + size_t size; + struct virtio_blk_inhdr *in; + struct virtio_blk_outhdr out; + VuServer *server; + struct VuVirtq *vq; +} VuBlockReq; + + +static void vu_block_req_complete(VuBlockReq *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); + + if (req->elem) { + free(req->elem); + } + + g_free(req); +} + +static VuBlockDev *get_vu_block_device_by_server(VuServer *server) +{ + return container_of(server, VuBlockDev, vu_server); +} + +static int coroutine_fn +vu_block_discard_write_zeroes(VuBlockReq *req, struct iovec *iov, + uint32_t iovcnt, uint32_t type) +{ + struct virtio_blk_discard_write_zeroes desc; + ssize_t size = iov_to_buf(iov, iovcnt, 0, &desc, sizeof(desc)); + if (unlikely(size != sizeof(desc))) { + error_report("Invalid size %ld, expect %ld", size, sizeof(desc)); + return -EINVAL; + } + + VuBlockDev *vdev_blk = get_vu_block_device_by_server(req->server); + uint64_t range[2] = { le64_to_cpu(desc.sector) << 9, + le32_to_cpu(desc.num_sectors) << 9 }; + if (type == VIRTIO_BLK_T_DISCARD) { + if (blk_co_pdiscard(vdev_blk->backend, range[0], range[1]) == 0) { + return 0; + } + } else if (type == VIRTIO_BLK_T_WRITE_ZEROES) { + if (blk_co_pwrite_zeroes(vdev_blk->backend, + range[0], range[1], 0) == 0) { + return 0; + } + } + + return -EINVAL; +} + + +static void coroutine_fn vu_block_flush(VuBlockReq *req) +{ + VuBlockDev *vdev_blk = get_vu_block_device_by_server(req->server); + BlockBackend *backend = vdev_blk->backend; + blk_co_flush(backend); +} + + +struct req_data { + VuServer *server; + VuVirtq *vq; + VuVirtqElement *elem; +}; + +static void coroutine_fn vu_block_virtio_process_req(void *opaque) +{ + struct req_data *data = opaque; + VuServer *server = data->server; + VuVirtq *vq = data->vq; + VuVirtqElement *elem = data->elem; + uint32_t type; + VuBlockReq *req; + + VuBlockDev *vdev_blk = get_vu_block_device_by_server(server); + BlockBackend *backend = vdev_blk->backend; + + 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"); + free(elem); + return; + } + + req = g_new0(VuBlockReq, 1); + req->server = server; + req->vq = vq; + req->elem = elem; + + 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: { + ssize_t ret = 0; + bool is_write = type & VIRTIO_BLK_T_OUT; + req->sector_num = le64_to_cpu(req->out.sector); + + int64_t offset = req->sector_num * vdev_blk->blk_size; + QEMUIOVector qiov; + if (is_write) { + qemu_iovec_init_external(&qiov, out_iov, out_num); + ret = blk_co_pwritev(backend, offset, qiov.size, + &qiov, 0); + } else { + qemu_iovec_init_external(&qiov, in_iov, in_num); + ret = blk_co_preadv(backend, 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: + vu_block_flush(req); + req->in->status = VIRTIO_BLK_S_OK; + 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_server"); + 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: { + int rc; + rc = vu_block_discard_write_zeroes(req, &elem->out_sg[1], + out_num, type); + if (rc == 0) { + req->in->status = VIRTIO_BLK_S_OK; + } else { + req->in->status = VIRTIO_BLK_S_IOERR; + } + break; + } + default: + req->in->status = VIRTIO_BLK_S_UNSUPP; + break; + } + + vu_block_req_complete(req); + return; + +err: + free(elem); + g_free(req); + return; +} + + + +static void vu_block_process_vq(VuDev *vu_dev, int idx) +{ + VuServer *server; + VuVirtq *vq; + + server = container_of(vu_dev, VuServer, vu_dev); + assert(server); + + vq = vu_get_queue(vu_dev, idx); + assert(vq); + VuVirtqElement *elem; + while (1) { + elem = vu_queue_pop(vu_dev, vq, sizeof(VuVirtqElement) + + sizeof(VuBlockReq)); + if (elem) { + struct req_data req_data = { + .server = server, + .vq = vq, + .elem = elem + };This is on the stack of the function.+ Coroutine *co = qemu_coroutine_create(vu_block_virtio_process_req, + &req_data); + aio_co_enter(server->ioc->ctx, co);Therefore, this code is only correct, if co accesses the data only while the function has not returned yet. This function is called in the context of vu_dispatch(), which in turn is called from vu_client_trip(). So we already run in a coroutine. In this case, aio_co_enter() only schedules co to run after the current coroutine yields or terminates. In other words, this looks wrong to me because req_data will be accessed when it's long out of scope. I think we need to malloc it.
vu_dispatch is only for reading vhost-user message. This function is called by the kick handler which is no longer run as a coroutine since I followed the advice to make better use of contrib/libvhost. Although no error has appeared or been reported by address sanitizer with --enable-sanitizers, using malloc is the correct way. I've fixed it in v10.
+ } else { + break; + } + } +} + +static void vu_block_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_block_process_vq : NULL); +} + +static uint64_t vu_block_get_features(VuDev *dev) +{ + uint64_t features; + VuServer *server = container_of(dev, VuServer, vu_dev); + VuBlockDev *vdev_blk = get_vu_block_device_by_server(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_F_VERSION_1 | + 1ull << VIRTIO_RING_F_INDIRECT_DESC | + 1ull << VIRTIO_RING_F_EVENT_IDX | + 1ull << VHOST_USER_F_PROTOCOL_FEATURES; + + if (!vdev_blk->writable) { + features |= 1ull << VIRTIO_BLK_F_RO; + } + + return features; +} + +static uint64_t vu_block_get_protocol_features(VuDev *dev) +{ + return 1ull << VHOST_USER_PROTOCOL_F_CONFIG | + 1ull << VHOST_USER_PROTOCOL_F_INFLIGHT_SHMFD; +} + +static int +vu_block_get_config(VuDev *vu_dev, uint8_t *config, uint32_t len) +{ + VuServer *server = container_of(vu_dev, VuServer, vu_dev); + VuBlockDev *vdev_blk = get_vu_block_device_by_server(server); + memcpy(config, &vdev_blk->blkcfg, len); + + return 0; +} + +static int +vu_block_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); + VuBlockDev *vdev_blk = get_vu_block_device_by_server(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; + if (wce == vdev_blk->blkcfg.wce) { + /* Do nothing as same with old configuration */ + return 0; + }This check is unnecessary. Nothing bad happens if you set the same value again.
Yes, removing it also simplifies the code.
+ vdev_blk->blkcfg.wce = wce; + blk_set_enable_write_cache(vdev_blk->backend, 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_block_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_block_iface = { + .get_features = vu_block_get_features, + .queue_set_started = vu_block_queue_set_started, + .get_protocol_features = vu_block_get_protocol_features, + .get_config = vu_block_get_config, + .set_config = vu_block_set_config, + .process_msg = vu_block_process_msg, +}; + +static void blk_aio_attached(AioContext *ctx, void *opaque) +{ + VuBlockDev *vub_dev = opaque; + aio_context_acquire(ctx); + vhost_user_server_set_aio_context(ctx, &vub_dev->vu_server); + aio_context_release(ctx); +} + +static void blk_aio_detach(void *opaque) +{ + VuBlockDev *vub_dev = opaque; + AioContext *ctx = vub_dev->vu_server.ctx; + aio_context_acquire(ctx); + vhost_user_server_set_aio_context(NULL, &vub_dev->vu_server); + aio_context_release(ctx); +} + + +static void +vu_block_initialize_config(BlockDriverState *bs, + struct virtio_blk_config *config, uint32_t blk_size) +{ + config->capacity = bdrv_getlength(bs) >> BDRV_SECTOR_BITS; + config->blk_size = blk_size; + config->size_max = 0; + config->seg_max = 128 - 2; + config->min_io_size = 1; + config->opt_io_size = 1; + config->num_queues = VHOST_USER_BLK_MAX_QUEUES; + config->max_discard_sectors = 32768; + config->max_discard_seg = 1; + config->discard_sector_alignment = config->blk_size >> 9; + config->max_write_zeroes_sectors = 32768; + config->max_write_zeroes_seg = 1; +} + + +static VuBlockDev *vu_block_init(VuBlockDev *vu_block_device, Error **errp) +{ + + BlockBackend *blk; + Error *local_error = NULL; + const char *node_name = vu_block_device->node_name; + bool writable = vu_block_device->writable; + /* + * Don't allow resize while the vhost user server is running, + * otherwise we don't care what happens with the node. + */I think this comment belong to the blk_new() below where the shared permissions are specified.
Yes, it makes more sense to put the comment right above blk_new)_.
+ uint64_t perm = BLK_PERM_CONSISTENT_READ; + int ret; + + AioContext *ctx; + + BlockDriverState *bs = bdrv_lookup_bs(node_name, node_name, &local_error); + + if (!bs) { + error_propagate(errp, local_error); + return NULL; + } + + if (bdrv_is_read_only(bs)) { + writable = false; + } + + if (writable) { + perm |= BLK_PERM_WRITE; + } + + ctx = bdrv_get_aio_context(bs); + aio_context_acquire(ctx); + bdrv_invalidate_cache(bs, NULL); + aio_context_release(ctx); + + blk = blk_new(bdrv_get_aio_context(bs), perm, + BLK_PERM_CONSISTENT_READ | BLK_PERM_WRITE_UNCHANGED | + BLK_PERM_WRITE | BLK_PERM_GRAPH_MOD); + ret = blk_insert_bs(blk, bs, errp); + + if (ret < 0) { + goto fail; + } + + blk_set_enable_write_cache(blk, false); + + blk_set_allow_aio_context_change(blk, true); + + vu_block_device->blkcfg.wce = 0; + vu_block_device->backend = blk; + if (!vu_block_device->blk_size) { + vu_block_device->blk_size = BDRV_SECTOR_SIZE; + } + vu_block_device->blkcfg.blk_size = vu_block_device->blk_size; + blk_set_guest_block_size(blk, vu_block_device->blk_size); + vu_block_initialize_config(bs, &vu_block_device->blkcfg, + vu_block_device->blk_size); + return vu_block_device; + +fail: + blk_unref(blk); + return NULL; +} + +static void vhost_user_blk_server_stop(VuBlockDev *vu_block_device) +{ + if (!vu_block_device) { + return; + } + + vhost_user_server_stop(&vu_block_device->vu_server); + + if (vu_block_device->backend) { + blk_remove_aio_context_notifier(vu_block_device->backend, blk_aio_attached, + blk_aio_detach, vu_block_device); + } + + blk_unref(vu_block_device->backend); + +} + + +static void vhost_user_blk_server_start(VuBlockDev *vu_block_device, + Error **errp) +{ + SocketAddress *addr = vu_block_device->addr; + + if (!vu_block_init(vu_block_device, errp)) { + return; + } + + AioContext *ctx = bdrv_get_aio_context(blk_bs(vu_block_device->backend));Please move declarations to the top of the function.
Been fixed in v10.
+ if (!vhost_user_server_start(&vu_block_device->vu_server, addr, ctx, + VHOST_USER_BLK_MAX_QUEUES, + NULL, &vu_block_iface, + errp)) { + goto error; + } + + blk_add_aio_context_notifier(vu_block_device->backend, blk_aio_attached, + blk_aio_detach, vu_block_device); + vu_block_device->running = true; + return; + + error: + vhost_user_blk_server_stop(vu_block_device);vu_block_device hasn't been fully set up. You need to undo only vu_block_init(). You must not call vhost_user_server_stop().+} + +static bool vu_prop_modificable(VuBlockDev *vus, Error **errp)The word is "modifiable".
Thank you for correcting my spelling!
+{ + if (vus->running) { + error_setg(errp, "The property can't be modified " + "while the server is running"); + return false;The indentation is off here.+ } + return true; +} +static void vu_set_node_name(Object *obj, const char *value, Error **errp) +{ + VuBlockDev *vus = VHOST_USER_BLK_SERVER(obj); + + if (vus->node_name) { + if (!vu_prop_modificable(vus, errp)) { + return; + }Why don't we need to check vu_prop_modificable() when the property isn't set yet? I assume it's because the server can't even be started without a node name, but it would be more obviously correct if the check were done unconditionally.+ g_free(vus->node_name); + } + + vus->node_name = g_strdup(value); +} + +static char *vu_get_node_name(Object *obj, Error **errp) +{ + VuBlockDev *vus = VHOST_USER_BLK_SERVER(obj); + return g_strdup(vus->node_name); +} + + +static void vu_set_unix_socket(Object *obj, const char *value, + Error **errp) +{ + VuBlockDev *vus = VHOST_USER_BLK_SERVER(obj); + + if (vus->addr) { + if (!vu_prop_modificable(vus, errp)) { + return; + }Same here.
It makes the code more readable. Thank you!
+ g_free(vus->addr->u.q_unix.path); + g_free(vus->addr); + } + + SocketAddress *addr = g_new0(SocketAddress, 1); + addr->type = SOCKET_ADDRESS_TYPE_UNIX; + addr->u.q_unix.path = g_strdup(value); + vus->addr = addr; +} + +static char *vu_get_unix_socket(Object *obj, Error **errp) +{ + VuBlockDev *vus = VHOST_USER_BLK_SERVER(obj); + return g_strdup(vus->addr->u.q_unix.path); +} + +static bool vu_get_block_writable(Object *obj, Error **errp) +{ + VuBlockDev *vus = VHOST_USER_BLK_SERVER(obj); + return vus->writable; +} + +static void vu_set_block_writable(Object *obj, bool value, Error **errp) +{ + VuBlockDev *vus = VHOST_USER_BLK_SERVER(obj); + + if (!vu_prop_modificable(vus, errp)) { + return; + } + + vus->writable = value; +} + +static void vu_get_blk_size(Object *obj, Visitor *v, const char *name, + void *opaque, Error **errp) +{ + VuBlockDev *vus = VHOST_USER_BLK_SERVER(obj); + uint32_t value = vus->blk_size; + + visit_type_uint32(v, name, &value, errp); +} + +static void vu_set_blk_size(Object *obj, Visitor *v, const char *name, + void *opaque, Error **errp) +{ + VuBlockDev *vus = VHOST_USER_BLK_SERVER(obj); + + Error *local_err = NULL; + uint32_t value; + + if (!vu_prop_modificable(vus, errp)) { + return; + } + + visit_type_uint32(v, name, &value, &local_err); + if (local_err) { + goto out; + } + + check_logical_block_size(object_get_typename(obj), name, value, &local_err); + if (local_err) { + goto out; + } + + vus->blk_size = value; + +out: + error_propagate(errp, local_err); + vus->blk_size = value;Surely you don't want to set the value here, when some check failed?
Yes, I must have left this line of code here by mistake.
+} + + +static void vhost_user_blk_server_instance_finalize(Object *obj) +{ + VuBlockDev *vub = VHOST_USER_BLK_SERVER(obj); + + vhost_user_blk_server_stop(vub); +} + +static void vhost_user_blk_server_complete(UserCreatable *obj, Error **errp) +{ + Error *local_error = NULL; + VuBlockDev *vub = VHOST_USER_BLK_SERVER(obj); + + vhost_user_blk_server_start(vub, &local_error); + + if (local_error) { + error_propagate(errp, local_error); + return; + }If you don't do anything with local_error (which is named inconsistently with local_err used above), you can just directly pass errp to vhost_user_blk_server_start().+} + +static void vhost_user_blk_server_class_init(ObjectClass *klass, + void *class_data) +{ + UserCreatableClass *ucc = USER_CREATABLE_CLASS(klass); + ucc->complete = vhost_user_blk_server_complete; + + object_class_property_add_bool(klass, "writable", + vu_get_block_writable, + vu_set_block_writable); + + object_class_property_add_str(klass, "node-name", + vu_get_node_name, + vu_set_node_name); + + object_class_property_add_str(klass, "unix-socket", + vu_get_unix_socket, + vu_set_unix_socket); + + object_class_property_add(klass, "logical-block-size", "uint32", + vu_get_blk_size, vu_set_blk_size, + NULL, NULL); +} + +static const TypeInfo vhost_user_blk_server_info = { + .name = TYPE_VHOST_USER_BLK_SERVER, + .parent = TYPE_OBJECT, + .instance_size = sizeof(VuBlockDev), + .instance_finalize = vhost_user_blk_server_instance_finalize, + .class_init = vhost_user_blk_server_class_init, + .interfaces = (InterfaceInfo[]) { + {TYPE_USER_CREATABLE}, + {} + }, +}; + +static void vhost_user_blk_server_register_types(void) +{ + type_register_static(&vhost_user_blk_server_info); +} +Please remove the trailing empty line. Compared to the last version that I reviewed, this seems to get the architecture for concurrent requests right, which is an important improvement. I feel we're getting quite close to mergable now. Kevin
Thank you for the guidance and helpful feedbacks along the way:) -- Best regards, Coiby
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