diff options
Diffstat (limited to '')
| -rw-r--r-- | drivers/xen/pvcalls-back.c | 1242 |
1 files changed, 1242 insertions, 0 deletions
diff --git a/drivers/xen/pvcalls-back.c b/drivers/xen/pvcalls-back.c new file mode 100644 index 000000000..0bff02ac0 --- /dev/null +++ b/drivers/xen/pvcalls-back.c @@ -0,0 +1,1242 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * (c) 2017 Stefano Stabellini <stefano@aporeto.com> + */ + +#include <linux/inet.h> +#include <linux/kthread.h> +#include <linux/list.h> +#include <linux/radix-tree.h> +#include <linux/module.h> +#include <linux/semaphore.h> +#include <linux/wait.h> +#include <net/sock.h> +#include <net/inet_common.h> +#include <net/inet_connection_sock.h> +#include <net/request_sock.h> + +#include <xen/events.h> +#include <xen/grant_table.h> +#include <xen/xen.h> +#include <xen/xenbus.h> +#include <xen/interface/io/pvcalls.h> + +#define PVCALLS_VERSIONS "1" +#define MAX_RING_ORDER XENBUS_MAX_RING_GRANT_ORDER + +static struct pvcalls_back_global { + struct list_head frontends; + struct semaphore frontends_lock; +} pvcalls_back_global; + +/* + * Per-frontend data structure. It contains pointers to the command + * ring, its event channel, a list of active sockets and a tree of + * passive sockets. + */ +struct pvcalls_fedata { + struct list_head list; + struct xenbus_device *dev; + struct xen_pvcalls_sring *sring; + struct xen_pvcalls_back_ring ring; + int irq; + struct list_head socket_mappings; + struct radix_tree_root socketpass_mappings; + struct semaphore socket_lock; +}; + +struct pvcalls_ioworker { + struct work_struct register_work; + struct workqueue_struct *wq; +}; + +struct sock_mapping { + struct list_head list; + struct pvcalls_fedata *fedata; + struct sockpass_mapping *sockpass; + struct socket *sock; + uint64_t id; + grant_ref_t ref; + struct pvcalls_data_intf *ring; + void *bytes; + struct pvcalls_data data; + uint32_t ring_order; + int irq; + atomic_t read; + atomic_t write; + atomic_t io; + atomic_t release; + atomic_t eoi; + void (*saved_data_ready)(struct sock *sk); + struct pvcalls_ioworker ioworker; +}; + +struct sockpass_mapping { + struct list_head list; + struct pvcalls_fedata *fedata; + struct socket *sock; + uint64_t id; + struct xen_pvcalls_request reqcopy; + spinlock_t copy_lock; + struct workqueue_struct *wq; + struct work_struct register_work; + void (*saved_data_ready)(struct sock *sk); +}; + +static irqreturn_t pvcalls_back_conn_event(int irq, void *sock_map); +static int pvcalls_back_release_active(struct xenbus_device *dev, + struct pvcalls_fedata *fedata, + struct sock_mapping *map); + +static bool pvcalls_conn_back_read(void *opaque) +{ + struct sock_mapping *map = (struct sock_mapping *)opaque; + struct msghdr msg; + struct kvec vec[2]; + RING_IDX cons, prod, size, wanted, array_size, masked_prod, masked_cons; + int32_t error; + struct pvcalls_data_intf *intf = map->ring; + struct pvcalls_data *data = &map->data; + unsigned long flags; + int ret; + + array_size = XEN_FLEX_RING_SIZE(map->ring_order); + cons = intf->in_cons; + prod = intf->in_prod; + error = intf->in_error; + /* read the indexes first, then deal with the data */ + virt_mb(); + + if (error) + return false; + + size = pvcalls_queued(prod, cons, array_size); + if (size >= array_size) + return false; + spin_lock_irqsave(&map->sock->sk->sk_receive_queue.lock, flags); + if (skb_queue_empty(&map->sock->sk->sk_receive_queue)) { + atomic_set(&map->read, 0); + spin_unlock_irqrestore(&map->sock->sk->sk_receive_queue.lock, + flags); + return true; + } + spin_unlock_irqrestore(&map->sock->sk->sk_receive_queue.lock, flags); + wanted = array_size - size; + masked_prod = pvcalls_mask(prod, array_size); + masked_cons = pvcalls_mask(cons, array_size); + + memset(&msg, 0, sizeof(msg)); + if (masked_prod < masked_cons) { + vec[0].iov_base = data->in + masked_prod; + vec[0].iov_len = wanted; + iov_iter_kvec(&msg.msg_iter, ITER_DEST, vec, 1, wanted); + } else { + vec[0].iov_base = data->in + masked_prod; + vec[0].iov_len = array_size - masked_prod; + vec[1].iov_base = data->in; + vec[1].iov_len = wanted - vec[0].iov_len; + iov_iter_kvec(&msg.msg_iter, ITER_DEST, vec, 2, wanted); + } + + atomic_set(&map->read, 0); + ret = inet_recvmsg(map->sock, &msg, wanted, MSG_DONTWAIT); + WARN_ON(ret > wanted); + if (ret == -EAGAIN) /* shouldn't happen */ + return true; + if (!ret) + ret = -ENOTCONN; + spin_lock_irqsave(&map->sock->sk->sk_receive_queue.lock, flags); + if (ret > 0 && !skb_queue_empty(&map->sock->sk->sk_receive_queue)) + atomic_inc(&map->read); + spin_unlock_irqrestore(&map->sock->sk->sk_receive_queue.lock, flags); + + /* write the data, then modify the indexes */ + virt_wmb(); + if (ret < 0) { + atomic_set(&map->read, 0); + intf->in_error = ret; + } else + intf->in_prod = prod + ret; + /* update the indexes, then notify the other end */ + virt_wmb(); + notify_remote_via_irq(map->irq); + + return true; +} + +static bool pvcalls_conn_back_write(struct sock_mapping *map) +{ + struct pvcalls_data_intf *intf = map->ring; + struct pvcalls_data *data = &map->data; + struct msghdr msg; + struct kvec vec[2]; + RING_IDX cons, prod, size, array_size; + int ret; + + cons = intf->out_cons; + prod = intf->out_prod; + /* read the indexes before dealing with the data */ + virt_mb(); + + array_size = XEN_FLEX_RING_SIZE(map->ring_order); + size = pvcalls_queued(prod, cons, array_size); + if (size == 0) + return false; + + memset(&msg, 0, sizeof(msg)); + msg.msg_flags |= MSG_DONTWAIT; + if (pvcalls_mask(prod, array_size) > pvcalls_mask(cons, array_size)) { + vec[0].iov_base = data->out + pvcalls_mask(cons, array_size); + vec[0].iov_len = size; + iov_iter_kvec(&msg.msg_iter, ITER_SOURCE, vec, 1, size); + } else { + vec[0].iov_base = data->out + pvcalls_mask(cons, array_size); + vec[0].iov_len = array_size - pvcalls_mask(cons, array_size); + vec[1].iov_base = data->out; + vec[1].iov_len = size - vec[0].iov_len; + iov_iter_kvec(&msg.msg_iter, ITER_SOURCE, vec, 2, size); + } + + atomic_set(&map->write, 0); + ret = inet_sendmsg(map->sock, &msg, size); + if (ret == -EAGAIN) { + atomic_inc(&map->write); + atomic_inc(&map->io); + return true; + } + + /* write the data, then update the indexes */ + virt_wmb(); + if (ret < 0) { + intf->out_error = ret; + } else { + intf->out_error = 0; + intf->out_cons = cons + ret; + prod = intf->out_prod; + } + /* update the indexes, then notify the other end */ + virt_wmb(); + if (prod != cons + ret) { + atomic_inc(&map->write); + atomic_inc(&map->io); + } + notify_remote_via_irq(map->irq); + + return true; +} + +static void pvcalls_back_ioworker(struct work_struct *work) +{ + struct pvcalls_ioworker *ioworker = container_of(work, + struct pvcalls_ioworker, register_work); + struct sock_mapping *map = container_of(ioworker, struct sock_mapping, + ioworker); + unsigned int eoi_flags = XEN_EOI_FLAG_SPURIOUS; + + while (atomic_read(&map->io) > 0) { + if (atomic_read(&map->release) > 0) { + atomic_set(&map->release, 0); + return; + } + + if (atomic_read(&map->read) > 0 && + pvcalls_conn_back_read(map)) + eoi_flags = 0; + if (atomic_read(&map->write) > 0 && + pvcalls_conn_back_write(map)) + eoi_flags = 0; + + if (atomic_read(&map->eoi) > 0 && !atomic_read(&map->write)) { + atomic_set(&map->eoi, 0); + xen_irq_lateeoi(map->irq, eoi_flags); + eoi_flags = XEN_EOI_FLAG_SPURIOUS; + } + + atomic_dec(&map->io); + } +} + +static int pvcalls_back_socket(struct xenbus_device *dev, + struct xen_pvcalls_request *req) +{ + struct pvcalls_fedata *fedata; + int ret; + struct xen_pvcalls_response *rsp; + + fedata = dev_get_drvdata(&dev->dev); + + if (req->u.socket.domain != AF_INET || + req->u.socket.type != SOCK_STREAM || + (req->u.socket.protocol != IPPROTO_IP && + req->u.socket.protocol != AF_INET)) + ret = -EAFNOSUPPORT; + else + ret = 0; + + /* leave the actual socket allocation for later */ + + rsp = RING_GET_RESPONSE(&fedata->ring, fedata->ring.rsp_prod_pvt++); + rsp->req_id = req->req_id; + rsp->cmd = req->cmd; + rsp->u.socket.id = req->u.socket.id; + rsp->ret = ret; + + return 0; +} + +static void pvcalls_sk_state_change(struct sock *sock) +{ + struct sock_mapping *map = sock->sk_user_data; + + if (map == NULL) + return; + + atomic_inc(&map->read); + notify_remote_via_irq(map->irq); +} + +static void pvcalls_sk_data_ready(struct sock *sock) +{ + struct sock_mapping *map = sock->sk_user_data; + struct pvcalls_ioworker *iow; + + if (map == NULL) + return; + + iow = &map->ioworker; + atomic_inc(&map->read); + atomic_inc(&map->io); + queue_work(iow->wq, &iow->register_work); +} + +static struct sock_mapping *pvcalls_new_active_socket( + struct pvcalls_fedata *fedata, + uint64_t id, + grant_ref_t ref, + evtchn_port_t evtchn, + struct socket *sock) +{ + int ret; + struct sock_mapping *map; + void *page; + + map = kzalloc(sizeof(*map), GFP_KERNEL); + if (map == NULL) { + sock_release(sock); + return NULL; + } + + map->fedata = fedata; + map->sock = sock; + map->id = id; + map->ref = ref; + + ret = xenbus_map_ring_valloc(fedata->dev, &ref, 1, &page); + if (ret < 0) + goto out; + map->ring = page; + map->ring_order = map->ring->ring_order; + /* first read the order, then map the data ring */ + virt_rmb(); + if (map->ring_order > MAX_RING_ORDER) { + pr_warn("%s frontend requested ring_order %u, which is > MAX (%u)\n", + __func__, map->ring_order, MAX_RING_ORDER); + goto out; + } + ret = xenbus_map_ring_valloc(fedata->dev, map->ring->ref, + (1 << map->ring_order), &page); + if (ret < 0) + goto out; + map->bytes = page; + + ret = bind_interdomain_evtchn_to_irqhandler_lateeoi( + fedata->dev, evtchn, + pvcalls_back_conn_event, 0, "pvcalls-backend", map); + if (ret < 0) + goto out; + map->irq = ret; + + map->data.in = map->bytes; + map->data.out = map->bytes + XEN_FLEX_RING_SIZE(map->ring_order); + + map->ioworker.wq = alloc_workqueue("pvcalls_io", WQ_UNBOUND, 1); + if (!map->ioworker.wq) + goto out; + atomic_set(&map->io, 1); + INIT_WORK(&map->ioworker.register_work, pvcalls_back_ioworker); + + down(&fedata->socket_lock); + list_add_tail(&map->list, &fedata->socket_mappings); + up(&fedata->socket_lock); + + write_lock_bh(&map->sock->sk->sk_callback_lock); + map->saved_data_ready = map->sock->sk->sk_data_ready; + map->sock->sk->sk_user_data = map; + map->sock->sk->sk_data_ready = pvcalls_sk_data_ready; + map->sock->sk->sk_state_change = pvcalls_sk_state_change; + write_unlock_bh(&map->sock->sk->sk_callback_lock); + + return map; +out: + down(&fedata->socket_lock); + list_del(&map->list); + pvcalls_back_release_active(fedata->dev, fedata, map); + up(&fedata->socket_lock); + return NULL; +} + +static int pvcalls_back_connect(struct xenbus_device *dev, + struct xen_pvcalls_request *req) +{ + struct pvcalls_fedata *fedata; + int ret = -EINVAL; + struct socket *sock; + struct sock_mapping *map; + struct xen_pvcalls_response *rsp; + struct sockaddr *sa = (struct sockaddr *)&req->u.connect.addr; + + fedata = dev_get_drvdata(&dev->dev); + + if (req->u.connect.len < sizeof(sa->sa_family) || + req->u.connect.len > sizeof(req->u.connect.addr) || + sa->sa_family != AF_INET) + goto out; + + ret = sock_create(AF_INET, SOCK_STREAM, 0, &sock); + if (ret < 0) + goto out; + ret = inet_stream_connect(sock, sa, req->u.connect.len, 0); + if (ret < 0) { + sock_release(sock); + goto out; + } + + map = pvcalls_new_active_socket(fedata, + req->u.connect.id, + req->u.connect.ref, + req->u.connect.evtchn, + sock); + if (!map) + ret = -EFAULT; + +out: + rsp = RING_GET_RESPONSE(&fedata->ring, fedata->ring.rsp_prod_pvt++); + rsp->req_id = req->req_id; + rsp->cmd = req->cmd; + rsp->u.connect.id = req->u.connect.id; + rsp->ret = ret; + + return 0; +} + +static int pvcalls_back_release_active(struct xenbus_device *dev, + struct pvcalls_fedata *fedata, + struct sock_mapping *map) +{ + disable_irq(map->irq); + if (map->sock->sk != NULL) { + write_lock_bh(&map->sock->sk->sk_callback_lock); + map->sock->sk->sk_user_data = NULL; + map->sock->sk->sk_data_ready = map->saved_data_ready; + write_unlock_bh(&map->sock->sk->sk_callback_lock); + } + + atomic_set(&map->release, 1); + flush_work(&map->ioworker.register_work); + + xenbus_unmap_ring_vfree(dev, map->bytes); + xenbus_unmap_ring_vfree(dev, (void *)map->ring); + unbind_from_irqhandler(map->irq, map); + + sock_release(map->sock); + kfree(map); + + return 0; +} + +static int pvcalls_back_release_passive(struct xenbus_device *dev, + struct pvcalls_fedata *fedata, + struct sockpass_mapping *mappass) +{ + if (mappass->sock->sk != NULL) { + write_lock_bh(&mappass->sock->sk->sk_callback_lock); + mappass->sock->sk->sk_user_data = NULL; + mappass->sock->sk->sk_data_ready = mappass->saved_data_ready; + write_unlock_bh(&mappass->sock->sk->sk_callback_lock); + } + sock_release(mappass->sock); + destroy_workqueue(mappass->wq); + kfree(mappass); + + return 0; +} + +static int pvcalls_back_release(struct xenbus_device *dev, + struct xen_pvcalls_request *req) +{ + struct pvcalls_fedata *fedata; + struct sock_mapping *map, *n; + struct sockpass_mapping *mappass; + int ret = 0; + struct xen_pvcalls_response *rsp; + + fedata = dev_get_drvdata(&dev->dev); + + down(&fedata->socket_lock); + list_for_each_entry_safe(map, n, &fedata->socket_mappings, list) { + if (map->id == req->u.release.id) { + list_del(&map->list); + up(&fedata->socket_lock); + ret = pvcalls_back_release_active(dev, fedata, map); + goto out; + } + } + mappass = radix_tree_lookup(&fedata->socketpass_mappings, + req->u.release.id); + if (mappass != NULL) { + radix_tree_delete(&fedata->socketpass_mappings, mappass->id); + up(&fedata->socket_lock); + ret = pvcalls_back_release_passive(dev, fedata, mappass); + } else + up(&fedata->socket_lock); + +out: + rsp = RING_GET_RESPONSE(&fedata->ring, fedata->ring.rsp_prod_pvt++); + rsp->req_id = req->req_id; + rsp->u.release.id = req->u.release.id; + rsp->cmd = req->cmd; + rsp->ret = ret; + return 0; +} + +static void __pvcalls_back_accept(struct work_struct *work) +{ + struct sockpass_mapping *mappass = container_of( + work, struct sockpass_mapping, register_work); + struct sock_mapping *map; + struct pvcalls_ioworker *iow; + struct pvcalls_fedata *fedata; + struct socket *sock; + struct xen_pvcalls_response *rsp; + struct xen_pvcalls_request *req; + int notify; + int ret = -EINVAL; + unsigned long flags; + + fedata = mappass->fedata; + /* + * __pvcalls_back_accept can race against pvcalls_back_accept. + * We only need to check the value of "cmd" on read. It could be + * done atomically, but to simplify the code on the write side, we + * use a spinlock. + */ + spin_lock_irqsave(&mappass->copy_lock, flags); + req = &mappass->reqcopy; + if (req->cmd != PVCALLS_ACCEPT) { + spin_unlock_irqrestore(&mappass->copy_lock, flags); + return; + } + spin_unlock_irqrestore(&mappass->copy_lock, flags); + + sock = sock_alloc(); + if (sock == NULL) + goto out_error; + sock->type = mappass->sock->type; + sock->ops = mappass->sock->ops; + + ret = inet_accept(mappass->sock, sock, O_NONBLOCK, true); + if (ret == -EAGAIN) { + sock_release(sock); + return; + } + + map = pvcalls_new_active_socket(fedata, + req->u.accept.id_new, + req->u.accept.ref, + req->u.accept.evtchn, + sock); + if (!map) { + ret = -EFAULT; + goto out_error; + } + + map->sockpass = mappass; + iow = &map->ioworker; + atomic_inc(&map->read); + atomic_inc(&map->io); + queue_work(iow->wq, &iow->register_work); + +out_error: + rsp = RING_GET_RESPONSE(&fedata->ring, fedata->ring.rsp_prod_pvt++); + rsp->req_id = req->req_id; + rsp->cmd = req->cmd; + rsp->u.accept.id = req->u.accept.id; + rsp->ret = ret; + RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(&fedata->ring, notify); + if (notify) + notify_remote_via_irq(fedata->irq); + + mappass->reqcopy.cmd = 0; +} + +static void pvcalls_pass_sk_data_ready(struct sock *sock) +{ + struct sockpass_mapping *mappass = sock->sk_user_data; + struct pvcalls_fedata *fedata; + struct xen_pvcalls_response *rsp; + unsigned long flags; + int notify; + + if (mappass == NULL) + return; + + fedata = mappass->fedata; + spin_lock_irqsave(&mappass->copy_lock, flags); + if (mappass->reqcopy.cmd == PVCALLS_POLL) { + rsp = RING_GET_RESPONSE(&fedata->ring, + fedata->ring.rsp_prod_pvt++); + rsp->req_id = mappass->reqcopy.req_id; + rsp->u.poll.id = mappass->reqcopy.u.poll.id; + rsp->cmd = mappass->reqcopy.cmd; + rsp->ret = 0; + + mappass->reqcopy.cmd = 0; + spin_unlock_irqrestore(&mappass->copy_lock, flags); + + RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(&fedata->ring, notify); + if (notify) + notify_remote_via_irq(mappass->fedata->irq); + } else { + spin_unlock_irqrestore(&mappass->copy_lock, flags); + queue_work(mappass->wq, &mappass->register_work); + } +} + +static int pvcalls_back_bind(struct xenbus_device *dev, + struct xen_pvcalls_request *req) +{ + struct pvcalls_fedata *fedata; + int ret; + struct sockpass_mapping *map; + struct xen_pvcalls_response *rsp; + + fedata = dev_get_drvdata(&dev->dev); + + map = kzalloc(sizeof(*map), GFP_KERNEL); + if (map == NULL) { + ret = -ENOMEM; + goto out; + } + + INIT_WORK(&map->register_work, __pvcalls_back_accept); + spin_lock_init(&map->copy_lock); + map->wq = alloc_workqueue("pvcalls_wq", WQ_UNBOUND, 1); + if (!map->wq) { + ret = -ENOMEM; + goto out; + } + + ret = sock_create(AF_INET, SOCK_STREAM, 0, &map->sock); + if (ret < 0) + goto out; + + ret = inet_bind(map->sock, (struct sockaddr *)&req->u.bind.addr, + req->u.bind.len); + if (ret < 0) + goto out; + + map->fedata = fedata; + map->id = req->u.bind.id; + + down(&fedata->socket_lock); + ret = radix_tree_insert(&fedata->socketpass_mappings, map->id, + map); + up(&fedata->socket_lock); + if (ret) + goto out; + + write_lock_bh(&map->sock->sk->sk_callback_lock); + map->saved_data_ready = map->sock->sk->sk_data_ready; + map->sock->sk->sk_user_data = map; + map->sock->sk->sk_data_ready = pvcalls_pass_sk_data_ready; + write_unlock_bh(&map->sock->sk->sk_callback_lock); + +out: + if (ret) { + if (map && map->sock) + sock_release(map->sock); + if (map && map->wq) + destroy_workqueue(map->wq); + kfree(map); + } + rsp = RING_GET_RESPONSE(&fedata->ring, fedata->ring.rsp_prod_pvt++); + rsp->req_id = req->req_id; + rsp->cmd = req->cmd; + rsp->u.bind.id = req->u.bind.id; + rsp->ret = ret; + return 0; +} + +static int pvcalls_back_listen(struct xenbus_device *dev, + struct xen_pvcalls_request *req) +{ + struct pvcalls_fedata *fedata; + int ret = -EINVAL; + struct sockpass_mapping *map; + struct xen_pvcalls_response *rsp; + + fedata = dev_get_drvdata(&dev->dev); + + down(&fedata->socket_lock); + map = radix_tree_lookup(&fedata->socketpass_mappings, req->u.listen.id); + up(&fedata->socket_lock); + if (map == NULL) + goto out; + + ret = inet_listen(map->sock, req->u.listen.backlog); + +out: + rsp = RING_GET_RESPONSE(&fedata->ring, fedata->ring.rsp_prod_pvt++); + rsp->req_id = req->req_id; + rsp->cmd = req->cmd; + rsp->u.listen.id = req->u.listen.id; + rsp->ret = ret; + return 0; +} + +static int pvcalls_back_accept(struct xenbus_device *dev, + struct xen_pvcalls_request *req) +{ + struct pvcalls_fedata *fedata; + struct sockpass_mapping *mappass; + int ret = -EINVAL; + struct xen_pvcalls_response *rsp; + unsigned long flags; + + fedata = dev_get_drvdata(&dev->dev); + + down(&fedata->socket_lock); + mappass = radix_tree_lookup(&fedata->socketpass_mappings, + req->u.accept.id); + up(&fedata->socket_lock); + if (mappass == NULL) + goto out_error; + + /* + * Limitation of the current implementation: only support one + * concurrent accept or poll call on one socket. + */ + spin_lock_irqsave(&mappass->copy_lock, flags); + if (mappass->reqcopy.cmd != 0) { + spin_unlock_irqrestore(&mappass->copy_lock, flags); + ret = -EINTR; + goto out_error; + } + + mappass->reqcopy = *req; + spin_unlock_irqrestore(&mappass->copy_lock, flags); + queue_work(mappass->wq, &mappass->register_work); + + /* Tell the caller we don't need to send back a notification yet */ + return -1; + +out_error: + rsp = RING_GET_RESPONSE(&fedata->ring, fedata->ring.rsp_prod_pvt++); + rsp->req_id = req->req_id; + rsp->cmd = req->cmd; + rsp->u.accept.id = req->u.accept.id; + rsp->ret = ret; + return 0; +} + +static int pvcalls_back_poll(struct xenbus_device *dev, + struct xen_pvcalls_request *req) +{ + struct pvcalls_fedata *fedata; + struct sockpass_mapping *mappass; + struct xen_pvcalls_response *rsp; + struct inet_connection_sock *icsk; + struct request_sock_queue *queue; + unsigned long flags; + int ret; + bool data; + + fedata = dev_get_drvdata(&dev->dev); + + down(&fedata->socket_lock); + mappass = radix_tree_lookup(&fedata->socketpass_mappings, + req->u.poll.id); + up(&fedata->socket_lock); + if (mappass == NULL) + return -EINVAL; + + /* + * Limitation of the current implementation: only support one + * concurrent accept or poll call on one socket. + */ + spin_lock_irqsave(&mappass->copy_lock, flags); + if (mappass->reqcopy.cmd != 0) { + ret = -EINTR; + goto out; + } + + mappass->reqcopy = *req; + icsk = inet_csk(mappass->sock->sk); + queue = &icsk->icsk_accept_queue; + data = READ_ONCE(queue->rskq_accept_head) != NULL; + if (data) { + mappass->reqcopy.cmd = 0; + ret = 0; + goto out; + } + spin_unlock_irqrestore(&mappass->copy_lock, flags); + + /* Tell the caller we don't need to send back a notification yet */ + return -1; + +out: + spin_unlock_irqrestore(&mappass->copy_lock, flags); + + rsp = RING_GET_RESPONSE(&fedata->ring, fedata->ring.rsp_prod_pvt++); + rsp->req_id = req->req_id; + rsp->cmd = req->cmd; + rsp->u.poll.id = req->u.poll.id; + rsp->ret = ret; + return 0; +} + +static int pvcalls_back_handle_cmd(struct xenbus_device *dev, + struct xen_pvcalls_request *req) +{ + int ret = 0; + + switch (req->cmd) { + case PVCALLS_SOCKET: + ret = pvcalls_back_socket(dev, req); + break; + case PVCALLS_CONNECT: + ret = pvcalls_back_connect(dev, req); + break; + case PVCALLS_RELEASE: + ret = pvcalls_back_release(dev, req); + break; + case PVCALLS_BIND: + ret = pvcalls_back_bind(dev, req); + break; + case PVCALLS_LISTEN: + ret = pvcalls_back_listen(dev, req); + break; + case PVCALLS_ACCEPT: + ret = pvcalls_back_accept(dev, req); + break; + case PVCALLS_POLL: + ret = pvcalls_back_poll(dev, req); + break; + default: + { + struct pvcalls_fedata *fedata; + struct xen_pvcalls_response *rsp; + + fedata = dev_get_drvdata(&dev->dev); + rsp = RING_GET_RESPONSE( + &fedata->ring, fedata->ring.rsp_prod_pvt++); + rsp->req_id = req->req_id; + rsp->cmd = req->cmd; + rsp->ret = -ENOTSUPP; + break; + } + } + return ret; +} + +static void pvcalls_back_work(struct pvcalls_fedata *fedata) +{ + int notify, notify_all = 0, more = 1; + struct xen_pvcalls_request req; + struct xenbus_device *dev = fedata->dev; + + while (more) { + while (RING_HAS_UNCONSUMED_REQUESTS(&fedata->ring)) { + RING_COPY_REQUEST(&fedata->ring, + fedata->ring.req_cons++, + &req); + + if (!pvcalls_back_handle_cmd(dev, &req)) { + RING_PUSH_RESPONSES_AND_CHECK_NOTIFY( + &fedata->ring, notify); + notify_all += notify; + } + } + + if (notify_all) { + notify_remote_via_irq(fedata->irq); + notify_all = 0; + } + + RING_FINAL_CHECK_FOR_REQUESTS(&fedata->ring, more); + } +} + +static irqreturn_t pvcalls_back_event(int irq, void *dev_id) +{ + struct xenbus_device *dev = dev_id; + struct pvcalls_fedata *fedata = NULL; + unsigned int eoi_flags = XEN_EOI_FLAG_SPURIOUS; + + if (dev) { + fedata = dev_get_drvdata(&dev->dev); + if (fedata) { + pvcalls_back_work(fedata); + eoi_flags = 0; + } + } + + xen_irq_lateeoi(irq, eoi_flags); + + return IRQ_HANDLED; +} + +static irqreturn_t pvcalls_back_conn_event(int irq, void *sock_map) +{ + struct sock_mapping *map = sock_map; + struct pvcalls_ioworker *iow; + + if (map == NULL || map->sock == NULL || map->sock->sk == NULL || + map->sock->sk->sk_user_data != map) { + xen_irq_lateeoi(irq, 0); + return IRQ_HANDLED; + } + + iow = &map->ioworker; + + atomic_inc(&map->write); + atomic_inc(&map->eoi); + atomic_inc(&map->io); + queue_work(iow->wq, &iow->register_work); + + return IRQ_HANDLED; +} + +static int backend_connect(struct xenbus_device *dev) +{ + int err; + evtchn_port_t evtchn; + grant_ref_t ring_ref; + struct pvcalls_fedata *fedata = NULL; + + fedata = kzalloc(sizeof(struct pvcalls_fedata), GFP_KERNEL); + if (!fedata) + return -ENOMEM; + + fedata->irq = -1; + err = xenbus_scanf(XBT_NIL, dev->otherend, "port", "%u", + &evtchn); + if (err != 1) { + err = -EINVAL; + xenbus_dev_fatal(dev, err, "reading %s/event-channel", + dev->otherend); + goto error; + } + + err = xenbus_scanf(XBT_NIL, dev->otherend, "ring-ref", "%u", &ring_ref); + if (err != 1) { + err = -EINVAL; + xenbus_dev_fatal(dev, err, "reading %s/ring-ref", + dev->otherend); + goto error; + } + + err = bind_interdomain_evtchn_to_irq_lateeoi(dev, evtchn); + if (err < 0) + goto error; + fedata->irq = err; + + err = request_threaded_irq(fedata->irq, NULL, pvcalls_back_event, + IRQF_ONESHOT, "pvcalls-back", dev); + if (err < 0) + goto error; + + err = xenbus_map_ring_valloc(dev, &ring_ref, 1, + (void **)&fedata->sring); + if (err < 0) + goto error; + + BACK_RING_INIT(&fedata->ring, fedata->sring, XEN_PAGE_SIZE * 1); + fedata->dev = dev; + + INIT_LIST_HEAD(&fedata->socket_mappings); + INIT_RADIX_TREE(&fedata->socketpass_mappings, GFP_KERNEL); + sema_init(&fedata->socket_lock, 1); + dev_set_drvdata(&dev->dev, fedata); + + down(&pvcalls_back_global.frontends_lock); + list_add_tail(&fedata->list, &pvcalls_back_global.frontends); + up(&pvcalls_back_global.frontends_lock); + + return 0; + + error: + if (fedata->irq >= 0) + unbind_from_irqhandler(fedata->irq, dev); + if (fedata->sring != NULL) + xenbus_unmap_ring_vfree(dev, fedata->sring); + kfree(fedata); + return err; +} + +static int backend_disconnect(struct xenbus_device *dev) +{ + struct pvcalls_fedata *fedata; + struct sock_mapping *map, *n; + struct sockpass_mapping *mappass; + struct radix_tree_iter iter; + void **slot; + + + fedata = dev_get_drvdata(&dev->dev); + + down(&fedata->socket_lock); + list_for_each_entry_safe(map, n, &fedata->socket_mappings, list) { + list_del(&map->list); + pvcalls_back_release_active(dev, fedata, map); + } + + radix_tree_for_each_slot(slot, &fedata->socketpass_mappings, &iter, 0) { + mappass = radix_tree_deref_slot(slot); + if (!mappass) + continue; + if (radix_tree_exception(mappass)) { + if (radix_tree_deref_retry(mappass)) + slot = radix_tree_iter_retry(&iter); + } else { + radix_tree_delete(&fedata->socketpass_mappings, + mappass->id); + pvcalls_back_release_passive(dev, fedata, mappass); + } + } + up(&fedata->socket_lock); + + unbind_from_irqhandler(fedata->irq, dev); + xenbus_unmap_ring_vfree(dev, fedata->sring); + + list_del(&fedata->list); + kfree(fedata); + dev_set_drvdata(&dev->dev, NULL); + + return 0; +} + +static int pvcalls_back_probe(struct xenbus_device *dev, + const struct xenbus_device_id *id) +{ + int err, abort; + struct xenbus_transaction xbt; + +again: + abort = 1; + + err = xenbus_transaction_start(&xbt); + if (err) { + pr_warn("%s cannot create xenstore transaction\n", __func__); + return err; + } + + err = xenbus_printf(xbt, dev->nodename, "versions", "%s", + PVCALLS_VERSIONS); + if (err) { + pr_warn("%s write out 'versions' failed\n", __func__); + goto abort; + } + + err = xenbus_printf(xbt, dev->nodename, "max-page-order", "%u", + MAX_RING_ORDER); + if (err) { + pr_warn("%s write out 'max-page-order' failed\n", __func__); + goto abort; + } + + err = xenbus_printf(xbt, dev->nodename, "function-calls", + XENBUS_FUNCTIONS_CALLS); + if (err) { + pr_warn("%s write out 'function-calls' failed\n", __func__); + goto abort; + } + + abort = 0; +abort: + err = xenbus_transaction_end(xbt, abort); + if (err) { + if (err == -EAGAIN && !abort) + goto again; + pr_warn("%s cannot complete xenstore transaction\n", __func__); + return err; + } + + if (abort) + return -EFAULT; + + xenbus_switch_state(dev, XenbusStateInitWait); + + return 0; +} + +static void set_backend_state(struct xenbus_device *dev, + enum xenbus_state state) +{ + while (dev->state != state) { + switch (dev->state) { + case XenbusStateClosed: + switch (state) { + case XenbusStateInitWait: + case XenbusStateConnected: + xenbus_switch_state(dev, XenbusStateInitWait); + break; + case XenbusStateClosing: + xenbus_switch_state(dev, XenbusStateClosing); + break; + default: + WARN_ON(1); + } + break; + case XenbusStateInitWait: + case XenbusStateInitialised: + switch (state) { + case XenbusStateConnected: + if (backend_connect(dev)) + return; + xenbus_switch_state(dev, XenbusStateConnected); + break; + case XenbusStateClosing: + case XenbusStateClosed: + xenbus_switch_state(dev, XenbusStateClosing); + break; + default: + WARN_ON(1); + } + break; + case XenbusStateConnected: + switch (state) { + case XenbusStateInitWait: + case XenbusStateClosing: + case XenbusStateClosed: + down(&pvcalls_back_global.frontends_lock); + backend_disconnect(dev); + up(&pvcalls_back_global.frontends_lock); + xenbus_switch_state(dev, XenbusStateClosing); + break; + default: + WARN_ON(1); + } + break; + case XenbusStateClosing: + switch (state) { + case XenbusStateInitWait: + case XenbusStateConnected: + case XenbusStateClosed: + xenbus_switch_state(dev, XenbusStateClosed); + break; + default: + WARN_ON(1); + } + break; + default: + WARN_ON(1); + } + } +} + +static void pvcalls_back_changed(struct xenbus_device *dev, + enum xenbus_state frontend_state) +{ + switch (frontend_state) { + case XenbusStateInitialising: + set_backend_state(dev, XenbusStateInitWait); + break; + + case XenbusStateInitialised: + case XenbusStateConnected: + set_backend_state(dev, XenbusStateConnected); + break; + + case XenbusStateClosing: + set_backend_state(dev, XenbusStateClosing); + break; + + case XenbusStateClosed: + set_backend_state(dev, XenbusStateClosed); + if (xenbus_dev_is_online(dev)) + break; + device_unregister(&dev->dev); + break; + case XenbusStateUnknown: + set_backend_state(dev, XenbusStateClosed); + device_unregister(&dev->dev); + break; + + default: + xenbus_dev_fatal(dev, -EINVAL, "saw state %d at frontend", + frontend_state); + break; + } +} + +static int pvcalls_back_remove(struct xenbus_device *dev) +{ + return 0; +} + +static int pvcalls_back_uevent(struct xenbus_device *xdev, + struct kobj_uevent_env *env) +{ + return 0; +} + +static const struct xenbus_device_id pvcalls_back_ids[] = { + { "pvcalls" }, + { "" } +}; + +static struct xenbus_driver pvcalls_back_driver = { + .ids = pvcalls_back_ids, + .probe = pvcalls_back_probe, + .remove = pvcalls_back_remove, + .uevent = pvcalls_back_uevent, + .otherend_changed = pvcalls_back_changed, +}; + +static int __init pvcalls_back_init(void) +{ + int ret; + + if (!xen_domain()) + return -ENODEV; + + ret = xenbus_register_backend(&pvcalls_back_driver); + if (ret < 0) + return ret; + + sema_init(&pvcalls_back_global.frontends_lock, 1); + INIT_LIST_HEAD(&pvcalls_back_global.frontends); + return 0; +} +module_init(pvcalls_back_init); + +static void __exit pvcalls_back_fin(void) +{ + struct pvcalls_fedata *fedata, *nfedata; + + down(&pvcalls_back_global.frontends_lock); + list_for_each_entry_safe(fedata, nfedata, + &pvcalls_back_global.frontends, list) { + backend_disconnect(fedata->dev); + } + up(&pvcalls_back_global.frontends_lock); + + xenbus_unregister_driver(&pvcalls_back_driver); +} + +module_exit(pvcalls_back_fin); + +MODULE_DESCRIPTION("Xen PV Calls backend driver"); +MODULE_AUTHOR("Stefano Stabellini <sstabellini@kernel.org>"); +MODULE_LICENSE("GPL"); |