diff options
Diffstat (limited to 'drivers/xen/pvcalls-front.c')
| -rw-r--r-- | drivers/xen/pvcalls-front.c | 1297 |
1 files changed, 1297 insertions, 0 deletions
diff --git a/drivers/xen/pvcalls-front.c b/drivers/xen/pvcalls-front.c new file mode 100644 index 000000000..9b5692787 --- /dev/null +++ b/drivers/xen/pvcalls-front.c @@ -0,0 +1,1297 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * (c) 2017 Stefano Stabellini <stefano@aporeto.com> + */ + +#include <linux/module.h> +#include <linux/net.h> +#include <linux/socket.h> + +#include <net/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> + +#include "pvcalls-front.h" + +#define PVCALLS_INVALID_ID UINT_MAX +#define PVCALLS_RING_ORDER XENBUS_MAX_RING_GRANT_ORDER +#define PVCALLS_NR_RSP_PER_RING __CONST_RING_SIZE(xen_pvcalls, XEN_PAGE_SIZE) +#define PVCALLS_FRONT_MAX_SPIN 5000 + +static struct proto pvcalls_proto = { + .name = "PVCalls", + .owner = THIS_MODULE, + .obj_size = sizeof(struct sock), +}; + +struct pvcalls_bedata { + struct xen_pvcalls_front_ring ring; + grant_ref_t ref; + int irq; + + struct list_head socket_mappings; + spinlock_t socket_lock; + + wait_queue_head_t inflight_req; + struct xen_pvcalls_response rsp[PVCALLS_NR_RSP_PER_RING]; +}; +/* Only one front/back connection supported. */ +static struct xenbus_device *pvcalls_front_dev; +static atomic_t pvcalls_refcount; + +/* first increment refcount, then proceed */ +#define pvcalls_enter() { \ + atomic_inc(&pvcalls_refcount); \ +} + +/* first complete other operations, then decrement refcount */ +#define pvcalls_exit() { \ + atomic_dec(&pvcalls_refcount); \ +} + +struct sock_mapping { + bool active_socket; + struct list_head list; + struct socket *sock; + atomic_t refcount; + union { + struct { + int irq; + grant_ref_t ref; + struct pvcalls_data_intf *ring; + struct pvcalls_data data; + struct mutex in_mutex; + struct mutex out_mutex; + + wait_queue_head_t inflight_conn_req; + } active; + struct { + /* + * Socket status, needs to be 64-bit aligned due to the + * test_and_* functions which have this requirement on arm64. + */ +#define PVCALLS_STATUS_UNINITALIZED 0 +#define PVCALLS_STATUS_BIND 1 +#define PVCALLS_STATUS_LISTEN 2 + uint8_t status __attribute__((aligned(8))); + /* + * Internal state-machine flags. + * Only one accept operation can be inflight for a socket. + * Only one poll operation can be inflight for a given socket. + * flags needs to be 64-bit aligned due to the test_and_* + * functions which have this requirement on arm64. + */ +#define PVCALLS_FLAG_ACCEPT_INFLIGHT 0 +#define PVCALLS_FLAG_POLL_INFLIGHT 1 +#define PVCALLS_FLAG_POLL_RET 2 + uint8_t flags __attribute__((aligned(8))); + uint32_t inflight_req_id; + struct sock_mapping *accept_map; + wait_queue_head_t inflight_accept_req; + } passive; + }; +}; + +static inline struct sock_mapping *pvcalls_enter_sock(struct socket *sock) +{ + struct sock_mapping *map; + + if (!pvcalls_front_dev || + dev_get_drvdata(&pvcalls_front_dev->dev) == NULL) + return ERR_PTR(-ENOTCONN); + + map = (struct sock_mapping *)sock->sk->sk_send_head; + if (map == NULL) + return ERR_PTR(-ENOTSOCK); + + pvcalls_enter(); + atomic_inc(&map->refcount); + return map; +} + +static inline void pvcalls_exit_sock(struct socket *sock) +{ + struct sock_mapping *map; + + map = (struct sock_mapping *)sock->sk->sk_send_head; + atomic_dec(&map->refcount); + pvcalls_exit(); +} + +static inline int get_request(struct pvcalls_bedata *bedata, int *req_id) +{ + *req_id = bedata->ring.req_prod_pvt & (RING_SIZE(&bedata->ring) - 1); + if (RING_FULL(&bedata->ring) || + bedata->rsp[*req_id].req_id != PVCALLS_INVALID_ID) + return -EAGAIN; + return 0; +} + +static bool pvcalls_front_write_todo(struct sock_mapping *map) +{ + struct pvcalls_data_intf *intf = map->active.ring; + RING_IDX cons, prod, size = XEN_FLEX_RING_SIZE(PVCALLS_RING_ORDER); + int32_t error; + + error = intf->out_error; + if (error == -ENOTCONN) + return false; + if (error != 0) + return true; + + cons = intf->out_cons; + prod = intf->out_prod; + return !!(size - pvcalls_queued(prod, cons, size)); +} + +static bool pvcalls_front_read_todo(struct sock_mapping *map) +{ + struct pvcalls_data_intf *intf = map->active.ring; + RING_IDX cons, prod; + int32_t error; + + cons = intf->in_cons; + prod = intf->in_prod; + error = intf->in_error; + return (error != 0 || + pvcalls_queued(prod, cons, + XEN_FLEX_RING_SIZE(PVCALLS_RING_ORDER)) != 0); +} + +static irqreturn_t pvcalls_front_event_handler(int irq, void *dev_id) +{ + struct xenbus_device *dev = dev_id; + struct pvcalls_bedata *bedata; + struct xen_pvcalls_response *rsp; + uint8_t *src, *dst; + int req_id = 0, more = 0, done = 0; + + if (dev == NULL) + return IRQ_HANDLED; + + pvcalls_enter(); + bedata = dev_get_drvdata(&dev->dev); + if (bedata == NULL) { + pvcalls_exit(); + return IRQ_HANDLED; + } + +again: + while (RING_HAS_UNCONSUMED_RESPONSES(&bedata->ring)) { + rsp = RING_GET_RESPONSE(&bedata->ring, bedata->ring.rsp_cons); + + req_id = rsp->req_id; + if (rsp->cmd == PVCALLS_POLL) { + struct sock_mapping *map = (struct sock_mapping *)(uintptr_t) + rsp->u.poll.id; + + clear_bit(PVCALLS_FLAG_POLL_INFLIGHT, + (void *)&map->passive.flags); + /* + * clear INFLIGHT, then set RET. It pairs with + * the checks at the beginning of + * pvcalls_front_poll_passive. + */ + smp_wmb(); + set_bit(PVCALLS_FLAG_POLL_RET, + (void *)&map->passive.flags); + } else { + dst = (uint8_t *)&bedata->rsp[req_id] + + sizeof(rsp->req_id); + src = (uint8_t *)rsp + sizeof(rsp->req_id); + memcpy(dst, src, sizeof(*rsp) - sizeof(rsp->req_id)); + /* + * First copy the rest of the data, then req_id. It is + * paired with the barrier when accessing bedata->rsp. + */ + smp_wmb(); + bedata->rsp[req_id].req_id = req_id; + } + + done = 1; + bedata->ring.rsp_cons++; + } + + RING_FINAL_CHECK_FOR_RESPONSES(&bedata->ring, more); + if (more) + goto again; + if (done) + wake_up(&bedata->inflight_req); + pvcalls_exit(); + return IRQ_HANDLED; +} + +static void free_active_ring(struct sock_mapping *map); + +static void pvcalls_front_free_map(struct pvcalls_bedata *bedata, + struct sock_mapping *map) +{ + int i; + + unbind_from_irqhandler(map->active.irq, map); + + spin_lock(&bedata->socket_lock); + if (!list_empty(&map->list)) + list_del_init(&map->list); + spin_unlock(&bedata->socket_lock); + + for (i = 0; i < (1 << PVCALLS_RING_ORDER); i++) + gnttab_end_foreign_access(map->active.ring->ref[i], NULL); + gnttab_end_foreign_access(map->active.ref, NULL); + free_active_ring(map); + + kfree(map); +} + +static irqreturn_t pvcalls_front_conn_handler(int irq, void *sock_map) +{ + struct sock_mapping *map = sock_map; + + if (map == NULL) + return IRQ_HANDLED; + + wake_up_interruptible(&map->active.inflight_conn_req); + + return IRQ_HANDLED; +} + +int pvcalls_front_socket(struct socket *sock) +{ + struct pvcalls_bedata *bedata; + struct sock_mapping *map = NULL; + struct xen_pvcalls_request *req; + int notify, req_id, ret; + + /* + * PVCalls only supports domain AF_INET, + * type SOCK_STREAM and protocol 0 sockets for now. + * + * Check socket type here, AF_INET and protocol checks are done + * by the caller. + */ + if (sock->type != SOCK_STREAM) + return -EOPNOTSUPP; + + pvcalls_enter(); + if (!pvcalls_front_dev) { + pvcalls_exit(); + return -EACCES; + } + bedata = dev_get_drvdata(&pvcalls_front_dev->dev); + + map = kzalloc(sizeof(*map), GFP_KERNEL); + if (map == NULL) { + pvcalls_exit(); + return -ENOMEM; + } + + spin_lock(&bedata->socket_lock); + + ret = get_request(bedata, &req_id); + if (ret < 0) { + kfree(map); + spin_unlock(&bedata->socket_lock); + pvcalls_exit(); + return ret; + } + + /* + * sock->sk->sk_send_head is not used for ip sockets: reuse the + * field to store a pointer to the struct sock_mapping + * corresponding to the socket. This way, we can easily get the + * struct sock_mapping from the struct socket. + */ + sock->sk->sk_send_head = (void *)map; + list_add_tail(&map->list, &bedata->socket_mappings); + + req = RING_GET_REQUEST(&bedata->ring, req_id); + req->req_id = req_id; + req->cmd = PVCALLS_SOCKET; + req->u.socket.id = (uintptr_t) map; + req->u.socket.domain = AF_INET; + req->u.socket.type = SOCK_STREAM; + req->u.socket.protocol = IPPROTO_IP; + + bedata->ring.req_prod_pvt++; + RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&bedata->ring, notify); + spin_unlock(&bedata->socket_lock); + if (notify) + notify_remote_via_irq(bedata->irq); + + wait_event(bedata->inflight_req, + READ_ONCE(bedata->rsp[req_id].req_id) == req_id); + + /* read req_id, then the content */ + smp_rmb(); + ret = bedata->rsp[req_id].ret; + bedata->rsp[req_id].req_id = PVCALLS_INVALID_ID; + + pvcalls_exit(); + return ret; +} + +static void free_active_ring(struct sock_mapping *map) +{ + if (!map->active.ring) + return; + + free_pages_exact(map->active.data.in, + PAGE_SIZE << map->active.ring->ring_order); + free_page((unsigned long)map->active.ring); +} + +static int alloc_active_ring(struct sock_mapping *map) +{ + void *bytes; + + map->active.ring = (struct pvcalls_data_intf *) + get_zeroed_page(GFP_KERNEL); + if (!map->active.ring) + goto out; + + map->active.ring->ring_order = PVCALLS_RING_ORDER; + bytes = alloc_pages_exact(PAGE_SIZE << PVCALLS_RING_ORDER, + GFP_KERNEL | __GFP_ZERO); + if (!bytes) + goto out; + + map->active.data.in = bytes; + map->active.data.out = bytes + + XEN_FLEX_RING_SIZE(PVCALLS_RING_ORDER); + + return 0; + +out: + free_active_ring(map); + return -ENOMEM; +} + +static int create_active(struct sock_mapping *map, evtchn_port_t *evtchn) +{ + void *bytes; + int ret, irq = -1, i; + + *evtchn = 0; + init_waitqueue_head(&map->active.inflight_conn_req); + + bytes = map->active.data.in; + for (i = 0; i < (1 << PVCALLS_RING_ORDER); i++) + map->active.ring->ref[i] = gnttab_grant_foreign_access( + pvcalls_front_dev->otherend_id, + pfn_to_gfn(virt_to_pfn(bytes) + i), 0); + + map->active.ref = gnttab_grant_foreign_access( + pvcalls_front_dev->otherend_id, + pfn_to_gfn(virt_to_pfn((void *)map->active.ring)), 0); + + ret = xenbus_alloc_evtchn(pvcalls_front_dev, evtchn); + if (ret) + goto out_error; + irq = bind_evtchn_to_irqhandler(*evtchn, pvcalls_front_conn_handler, + 0, "pvcalls-frontend", map); + if (irq < 0) { + ret = irq; + goto out_error; + } + + map->active.irq = irq; + map->active_socket = true; + mutex_init(&map->active.in_mutex); + mutex_init(&map->active.out_mutex); + + return 0; + +out_error: + if (*evtchn > 0) + xenbus_free_evtchn(pvcalls_front_dev, *evtchn); + return ret; +} + +int pvcalls_front_connect(struct socket *sock, struct sockaddr *addr, + int addr_len, int flags) +{ + struct pvcalls_bedata *bedata; + struct sock_mapping *map = NULL; + struct xen_pvcalls_request *req; + int notify, req_id, ret; + evtchn_port_t evtchn; + + if (addr->sa_family != AF_INET || sock->type != SOCK_STREAM) + return -EOPNOTSUPP; + + map = pvcalls_enter_sock(sock); + if (IS_ERR(map)) + return PTR_ERR(map); + + bedata = dev_get_drvdata(&pvcalls_front_dev->dev); + ret = alloc_active_ring(map); + if (ret < 0) { + pvcalls_exit_sock(sock); + return ret; + } + + spin_lock(&bedata->socket_lock); + ret = get_request(bedata, &req_id); + if (ret < 0) { + spin_unlock(&bedata->socket_lock); + free_active_ring(map); + pvcalls_exit_sock(sock); + return ret; + } + ret = create_active(map, &evtchn); + if (ret < 0) { + spin_unlock(&bedata->socket_lock); + free_active_ring(map); + pvcalls_exit_sock(sock); + return ret; + } + + req = RING_GET_REQUEST(&bedata->ring, req_id); + req->req_id = req_id; + req->cmd = PVCALLS_CONNECT; + req->u.connect.id = (uintptr_t)map; + req->u.connect.len = addr_len; + req->u.connect.flags = flags; + req->u.connect.ref = map->active.ref; + req->u.connect.evtchn = evtchn; + memcpy(req->u.connect.addr, addr, sizeof(*addr)); + + map->sock = sock; + + bedata->ring.req_prod_pvt++; + RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&bedata->ring, notify); + spin_unlock(&bedata->socket_lock); + + if (notify) + notify_remote_via_irq(bedata->irq); + + wait_event(bedata->inflight_req, + READ_ONCE(bedata->rsp[req_id].req_id) == req_id); + + /* read req_id, then the content */ + smp_rmb(); + ret = bedata->rsp[req_id].ret; + bedata->rsp[req_id].req_id = PVCALLS_INVALID_ID; + pvcalls_exit_sock(sock); + return ret; +} + +static int __write_ring(struct pvcalls_data_intf *intf, + struct pvcalls_data *data, + struct iov_iter *msg_iter, + int len) +{ + RING_IDX cons, prod, size, masked_prod, masked_cons; + RING_IDX array_size = XEN_FLEX_RING_SIZE(PVCALLS_RING_ORDER); + int32_t error; + + error = intf->out_error; + if (error < 0) + return error; + cons = intf->out_cons; + prod = intf->out_prod; + /* read indexes before continuing */ + virt_mb(); + + size = pvcalls_queued(prod, cons, array_size); + if (size > array_size) + return -EINVAL; + if (size == array_size) + return 0; + if (len > array_size - size) + len = array_size - size; + + masked_prod = pvcalls_mask(prod, array_size); + masked_cons = pvcalls_mask(cons, array_size); + + if (masked_prod < masked_cons) { + len = copy_from_iter(data->out + masked_prod, len, msg_iter); + } else { + if (len > array_size - masked_prod) { + int ret = copy_from_iter(data->out + masked_prod, + array_size - masked_prod, msg_iter); + if (ret != array_size - masked_prod) { + len = ret; + goto out; + } + len = ret + copy_from_iter(data->out, len - ret, msg_iter); + } else { + len = copy_from_iter(data->out + masked_prod, len, msg_iter); + } + } +out: + /* write to ring before updating pointer */ + virt_wmb(); + intf->out_prod += len; + + return len; +} + +int pvcalls_front_sendmsg(struct socket *sock, struct msghdr *msg, + size_t len) +{ + struct sock_mapping *map; + int sent, tot_sent = 0; + int count = 0, flags; + + flags = msg->msg_flags; + if (flags & (MSG_CONFIRM|MSG_DONTROUTE|MSG_EOR|MSG_OOB)) + return -EOPNOTSUPP; + + map = pvcalls_enter_sock(sock); + if (IS_ERR(map)) + return PTR_ERR(map); + + mutex_lock(&map->active.out_mutex); + if ((flags & MSG_DONTWAIT) && !pvcalls_front_write_todo(map)) { + mutex_unlock(&map->active.out_mutex); + pvcalls_exit_sock(sock); + return -EAGAIN; + } + if (len > INT_MAX) + len = INT_MAX; + +again: + count++; + sent = __write_ring(map->active.ring, + &map->active.data, &msg->msg_iter, + len); + if (sent > 0) { + len -= sent; + tot_sent += sent; + notify_remote_via_irq(map->active.irq); + } + if (sent >= 0 && len > 0 && count < PVCALLS_FRONT_MAX_SPIN) + goto again; + if (sent < 0) + tot_sent = sent; + + mutex_unlock(&map->active.out_mutex); + pvcalls_exit_sock(sock); + return tot_sent; +} + +static int __read_ring(struct pvcalls_data_intf *intf, + struct pvcalls_data *data, + struct iov_iter *msg_iter, + size_t len, int flags) +{ + RING_IDX cons, prod, size, masked_prod, masked_cons; + RING_IDX array_size = XEN_FLEX_RING_SIZE(PVCALLS_RING_ORDER); + int32_t error; + + cons = intf->in_cons; + prod = intf->in_prod; + error = intf->in_error; + /* get pointers before reading from the ring */ + virt_rmb(); + + size = pvcalls_queued(prod, cons, array_size); + masked_prod = pvcalls_mask(prod, array_size); + masked_cons = pvcalls_mask(cons, array_size); + + if (size == 0) + return error ?: size; + + if (len > size) + len = size; + + if (masked_prod > masked_cons) { + len = copy_to_iter(data->in + masked_cons, len, msg_iter); + } else { + if (len > (array_size - masked_cons)) { + int ret = copy_to_iter(data->in + masked_cons, + array_size - masked_cons, msg_iter); + if (ret != array_size - masked_cons) { + len = ret; + goto out; + } + len = ret + copy_to_iter(data->in, len - ret, msg_iter); + } else { + len = copy_to_iter(data->in + masked_cons, len, msg_iter); + } + } +out: + /* read data from the ring before increasing the index */ + virt_mb(); + if (!(flags & MSG_PEEK)) + intf->in_cons += len; + + return len; +} + +int pvcalls_front_recvmsg(struct socket *sock, struct msghdr *msg, size_t len, + int flags) +{ + int ret; + struct sock_mapping *map; + + if (flags & (MSG_CMSG_CLOEXEC|MSG_ERRQUEUE|MSG_OOB|MSG_TRUNC)) + return -EOPNOTSUPP; + + map = pvcalls_enter_sock(sock); + if (IS_ERR(map)) + return PTR_ERR(map); + + mutex_lock(&map->active.in_mutex); + if (len > XEN_FLEX_RING_SIZE(PVCALLS_RING_ORDER)) + len = XEN_FLEX_RING_SIZE(PVCALLS_RING_ORDER); + + while (!(flags & MSG_DONTWAIT) && !pvcalls_front_read_todo(map)) { + wait_event_interruptible(map->active.inflight_conn_req, + pvcalls_front_read_todo(map)); + } + ret = __read_ring(map->active.ring, &map->active.data, + &msg->msg_iter, len, flags); + + if (ret > 0) + notify_remote_via_irq(map->active.irq); + if (ret == 0) + ret = (flags & MSG_DONTWAIT) ? -EAGAIN : 0; + if (ret == -ENOTCONN) + ret = 0; + + mutex_unlock(&map->active.in_mutex); + pvcalls_exit_sock(sock); + return ret; +} + +int pvcalls_front_bind(struct socket *sock, struct sockaddr *addr, int addr_len) +{ + struct pvcalls_bedata *bedata; + struct sock_mapping *map = NULL; + struct xen_pvcalls_request *req; + int notify, req_id, ret; + + if (addr->sa_family != AF_INET || sock->type != SOCK_STREAM) + return -EOPNOTSUPP; + + map = pvcalls_enter_sock(sock); + if (IS_ERR(map)) + return PTR_ERR(map); + bedata = dev_get_drvdata(&pvcalls_front_dev->dev); + + spin_lock(&bedata->socket_lock); + ret = get_request(bedata, &req_id); + if (ret < 0) { + spin_unlock(&bedata->socket_lock); + pvcalls_exit_sock(sock); + return ret; + } + req = RING_GET_REQUEST(&bedata->ring, req_id); + req->req_id = req_id; + map->sock = sock; + req->cmd = PVCALLS_BIND; + req->u.bind.id = (uintptr_t)map; + memcpy(req->u.bind.addr, addr, sizeof(*addr)); + req->u.bind.len = addr_len; + + init_waitqueue_head(&map->passive.inflight_accept_req); + + map->active_socket = false; + + bedata->ring.req_prod_pvt++; + RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&bedata->ring, notify); + spin_unlock(&bedata->socket_lock); + if (notify) + notify_remote_via_irq(bedata->irq); + + wait_event(bedata->inflight_req, + READ_ONCE(bedata->rsp[req_id].req_id) == req_id); + + /* read req_id, then the content */ + smp_rmb(); + ret = bedata->rsp[req_id].ret; + bedata->rsp[req_id].req_id = PVCALLS_INVALID_ID; + + map->passive.status = PVCALLS_STATUS_BIND; + pvcalls_exit_sock(sock); + return 0; +} + +int pvcalls_front_listen(struct socket *sock, int backlog) +{ + struct pvcalls_bedata *bedata; + struct sock_mapping *map; + struct xen_pvcalls_request *req; + int notify, req_id, ret; + + map = pvcalls_enter_sock(sock); + if (IS_ERR(map)) + return PTR_ERR(map); + bedata = dev_get_drvdata(&pvcalls_front_dev->dev); + + if (map->passive.status != PVCALLS_STATUS_BIND) { + pvcalls_exit_sock(sock); + return -EOPNOTSUPP; + } + + spin_lock(&bedata->socket_lock); + ret = get_request(bedata, &req_id); + if (ret < 0) { + spin_unlock(&bedata->socket_lock); + pvcalls_exit_sock(sock); + return ret; + } + req = RING_GET_REQUEST(&bedata->ring, req_id); + req->req_id = req_id; + req->cmd = PVCALLS_LISTEN; + req->u.listen.id = (uintptr_t) map; + req->u.listen.backlog = backlog; + + bedata->ring.req_prod_pvt++; + RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&bedata->ring, notify); + spin_unlock(&bedata->socket_lock); + if (notify) + notify_remote_via_irq(bedata->irq); + + wait_event(bedata->inflight_req, + READ_ONCE(bedata->rsp[req_id].req_id) == req_id); + + /* read req_id, then the content */ + smp_rmb(); + ret = bedata->rsp[req_id].ret; + bedata->rsp[req_id].req_id = PVCALLS_INVALID_ID; + + map->passive.status = PVCALLS_STATUS_LISTEN; + pvcalls_exit_sock(sock); + return ret; +} + +int pvcalls_front_accept(struct socket *sock, struct socket *newsock, int flags) +{ + struct pvcalls_bedata *bedata; + struct sock_mapping *map; + struct sock_mapping *map2 = NULL; + struct xen_pvcalls_request *req; + int notify, req_id, ret, nonblock; + evtchn_port_t evtchn; + + map = pvcalls_enter_sock(sock); + if (IS_ERR(map)) + return PTR_ERR(map); + bedata = dev_get_drvdata(&pvcalls_front_dev->dev); + + if (map->passive.status != PVCALLS_STATUS_LISTEN) { + pvcalls_exit_sock(sock); + return -EINVAL; + } + + nonblock = flags & SOCK_NONBLOCK; + /* + * Backend only supports 1 inflight accept request, will return + * errors for the others + */ + if (test_and_set_bit(PVCALLS_FLAG_ACCEPT_INFLIGHT, + (void *)&map->passive.flags)) { + req_id = READ_ONCE(map->passive.inflight_req_id); + if (req_id != PVCALLS_INVALID_ID && + READ_ONCE(bedata->rsp[req_id].req_id) == req_id) { + map2 = map->passive.accept_map; + goto received; + } + if (nonblock) { + pvcalls_exit_sock(sock); + return -EAGAIN; + } + if (wait_event_interruptible(map->passive.inflight_accept_req, + !test_and_set_bit(PVCALLS_FLAG_ACCEPT_INFLIGHT, + (void *)&map->passive.flags))) { + pvcalls_exit_sock(sock); + return -EINTR; + } + } + + map2 = kzalloc(sizeof(*map2), GFP_KERNEL); + if (map2 == NULL) { + clear_bit(PVCALLS_FLAG_ACCEPT_INFLIGHT, + (void *)&map->passive.flags); + pvcalls_exit_sock(sock); + return -ENOMEM; + } + ret = alloc_active_ring(map2); + if (ret < 0) { + clear_bit(PVCALLS_FLAG_ACCEPT_INFLIGHT, + (void *)&map->passive.flags); + kfree(map2); + pvcalls_exit_sock(sock); + return ret; + } + spin_lock(&bedata->socket_lock); + ret = get_request(bedata, &req_id); + if (ret < 0) { + clear_bit(PVCALLS_FLAG_ACCEPT_INFLIGHT, + (void *)&map->passive.flags); + spin_unlock(&bedata->socket_lock); + free_active_ring(map2); + kfree(map2); + pvcalls_exit_sock(sock); + return ret; + } + + ret = create_active(map2, &evtchn); + if (ret < 0) { + free_active_ring(map2); + kfree(map2); + clear_bit(PVCALLS_FLAG_ACCEPT_INFLIGHT, + (void *)&map->passive.flags); + spin_unlock(&bedata->socket_lock); + pvcalls_exit_sock(sock); + return ret; + } + list_add_tail(&map2->list, &bedata->socket_mappings); + + req = RING_GET_REQUEST(&bedata->ring, req_id); + req->req_id = req_id; + req->cmd = PVCALLS_ACCEPT; + req->u.accept.id = (uintptr_t) map; + req->u.accept.ref = map2->active.ref; + req->u.accept.id_new = (uintptr_t) map2; + req->u.accept.evtchn = evtchn; + map->passive.accept_map = map2; + + bedata->ring.req_prod_pvt++; + RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&bedata->ring, notify); + spin_unlock(&bedata->socket_lock); + if (notify) + notify_remote_via_irq(bedata->irq); + /* We could check if we have received a response before returning. */ + if (nonblock) { + WRITE_ONCE(map->passive.inflight_req_id, req_id); + pvcalls_exit_sock(sock); + return -EAGAIN; + } + + if (wait_event_interruptible(bedata->inflight_req, + READ_ONCE(bedata->rsp[req_id].req_id) == req_id)) { + pvcalls_exit_sock(sock); + return -EINTR; + } + /* read req_id, then the content */ + smp_rmb(); + +received: + map2->sock = newsock; + newsock->sk = sk_alloc(sock_net(sock->sk), PF_INET, GFP_KERNEL, &pvcalls_proto, false); + if (!newsock->sk) { + bedata->rsp[req_id].req_id = PVCALLS_INVALID_ID; + map->passive.inflight_req_id = PVCALLS_INVALID_ID; + clear_bit(PVCALLS_FLAG_ACCEPT_INFLIGHT, + (void *)&map->passive.flags); + pvcalls_front_free_map(bedata, map2); + pvcalls_exit_sock(sock); + return -ENOMEM; + } + newsock->sk->sk_send_head = (void *)map2; + + ret = bedata->rsp[req_id].ret; + bedata->rsp[req_id].req_id = PVCALLS_INVALID_ID; + map->passive.inflight_req_id = PVCALLS_INVALID_ID; + + clear_bit(PVCALLS_FLAG_ACCEPT_INFLIGHT, (void *)&map->passive.flags); + wake_up(&map->passive.inflight_accept_req); + + pvcalls_exit_sock(sock); + return ret; +} + +static __poll_t pvcalls_front_poll_passive(struct file *file, + struct pvcalls_bedata *bedata, + struct sock_mapping *map, + poll_table *wait) +{ + int notify, req_id, ret; + struct xen_pvcalls_request *req; + + if (test_bit(PVCALLS_FLAG_ACCEPT_INFLIGHT, + (void *)&map->passive.flags)) { + uint32_t req_id = READ_ONCE(map->passive.inflight_req_id); + + if (req_id != PVCALLS_INVALID_ID && + READ_ONCE(bedata->rsp[req_id].req_id) == req_id) + return EPOLLIN | EPOLLRDNORM; + + poll_wait(file, &map->passive.inflight_accept_req, wait); + return 0; + } + + if (test_and_clear_bit(PVCALLS_FLAG_POLL_RET, + (void *)&map->passive.flags)) + return EPOLLIN | EPOLLRDNORM; + + /* + * First check RET, then INFLIGHT. No barriers necessary to + * ensure execution ordering because of the conditional + * instructions creating control dependencies. + */ + + if (test_and_set_bit(PVCALLS_FLAG_POLL_INFLIGHT, + (void *)&map->passive.flags)) { + poll_wait(file, &bedata->inflight_req, wait); + return 0; + } + + spin_lock(&bedata->socket_lock); + ret = get_request(bedata, &req_id); + if (ret < 0) { + spin_unlock(&bedata->socket_lock); + return ret; + } + req = RING_GET_REQUEST(&bedata->ring, req_id); + req->req_id = req_id; + req->cmd = PVCALLS_POLL; + req->u.poll.id = (uintptr_t) map; + + bedata->ring.req_prod_pvt++; + RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&bedata->ring, notify); + spin_unlock(&bedata->socket_lock); + if (notify) + notify_remote_via_irq(bedata->irq); + + poll_wait(file, &bedata->inflight_req, wait); + return 0; +} + +static __poll_t pvcalls_front_poll_active(struct file *file, + struct pvcalls_bedata *bedata, + struct sock_mapping *map, + poll_table *wait) +{ + __poll_t mask = 0; + int32_t in_error, out_error; + struct pvcalls_data_intf *intf = map->active.ring; + + out_error = intf->out_error; + in_error = intf->in_error; + + poll_wait(file, &map->active.inflight_conn_req, wait); + if (pvcalls_front_write_todo(map)) + mask |= EPOLLOUT | EPOLLWRNORM; + if (pvcalls_front_read_todo(map)) + mask |= EPOLLIN | EPOLLRDNORM; + if (in_error != 0 || out_error != 0) + mask |= EPOLLERR; + + return mask; +} + +__poll_t pvcalls_front_poll(struct file *file, struct socket *sock, + poll_table *wait) +{ + struct pvcalls_bedata *bedata; + struct sock_mapping *map; + __poll_t ret; + + map = pvcalls_enter_sock(sock); + if (IS_ERR(map)) + return EPOLLNVAL; + bedata = dev_get_drvdata(&pvcalls_front_dev->dev); + + if (map->active_socket) + ret = pvcalls_front_poll_active(file, bedata, map, wait); + else + ret = pvcalls_front_poll_passive(file, bedata, map, wait); + pvcalls_exit_sock(sock); + return ret; +} + +int pvcalls_front_release(struct socket *sock) +{ + struct pvcalls_bedata *bedata; + struct sock_mapping *map; + int req_id, notify, ret; + struct xen_pvcalls_request *req; + + if (sock->sk == NULL) + return 0; + + map = pvcalls_enter_sock(sock); + if (IS_ERR(map)) { + if (PTR_ERR(map) == -ENOTCONN) + return -EIO; + else + return 0; + } + bedata = dev_get_drvdata(&pvcalls_front_dev->dev); + + spin_lock(&bedata->socket_lock); + ret = get_request(bedata, &req_id); + if (ret < 0) { + spin_unlock(&bedata->socket_lock); + pvcalls_exit_sock(sock); + return ret; + } + sock->sk->sk_send_head = NULL; + + req = RING_GET_REQUEST(&bedata->ring, req_id); + req->req_id = req_id; + req->cmd = PVCALLS_RELEASE; + req->u.release.id = (uintptr_t)map; + + bedata->ring.req_prod_pvt++; + RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&bedata->ring, notify); + spin_unlock(&bedata->socket_lock); + if (notify) + notify_remote_via_irq(bedata->irq); + + wait_event(bedata->inflight_req, + READ_ONCE(bedata->rsp[req_id].req_id) == req_id); + + if (map->active_socket) { + /* + * Set in_error and wake up inflight_conn_req to force + * recvmsg waiters to exit. + */ + map->active.ring->in_error = -EBADF; + wake_up_interruptible(&map->active.inflight_conn_req); + + /* + * We need to make sure that sendmsg/recvmsg on this socket have + * not started before we've cleared sk_send_head here. The + * easiest way to guarantee this is to see that no pvcalls + * (other than us) is in progress on this socket. + */ + while (atomic_read(&map->refcount) > 1) + cpu_relax(); + + pvcalls_front_free_map(bedata, map); + } else { + wake_up(&bedata->inflight_req); + wake_up(&map->passive.inflight_accept_req); + + while (atomic_read(&map->refcount) > 1) + cpu_relax(); + + spin_lock(&bedata->socket_lock); + list_del(&map->list); + spin_unlock(&bedata->socket_lock); + if (READ_ONCE(map->passive.inflight_req_id) != PVCALLS_INVALID_ID && + READ_ONCE(map->passive.inflight_req_id) != 0) { + pvcalls_front_free_map(bedata, + map->passive.accept_map); + } + kfree(map); + } + WRITE_ONCE(bedata->rsp[req_id].req_id, PVCALLS_INVALID_ID); + + pvcalls_exit(); + return 0; +} + +static const struct xenbus_device_id pvcalls_front_ids[] = { + { "pvcalls" }, + { "" } +}; + +static int pvcalls_front_remove(struct xenbus_device *dev) +{ + struct pvcalls_bedata *bedata; + struct sock_mapping *map = NULL, *n; + + bedata = dev_get_drvdata(&pvcalls_front_dev->dev); + dev_set_drvdata(&dev->dev, NULL); + pvcalls_front_dev = NULL; + if (bedata->irq >= 0) + unbind_from_irqhandler(bedata->irq, dev); + + list_for_each_entry_safe(map, n, &bedata->socket_mappings, list) { + map->sock->sk->sk_send_head = NULL; + if (map->active_socket) { + map->active.ring->in_error = -EBADF; + wake_up_interruptible(&map->active.inflight_conn_req); + } + } + + smp_mb(); + while (atomic_read(&pvcalls_refcount) > 0) + cpu_relax(); + list_for_each_entry_safe(map, n, &bedata->socket_mappings, list) { + if (map->active_socket) { + /* No need to lock, refcount is 0 */ + pvcalls_front_free_map(bedata, map); + } else { + list_del(&map->list); + kfree(map); + } + } + if (bedata->ref != -1) + gnttab_end_foreign_access(bedata->ref, NULL); + kfree(bedata->ring.sring); + kfree(bedata); + xenbus_switch_state(dev, XenbusStateClosed); + return 0; +} + +static int pvcalls_front_probe(struct xenbus_device *dev, + const struct xenbus_device_id *id) +{ + int ret = -ENOMEM, i; + evtchn_port_t evtchn; + unsigned int max_page_order, function_calls, len; + char *versions; + grant_ref_t gref_head = 0; + struct xenbus_transaction xbt; + struct pvcalls_bedata *bedata = NULL; + struct xen_pvcalls_sring *sring; + + if (pvcalls_front_dev != NULL) { + dev_err(&dev->dev, "only one PV Calls connection supported\n"); + return -EINVAL; + } + + versions = xenbus_read(XBT_NIL, dev->otherend, "versions", &len); + if (IS_ERR(versions)) + return PTR_ERR(versions); + if (!len) + return -EINVAL; + if (strcmp(versions, "1")) { + kfree(versions); + return -EINVAL; + } + kfree(versions); + max_page_order = xenbus_read_unsigned(dev->otherend, + "max-page-order", 0); + if (max_page_order < PVCALLS_RING_ORDER) + return -ENODEV; + function_calls = xenbus_read_unsigned(dev->otherend, + "function-calls", 0); + /* See XENBUS_FUNCTIONS_CALLS in pvcalls.h */ + if (function_calls != 1) + return -ENODEV; + pr_info("%s max-page-order is %u\n", __func__, max_page_order); + + bedata = kzalloc(sizeof(struct pvcalls_bedata), GFP_KERNEL); + if (!bedata) + return -ENOMEM; + + dev_set_drvdata(&dev->dev, bedata); + pvcalls_front_dev = dev; + init_waitqueue_head(&bedata->inflight_req); + INIT_LIST_HEAD(&bedata->socket_mappings); + spin_lock_init(&bedata->socket_lock); + bedata->irq = -1; + bedata->ref = -1; + + for (i = 0; i < PVCALLS_NR_RSP_PER_RING; i++) + bedata->rsp[i].req_id = PVCALLS_INVALID_ID; + + sring = (struct xen_pvcalls_sring *) __get_free_page(GFP_KERNEL | + __GFP_ZERO); + if (!sring) + goto error; + SHARED_RING_INIT(sring); + FRONT_RING_INIT(&bedata->ring, sring, XEN_PAGE_SIZE); + + ret = xenbus_alloc_evtchn(dev, &evtchn); + if (ret) + goto error; + + bedata->irq = bind_evtchn_to_irqhandler(evtchn, + pvcalls_front_event_handler, + 0, "pvcalls-frontend", dev); + if (bedata->irq < 0) { + ret = bedata->irq; + goto error; + } + + ret = gnttab_alloc_grant_references(1, &gref_head); + if (ret < 0) + goto error; + ret = gnttab_claim_grant_reference(&gref_head); + if (ret < 0) + goto error; + bedata->ref = ret; + gnttab_grant_foreign_access_ref(bedata->ref, dev->otherend_id, + virt_to_gfn((void *)sring), 0); + + again: + ret = xenbus_transaction_start(&xbt); + if (ret) { + xenbus_dev_fatal(dev, ret, "starting transaction"); + goto error; + } + ret = xenbus_printf(xbt, dev->nodename, "version", "%u", 1); + if (ret) + goto error_xenbus; + ret = xenbus_printf(xbt, dev->nodename, "ring-ref", "%d", bedata->ref); + if (ret) + goto error_xenbus; + ret = xenbus_printf(xbt, dev->nodename, "port", "%u", + evtchn); + if (ret) + goto error_xenbus; + ret = xenbus_transaction_end(xbt, 0); + if (ret) { + if (ret == -EAGAIN) + goto again; + xenbus_dev_fatal(dev, ret, "completing transaction"); + goto error; + } + xenbus_switch_state(dev, XenbusStateInitialised); + + return 0; + + error_xenbus: + xenbus_transaction_end(xbt, 1); + xenbus_dev_fatal(dev, ret, "writing xenstore"); + error: + pvcalls_front_remove(dev); + return ret; +} + +static void pvcalls_front_changed(struct xenbus_device *dev, + enum xenbus_state backend_state) +{ + switch (backend_state) { + case XenbusStateReconfiguring: + case XenbusStateReconfigured: + case XenbusStateInitialising: + case XenbusStateInitialised: + case XenbusStateUnknown: + break; + + case XenbusStateInitWait: + break; + + case XenbusStateConnected: + xenbus_switch_state(dev, XenbusStateConnected); + break; + + case XenbusStateClosed: + if (dev->state == XenbusStateClosed) + break; + /* Missed the backend's CLOSING state */ + fallthrough; + case XenbusStateClosing: + xenbus_frontend_closed(dev); + break; + } +} + +static struct xenbus_driver pvcalls_front_driver = { + .ids = pvcalls_front_ids, + .probe = pvcalls_front_probe, + .remove = pvcalls_front_remove, + .otherend_changed = pvcalls_front_changed, + .not_essential = true, +}; + +static int __init pvcalls_frontend_init(void) +{ + if (!xen_domain()) + return -ENODEV; + + pr_info("Initialising Xen pvcalls frontend driver\n"); + + return xenbus_register_frontend(&pvcalls_front_driver); +} + +module_init(pvcalls_frontend_init); + +MODULE_DESCRIPTION("Xen PV Calls frontend driver"); +MODULE_AUTHOR("Stefano Stabellini <sstabellini@kernel.org>"); +MODULE_LICENSE("GPL"); |