blob: 7984645b59563b7fc974ec4ecfcc10fb2dbf3e39 [file] [log] [blame] [edit]
// 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 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], 0, 0);
gnttab_end_foreign_access(map->active.ref, 0, 0);
free_page((unsigned long)map->active.ring);
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((unsigned long)map->active.data.in,
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 = (void *)__get_free_pages(GFP_KERNEL | __GFP_ZERO,
PVCALLS_RING_ORDER);
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, 0, 0);
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,
};
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");