path: root/drivers/xen/pvcalls-front.c

// 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