/*
* (c) 2017 Stefano Stabellini <stefano@aporeto.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*/
#include <linux/module.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_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)
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;
};
static irqreturn_t pvcalls_front_event_handler(int irq, void *dev_id)
{
return IRQ_HANDLED;
}
static void pvcalls_front_free_map(struct pvcalls_bedata *bedata,
struct sock_mapping *map)
{
}
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);
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 >= 0)
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)
{
return 0;
}
static void pvcalls_front_changed(struct xenbus_device *dev,
enum xenbus_state backend_state)
{
}
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);
