Commit cb1c7d9b authored by Stefano Stabellini's avatar Stefano Stabellini Committed by Boris Ostrovsky
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xen/pvcalls: implement connect command 



Send PVCALLS_CONNECT to the backend. Allocate a new ring and evtchn for
the active socket.

Introduce fields in struct sock_mapping to keep track of active sockets.
Introduce a waitqueue to allow the frontend to wait on data coming from
the backend on the active socket (recvmsg command).

Two mutexes (one of reads and one for writes) will be used to protect
the active socket in and out rings from concurrent accesses.

Signed-off-by: default avatarStefano Stabellini <stefano@aporeto.com>
Reviewed-by: default avatarBoris Ostrovsky <boris.ostrovsky@oracle.com>
CC: boris.ostrovsky@oracle.com
CC: jgross@suse.com
Signed-off-by: default avatarBoris Ostrovsky <boris.ostrovsky@oracle.com>
parent 2195046b

drivers/xen/pvcalls-front.c

+158 −0
Original line number Diff line number Diff line
@@ -59,6 +59,18 @@ struct sock_mapping { 
	bool active_socket;

	struct list_head list;

	struct socket *sock;

	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;

	};

};



static inline int get_request(struct pvcalls_bedata *bedata, int *req_id)
@@ -121,6 +133,18 @@ static void pvcalls_front_free_map(struct pvcalls_bedata *bedata, 
{

}



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;
@@ -196,6 +220,132 @@ int pvcalls_front_socket(struct socket *sock) 
	return ret;

}



static int create_active(struct sock_mapping *map, int *evtchn)

{

	void *bytes;

	int ret = -ENOMEM, irq = -1, i;



	*evtchn = -1;

	init_waitqueue_head(&map->active.inflight_conn_req);



	map->active.ring = (struct pvcalls_data_intf *)

		__get_free_page(GFP_KERNEL | __GFP_ZERO);

	if (map->active.ring == NULL)

		goto out_error;

	map->active.ring->ring_order = PVCALLS_RING_ORDER;

	bytes = (void *)__get_free_pages(GFP_KERNEL | __GFP_ZERO,

					PVCALLS_RING_ORDER);

	if (bytes == NULL)

		goto out_error;

	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);



	map->active.data.in = bytes;

	map->active.data.out = bytes +

		XEN_FLEX_RING_SIZE(PVCALLS_RING_ORDER);



	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 (irq >= 0)

		unbind_from_irqhandler(irq, map);

	else if (*evtchn >= 0)

		xenbus_free_evtchn(pvcalls_front_dev, *evtchn);

	kfree(map->active.data.in);

	kfree(map->active.ring);

	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;



	if (addr->sa_family != AF_INET || sock->type != SOCK_STREAM)

		return -EOPNOTSUPP;



	pvcalls_enter();

	if (!pvcalls_front_dev) {

		pvcalls_exit();

		return -ENOTCONN;

	}



	bedata = dev_get_drvdata(&pvcalls_front_dev->dev);



	map = (struct sock_mapping *)sock->sk->sk_send_head;

	if (!map) {

		pvcalls_exit();

		return -ENOTSOCK;

	}



	spin_lock(&bedata->socket_lock);

	ret = get_request(bedata, &req_id);

	if (ret < 0) {

		spin_unlock(&bedata->socket_lock);

		pvcalls_exit();

		return ret;

	}

	ret = create_active(map, &evtchn);

	if (ret < 0) {

		spin_unlock(&bedata->socket_lock);

		pvcalls_exit();

		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();

	return ret;

}



static const struct xenbus_device_id pvcalls_front_ids[] = {

	{ "pvcalls" },

	{ "" }
@@ -212,6 +362,14 @@ static int pvcalls_front_remove(struct xenbus_device *dev) 
	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();

drivers/xen/pvcalls-front.h

+2 −0
Original line number Diff line number Diff line
@@ -4,5 +4,7 @@ 
#include <linux/net.h>



int pvcalls_front_socket(struct socket *sock);

int pvcalls_front_connect(struct socket *sock, struct sockaddr *addr,

			  int addr_len, int flags);



#endif

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