[Xen-devel] [PATCH v7 08/18] xen/pvcalls: implement connect command

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

Allocate a socket. Keep track of socket <-> ring mappings with a new data
structure, called sock_mapping. Implement the connect command by calling
inet_stream_connect, and mapping the new indexes page and data ring.
Allocate a workqueue and a work_struct, called ioworker, to perform
reads and writes to the socket.

When an active socket is closed (sk_state_change), set in_error to
-ENOTCONN and notify the other end, as specified by the protocol.

sk_data_ready and pvcalls_back_ioworker will be implemented later.

Signed-off-by: Stefano Stabellini <stefano@xxxxxxxxxxx>
CC: boris.ostrovsky@xxxxxxxxxx
CC: jgross@xxxxxxxx
---
 drivers/xen/pvcalls-back.c | 179 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 179 insertions(+)

diff --git a/drivers/xen/pvcalls-back.c b/drivers/xen/pvcalls-back.c
index 1f176eb..13e4d62 100644
--- a/drivers/xen/pvcalls-back.c
+++ b/drivers/xen/pvcalls-back.c
@@ -54,6 +54,39 @@ struct pvcalls_fedata {
        struct semaphore socket_lock;
 };
 
+struct pvcalls_ioworker {
+       struct work_struct register_work;
+       struct workqueue_struct *wq;
+};
+
+struct sock_mapping {
+       struct list_head list;
+       struct pvcalls_fedata *fedata;
+       struct socket *sock;
+       uint64_t id;
+       grant_ref_t ref;
+       struct pvcalls_data_intf *ring;
+       void *bytes;
+       struct pvcalls_data data;
+       uint32_t ring_order;
+       int irq;
+       atomic_t read;
+       atomic_t write;
+       atomic_t io;
+       atomic_t release;
+       void (*saved_data_ready)(struct sock *sk);
+       struct pvcalls_ioworker ioworker;
+};
+
+static irqreturn_t pvcalls_back_conn_event(int irq, void *sock_map);
+static int pvcalls_back_release_active(struct xenbus_device *dev,
+                                      struct pvcalls_fedata *fedata,
+                                      struct sock_mapping *map);
+
+static void pvcalls_back_ioworker(struct work_struct *work)
+{
+}
+
 static int pvcalls_back_socket(struct xenbus_device *dev,
                struct xen_pvcalls_request *req)
 {
@@ -82,9 +115,150 @@ static int pvcalls_back_socket(struct xenbus_device *dev,
        return 0;
 }
 
+static void pvcalls_sk_state_change(struct sock *sock)
+{
+       struct sock_mapping *map = sock->sk_user_data;
+       struct pvcalls_data_intf *intf;
+
+       if (map == NULL)
+               return;
+
+       intf = map->ring;
+       intf->in_error = -ENOTCONN;
+       notify_remote_via_irq(map->irq);
+}
+
+static void pvcalls_sk_data_ready(struct sock *sock)
+{
+}
+
+static struct sock_mapping *pvcalls_new_active_socket(
+               struct pvcalls_fedata *fedata,
+               uint64_t id,
+               grant_ref_t ref,
+               uint32_t evtchn,
+               struct socket *sock)
+{
+       int ret;
+       struct sock_mapping *map;
+       void *page;
+
+       map = kzalloc(sizeof(*map), GFP_KERNEL);
+       if (map == NULL)
+               return NULL;
+
+       map->fedata = fedata;
+       map->sock = sock;
+       map->id = id;
+       map->ref = ref;
+
+       ret = xenbus_map_ring_valloc(fedata->dev, &ref, 1, &page);
+       if (ret < 0)
+               goto out;
+       map->ring = page;
+       map->ring_order = map->ring->ring_order;
+       /* first read the order, then map the data ring */
+       virt_rmb();
+       if (map->ring_order > MAX_RING_ORDER) {
+               pr_warn("%s frontend requested ring_order %u, which is > MAX 
(%u)\n",
+                               __func__, map->ring_order, MAX_RING_ORDER);
+               goto out;
+       }
+       ret = xenbus_map_ring_valloc(fedata->dev, map->ring->ref,
+                                    (1 << map->ring_order), &page);
+       if (ret < 0)
+               goto out;
+       map->bytes = page;
+
+       ret = bind_interdomain_evtchn_to_irqhandler(fedata->dev->otherend_id,
+                                                   evtchn,
+                                                   pvcalls_back_conn_event,
+                                                   0,
+                                                   "pvcalls-backend",
+                                                   map);
+       if (ret < 0)
+               goto out;
+       map->irq = ret;
+
+       map->data.in = map->bytes;
+       map->data.out = map->bytes + XEN_FLEX_RING_SIZE(map->ring_order);
+       
+       map->ioworker.wq = alloc_workqueue("pvcalls_io", WQ_UNBOUND, 1);
+       if (!map->ioworker.wq)
+               goto out;
+       atomic_set(&map->io, 1);
+       INIT_WORK(&map->ioworker.register_work, pvcalls_back_ioworker);
+
+       down(&fedata->socket_lock);
+       list_add_tail(&map->list, &fedata->socket_mappings);
+       up(&fedata->socket_lock);
+
+       write_lock_bh(&map->sock->sk->sk_callback_lock);
+       map->saved_data_ready = map->sock->sk->sk_data_ready;
+       map->sock->sk->sk_user_data = map;
+       map->sock->sk->sk_data_ready = pvcalls_sk_data_ready;
+       map->sock->sk->sk_state_change = pvcalls_sk_state_change;
+       write_unlock_bh(&map->sock->sk->sk_callback_lock);
+
+       return map;
+out:
+       down(&fedata->socket_lock);
+       list_del(&map->list);
+       pvcalls_back_release_active(fedata->dev, fedata, map);
+       up(&fedata->socket_lock);
+       return NULL;
+}
+
 static int pvcalls_back_connect(struct xenbus_device *dev,
                                struct xen_pvcalls_request *req)
 {
+       struct pvcalls_fedata *fedata;
+       int ret = -EINVAL;
+       struct socket *sock;
+       struct sock_mapping *map;
+       struct xen_pvcalls_response *rsp;
+       struct sockaddr *sa = (struct sockaddr *)&req->u.connect.addr;
+
+       fedata = dev_get_drvdata(&dev->dev);
+
+       if (req->u.connect.len < sizeof(sa->sa_family) ||
+           req->u.connect.len > sizeof(req->u.connect.addr) ||
+           sa->sa_family != AF_INET)
+               goto out;
+
+       ret = sock_create(AF_INET, SOCK_STREAM, 0, &sock);
+       if (ret < 0)
+               goto out;
+       ret = inet_stream_connect(sock, sa, req->u.connect.len, 0);
+       if (ret < 0) {
+               sock_release(sock);
+               goto out;
+       }
+       
+       map = pvcalls_new_active_socket(fedata,
+                                       req->u.connect.id,
+                                       req->u.connect.ref,
+                                       req->u.connect.evtchn,
+                                       sock);
+       if (!map) {
+               ret = -EFAULT;
+               sock_release(map->sock);
+       }
+
+out:
+       rsp = RING_GET_RESPONSE(&fedata->ring, fedata->ring.rsp_prod_pvt++);
+       rsp->req_id = req->req_id;
+       rsp->cmd = req->cmd;
+       rsp->u.connect.id = req->u.connect.id;
+       rsp->ret = ret;
+
+       return 0;
+}
+
+static int pvcalls_back_release_active(struct xenbus_device *dev,
+                                      struct pvcalls_fedata *fedata,
+                                      struct sock_mapping *map)
+{
        return 0;
 }
 
@@ -206,6 +380,11 @@ static irqreturn_t pvcalls_back_event(int irq, void 
*dev_id)
        return IRQ_HANDLED;
 }
 
+static irqreturn_t pvcalls_back_conn_event(int irq, void *sock_map)
+{
+       return IRQ_HANDLED;
+}
+
 static int backend_connect(struct xenbus_device *dev)
 {
        int err, evtchn;
-- 
1.9.1


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