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From:   Stefano Garzarella <sgarzare@redhat.com>
To:     netdev@vger.kernel.org
Cc:     "Michael S. Tsirkin" <mst@redhat.com>, kvm@vger.kernel.org,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Jason Wang <jasowang@redhat.com>,
        "David S. Miller" <davem@davemloft.net>,
        Dexuan Cui <decui@microsoft.com>,
        Haiyang Zhang <haiyangz@microsoft.com>,
        Jorgen Hansen <jhansen@vmware.com>,
        Sasha Levin <sashal@kernel.org>, linux-kernel@vger.kernel.org,
        Arnd Bergmann <arnd@arndb.de>,
        Stefan Hajnoczi <stefanha@redhat.com>,
        linux-hyperv@vger.kernel.org,
        "K. Y. Srinivasan" <kys@microsoft.com>,
        Stephen Hemminger <sthemmin@microsoft.com>,
        virtualization@lists.linux-foundation.org
Subject: [PATCH net-next 12/14] vsock/vmci: register vmci_transport only when VMCI guest/host are active
Date:   Wed, 23 Oct 2019 11:55:52 +0200
Message-Id: <20191023095554.11340-13-sgarzare@redhat.com>
In-Reply-To: <20191023095554.11340-1-sgarzare@redhat.com>
References: <20191023095554.11340-1-sgarzare@redhat.com>
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Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

To allow other transports to be loaded with vmci_transport,
we register the vmci_transport as G2H or H2G only when a VMCI guest
or host is active.

To do that, this patch adds a callback registered in the vmci driver
that will be called when a new host or guest become active.
This callback will register the vmci_transport in the VSOCK core.
If the transport is already registered, we ignore the error coming
from vsock_core_register().

Cc: Jorgen Hansen <jhansen@vmware.com>
Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
---
 drivers/misc/vmw_vmci/vmci_driver.c | 50 +++++++++++++++++++++++++++++
 drivers/misc/vmw_vmci/vmci_driver.h |  2 ++
 drivers/misc/vmw_vmci/vmci_guest.c  |  2 ++
 drivers/misc/vmw_vmci/vmci_host.c   |  7 ++++
 include/linux/vmw_vmci_api.h        |  2 ++
 net/vmw_vsock/vmci_transport.c      | 29 +++++++++++------
 6 files changed, 82 insertions(+), 10 deletions(-)

diff --git a/drivers/misc/vmw_vmci/vmci_driver.c b/drivers/misc/vmw_vmci/vm=
ci_driver.c
index 819e35995d32..195afbd7edc1 100644
--- a/drivers/misc/vmw_vmci/vmci_driver.c
+++ b/drivers/misc/vmw_vmci/vmci_driver.c
@@ -28,6 +28,9 @@ MODULE_PARM_DESC(disable_guest,
 static bool vmci_guest_personality_initialized;
 static bool vmci_host_personality_initialized;
=20
+static DEFINE_MUTEX(vmci_vsock_mutex); /* protects vmci_vsock_transport_cb=
 */
+static vmci_vsock_cb vmci_vsock_transport_cb;
+
 /*
  * vmci_get_context_id() - Gets the current context ID.
  *
@@ -45,6 +48,53 @@ u32 vmci_get_context_id(void)
 }
 EXPORT_SYMBOL_GPL(vmci_get_context_id);
=20
+/*
+ * vmci_register_vsock_callback() - Register the VSOCK vmci_transport call=
back.
+ *
+ * The callback will be called every time a new host or guest become activ=
e,
+ * or if they are already active when this function is called.
+ * To unregister the callback, call this function with NULL parameter.
+ *
+ * Returns 0 on success. -EBUSY if a callback is already registered.
+ */
+int vmci_register_vsock_callback(vmci_vsock_cb callback)
+{
+=09int err =3D 0;
+
+=09mutex_lock(&vmci_vsock_mutex);
+
+=09if (vmci_vsock_transport_cb && callback) {
+=09=09err =3D -EBUSY;
+=09=09goto out;
+=09}
+
+=09vmci_vsock_transport_cb =3D callback;
+
+=09if (!vmci_vsock_transport_cb)
+=09=09goto out;
+
+=09if (vmci_guest_code_active())
+=09=09vmci_vsock_transport_cb(false);
+
+=09if (vmci_host_users() > 0)
+=09=09vmci_vsock_transport_cb(true);
+
+out:
+=09mutex_unlock(&vmci_vsock_mutex);
+=09return err;
+}
+EXPORT_SYMBOL_GPL(vmci_register_vsock_callback);
+
+void vmci_call_vsock_callback(bool is_host)
+{
+=09mutex_lock(&vmci_vsock_mutex);
+
+=09if (vmci_vsock_transport_cb)
+=09=09vmci_vsock_transport_cb(is_host);
+
+=09mutex_unlock(&vmci_vsock_mutex);
+}
+
 static int __init vmci_drv_init(void)
 {
 =09int vmci_err;
diff --git a/drivers/misc/vmw_vmci/vmci_driver.h b/drivers/misc/vmw_vmci/vm=
ci_driver.h
index aab81b67670c..990682480bf6 100644
--- a/drivers/misc/vmw_vmci/vmci_driver.h
+++ b/drivers/misc/vmw_vmci/vmci_driver.h
@@ -36,10 +36,12 @@ extern struct pci_dev *vmci_pdev;
=20
 u32 vmci_get_context_id(void);
 int vmci_send_datagram(struct vmci_datagram *dg);
+void vmci_call_vsock_callback(bool is_host);
=20
 int vmci_host_init(void);
 void vmci_host_exit(void);
 bool vmci_host_code_active(void);
+int vmci_host_users(void);
=20
 int vmci_guest_init(void);
 void vmci_guest_exit(void);
diff --git a/drivers/misc/vmw_vmci/vmci_guest.c b/drivers/misc/vmw_vmci/vmc=
i_guest.c
index 7a84a48c75da..cc8eeb361fcd 100644
--- a/drivers/misc/vmw_vmci/vmci_guest.c
+++ b/drivers/misc/vmw_vmci/vmci_guest.c
@@ -637,6 +637,8 @@ static int vmci_guest_probe_device(struct pci_dev *pdev=
,
 =09=09  vmci_dev->iobase + VMCI_CONTROL_ADDR);
=20
 =09pci_set_drvdata(pdev, vmci_dev);
+
+=09vmci_call_vsock_callback(false);
 =09return 0;
=20
 err_free_irq:
diff --git a/drivers/misc/vmw_vmci/vmci_host.c b/drivers/misc/vmw_vmci/vmci=
_host.c
index 833e2bd248a5..ff3c396146ff 100644
--- a/drivers/misc/vmw_vmci/vmci_host.c
+++ b/drivers/misc/vmw_vmci/vmci_host.c
@@ -108,6 +108,11 @@ bool vmci_host_code_active(void)
 =09     atomic_read(&vmci_host_active_users) > 0);
 }
=20
+int vmci_host_users(void)
+{
+=09return atomic_read(&vmci_host_active_users);
+}
+
 /*
  * Called on open of /dev/vmci.
  */
@@ -338,6 +343,8 @@ static int vmci_host_do_init_context(struct vmci_host_d=
ev *vmci_host_dev,
 =09vmci_host_dev->ct_type =3D VMCIOBJ_CONTEXT;
 =09atomic_inc(&vmci_host_active_users);
=20
+=09vmci_call_vsock_callback(true);
+
 =09retval =3D 0;
=20
 out:
diff --git a/include/linux/vmw_vmci_api.h b/include/linux/vmw_vmci_api.h
index acd9fafe4fc6..f28907345c80 100644
--- a/include/linux/vmw_vmci_api.h
+++ b/include/linux/vmw_vmci_api.h
@@ -19,6 +19,7 @@
 struct msghdr;
 typedef void (vmci_device_shutdown_fn) (void *device_registration,
 =09=09=09=09=09void *user_data);
+typedef void (*vmci_vsock_cb) (bool is_host);
=20
 int vmci_datagram_create_handle(u32 resource_id, u32 flags,
 =09=09=09=09vmci_datagram_recv_cb recv_cb,
@@ -37,6 +38,7 @@ int vmci_doorbell_destroy(struct vmci_handle handle);
 int vmci_doorbell_notify(struct vmci_handle handle, u32 priv_flags);
 u32 vmci_get_context_id(void);
 bool vmci_is_context_owner(u32 context_id, kuid_t uid);
+int vmci_register_vsock_callback(vmci_vsock_cb callback);
=20
 int vmci_event_subscribe(u32 event,
 =09=09=09 vmci_event_cb callback, void *callback_data,
diff --git a/net/vmw_vsock/vmci_transport.c b/net/vmw_vsock/vmci_transport.=
c
index 2eb3f16d53e7..04437f822d82 100644
--- a/net/vmw_vsock/vmci_transport.c
+++ b/net/vmw_vsock/vmci_transport.c
@@ -2053,19 +2053,22 @@ static bool vmci_check_transport(struct vsock_sock =
*vsk)
 =09return vsk->transport =3D=3D &vmci_transport;
 }
=20
-static int __init vmci_transport_init(void)
+void vmci_vsock_transport_cb(bool is_host)
 {
-=09int features =3D VSOCK_TRANSPORT_F_DGRAM | VSOCK_TRANSPORT_F_H2G;
-=09int cid;
-=09int err;
+=09int features;
=20
-=09cid =3D vmci_get_context_id();
+=09if (is_host)
+=09=09features =3D VSOCK_TRANSPORT_F_H2G;
+=09else
+=09=09features =3D VSOCK_TRANSPORT_F_G2H;
=20
-=09if (cid =3D=3D VMCI_INVALID_ID)
-=09=09return -EINVAL;
+=09vsock_core_register(&vmci_transport, features);
+}
=20
-=09if (cid !=3D VMCI_HOST_CONTEXT_ID)
-=09=09features |=3D VSOCK_TRANSPORT_F_G2H;
+static int __init vmci_transport_init(void)
+{
+=09int features =3D VSOCK_TRANSPORT_F_DGRAM;
+=09int err;
=20
 =09/* Create the datagram handle that we will use to send and receive all
 =09 * VSocket control messages for this context.
@@ -2079,7 +2082,6 @@ static int __init vmci_transport_init(void)
 =09=09pr_err("Unable to create datagram handle. (%d)\n", err);
 =09=09return vmci_transport_error_to_vsock_error(err);
 =09}
-
 =09err =3D vmci_event_subscribe(VMCI_EVENT_QP_RESUMED,
 =09=09=09=09   vmci_transport_qp_resumed_cb,
 =09=09=09=09   NULL, &vmci_transport_qp_resumed_sub_id);
@@ -2094,8 +2096,14 @@ static int __init vmci_transport_init(void)
 =09if (err < 0)
 =09=09goto err_unsubscribe;
=20
+=09err =3D vmci_register_vsock_callback(vmci_vsock_transport_cb);
+=09if (err < 0)
+=09=09goto err_unregister;
+
 =09return 0;
=20
+err_unregister:
+=09vsock_core_unregister(&vmci_transport);
 err_unsubscribe:
 =09vmci_event_unsubscribe(vmci_transport_qp_resumed_sub_id);
 err_destroy_stream_handle:
@@ -2121,6 +2129,7 @@ static void __exit vmci_transport_exit(void)
 =09=09vmci_transport_qp_resumed_sub_id =3D VMCI_INVALID_ID;
 =09}
=20
+=09vmci_register_vsock_callback(NULL);
 =09vsock_core_unregister(&vmci_transport);
 }
 module_exit(vmci_transport_exit);
--=20
2.21.0