Re: [PATCH net-next 12/14] vsock/vmci: register vmci_transport only when VMCI guest/host are active

Stefano Garzarella
2019-11-04T10:10:20Z

Hi Jorgen,
I'm preparing the v2, but first, if you have time, I'd like to have
a comment from you on this patch that modifies a bit vmci.

Thank you very much,
Stefano

On Wed, Oct 23, 2019 at 11:55:52AM +0200, Stefano Garzarella wrote:
> 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/vmci_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;
>
> +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);
>
> +/*
> + * vmci_register_vsock_callback() - Register the VSOCK vmci_transport callback.
> + *
> + * The callback will be called every time a new host or guest become active,
> + * 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)
> +{
> + int err = 0;
> +
> + mutex_lock(&vmci_vsock_mutex);
> +
> + if (vmci_vsock_transport_cb && callback) {
> + err = -EBUSY;
> + goto out;
> + }
> +
> + vmci_vsock_transport_cb = callback;
> +
> + if (!vmci_vsock_transport_cb)
> + goto out;
> +
> + if (vmci_guest_code_active())
> + vmci_vsock_transport_cb(false);
> +
> + if (vmci_host_users() > 0)
> + vmci_vsock_transport_cb(true);
> +
> +out:
> + mutex_unlock(&vmci_vsock_mutex);
> + return err;
> +}
> +EXPORT_SYMBOL_GPL(vmci_register_vsock_callback);
> +
> +void vmci_call_vsock_callback(bool is_host)
> +{
> + mutex_lock(&vmci_vsock_mutex);
> +
> + if (vmci_vsock_transport_cb)
> + vmci_vsock_transport_cb(is_host);
> +
> + mutex_unlock(&vmci_vsock_mutex);
> +}
> +
> static int __init vmci_drv_init(void)
> {
> int vmci_err;
> diff --git a/drivers/misc/vmw_vmci/vmci_driver.h b/drivers/misc/vmw_vmci/vmci_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;
>
> u32 vmci_get_context_id(void);
> int vmci_send_datagram(struct vmci_datagram *dg);
> +void vmci_call_vsock_callback(bool is_host);
>
> int vmci_host_init(void);
> void vmci_host_exit(void);
> bool vmci_host_code_active(void);
> +int vmci_host_users(void);
>
> 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/vmci_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,
> vmci_dev->iobase + VMCI_CONTROL_ADDR);
>
> pci_set_drvdata(pdev, vmci_dev);
> +
> + vmci_call_vsock_callback(false);
> return 0;
>
> 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)
> atomic_read(&vmci_host_active_users) > 0);
> }
>
> +int vmci_host_users(void)
> +{
> + return 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_dev *vmci_host_dev,
> vmci_host_dev->ct_type = VMCIOBJ_CONTEXT;
> atomic_inc(&vmci_host_active_users);
>
> + vmci_call_vsock_callback(true);
> +
> retval = 0;
>
> 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,
> void *user_data);
> +typedef void (*vmci_vsock_cb) (bool is_host);
>
> int vmci_datagram_create_handle(u32 resource_id, u32 flags,
> vmci_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);
>
> int vmci_event_subscribe(u32 event,
> 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)
> return vsk->transport == &vmci_transport;
> }
>
> -static int __init vmci_transport_init(void)
> +void vmci_vsock_transport_cb(bool is_host)
> {
> - int features = VSOCK_TRANSPORT_F_DGRAM | VSOCK_TRANSPORT_F_H2G;
> - int cid;
> - int err;
> + int features;
>
> - cid = vmci_get_context_id();
> + if (is_host)
> + features = VSOCK_TRANSPORT_F_H2G;
> + else
> + features = VSOCK_TRANSPORT_F_G2H;
>
> - if (cid == VMCI_INVALID_ID)
> - return -EINVAL;
> + vsock_core_register(&vmci_transport, features);
> +}
>
> - if (cid != VMCI_HOST_CONTEXT_ID)
> - features |= VSOCK_TRANSPORT_F_G2H;
> +static int __init vmci_transport_init(void)
> +{
> + int features = VSOCK_TRANSPORT_F_DGRAM;
> + int err;
>
> /* Create the datagram handle that we will use to send and receive all
> * VSocket control messages for this context.
> @@ -2079,7 +2082,6 @@ static int __init vmci_transport_init(void)
> pr_err("Unable to create datagram handle. (%d)\n", err);
> return vmci_transport_error_to_vsock_error(err);
> }
> -
> err = vmci_event_subscribe(VMCI_EVENT_QP_RESUMED,
> vmci_transport_qp_resumed_cb,
> NULL, &vmci_transport_qp_resumed_sub_id);
> @@ -2094,8 +2096,14 @@ static int __init vmci_transport_init(void)
> if (err < 0)
> goto err_unsubscribe;
>
> + err = vmci_register_vsock_callback(vmci_vsock_transport_cb);
> + if (err < 0)
> + goto err_unregister;
> +
> return 0;
>
> +err_unregister:
> + vsock_core_unregister(&vmci_transport);
> err_unsubscribe:
> vmci_event_unsubscribe(vmci_transport_qp_resumed_sub_id);
> err_destroy_stream_handle:
> @@ -2121,6 +2129,7 @@ static void __exit vmci_transport_exit(void)
> vmci_transport_qp_resumed_sub_id = VMCI_INVALID_ID;
> }
>
> + vmci_register_vsock_callback(NULL);
> vsock_core_unregister(&vmci_transport);
> }
> module_exit(vmci_transport_exit);
> --
> 2.21.0
>

--