Linux-HyperV Archive on lore.kernel.org
 help / color / Atom feed
From: Jorgen Hansen <jhansen@vmware.com>
To: 'Stefano Garzarella' <sgarzare@redhat.com>
Cc: "netdev@vger.kernel.org" <netdev@vger.kernel.org>,
	"Michael S. Tsirkin" <mst@redhat.com>,
	"kvm@vger.kernel.org" <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>,
	Sasha Levin <sashal@kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Arnd Bergmann <arnd@arndb.de>,
	Stefan Hajnoczi <stefanha@redhat.com>,
	"linux-hyperv@vger.kernel.org" <linux-hyperv@vger.kernel.org>,
	"K. Y. Srinivasan" <kys@microsoft.com>,
	Stephen Hemminger <sthemmin@microsoft.com>,
	"virtualization@lists.linux-foundation.org" 
	<virtualization@lists.linux-foundation.org>
Subject: RE: [PATCH net-next 12/14] vsock/vmci: register vmci_transport only when VMCI guest/host are active
Date: Tue, 12 Nov 2019 10:03:54 +0000
Message-ID: <MWHPR05MB33769FD52B833FC1C82F0A80DA770@MWHPR05MB3376.namprd05.prod.outlook.com> (raw)
In-Reply-To: <20191111173053.erwfzawioxje635o@steredhat>

> From: Stefano Garzarella [mailto:sgarzare@redhat.com]
> Sent: Monday, November 11, 2019 6:31 PM
> On Mon, Nov 11, 2019 at 04:27:28PM +0000, Jorgen Hansen wrote:
> > > From: Stefano Garzarella [mailto:sgarzare@redhat.com]
> > > Sent: Wednesday, October 23, 2019 11:56 AM
> > >
> > > 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().
> >
> > So today this is mainly an issue for the VMCI vsock transport, because
> > VMCI autoloads with vsock (and with this solution it can continue to
> > do that, so none of our old products break due to changed behavior,
> > which is great).
> 
> I tried to not break anything :-)
> 
> >                  Shouldn't vhost behave similar, so that any module
> > that registers a h2g transport only does so if it is in active use?
> >
> 
> The vhost-vsock module will load when the first hypervisor open
> /dev/vhost-vsock, so in theory, when there's at least one active user.

Ok, sounds good then. 

> 
> >
> > > --- 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);
> > > +
> >
> > Since we don't unregister the transport if user count drops back to 0, we
> could
> > just call this the first time, a VM is powered on after the module is loaded.
> 
> Yes, make sense. can I use the 'vmci_host_active_users' or is better to
> add a new 'vmci_host_vsock_loaded'?
> 
> My doubt is that vmci_host_active_users can return to 0, so when it returns
> to 1, we call vmci_call_vsock_callback() again.

vmci_host_active_users can drop to 0 and then increase again, so having a flag
indicating whether the callback has been invoked would ensure that it is only
called once.

Thanks,
Jorgen



  reply index

Thread overview: 46+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-10-23  9:55 [PATCH net-next 00/14] vsock: add multi-transports support Stefano Garzarella
2019-10-23  9:55 ` [PATCH net-next 01/14] vsock/vmci: remove unused VSOCK_DEFAULT_CONNECT_TIMEOUT Stefano Garzarella
2019-10-30 14:54   ` Jorgen Hansen
2019-10-23  9:55 ` [PATCH net-next 02/14] vsock: remove vm_sockets_get_local_cid() Stefano Garzarella
2019-10-30 14:55   ` Jorgen Hansen
2019-10-23  9:55 ` [PATCH net-next 03/14] vsock: remove include/linux/vm_sockets.h file Stefano Garzarella
2019-10-30 14:57   ` Jorgen Hansen
2019-10-23  9:55 ` [PATCH net-next 04/14] vsock: add 'transport' member in the struct vsock_sock Stefano Garzarella
2019-10-30 14:57   ` Jorgen Hansen
2019-10-23  9:55 ` [PATCH net-next 05/14] vsock/virtio: add transport parameter to the virtio_transport_reset_no_sock() Stefano Garzarella
2019-10-23  9:55 ` [PATCH net-next 06/14] vsock: add 'struct vsock_sock *' param to vsock_core_get_transport() Stefano Garzarella
2019-10-30 15:01   ` Jorgen Hansen
2019-10-23  9:55 ` [PATCH net-next 07/14] vsock: handle buffer_size sockopts in the core Stefano Garzarella
2019-10-27  8:08   ` Stefan Hajnoczi
2019-10-30 15:08   ` Jorgen Hansen
2019-10-31  8:50     ` Stefano Garzarella
2019-10-23  9:55 ` [PATCH net-next 08/14] vsock: add vsock_create_connected() called by transports Stefano Garzarella
2019-10-27  8:12   ` Stefan Hajnoczi
2019-10-30 15:12   ` Jorgen Hansen
2019-10-23  9:55 ` [PATCH net-next 09/14] vsock: move vsock_insert_unbound() in the vsock_create() Stefano Garzarella
2019-10-30 15:12   ` Jorgen Hansen
2019-10-23  9:55 ` [PATCH net-next 10/14] hv_sock: set VMADDR_CID_HOST in the hvs_remote_addr_init() Stefano Garzarella
2019-10-23  9:55 ` [PATCH net-next 11/14] vsock: add multi-transports support Stefano Garzarella
2019-10-23 15:08   ` Stefano Garzarella
2019-10-30 15:40     ` Jorgen Hansen
2019-10-31  8:54       ` Stefano Garzarella
2019-11-11 13:53   ` Jorgen Hansen
2019-11-11 17:17     ` Stefano Garzarella
2019-11-12  9:59       ` Jorgen Hansen
2019-11-12 10:36         ` Stefano Garzarella
2019-11-13 14:30           ` Jorgen Hansen
2019-11-13 16:38             ` Stefano Garzarella
2019-10-23  9:55 ` [PATCH net-next 12/14] vsock/vmci: register vmci_transport only when VMCI guest/host are active Stefano Garzarella
2019-10-27  8:17   ` Stefan Hajnoczi
2019-10-29 16:35     ` Stefano Garzarella
2019-11-04 10:10   ` Stefano Garzarella
2019-11-11 16:27   ` Jorgen Hansen
2019-11-11 17:30     ` Stefano Garzarella
2019-11-12 10:03       ` Jorgen Hansen [this message]
2019-11-12 10:42         ` Stefano Garzarella
2019-10-23  9:55 ` [PATCH net-next 13/14] vsock: prevent transport modules unloading Stefano Garzarella
2019-11-11 16:36   ` Jorgen Hansen
2019-10-23  9:55 ` [PATCH net-next 14/14] vsock: fix bind() behaviour taking care of CID Stefano Garzarella
2019-11-11 16:53   ` Jorgen Hansen
2019-10-27  8:01 ` [PATCH net-next 00/14] vsock: add multi-transports support Stefan Hajnoczi
2019-10-29 16:27   ` Stefano Garzarella

Reply instructions:

You may reply publically to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=MWHPR05MB33769FD52B833FC1C82F0A80DA770@MWHPR05MB3376.namprd05.prod.outlook.com \
    --to=jhansen@vmware.com \
    --cc=arnd@arndb.de \
    --cc=davem@davemloft.net \
    --cc=decui@microsoft.com \
    --cc=gregkh@linuxfoundation.org \
    --cc=haiyangz@microsoft.com \
    --cc=jasowang@redhat.com \
    --cc=kvm@vger.kernel.org \
    --cc=kys@microsoft.com \
    --cc=linux-hyperv@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=mst@redhat.com \
    --cc=netdev@vger.kernel.org \
    --cc=sashal@kernel.org \
    --cc=sgarzare@redhat.com \
    --cc=stefanha@redhat.com \
    --cc=sthemmin@microsoft.com \
    --cc=virtualization@lists.linux-foundation.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

Linux-HyperV Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/linux-hyperv/0 linux-hyperv/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-hyperv linux-hyperv/ https://lore.kernel.org/linux-hyperv \
		linux-hyperv@vger.kernel.org
	public-inbox-index linux-hyperv

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.linux-hyperv


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git