linux-kernel - RE: [PATCH net-next 1/3] VMCI: only load on VMware hypervisor

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Date:   Thu, 17 Aug 2017 08:10:05 +0000
From:   Dexuan Cui <decui@...rosoft.com>
To:     "'Jorgen S. Hansen'" <jhansen@...are.com>,
        "'davem@...emloft.net'" <davem@...emloft.net>
CC:     "'netdev@...r.kernel.org'" <netdev@...r.kernel.org>,
        "'gregkh@...uxfoundation.org'" <gregkh@...uxfoundation.org>,
        "'devel@...uxdriverproject.org'" <devel@...uxdriverproject.org>,
        "KY Srinivasan" <kys@...rosoft.com>,
        Haiyang Zhang <haiyangz@...rosoft.com>,
        Stephen Hemminger <sthemmin@...rosoft.com>,
        'George Zhang' <georgezhang@...are.com>,
        'Michal Kubecek' <mkubecek@...e.cz>,
        'Asias He' <asias@...hat.com>,
        'Stefan Hajnoczi' <stefanha@...hat.com>,
        "'Vitaly Kuznetsov'" <vkuznets@...hat.com>,
        'Cathy Avery' <cavery@...hat.com>,
        "'jasowang@...hat.com'" <jasowang@...hat.com>,
        'Rolf Neugebauer' <rolf.neugebauer@...ker.com>,
        'Dave Scott' <dave.scott@...ker.com>,
        "'Marcelo Cerri'" <marcelo.cerri@...onical.com>,
        "'apw@...onical.com'" <apw@...onical.com>,
        "'olaf@...fle.de'" <olaf@...fle.de>,
        "'joe@...ches.com'" <joe@...ches.com>,
        "'linux-kernel@...r.kernel.org'" <linux-kernel@...r.kernel.org>,
        'Dan Carpenter' <dan.carpenter@...cle.com>
Subject: RE: [PATCH net-next 1/3] VMCI: only load on VMware hypervisor

> From: Dexuan Cui
> Sent: Wednesday, August 16, 2017 15:34
> > From: Jorgen S. Hansen [mailto:jhansen@...are.com]
> > > Without the patch, vmw_vsock_vmci_transport.ko and vmw_vmci.ko can
> > > automatically load when an application creates an AF_VSOCK socket.
> > >
> > > This is the expected good behavior on VMware hypervisor, but as we
> > > are going to add hv_sock.ko (i.e. Hyper-V transport for AF_VSOCK), we
> > > should make sure vmw_vsock_vmci_transport.ko doesn't load on Hyper-
> V,
> > > otherwise there is a -EBUSY conflict when both
> vmw_vsock_vmci_transport.ko
> > > and hv_sock.ko try to call vsock_core_init() on Hyper-V.
> >
> > The VMCI driver (vmw_vmci.ko) is used both by the VMware guest support
> > (VMware Tools primarily) and by our Workstation product. Always
> disabling the
> > VMCI driver on Hyper-V means that user won’t be able to run Workstation
> > nested in Linux VMs on Hyper-V. Since the VMCI driver itself isn’t the
> problem
> > here, maybe we could move the check to vmw_vsock_vmci_transport.ko?
> > Ideally, there should be some way for a user to have access to both
> protocols,
> > but for now disabling the VMCI socket transport for Hyper-V (possibly with
> a
> > module option to skip that check and always load it) but leaving the VMCI
> driver
> > functional would be better,
> >
> > Jorgen
> 
> Thank you for explaining the background!
> Then I'll make a new patch, following your suggestion.
> 
> -- Dexuan

Hi Jorgen, David,

Just now I posted a new patch
 "[PATCH] vsock: only load vmci transport on VMware hypervisor by default"
to replace this patch.

@Jorgen: 
FWIW, with the new patch, when I create an AF_VSOCK sockets on Hyper-V,
vmw_vmci.ko is also automatically loaded and 3 lines of kernel messages are
printed, but I think I'm OK with this, since it's harmless.

-- Dexuan