From: "Jorgen S. Hansen" <jhansen@vmware.com>
To: Dexuan Cui <decui@microsoft.com>
CC: "davem@davemloft.net" <davem@davemloft.net>,
        "netdev@vger.kernel.org" <netdev@vger.kernel.org>,
        "gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>,
        "devel@linuxdriverproject.org" <devel@linuxdriverproject.org>,
        KY Srinivasan <kys@microsoft.com>,
        "Haiyang Zhang" <haiyangz@microsoft.com>,
        Stephen Hemminger <sthemmin@microsoft.com>,
        George Zhang <georgezhang@vmware.com>,
        Michal Kubecek <mkubecek@suse.cz>, Asias He <asias@redhat.com>,
        Stefan Hajnoczi <stefanha@redhat.com>,
        "Vitaly Kuznetsov" <vkuznets@redhat.com>,
        Cathy Avery <cavery@redhat.com>,
        "jasowang@redhat.com" <jasowang@redhat.com>,
        Rolf Neugebauer <rolf.neugebauer@docker.com>,
        Dave Scott <dave.scott@docker.com>,
        "Marcelo Cerri" <marcelo.cerri@canonical.com>,
        "apw@canonical.com" <apw@canonical.com>,
        "olaf@aepfle.de" <olaf@aepfle.de>, "joe@perches.com" <joe@perches.com>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Dan Carpenter <dan.carpenter@oracle.com>
Subject: Re: [PATCH net-next 1/3] VMCI: only load on VMware hypervisor
Thread-Topic: [PATCH net-next 1/3] VMCI: only load on VMware hypervisor
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Date: Wed, 16 Aug 2017 19:44:47 +0000
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> On Aug 16, 2017, at 12:13 AM, Dexuan Cui <decui@microsoft.com> wrote:
> 
> 
> 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,

Thanks,
Jorgen