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From:   Jorgen Hansen <jhansen@vmware.com>
To:     'Stefano Garzarella' <sgarzare@redhat.com>,
        "netdev@vger.kernel.org" <netdev@vger.kernel.org>
CC:     "virtualization@lists.linux-foundation.org" 
        <virtualization@lists.linux-foundation.org>,
        Dexuan Cui <decui@microsoft.com>,
        Stefan Hajnoczi <stefanha@redhat.com>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "kvm@vger.kernel.org" <kvm@vger.kernel.org>,
        "David S. Miller" <davem@davemloft.net>
Subject: RE: [PATCH net-next 0/6] vsock: add local transport support
Thread-Topic: [PATCH net-next 0/6] vsock: add local transport support
Thread-Index: AQHVnsi4kz4RAPX5S02yxj8Sa/r70aeVsxKg
Date:   Thu, 21 Nov 2019 14:45:32 +0000
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References: <20191119110121.14480-1-sgarzare@redhat.com>
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> From: Stefano Garzarella [mailto:sgarzare@redhat.com]
> Sent: Tuesday, November 19, 2019 12:01 PM
> This series introduces a new transport (vsock_loopback) to handle
> local communication.
> This could be useful to test vsock core itself and to allow developers
> to test their applications without launching a VM.
>=20
> Before this series, vmci and virtio transports allowed this behavior,
> but only in the guest.
> We are moving the loopback handling in a new transport, because it
> might be useful to provide this feature also in the host or when
> no H2G/G2H transports (hyperv, virtio, vmci) are loaded.
>=20
> The user can use the loopback with the new VMADDR_CID_LOCAL (that
> replaces VMADDR_CID_RESERVED) in any condition.
> Otherwise, if the G2H transport is loaded, it can also use the guest
> local CID as previously supported by vmci and virtio transports.
> If G2H transport is not loaded, the user can also use VMADDR_CID_HOST
> for local communication.
>=20
> Patch 1 is a cleanup to build virtio_transport_common without virtio
> Patch 2 adds the new VMADDR_CID_LOCAL, replacing
> VMADDR_CID_RESERVED
> Patch 3 adds a new feature flag to register a loopback transport
> Patch 4 adds the new vsock_loopback transport based on the loopback
>         implementation of virtio_transport
> Patch 5 implements the logic to use the local transport for loopback
>         communication
> Patch 6 removes the loopback from virtio_transport
>=20
> @Jorgen: Do you think it might be a problem to replace
> VMADDR_CID_RESERVED with VMADDR_CID_LOCAL?

No, that should be fine. It has never allowed for use with stream sockets i=
n
AF_VSOCK. The only potential use would be for datagram sockets, but that
side appears to be unaffected by your changes, since loopback is only
introduced for SOCK_STREAM.

>=20
> Thanks,
> Stefano
>=20
> Stefano Garzarella (6):
>   vsock/virtio_transport_common: remove unused virtio header includes
>   vsock: add VMADDR_CID_LOCAL definition
>   vsock: add local transport support in the vsock core
>   vsock: add vsock_loopback transport
>   vsock: use local transport when it is loaded
>   vsock/virtio: remove loopback handling
>=20
>  MAINTAINERS                             |   1 +
>  include/net/af_vsock.h                  |   2 +
>  include/uapi/linux/vm_sockets.h         |   8 +-
>  net/vmw_vsock/Kconfig                   |  12 ++
>  net/vmw_vsock/Makefile                  |   1 +
>  net/vmw_vsock/af_vsock.c                |  49 +++++-
>  net/vmw_vsock/virtio_transport.c        |  61 +------
>  net/vmw_vsock/virtio_transport_common.c |   3 -
>  net/vmw_vsock/vmci_transport.c          |   2 +-
>  net/vmw_vsock/vsock_loopback.c          | 217
> ++++++++++++++++++++++++
>  10 files changed, 283 insertions(+), 73 deletions(-)
>  create mode 100644 net/vmw_vsock/vsock_loopback.c
>=20
> --
> 2.21.0