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. 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. 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. 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 @Jorgen: Do you think it might be a problem to replace VMADDR_CID_RESERVED with VMADDR_CID_LOCAL? Thanks, Stefano 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 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 -- 2.21.0