[RFC PATCH 00/13] vsock: add multi-transports support

[Stefano Garzarella <sgarzare@redhat.com>]

Hi all,
this series adds the multi-transports support to vsock, following
this proposal:
https://www.spinics.net/lists/netdev/msg575792.html

With the multi-transports support, we can use vsock with nested VMs
(using also different hypervisors) loading both guest->host and
host->guest transports at the same time.
Before this series, vmci-transport supported this behavior but only
using VMware hypervisor on L0, L1, etc.

The first 8 patches are cleanups and preparations, maybe some of
these can go regardless of this series.

Patch 9 changes the hvs_remote_addr_init(). setting the
VMADDR_CID_HOST as remote CID instead of VMADDR_CID_ANY to make
the choice of transport to be used work properly.
@Dexuan Could this change break anything?

Patch 10 adds multi-transports support.
RFC:
- I'd like to move MODULE_ALIAS_NETPROTO(PF_VSOCK) to af_vsock.c.
  @Jorgen could this break the VMware products?

- DGRAM sockets are handled as before, I don't know if make sense
  work on it now, or when another transport will support DGRAM.
  The big issues here is that we cannot link 1-1 a socket to
  transport as for stream sockets since DGRAM is not
  connection-oriented.

Patches 11 and 12 maybe can be merged with patch 10.
Patch 11 maybe is tricky, but it allows to have vmci_transport and
vhost_vsock loaded at the same time and it also alleviates the
problem of having MODULE_ALIAS_NETPROTO(PF_VSOCK) in vmci_transport.c
Patch 12 prevents the transport modules unloading while sockets are
assigned to them.

Patch 13 fixes an issue in the bind() logic discoverable only with
the new multi-transport support.

I've tested this series with nested KVM (vsock-transport [L0,L1],
virtio-transport[L1,L2]) and with VMware (L0) + KVM (L1)
(vmci-transport [L0,L1], vhost-transport [L1], virtio-transport[L2]).

@Dexuan please can you test on HyperV that I didn't break anything
even without nested VMs?
I'll try to setup a Windows host where to test the nested VMs.

Thanks in advance for your comments and suggestions,
Stefano

Stefano Garzarella (13):
  vsock/vmci: remove unused VSOCK_DEFAULT_CONNECT_TIMEOUT
  vsock: remove vm_sockets_get_local_cid()
  vsock: remove include/linux/vm_sockets.h file
  vsock: add 'transport' member in the struct vsock_sock
  vsock/virtio: add transport parameter to the
    virtio_transport_reset_no_sock()
  vsock: add 'struct vsock_sock *' param to vsock_core_get_transport()
  vsock: handle buffer_size sockopts in the core
  vsock: move vsock_insert_unbound() in the vsock_create()
  hv_sock: set VMADDR_CID_HOST in the hvs_remote_addr_init()
  vsock: add multi-transports support
  vsock: add 'transport_hg' to handle g2h\h2g transports
  vsock: prevent transport modules unloading
  vsock: fix bind() behaviour taking care of CID

 drivers/vhost/vsock.c                   |  96 +++---
 include/linux/virtio_vsock.h            |  18 +-
 include/linux/vm_sockets.h              |  15 -
 include/net/af_vsock.h                  |  35 ++-
 include/net/vsock_addr.h                |   2 +-
 net/vmw_vsock/af_vsock.c                | 374 ++++++++++++++++++------
 net/vmw_vsock/hyperv_transport.c        |  68 ++---
 net/vmw_vsock/virtio_transport.c        | 177 ++++++-----
 net/vmw_vsock/virtio_transport_common.c | 127 +++-----
 net/vmw_vsock/vmci_transport.c          | 123 +++-----
 net/vmw_vsock/vmci_transport.h          |   3 -
 net/vmw_vsock/vmci_transport_notify.h   |   1 -
 12 files changed, 555 insertions(+), 484 deletions(-)
 delete mode 100644 include/linux/vm_sockets.h

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2.21.0