um: Add SPDX headers for files in arch/um/drivers

Convert files to use SPDX header. All files are licensed under the GPLv2.

Signed-off-by: Alex Dewar <alex.dewar@gmx.co.uk>
Signed-off-by: Richard Weinberger <richard@nod.at>

um: Added support for unix socket transports and bess transport

This adds support for the UNIX domain socket transports in
general and implements a Netsys::BESS compatible transport
interface.
For details on Netsys::BESS see https://github.com/NetSys/bess

Signed-off-by: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Signed-off-by: Richard Weinberger <richard@nod.at>

um: Add legacy tap support and rename existing vector to hybrid

1. Adds legacy tap support
2. Renames tap+raw as hybrid

Signed-off-by: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Signed-off-by: Richard Weinberger <richard@nod.at>

net: in virtio_net_hdr only add VLAN_HLEN to csum_start if payload holds vlan

Tun, tap, virtio, packet and uml vector all use struct virtio_net_hdr
to communicate packet metadata to userspace.

For skbuffs with vlan, the first two return the packet as it may have
existed on the wire, inserting the VLAN tag in the user buffer. Then
virtio_net_hdr.csum_start needs to be adjusted by VLAN_HLEN bytes.

Commit f09e2249c4f5 ("macvtap: restore vlan header on user read")
added this feature to macvtap. Commit 3ce9b20f1971 ("macvtap: Fix
csum_start when VLAN tags are present") then fixed up csum_start.

Virtio, packet and uml do not insert the vlan header in the user
buffer.

When introducing virtio_net_hdr_from_skb to deduplicate filling in
the virtio_net_hdr, the variant from macvtap which adds VLAN_HLEN was
applied uniformly, breaking csum offset for packets with vlan on
virtio and packet.

Make insertion of VLAN_HLEN optional. Convert the callers to pass it
when needed.

Fixes: e858fae2b0b8f4 ("virtio_net: use common code for virtio_net_hdr and skb GSO conversion")
Fixes: 1276f24eeef2 ("packet: use common code for virtio_net_hdr and skb GSO conversion")
Signed-off-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

High Performance UML Vector Network Driver

1. Provides infrastructure for vector IO using recvmmsg/sendmmsg.
1.1. Multi-message read.
1.2. Multi-message write.
1.3. Optimized queue support for multi-packet enqueue/dequeue.
1.4. BQL/DQL support.
2. Implements transports for several transports as well support
for direct wiring of PWEs to NIC. Allows direct connection of VMs
to host, other VMs and network devices with no switch in use.
2.1. Raw socket >4 times higher PPS and 10 times higher tcp RX
than existing pcap based transport (> 4Gbit)
2.2. New tap transport using socket RX and tap xmit. Similar
performance improvements (>4Gbit)
2.3. GRE transport - direct wiring to GRE PWE
2.4. L2TPv3 transport - direct wiring to L2TPv3 PWE
3. Tuning, performance and offload related setting support via ethtool.
4. Initial BPF support - used in tap/raw to avoid software looping
5. Scatter Gather support.
6. VNET and checksum offload support for raw socket transport.
7. TSO/GSO support where applicable or available
8. Migrates all error messages to netdevice_*() and rate limits
them where needed.

Signed-off-by: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Signed-off-by: Richard Weinberger <richard@nod.at>