opencores_eth: flush queue whenever can_receive can go from false to true

The following registers control whether MAC can receive frames:
- MODER.RXEN bit that enables/disables receiver;
- TX_BD_NUM register that specifies number of RX descriptors.
Notify QEMU networking core when the MAC is ready to receive frames.
Discard frame and raise BUSY interrupt when the frame arrives but the
current RX descriptor is not empty.

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
net: change vnet-hdr TAP prototypes

The tap_has_vnet_hdr() and tap_has_vnet_hdr_len() functions used
to return int, even though they only return true/false values.
This patch changes the prototypes to return bool.

Signed-off-by: Vincenzo Maffione <v.maffione@gmail.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
net: extend NetClientInfo for offloading

Some new callbacks have been added to generalize the operations done
by virtio-net and vmxnet3 frontends to manipulate TAP offloadings.

Signed-off-by: Vincenzo Maffione <v.maffione@gmail.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
net: TAP uses NetClientInfo offloading callbacks

The TAP NetClientInfo structure is inizialized with the TAP-specific
functions that manipulates offloading features.

Signed-off-by: Vincenzo Maffione <v.maffione@gmail.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
net: virtio-net and vmxnet3 use offloading API

With this patch, virtio-net and vmxnet3 frontends make
use of the qemu_peer_* API for backend offloadings manipulations,
instead of calling TAP-specific functions directly.
We also remove the existing checks which prevent those frontends
from using offloadings with backends different from TAP (e.g. netmap).

Signed-off-by: Vincenzo Maffione <v.maffione@gmail.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
net: make tap offloading callbacks static

Since TAP offloadings are manipulated through a new API, it's
not necessary to export them in include/net/tap.h anymore.

Signed-off-by: Vincenzo Maffione <v.maffione@gmail.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
net: add offloading support to netmap backend

Whit this patch, the netmap backend supports TSO/UFO/CSUM
offloadings, and accepts the virtio-net header, similarly to what
happens with TAP. The offloading callbacks in the NetClientInfo
interface have been implemented.

Signed-off-by: Vincenzo Maffione <v.maffione@gmail.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
net: Disable netmap backend when not supported

This patch fixes configure so that the netmap backend is not compiled in if the
host doesn't support an API version >= 11. A version upper bound (15) has been
added so that the netmap API can be extended with some minor features without
requiring QEMU code modifications.

Moreover, some changes have been done to net/netmap.c in order to reflect the
current netmap API/ABI (11).

The NETMAP_WITH_LIBS macro makes possible to include some utilities (e.g.
netmap ring macros, D(), RD() and other high level functions) through the netmap
headers. In this way we get rid of the D and RD macro definitions in the QEMU
code, and we open the way for further code simplifications that will be
introduced by future patches.

Signed-off-by: Vincenzo Maffione <v.maffione@gmail.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
net: remove implicit peer from offload API

The virtio_net offload APIs are used on the NIC's peer (i.e. the tap
device).  The API was defined to implicitly use nc->peer, saving the
caller the trouble.

This wasn't ideal because:
1. There are callers who have the peer but not the NIC.  Currently they
   are forced to bypass the API and access peer->info->... directly.
2. The rest of the net.h API uses nc, not nc->peer, so it is
   inconsistent.

This patch pushes nc->peer back up to callers.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
vhost_net: use offload API instead of bypassing it

There is no need to access backend->info->has_vnet_hdr() and friends
anymore.  Use the qemu_has_vnet_hdr() API instead.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
virtio-net: use qemu_get_queue() where possible

qemu_get_queue() is a shorthand for qemu_get_subqueue(n->nic, 0).  Use
the shorthand where possible.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Merge remote-tracking branch 'remotes/stefanha/tags/net-pull-request' into staging

Net patches

# gpg: Signature made Tue 25 Feb 2014 13:32:33 GMT using RSA key ID 81AB73C8
# gpg: Good signature from "Stefan Hajnoczi <stefanha@redhat.com>"
# gpg:                 aka "Stefan Hajnoczi <stefanha@gmail.com>"
# gpg: WARNING: This key is not certified with a trusted signature!
# gpg:          There is no indication that the signature belongs to the owner.
# Primary key fingerprint: 8695 A8BF D3F9 7CDA AC35  775A 9CA4 ABB3 81AB 73C8

* remotes/stefanha/tags/net-pull-request:
  virtio-net: use qemu_get_queue() where possible
  vhost_net: use offload API instead of bypassing it
  net: remove implicit peer from offload API
  net: Disable netmap backend when not supported
  net: add offloading support to netmap backend
  net: make tap offloading callbacks static
  net: virtio-net and vmxnet3 use offloading API
  net: TAP uses NetClientInfo offloading callbacks
  net: extend NetClientInfo for offloading
  net: change vnet-hdr TAP prototypes
  opencores_eth: flush queue whenever can_receive can go from false to true

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>