This patch introduces emulation for the Intel 82574 adapter, AKA e1000e.

This implementation is derived from the e1000 emulation code, and
utilizes the TX/RX packet abstractions that were initially developed for
the vmxnet3 device. Although some parts of the introduced code may be
shared with e1000, the differences are substantial enough so that the
only shared resources for the two devices are the definitions in
hw/net/e1000_regs.h.

Similarly to vmxnet3, the new device uses virtio headers for task
offloads (for backends that support virtio extensions). Usage of
virtio headers may be forcibly disabled via a boolean device property
"vnet" (which is enabled by default). In such case task offloads
will be performed in software, in the same way it is done on
backends that do not support virtio headers.

The device code is split into two parts:

  1. hw/net/e1000e.c: QEMU-specific code for a network device;
  2. hw/net/e1000e_core.[hc]: Device emulation according to the spec.

The new device name is e1000e.

Intel specifications for the 82574 controller are available at:
http://www.intel.com/content/dam/doc/datasheet/82574l-gbe-controller-datasheet.pdf

Throughput measurement results (iperf2):

                Fedora 22 guest, TCP, RX
    4 ++------------------------------------------+
      |                                           |
      |                           X   X   X   X   X
  3.5 ++          X   X   X   X                   |
      |       X                                   |
      |                                           |
    3 ++                                          |
G     |   X                                       |
b     |                                           |
/ 2.5 ++                                          |
s     |                                           |
      |                                           |
    2 ++                                          |
      |                                           |
      |                                           |
  1.5 X+                                          |
      |                                           |
      +   +   +   +   +   +   +   +   +   +   +   +
    1 ++--+---+---+---+---+---+---+---+---+---+---+
     32  64  128 256 512  1   2   4   8  16  32  64
      B   B   B   B   B   KB  KB  KB  KB KB  KB  KB
                       Buffer size

               Fedora 22 guest, TCP, TX
  18 ++-------------------------------------------+
     |                        X                   |
  16 ++                           X   X   X   X   X
     |                   X                        |
  14 ++                                           |
     |                                            |
  12 ++                                           |
G    |               X                            |
b 10 ++                                           |
/    |                                            |
s  8 ++                                           |
     |                                            |
   6 ++          X                                |
     |                                            |
   4 ++                                           |
     |       X                                    |
   2 ++  X                                        |
     X   +   +   +   +   +    +   +   +   +   +   +
   0 ++--+---+---+---+---+----+---+---+---+---+---+
    32  64  128 256 512  1    2   4   8  16  32  64
     B   B   B   B   B   KB   KB  KB  KB KB  KB  KB
                       Buffer size

                Fedora 22 guest, UDP, RX
    3 ++------------------------------------------+
      |                                           X
      |                                           |
  2.5 ++                                          |
      |                                           |
      |                                           |
    2 ++                                 X        |
G     |                                           |
b     |                                           |
/ 1.5 ++                                          |
s     |                         X                 |
      |                                           |
    1 ++                                          |
      |                                           |
      |                 X                         |
  0.5 ++                                          |
      |        X                                  |
      X        +        +       +        +        +
    0 ++-------+--------+-------+--------+--------+
     32       64       128     256      512       1
      B        B         B       B        B      KB
                       Datagram size

                Fedora 22 guest, UDP, TX
    1 ++------------------------------------------+
      |                                           X
  0.9 ++                                          |
      |                                           |
  0.8 ++                                          |
  0.7 ++                                          |
      |                                           |
G 0.6 ++                                          |
b     |                                           |
/ 0.5 ++                                          |
s     |                                  X        |
  0.4 ++                                          |
      |                                           |
  0.3 ++                                          |
  0.2 ++                        X                 |
      |                                           |
  0.1 ++                X                         |
      X        X        +       +        +        +
    0 ++-------+--------+-------+--------+--------+
     32       64       128     256      512       1
      B        B         B       B        B      KB
                       Datagram size

              Windows 2012R2 guest, TCP, RX
  3.2 ++------------------------------------------+
      |                                   X       |
    3 ++                                          |
      |                                           |
  2.8 ++                                          |
      |                                           |
  2.6 ++                              X           |
G     |   X                   X   X           X   X
b 2.4 ++      X       X                           |
/     |                                           |
s 2.2 ++                                          |
      |                                           |
    2 ++                                          |
      |           X       X                       |
  1.8 ++                                          |
      |                                           |
  1.6 X+                                          |
      +   +   +   +   +   +   +   +   +   +   +   +
  1.4 ++--+---+---+---+---+---+---+---+---+---+---+
     32  64  128 256 512  1   2   4   8  16  32  64
      B   B   B   B   B   KB  KB  KB  KB KB  KB  KB
                       Buffer size

             Windows 2012R2 guest, TCP, TX
  14 ++-------------------------------------------+
     |                                            |
     |                                        X   X
  12 ++                                           |
     |                                            |
  10 ++                                           |
     |                                            |
G    |                                            |
b  8 ++                                           |
/    |                                    X       |
s  6 ++                                           |
     |                                            |
     |                                            |
   4 ++                               X           |
     |                                            |
   2 ++                                           |
     |           X   X            X               |
     +   X   X   +   +   X    X   +   +   +   +   +
   0 X+--+---+---+---+---+----+---+---+---+---+---+
    32  64  128 256 512  1    2   4   8  16  32  64
     B   B   B   B   B   KB   KB  KB  KB KB  KB  KB
                       Buffer size

              Windows 2012R2 guest, UDP, RX
  1.6 ++------------------------------------------X
      |                                           |
  1.4 ++                                          |
      |                                           |
  1.2 ++                                          |
      |                                  X        |
      |                                           |
G   1 ++                                          |
b     |                                           |
/ 0.8 ++                                          |
s     |                                           |
  0.6 ++                        X                 |
      |                                           |
  0.4 ++                                          |
      |                 X                         |
      |                                           |
  0.2 ++       X                                  |
      X        +        +       +        +        +
    0 ++-------+--------+-------+--------+--------+
     32       64       128     256      512       1
      B        B         B       B        B      KB
                       Datagram size

              Windows 2012R2 guest, UDP, TX
  0.6 ++------------------------------------------+
      |                                           X
      |                                           |
  0.5 ++                                          |
      |                                           |
      |                                           |
  0.4 ++                                          |
G     |                                           |
b     |                                           |
/ 0.3 ++                                 X        |
s     |                                           |
      |                                           |
  0.2 ++                                          |
      |                                           |
      |                         X                 |
  0.1 ++                                          |
      |                 X                         |
      X        X        +       +        +        +
    0 ++-------+--------+-------+--------+--------+
     32       64       128     256      512       1
      B        B         B       B        B      KB
                       Datagram size
Signed-off-by: NDmitry Fleytman <dmitry.fleytman@ravellosystems.com>
Signed-off-by: NLeonid Bloch <leonid.bloch@ravellosystems.com>
Reviewed-by: NMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: NJason Wang <jasowang@redhat.com>