This reverts commit 3618ad2a.

When control vq is not negotiated, that commit causes a crash:

[   72.229171] kernel BUG at drivers/net/virtio_net.c:1667!
[   72.230266] invalid opcode: 0000 [#1] PREEMPT SMP
[   72.231172] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.9.0-rc8-02934-g3618ad2a #1
[   72.231172] EIP: virtnet_send_command+0x120/0x140
[   72.231172] Code: 00 0f 94 c0 8b 7d f0 65 33 3d 14 00 00 00 75 1c 8d 65 f4 5b 5e 5f 5d c3 66 90 be 01 00 00 00 e9 6e ff ff ff 8d b6 00
+00 00 00 <0f> 0b e8 d9 bb 82 00 eb 17 8d b4 26 00 00 00 00 8d b4 26 00 00 00
[   72.231172] EAX: 0000000d EBX: f72895c0 ECX: 00000017 EDX: 00000011
[   72.231172] ESI: f7197800 EDI: ed69bd00 EBP: ed69bcf4 ESP: ed69bc98
[   72.231172] DS: 007b ES: 007b FS: 00d8 GS: 00e0 SS: 0068 EFLAGS: 00010246
[   72.231172] CR0: 80050033 CR2: 00000000 CR3: 02c84000 CR4: 000406f0
[   72.231172] Call Trace:
[   72.231172]  ? __virt_addr_valid+0x45/0x60
[   72.231172]  ? ___cache_free+0x51f/0x760
[   72.231172]  ? kobject_uevent_env+0xf4/0x560
[   72.231172]  virtnet_set_guest_offloads+0x4d/0x80
[   72.231172]  virtnet_set_features+0x85/0x120
[   72.231172]  ? virtnet_set_guest_offloads+0x80/0x80
[   72.231172]  __netdev_update_features+0x27a/0x8e0
[   72.231172]  ? kobject_uevent+0xa/0x20
[   72.231172]  ? netdev_register_kobject+0x12c/0x160
[   72.231172]  register_netdevice+0x4fe/0x740
[   72.231172]  register_netdev+0x1c/0x40
[   72.231172]  virtnet_probe+0x728/0xb60
[   72.231172]  ? _raw_spin_unlock+0x1d/0x40
[   72.231172]  ? virtio_vdpa_get_status+0x1c/0x20
[   72.231172]  virtio_dev_probe+0x1c6/0x271
[   72.231172]  really_probe+0x195/0x2e0
[   72.231172]  driver_probe_device+0x26/0x60
[   72.231172]  device_driver_attach+0x49/0x60
[   72.231172]  __driver_attach+0x46/0xc0
[   72.231172]  ? device_driver_attach+0x60/0x60
[   72.231172]  bus_add_driver+0x197/0x1c0
[   72.231172]  driver_register+0x66/0xc0
[   72.231172]  register_virtio_driver+0x1b/0x40
[   72.231172]  virtio_net_driver_init+0x61/0x86
[   72.231172]  ? veth_init+0x14/0x14
[   72.231172]  do_one_initcall+0x76/0x2e4
[   72.231172]  ? rdinit_setup+0x2a/0x2a
[   72.231172]  do_initcalls+0xb2/0xd5
[   72.231172]  kernel_init_freeable+0x14f/0x179
[   72.231172]  ? rest_init+0x100/0x100
[   72.231172]  kernel_init+0xd/0xe0
[   72.231172]  ret_from_fork+0x1c/0x30
[   72.231172] Modules linked in:
[   72.269563] ---[ end trace a6ebc4afea0e6cb1 ]---

The reason is that virtnet_set_features now calls virtnet_set_guest_offloads
unconditionally, it used to only call it when there is something
to configure.

If device does not have a control vq, everything breaks.

Revert the original commit for now.

Cc: Tonghao Zhang <xiangxia.m.yue@gmail.com>
Fixes: 3618ad2a ("virtio-net: ethtool configurable RXCSUM")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Willem de Bruijn <willemb@google.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Link: https://lore.kernel.org/r/20201021142944.13615-1-mst@redhat.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>