Hello, It looks like there is a problem in QEMU related to usage of frontends without virtio extensions.
Normally on RX path QEMU receives packet metadata with offloads information in virtio header. In particular there is an information about checksumming state. For example, when packet is being transferred from guest to guest with offloads enabled on transmitter side, checksums won't be calculated, special flag will be set instead in virtio header indicating that the checksum is ok. Based on this flag device may notify guest that checksum verification for this packet is not required. Now, when virtio header is not supported on receiver side, there is no way device may be notified about the checksum state. Packet will be indicated to the guest as is and will be dropped by guest's network stack. I've tested this scenario with virtio devices and observed the issue described. Do I miss something? Is there any configuration option or something I'm not aware about? Thanks in advance, Dmitry Fleytman.
