Hi, I've been testing linux-next (tags later than 03/17) and hit new issues in virtio-net on s390x. I bisected the issue, and I found this patch to be the first buggy commit.
The issue seems to only be reproducible when running in Secure Execution. Tested in a KVM guest, the virtio-net performance appears greatly reduced, and the dmesg output shows many instances of the following error messages. Partial relevant logs ===================== [ 49.332028] macvtap0: bad gso: type: 0, size: 0, flags 1 tunnel 0 tnl csum 0 [ 74.365668] macvtap0: bad gso: type: 2e, size: 27948, flags 0 tunnel 0 tnl csum 0 [ 403.302168] macvtap0: bad csum: flags: 2, gso_type: 23 rx_tnl_csum 0 [ 403.302271] macvtap0: bad csum: flags: 2, gso_type: e0 rx_tnl_csum 0 [ 403.302279] macvtap0: bad csum: flags: 2, gso_type: e1 rx_tnl_csum 0 [ 403.309492] macvtap0: bad csum: flags: 2, gso_type: 4c rx_tnl_csum 0 [ 403.317029] macvtap0: bad csum: flags: 2, gso_type: e0 rx_tnl_csum 0 Steps to reproduce ================== 1. Boot a Linux guest implementing this patch under QEMU/KVM (*) with SE enabled and a virtio-net-ccw device attached. 2. Run dmesg. The error message is usually already present at boot time, but if not, it can be reproduced by creating any network traffic. (*) This patch was not tested in a non-KVM hypervisor environment. I've further confirmed that reverting this patch onto its parent commit resolves the issue. Please let me know if you'd like me to test a fix or if you would need more information. Thanks in advance. Best, Omar
