Re: [PATCH net-next] virtio_net: sync RX buffer before reading the header

patchwork-bot+netdevbpf
2026-03-27T03:20:28Z

Hello:

This patch was applied to netdev/net-next.git (main)
by Jakub Kicinski <kuba@kernel.org>:

On Tue, 24 Mar 2026 11:15:54 -0400 you wrote:
> receive_buf() reads the virtio header through buf before
> page_pool_dma_sync_for_cpu() runs in receive_small() or
> receive_mergeable(). The header buffer is thus unsynchronized at the
> point where flags and, for mergeable buffers, num_buffers are consumed.
>
> Omar Elghoul reported that on s390x Secure Execution this showed up as
> greatly reduced virtio-net performance together with "bad gso" and
> "bad csum" messages in dmesg. This is because with SE sync actually
> copies data, so the header is uninitialized.
>
> [...]

Here is the summary with links:
- [net-next] virtio_net: sync RX buffer before reading the header
https://git.kernel.org/netdev/net-next/c/fe3e54253f0b

You are awesome, thank you!
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