QE tested this series of patches v11 under linux-next repo with virtio-net regression tests, everything works fine.
Tested-by: Lei Yang leiyang@redhat.com
On Tue, Mar 18, 2025 at 8:29 AM Jason Wang jasowang@redhat.com wrote:
On Mon, Mar 17, 2025 at 6:58 PM Akihiko Odaki akihiko.odaki@daynix.com wrote:
virtio-net have two usage of hashes: one is RSS and another is hash reporting. Conventionally the hash calculation was done by the VMM. However, computing the hash after the queue was chosen defeats the purpose of RSS.
Another approach is to use eBPF steering program. This approach has another downside: it cannot report the calculated hash due to the restrictive nature of eBPF.
Introduce the code to compute hashes to the kernel in order to overcome thse challenges.
An alternative solution is to extend the eBPF steering program so that it will be able to report to the userspace, but it is based on context rewrites, which is in feature freeze. We can adopt kfuncs, but they will not be UAPIs. We opt to ioctl to align with other relevant UAPIs (KVM and vhost_net).
The patches for QEMU to use this new feature was submitted as RFC and is available at: https://patchew.org/QEMU/20250313-hash-v4-0-c75c494b495e@daynix.com/
This work was presented at LPC 2024: https://lpc.events/event/18/contributions/1963/
V1 -> V2: Changed to introduce a new BPF program type.
Signed-off-by: Akihiko Odaki akihiko.odaki@daynix.com
Changes in v11:
- Added the missing code to free vnet_hash in patch "tap: Introduce virtio-net hash feature".
- Link to v10: https://lore.kernel.org/r/20250313-rss-v10-0-3185d73a9af0@daynix.com
We only have 2 or 3 points that need to be sorted out. Let's hold on to the iteration until we had an agreement.
Thanks