From: "Michael S. Tsirkin" <mst@redhat.com>
To: Jason Wang <jasowang@redhat.com>
Cc: Heng Qi <hengqi@linux.alibaba.com>,
virtio-comment@lists.oasis-open.org,
virtio-dev@lists.oasis-open.org, Parav Pandit <parav@nvidia.com>,
Yuri Benditovich <yuri.benditovich@daynix.com>,
Cornelia Huck <cohuck@redhat.com>,
Xuan Zhuo <xuanzhuo@linux.alibaba.com>
Subject: Re: [PATCH v9] virtio-net: support inner header hash
Date: Tue, 28 Feb 2023 06:04:55 -0500 [thread overview]
Message-ID: <20230228060352-mutt-send-email-mst@kernel.org> (raw)
In-Reply-To: <CACGkMEvUaQuzMx4iwkaYg9t9Bz2Ev0eHAwgrWbNEwtQHZOkkvQ@mail.gmail.com>
On Tue, Feb 28, 2023 at 11:04:26AM +0800, Jason Wang wrote:
> On Tue, Feb 28, 2023 at 1:49 AM Michael S. Tsirkin <mst@redhat.com> wrote:
> >
> > On Mon, Feb 27, 2023 at 04:35:09PM +0800, Jason Wang wrote:
> > > On Mon, Feb 27, 2023 at 3:39 PM Michael S. Tsirkin <mst@redhat.com> wrote:
> > > >
> > > > On Mon, Feb 27, 2023 at 12:07:17PM +0800, Jason Wang wrote:
> > > > > Btw, this kind of 1:1 hash features seems not scalable and flexible.
> > > > > It requires an endless extension on bits/fields. Modern NICs allow the
> > > > > user to customize the hash calculation, for virtio-net we can allow to
> > > > > use eBPF program to classify the packets. It seems to be more flexible
> > > > > and scalable and there's almost no maintain burden in the spec (only
> > > > > bytecode is required, no need any fancy features/interactions like
> > > > > maps), easy to be migrated etc.
> > > > >
> > > > > Prototype is also easy, tun/tap had an eBPF classifier for years.
> > > > >
> > > > > Thanks
> > > >
> > > > Yea BPF offload would be great to have. We have been discussing it for
> > > > years though - security issues keep blocking it. *Maybe* it's finally
> > > > going to be there but I'm not going to block this work waiting for BPF
> > > > offload. And easily migrated is what BPF is not.
> > >
> > > Just to make sure we're at the same page. I meant to find a way to
> > > allow the driver/user to fully customize what it wants to
> > > hash/classify. Similar technologies which is based on private solution
> > > has been used by some vendors, which allow user to customize the
> > > classifier[1]
> > >
> > > ePBF looks like a good open-source solution candidate for this (there
> > > could be others). But there could be many kinds of eBPF programs that
> > > could be offloaded. One famous one is XDP which requires many features
> > > other than the bytecode/VM like map access, tailcall. Starting from
> > > such a complicated type is hard. Instead, we can start from a simple
> > > type, that is the eBPF classifier. All it needs is to pass the
> > > bytecode to the device, the device can choose to run it or compile it
> > > to what it can understand for classifying. We don't need maps, tail
> > > calls and other features.
> >
> > Until people start asking exactly for maps because they want
> > state for their classifier?
>
> Yes, but let's compare the eBPF without maps with the static feature
> proposed here. It is much more scalable and flexible.
I looked for some examples of RSS using BPF and only found this:
https://github.com/Netronome/bpf-samples/blob/master/programmable_rss/rss_user.c
seems to use maps.
> > And it makes sense - if you want
> > e.g. load balancing you need stats which needs maps.
>
> Yes, but we know it's possible to have that (through the XDP offload).
Not without a lot more work to make xdp offload happen.
> This is impossible with the approach proposed here.
>
> >
> > > We don't need to worry about the security
> > > because of its simplicity: the eBPF program is only in charge of doing
> > > classification, no other interactions with the driver and packet
> > > modification is prohibited. The feature is limited only to the
> > > VM/bytecode abstraction itself.
> > >
> > > What's more, it's a good first step to achieve full eBPF offloading in
> > > the future.
> > >
> > > Thanks
> > >
> > > [1] https://www.intel.com/content/www/us/en/architecture-and-technology/ethernet/dynamic-device-personalization-brief.html
> >
> > Dave seems to have nacked this approach, no?
>
> I may miss something but looking at kernel commit, there are few
> patches to support that:
>
> E.g
>
> commit c7648810961682b9388be2dd041df06915647445
> Author: Tony Nguyen <anthony.l.nguyen@intel.com>
> Date: Mon Sep 9 06:47:44 2019 -0700
>
> ice: Implement Dynamic Device Personalization (DDP) download
>
> And it has been used by DPDK drivers.
>
> Thanks
>
> >
> > > >
> > > > --
> > > > MST
> > > >
> >
next prev parent reply other threads:[~2023-02-28 11:04 UTC|newest]
Thread overview: 78+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-02-18 14:37 [PATCH v9] virtio-net: support inner header hash Heng Qi
2023-02-20 15:53 ` [virtio-comment] Re: [virtio-dev] " Heng Qi
2023-02-20 16:12 ` Michael S. Tsirkin
2023-02-21 4:20 ` Parav Pandit
2023-02-21 6:14 ` [virtio-comment] " Heng Qi
2023-02-21 12:47 ` Parav Pandit
2023-02-21 13:34 ` Heng Qi
2023-02-21 15:32 ` Parav Pandit
2023-02-21 16:44 ` [virtio-comment] Re: [virtio-dev] " Heng Qi
2023-02-21 16:50 ` Parav Pandit
2023-02-21 17:13 ` Michael S. Tsirkin
2023-02-21 17:40 ` [virtio-comment] " Parav Pandit
2023-02-21 17:44 ` Michael S. Tsirkin
2023-02-21 17:54 ` Parav Pandit
2023-02-21 17:17 ` [virtio-comment] " Heng Qi
2023-02-21 17:39 ` Parav Pandit
2023-02-21 13:37 ` Heng Qi
2023-02-21 17:05 ` Michael S. Tsirkin
2023-02-21 19:29 ` Parav Pandit
2023-02-21 21:23 ` Michael S. Tsirkin
2023-02-21 21:36 ` Parav Pandit
2023-02-21 21:46 ` Michael S. Tsirkin
2023-02-21 22:32 ` Parav Pandit
2023-02-21 23:18 ` Michael S. Tsirkin
2023-02-22 1:41 ` Parav Pandit
2023-02-22 2:51 ` [virtio-dev] " Heng Qi
2023-02-22 2:34 ` [virtio-dev] " Heng Qi
2023-02-22 6:21 ` Michael S. Tsirkin
2023-02-22 7:03 ` Heng Qi
2023-02-22 11:29 ` Michael S. Tsirkin
2023-02-21 17:50 ` Michael S. Tsirkin
2023-02-22 3:22 ` Jason Wang
2023-02-22 6:46 ` Heng Qi
2023-02-22 11:30 ` Michael S. Tsirkin
2023-02-23 2:50 ` Jason Wang
2023-02-23 4:41 ` [virtio-dev] " Heng Qi
2023-02-24 2:45 ` Jason Wang
2023-02-24 4:47 ` [virtio-comment] " Heng Qi
2023-02-24 8:07 ` Michael S. Tsirkin
2023-02-23 13:03 ` Michael S. Tsirkin
2023-02-24 2:26 ` Jason Wang
2023-02-24 8:06 ` [virtio-dev] " Michael S. Tsirkin
2023-02-27 4:07 ` Jason Wang
2023-02-27 7:39 ` Michael S. Tsirkin
2023-02-27 8:35 ` Jason Wang
2023-02-27 12:38 ` Heng Qi
2023-02-27 17:49 ` Michael S. Tsirkin
2023-02-28 3:04 ` Jason Wang
2023-02-28 8:52 ` Michael S. Tsirkin
2023-02-28 9:56 ` [virtio-dev] " Heng Qi
2023-02-28 11:04 ` Michael S. Tsirkin [this message]
2023-03-01 2:36 ` Jason Wang
2023-02-23 13:13 ` Michael S. Tsirkin
2023-02-23 14:40 ` [virtio-comment] " Parav Pandit
2023-02-24 8:13 ` Michael S. Tsirkin
2023-02-24 14:38 ` [virtio-dev] " Heng Qi
2023-02-24 17:10 ` Michael S. Tsirkin
2023-02-27 0:29 ` Parav Pandit
2023-02-24 4:42 ` Heng Qi
2023-02-24 8:04 ` Michael S. Tsirkin
2023-02-28 11:16 ` Michael S. Tsirkin
2023-03-01 2:56 ` [virtio-dev] " Heng Qi
2023-03-08 14:39 ` [virtio-comment] " Michael S. Tsirkin
2023-03-09 4:55 ` [virtio-comment] Re: [virtio-dev] " Heng Qi
2023-03-09 19:36 ` Michael S. Tsirkin
2023-03-11 3:23 ` Heng Qi
2023-03-15 11:58 ` Michael S. Tsirkin
2023-03-15 12:55 ` Heng Qi
2023-03-15 14:57 ` Michael S. Tsirkin
2023-03-16 13:17 ` Heng Qi
2023-03-20 19:45 ` Michael S. Tsirkin
2023-03-30 12:10 ` Heng Qi
2023-03-20 19:48 ` Michael S. Tsirkin
2023-03-30 12:37 ` Heng Qi
2023-04-08 10:29 ` Michael S. Tsirkin
2023-04-10 13:26 ` [virtio-comment] Re: [virtio-dev] " Heng Qi
2023-03-01 3:30 ` [virtio-comment] " Heng Qi
2023-03-09 12:28 ` [virtio-comment] Re: [virtio-dev] " Heng Qi
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