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Re: [RFC net-next 15/18] virtio_net: implement XDP prog offload function
From: |
Prashant Bhole |
Subject: |
Re: [RFC net-next 15/18] virtio_net: implement XDP prog offload functionality |
Date: |
Thu, 28 Nov 2019 11:53:41 +0900 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 |
On 11/28/19 5:42 AM, Michael S. Tsirkin wrote:
On Tue, Nov 26, 2019 at 07:07:41PM +0900, Prashant Bhole wrote:
From: Jason Wang <address@hidden>
This patch implements bpf_prog_offload_ops callbacks and adds handling
for XDP_SETUP_PROG_HW. Handling of XDP_SETUP_PROG_HW involves setting
up struct virtio_net_ctrl_ebpf_prog and appending program instructions
to it. This control buffer is sent to Qemu with class
VIRTIO_NET_CTRL_EBPF and command VIRTIO_NET_BPF_CMD_SET_OFFLOAD.
The expected behavior from Qemu is that it should try to load the
program in host os and report the status.
That's not great e.g. for migration: different hosts might have
a different idea about what's allowed.
Device capabilities should be preferably exported through
feature bits or config space such that it's easy to
intercept and limit these as needed.
These things are mentioned in the TODO section of cover letter.
Having offload feature enabled should be a migration blocker.
A feature bit in virtio for offloading capability needs to be added.
Also, how are we going to handle e.g. endian-ness here?
For now I feel we should block offloading in case of cross endian
virtualization. Further to support cross endian-ness, the requests for
offloading a map or program should include metadata such as BTF info.
Qemu needs to handle the conversion.
It also adds restriction to have either driver or offloaded program
at a time.
I'm not sure I understand what does the above say.
virtnet_xdp_offload_check?
Please add code comments so we remember what to do and when.
This restriction can be removed later after proper testing.
What kind of testing is missing here?
This restriction mentioned above is about having multiple programs
attached to the same device. It can be possible to have a program
attached in driver mode and other in offload mode, but in current code
only one mode at a time is supported because I wasn't aware whether
bpf tooling supports the case. I will add a comment or remove the
restriction in the next revision.
Signed-off-by: Jason Wang <address@hidden>
Co-developed-by: Prashant Bhole <address@hidden>
Signed-off-by: Prashant Bhole <address@hidden>
Any UAPI changes need to be copied to address@hidden
(subscriber only) list please.
Sure.
Thanks.
- [RFC net-next 00/18] virtio_net XDP offload, Prashant Bhole, 2019/11/26
- [RFC net-next 04/18] tuntap: check tun_msg_ctl type at necessary places, Prashant Bhole, 2019/11/26
- [RFC net-next 16/18] bpf: export function __bpf_map_get, Prashant Bhole, 2019/11/26
- [RFC net-next 18/18] virtio_net: restrict bpf helper calls from offloaded program, Prashant Bhole, 2019/11/26
- [RFC net-next 14/18] virtio_net: add XDP prog offload infrastructure, Prashant Bhole, 2019/11/26
- [RFC net-next 12/18] virtio-net: store xdp_prog in device, Prashant Bhole, 2019/11/26
- [RFC net-next 17/18] virtio_net: implment XDP map offload functionality, Prashant Bhole, 2019/11/26
- [RFC net-next 15/18] virtio_net: implement XDP prog offload functionality, Prashant Bhole, 2019/11/26
- [RFC net-next 10/18] tun: handle XDP_TX action of offloaded program, Prashant Bhole, 2019/11/26
- [RFC net-next 09/18] tun: add a way to inject Tx path packet into Rx path, Prashant Bhole, 2019/11/26
- [RFC net-next 07/18] tun: set offloaded xdp program, Prashant Bhole, 2019/11/26
- [RFC net-next 02/18] net: core: rename netif_receive_generic_xdp() to do_generic_xdp_core(), Prashant Bhole, 2019/11/26
- [RFC net-next 01/18] bpf: introduce bpf_prog_offload_verifier_setup(), Prashant Bhole, 2019/11/26
- [RFC net-next 13/18] virtio_net: use XDP attachment helpers, Prashant Bhole, 2019/11/26
- [RFC net-next 11/18] tun: run xdp prog when tun is read from file interface, Prashant Bhole, 2019/11/26
- [RFC net-next 08/18] tun: run offloaded XDP program in Tx path, Prashant Bhole, 2019/11/26
- [RFC net-next 06/18] tuntap: remove usage of ptr ring in vhost_net, Prashant Bhole, 2019/11/26
- [RFC net-next 03/18] net: core: export do_xdp_generic_core(), Prashant Bhole, 2019/11/26