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 <jasowang@xxxxxxxxxx>
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 <jasowang@xxxxxxxxxx>
Co-developed-by: Prashant Bhole <prashantbhole.linux@xxxxxxxxx>
Signed-off-by: Prashant Bhole <prashantbhole.linux@xxxxxxxxx>
Any UAPI changes need to be copied to virtio-dev@xxxxxxxxxxxxxxxxxxxx
(subscriber only) list please.
Sure.
Thanks.
