Re: Re: [RFC v1 0/6] virtio/vsock: introduce SOCK_DGRAM support

On Wed, Jun 9, 2021 at 6:51 PM Jason Wang [off-list ref] wrote:

在 2021/6/10 上午7:24, Jiang Wang 写道:

quoted

This patchset implements support of SOCK_DGRAM for virtio
transport.

Datagram sockets are connectionless and unreliable. To avoid unfair contention
with stream and other sockets, add two more virtqueues and
a new feature bit to indicate if those two new queues exist or not.

Dgram does not use the existing credit update mechanism for
stream sockets. When sending from the guest/driver, sending packets
synchronously, so the sender will get an error when the virtqueue is full.
When sending from the host/device, send packets asynchronously
because the descriptor memory belongs to the corresponding QEMU
process.

What's the use case for the datagram vsock?

One use case is for non critical info logging from the guest
to the host, such as the performance data of some applications.

It can also be used to replace UDP communications between
the guest and the host.

quoted

The virtio spec patch is here:
https://www.spinics.net/lists/linux-virtualization/msg50027.html

Have a quick glance, I suggest to split mergeable rx buffer into an
separate patch.

Sure.

But I think it's time to revisit the idea of unifying the virtio-net and
virtio-vsock. Otherwise we're duplicating features and bugs.

For mergeable rxbuf related code, I think a set of common helper
functions can be used by both virtio-net and virtio-vsock. For other
parts, that may not be very beneficial. I will think about more.

If there is a previous email discussion about this topic, could you send me
some links? I did a quick web search but did not find any related
info. Thanks.

Thanks

quoted

For those who prefer git repo, here is the link for the linux kernel：
https://github.com/Jiang1155/linux/tree/vsock-dgram-v1

qemu patch link:
https://github.com/Jiang1155/qemu/tree/vsock-dgram-v1


To do:
1. use skb when receiving packets
2. support multiple transport
3. support mergeable rx buffer


Jiang Wang (6):
   virtio/vsock: add VIRTIO_VSOCK_F_DGRAM feature bit
   virtio/vsock: add support for virtio datagram
   vhost/vsock: add support for vhost dgram.
   vsock_test: add tests for vsock dgram
   vhost/vsock: add kconfig for vhost dgram support
   virtio/vsock: add sysfs for rx buf len for dgram

  drivers/vhost/Kconfig                              |   8 +
  drivers/vhost/vsock.c                              | 207 ++++++++--
  include/linux/virtio_vsock.h                       |   9 +
  include/net/af_vsock.h                             |   1 +
  .../trace/events/vsock_virtio_transport_common.h   |   5 +-
  include/uapi/linux/virtio_vsock.h                  |   4 +
  net/vmw_vsock/af_vsock.c                           |  12 +
  net/vmw_vsock/virtio_transport.c                   | 433 ++++++++++++++++++---
  net/vmw_vsock/virtio_transport_common.c            | 184 ++++++++-
  tools/testing/vsock/util.c                         | 105 +++++
  tools/testing/vsock/util.h                         |   4 +
  tools/testing/vsock/vsock_test.c                   | 195 ++++++++++
  12 files changed, 1070 insertions(+), 97 deletions(-)