Re: [PATCH v1 00/13] various virtio docs, fixes and tweaks

[Alex Bennée]

"Michael S. Tsirkin" <mst@redhat.com> writes:

> On Mon, Mar 21, 2022 at 03:30:24PM +0000, Alex Bennée wrote:
>> Hi,
>> 
>> This series is a sub-set of patches while I was trying to re-rev my
>> virtio-rpmb patches. It attempts to address a few things:
>> 
>>   - improve documentation for virtio/vhost/vhost-user
>>   - document some of the API
>>   - a hacky fix for F_CONFIG handling
>>   - putting VhostUserState on a diet, make VhostUserHostNotifier dynamic
>
> So I think this is best deferred until after the release,
> more of a cleanup than a bugfix.

Sorry I should have made it clearer - I wasn't intending this for 7.0
but I also didn't want it bound up with the rpmb changes which will take
longer to land.

>
> I will tag this series, but please do remind me after the release
> to help make sure it does not get lost.
>
>
>> In particular I've been trying to better understand how vhost-user
>> interactions are meant to work and why there are two different methods
>> for instantiating them. If my supposition is correct perhaps a number
>> of devices that don't have in-kernel vhost equivalents could be converted?
>
> Hope I understand your question.  Well we started off with saying
> vhost-user is just a backend, so should not affect the frontend device.
> This is clean and makes migration work e.g. you can migrate between
> different backends, but it makes adding features more work.

This is covered in the doc patch, specifically:

  vhost_ops vs TYPE_VHOST_USER_BACKEND

>> While working onthe VhostUserHostNotifier changes I found it quite
>> hard to trigger the code. Is this rarely used code or just requires
>> backends we don't see in the testing?
>
> Which function are you asking about exactly?

  vhost_user_slave_handle_vring_host_notifier

which is the only place where a mapping is set up AFAICT.

>
>> Alex Bennée (10):
>>   hw/virtio: move virtio-pci.h into shared include space
>>   virtio-pci: add notification trace points
>>   hw/virtio: add vhost_user_[read|write] trace points
>>   vhost-user.rst: add clarifying language about protocol negotiation
>>   libvhost-user: expose vu_request_to_string
>>   docs/devel: start documenting writing VirtIO devices
>>   include/hw: start documenting the vhost API
>>   contrib/vhost-user-blk: fix 32 bit build and enable
>>   hw/virtio/vhost-user: don't suppress F_CONFIG when supported
>>   virtio/vhost-user: dynamically assign VhostUserHostNotifiers
>> 
>> Paolo Bonzini (3):
>>   docs: vhost-user: clean up request/reply description
>>   docs: vhost-user: rewrite section on ring state machine
>>   docs: vhost-user: replace master/slave with front-end/back-end
>> 
>>  docs/devel/index-internals.rst            |   1 +
>>  docs/devel/virtio-backends.rst            | 214 +++++++++
>>  docs/interop/vhost-user-gpu.rst           |  10 +-
>>  docs/interop/vhost-user.rst               | 555 ++++++++++++----------
>>  meson.build                               |   2 +-
>>  include/hw/virtio/vhost-user.h            |  43 +-
>>  include/hw/virtio/vhost.h                 | 132 ++++-
>>  {hw => include/hw}/virtio/virtio-pci.h    |   0
>>  subprojects/libvhost-user/libvhost-user.h |   9 +
>>  contrib/vhost-user-blk/vhost-user-blk.c   |   6 +-
>>  hw/scsi/vhost-user-scsi.c                 |   1 +
>>  hw/virtio/vhost-scsi-pci.c                |   2 +-
>>  hw/virtio/vhost-user-blk-pci.c            |   2 +-
>>  hw/virtio/vhost-user-fs-pci.c             |   2 +-
>>  hw/virtio/vhost-user-i2c-pci.c            |   2 +-
>>  hw/virtio/vhost-user-input-pci.c          |   2 +-
>>  hw/virtio/vhost-user-rng-pci.c            |   2 +-
>>  hw/virtio/vhost-user-scsi-pci.c           |   2 +-
>>  hw/virtio/vhost-user-vsock-pci.c          |   2 +-
>>  hw/virtio/vhost-user.c                    | 133 ++++--
>>  hw/virtio/vhost-vsock-pci.c               |   2 +-
>>  hw/virtio/virtio-9p-pci.c                 |   2 +-
>>  hw/virtio/virtio-balloon-pci.c            |   2 +-
>>  hw/virtio/virtio-blk-pci.c                |   2 +-
>>  hw/virtio/virtio-input-host-pci.c         |   2 +-
>>  hw/virtio/virtio-input-pci.c              |   2 +-
>>  hw/virtio/virtio-iommu-pci.c              |   2 +-
>>  hw/virtio/virtio-net-pci.c                |   2 +-
>>  hw/virtio/virtio-pci.c                    |   5 +-
>>  hw/virtio/virtio-rng-pci.c                |   2 +-
>>  hw/virtio/virtio-scsi-pci.c               |   2 +-
>>  hw/virtio/virtio-serial-pci.c             |   2 +-
>>  subprojects/libvhost-user/libvhost-user.c |   2 +-
>>  contrib/vhost-user-blk/meson.build        |   3 +-
>>  hw/virtio/trace-events                    |  10 +-
>>  35 files changed, 831 insertions(+), 333 deletions(-)
>>  create mode 100644 docs/devel/virtio-backends.rst
>>  rename {hw => include/hw}/virtio/virtio-pci.h (100%)
>> 
>> -- 
>> 2.30.2


-- 
Alex Bennée