Re: [PATCH 1/3] qapi/vfio: Add VFIO device migration state change QAPI event

[Markus Armbruster <armbru@redhat.com>]

Avihai Horon <avihaih@nvidia.com> writes:

> Add a new QAPI event for VFIO device migration state change. This event
> will be emitted when a VFIO device changes its migration state, for
> example, during migration or when stopping/starting the guest.
>
> This event can be used by management applications to get updates on the
> current state of the VFIO device for their own purposes.
>
> Signed-off-by: Avihai Horon <avihaih@nvidia.com>

Can you explain briefly why this event makes sense only for VFIO devices?

> ---
>  MAINTAINERS           |  1 +
>  qapi/qapi-schema.json |  1 +
>  qapi/vfio.json        | 61 +++++++++++++++++++++++++++++++++++++++++++
>  qapi/meson.build      |  1 +
>  4 files changed, 64 insertions(+)
>  create mode 100644 qapi/vfio.json
>
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 302b6fd00c..ef58a39d36 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -2159,6 +2159,7 @@ F: hw/vfio/*
>  F: include/hw/vfio/
>  F: docs/igd-assign.txt
>  F: docs/devel/migration/vfio.rst
> +F: qapi/vfio.json
>  
>  vfio-ccw
>  M: Eric Farman <farman@linux.ibm.com>
> diff --git a/qapi/qapi-schema.json b/qapi/qapi-schema.json
> index 5e33da7228..b1581988e4 100644
> --- a/qapi/qapi-schema.json
> +++ b/qapi/qapi-schema.json
> @@ -78,5 +78,6 @@
>  { 'include': 'pci.json' }
>  { 'include': 'stats.json' }
>  { 'include': 'virtio.json' }
> +{ 'include': 'vfio.json' }
>  { 'include': 'cryptodev.json' }
>  { 'include': 'cxl.json' }
> diff --git a/qapi/vfio.json b/qapi/vfio.json
> new file mode 100644
> index 0000000000..a38f26bccd
> --- /dev/null
> +++ b/qapi/vfio.json
> @@ -0,0 +1,61 @@
> +# -*- Mode: Python -*-
> +# vim: filetype=python
> +#
> +
> +##
> +# = VFIO devices
> +##
> +
> +##
> +# @VFIODeviceMigState:
> +#
> +# An enumeration of the VFIO device migration states.
> +#
> +# @stop: The device is stopped.
> +#
> +# @running: The device is running.
> +#
> +# @stop-copy: The device is stopped and its internal state is available
> +#     for reading.
> +#
> +# @resuming: The device is stopped and its internal state is available
> +#     for writing.
> +#
> +# @running-p2p: The device is running in the P2P quiescent state.
> +#
> +# @pre-copy: The device is running, tracking its internal state and its
> +#     internal state is available for reading.
> +#
> +# @pre-copy-p2p: The device is running in the P2P quiescent state,
> +#     tracking its internal state and its internal state is available
> +#     for reading.
> +#
> +# Since: 9.1
> +##
> +{ 'enum': 'VFIODeviceMigState',
> +  'data': [ 'stop', 'running', 'stop-copy', 'resuming', 'running-p2p',
> +            'pre-copy', 'pre-copy-p2p' ],
> +  'prefix': 'QAPI_VFIO_DEVICE_MIG_STATE' }
> +
> +##
> +# @VFIO_DEVICE_MIG_STATE_CHANGED:
> +#
> +# This event is emitted when a VFIO device migration state is changed.
> +#
> +# @device-id: The id of the VFIO device (final component of QOM path).

Provide the full QOM path, please.  Feel free to additionally provide
its qdev ID.

Precedence: events MEMORY_DEVICE_SIZE_CHANGE, DEVICE_DELETED,
DEVICE_UNPLUG_GUEST_ERROR, ...

> +#
> +# @device-state: The new changed device migration state.
> +#
> +# Since: 9.1
> +#
> +# Example:
> +#
> +#     <- {"timestamp": {"seconds": 1713771323, "microseconds": 212268},
> +#         "event": "VFIO_DEVICE_MIG_STATE_CHANGED",
> +#         "data": {"device-id": "vfio_dev1", "device-state": "stop"} }
> +##
> +{ 'event': 'VFIO_DEVICE_MIG_STATE_CHANGED',
> +  'data': {
> +      'device-id': 'str',
> +      'device-state': 'VFIODeviceMigState'
> +  } }
> diff --git a/qapi/meson.build b/qapi/meson.build
> index c92af6e063..e7bc54e5d0 100644
> --- a/qapi/meson.build
> +++ b/qapi/meson.build
> @@ -52,6 +52,7 @@ qapi_all_modules = [
>    'stats',
>    'trace',
>    'transaction',
> +  'vfio',
>    'virtio',
>    'yank',
>  ]