Re: [PATCH v8 02/12] accel: Introduce 'query-accels' QMP command

[Thomas Huth <thuth@redhat.com>]

On 26/05/2021 19.04, Philippe Mathieu-Daudé wrote:
> Introduce the 'query-accels' QMP command which returns a list
> of built-in accelerator names.
> 
> - Accelerator is a QAPI enum of all existing accelerators,
> 
> - AcceleratorInfo is a QAPI structure providing accelerator
>    specific information. Currently the common structure base
>    provides the name of the accelerator, while the specific
>    part is empty, but each accelerator can expand it.
> 
> - 'query-accels' QMP command returns a list of @AcceleratorInfo
> 
> For example on a KVM-only build we get:
> 
>      { "execute": "query-accels" }
>      {
>          "return": [
>              {
>                  "name": "qtest"
>              },
>              {
>                  "name": "kvm"
>              }
>          ]
>      }
> 
> Reviewed-by: Eric Blake <eblake@redhat.com>
> Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
> Tested-by: Alex Bennée <alex.bennee@linaro.org>
> Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
> ---
> v8:
> - Include code snippet from Markus adding to machine-target.json
>    to be able to use enum values or union branches conditional.
> - Use accel_find() on enum to be sure the accelerator is enabled
>    at runtime (chat with jsnow / eblake).
> 
> Cc: Eric Blake <eblake@redhat.com>
> Cc: John Snow <jsnow@redhat.com>
> Cc: Markus Armbruster <armbru@redhat.com>
> ---
>   qapi/machine-target.json | 54 ++++++++++++++++++++++++++++++++++++++++
>   accel/accel-qmp.c        | 32 ++++++++++++++++++++++++
>   accel/meson.build        |  2 +-
>   3 files changed, 87 insertions(+), 1 deletion(-)
>   create mode 100644 accel/accel-qmp.c
> 
> diff --git a/qapi/machine-target.json b/qapi/machine-target.json
> index e7811654b72..586a61b5d99 100644
> --- a/qapi/machine-target.json
> +++ b/qapi/machine-target.json
> @@ -329,3 +329,57 @@
>   ##
>   { 'command': 'query-cpu-definitions', 'returns': ['CpuDefinitionInfo'],
>     'if': 'defined(TARGET_PPC) || defined(TARGET_ARM) || defined(TARGET_I386) || defined(TARGET_S390X) || defined(TARGET_MIPS)' }
> +
> +##
> +# @Accelerator:
> +#
> +# An enumeration of accelerator names.
> +#
> +# Since: 6.1
> +##
> +{ 'enum': 'Accelerator',
> +  'data': [
> +      { 'name': 'hax', 'if': 'defined(CONFIG_HAX)' },
> +      { 'name': 'hvf', 'if': 'defined(CONFIG_HVF)' },
> +      { 'name': 'kvm', 'if': 'defined(CONFIG_KVM)' },
> +      { 'name': 'qtest' },
> +      { 'name': 'tcg', 'if': 'defined(CONFIG_TCG)' },
> +      { 'name': 'whpx', 'if': 'defined(CONFIG_WHPX)' },
> +      { 'name': 'xen', 'if': 'defined(CONFIG_XEN_BACKEND)' } ] }
> +
> +##
> +# @AcceleratorInfo:
> +#
> +# Accelerator information.
> +#
> +# @name: The accelerator name.
> +#
> +# Since: 6.1
> +##
> +{ 'struct': 'AcceleratorInfo',
> +  'data': { 'name': 'Accelerator' } }
> +
> +##
> +# @query-accels:
> +#
> +# Get a list of AcceleratorInfo for all built-in accelerators.
> +#
> +# Returns: a list of @AcceleratorInfo describing each accelerator.
> +#
> +# Since: 6.1
> +#
> +# Example:
> +#
> +# -> { "execute": "query-accels" }
> +# <- { "return": [
> +#        {
> +#            "name": "qtest"
> +#        },
> +#        {
> +#            "name": "kvm"
> +#        }
> +#    ] }
> +#
> +##
> +{ 'command': 'query-accels',
> +  'returns': ['AcceleratorInfo'] }

What about Markus' comment here:

  https://lore.kernel.org/qemu-devel/87mtsoieyz.fsf@dusky.pond.sub.org/

?

If I've got him right, you don't need the command at all, the Accelerator
enum should be sufficient?

  Thomas