Re: [PATCH v2 2/2] tpm: Return QMP error when TPM is disabled in build

[Eric Blake <eblake@redhat.com>]

On Wed, Jun 09, 2021 at 08:49:55PM +0200, Philippe Mathieu-Daudé wrote:
> When the management layer queries a binary built using --disable-tpm
> for TPM devices, it gets confused by getting empty responses:
> 
...
> 
> To make it clearer by returning an error:
> - Make the TPM QAPI schema conditional
> - Adapt the HMP command
> - Remove stubs which became unnecessary
> 
> The management layer now gets a 'CommandNotFound' error:
> 
>   { "execute": "query-tpm" }
>   {
>       "error": {
>           "class": "CommandNotFound",
>           "desc": "The command query-tpm has not been found"
>       }
>   }
> 
> Suggested-by: Marc-André Lureau <marcandre.lureau@redhat.com>
> Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
> ---
>  qapi/tpm.json      |  9 ++++++---
>  monitor/hmp-cmds.c |  4 ++++
>  stubs/tpm.c        | 16 ----------------
>  3 files changed, 10 insertions(+), 19 deletions(-)

Yes, looks nicer.

> 
> diff --git a/qapi/tpm.json b/qapi/tpm.json
> index 6a10c9ed8d2..09332e6f996 100644
> --- a/qapi/tpm.json
> +++ b/qapi/tpm.json
> @@ -33,7 +33,8 @@
>  # <- { "return": [ "tpm-tis", "tpm-crb", "tpm-spapr" ] }
>  #
>  ##
> -{ 'command': 'query-tpm-models', 'returns': ['TpmModel'] }
> +{ 'command': 'query-tpm-models', 'returns': ['TpmModel'],
> +  'if': 'defined(CONFIG_TPM)' }

May need a rebase if the series to make 'if' language-agnostic lands
first (in fact, that would probably result in a build-time semantic
conflict rather than a patch-application-time merge conflict), but
that's not enough to prevent me from giving:

Reviewed-by: Eric Blake <eblake@redhat.com

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org