Re: [PATCH v14 10/11] qapi/s390/cpu topology: POLARITY_CHANGE qapi event

[Thomas Huth]

On 05/01/2023 15.53, Pierre Morel wrote:
> When the guest asks to change the polarity this change
> is forwarded to the admin using QAPI.
> The admin is supposed to take according decisions concerning
> CPU provisioning.

I somehow doubt that an average admin will monitor QEMU for such events ... 
so this rather should be handled by upper layers like libvirt one day?

> Signed-off-by: Pierre Morel <pmorel@linux.ibm.com>
> ---
>   qapi/machine-target.json | 21 +++++++++++++++++++++
>   hw/s390x/cpu-topology.c  |  2 ++
>   2 files changed, 23 insertions(+)
>
> diff --git a/qapi/machine-target.json b/qapi/machine-target.json
> index 927618a78f..10235cfb45 100644
> --- a/qapi/machine-target.json
> +++ b/qapi/machine-target.json
> @@ -437,3 +437,24 @@
>     'returns': ['S390CpuTopology'],
>     'if': { 'all': [ 'TARGET_S390X', 'CONFIG_KVM' ] }
>   }
> +
> +##
> +# @POLARITY_CHANGE:

I'd maybe rather call it CPU_POLARITY_CHANGE ... in case "polarity" is one 
day also used for some other devices.

> +#
> +# Emitted when the guest asks to change the polarity.
> +#
> +# @polarity: polarity specified by the guest

Please elaborate: Where does the value come from (the PTF instruction)? 
Which values are possible?

 Thomas


> +#
> +# Since: 8.0
> +#
> +# Example:
> +#
> +# <- { "event": "POLARITY_CHANGE",
> +#      "data": { "polarity": 0 },
> +#      "timestamp": { "seconds": 1401385907, "microseconds": 422329 } }
> +#
> +##
> +{ 'event': 'POLARITY_CHANGE',
> +  'data': { 'polarity': 'int' },
> +   'if': { 'all': [ 'TARGET_S390X', 'CONFIG_KVM'] }
> +}
> diff --git a/hw/s390x/cpu-topology.c b/hw/s390x/cpu-topology.c
> index c3748654ff..45621387d5 100644
> --- a/hw/s390x/cpu-topology.c
> +++ b/hw/s390x/cpu-topology.c
> @@ -19,6 +19,7 @@
>   #include "hw/s390x/s390-virtio-ccw.h"
>   #include "hw/s390x/cpu-topology.h"
>   #include "qapi/qapi-commands-machine-target.h"
> +#include "qapi/qapi-events-machine-target.h"
>   #include "qapi/qmp/qdict.h"
>   #include "monitor/hmp.h"
>   #include "monitor/monitor.h"
> @@ -128,6 +129,7 @@ void s390_topology_set_polarity(int polarity)
>           }
>       }
>       s390_cpu_topology_set();
> +    qapi_event_send_polarity_change(polarity);
>   }
>   
>   /*