Re: [PATCH v15 01/11] s390x/cpu topology: adding s390 specificities to CPU topology

[Nina Schoetterl-Glausch <nsg@linux.ibm.com>]

Nit patch title: s390x/cpu topology: add s390 specifics to CPU topology ?

On Wed, 2023-02-01 at 14:20 +0100, Pierre Morel wrote:
> S390 adds two new SMP levels, drawers and books to the CPU
> topology.
> The S390 CPU have specific toplogy features like dedication
                                ^o
> and polarity to give to the guest indications on the host
> vCPUs scheduling and help the guest take the best decisions
> on the scheduling of threads on the vCPUs.
> 
> Let us provide the SMP properties with books and drawers levels
> and S390 CPU with dedication and polarity,
> 
> Signed-off-by: Pierre Morel <pmorel@linux.ibm.com>
> ---
>  qapi/machine.json               | 14 ++++++++--
>  include/hw/boards.h             | 10 ++++++-
>  include/hw/s390x/cpu-topology.h | 24 +++++++++++++++++
>  target/s390x/cpu.h              |  5 ++++
>  hw/core/machine-smp.c           | 48 ++++++++++++++++++++++++++++-----
>  hw/core/machine.c               |  4 +++
>  hw/s390x/s390-virtio-ccw.c      |  2 ++
>  softmmu/vl.c                    |  6 +++++
>  target/s390x/cpu.c              |  7 +++++
>  qemu-options.hx                 |  7 +++--
>  10 files changed, 115 insertions(+), 12 deletions(-)
>  create mode 100644 include/hw/s390x/cpu-topology.h
> 
[...]
> 
> diff --git a/include/hw/s390x/cpu-topology.h b/include/hw/s390x/cpu-topology.h
> new file mode 100644
> index 0000000000..7a84b30a21
> --- /dev/null
> +++ b/include/hw/s390x/cpu-topology.h
> @@ -0,0 +1,24 @@
> +/*
> + * CPU Topology
> + *
> + * Copyright IBM Corp. 2022
> + *
> + * This work is licensed under the terms of the GNU GPL, version 2 or (at
> + * your option) any later version. See the COPYING file in the top-level
> + * directory.
> + */
> +#ifndef HW_S390X_CPU_TOPOLOGY_H
> +#define HW_S390X_CPU_TOPOLOGY_H
> +
> +#define S390_TOPOLOGY_CPU_IFL   0x03
> +
> +enum s390_topology_polarity {
> +    POLARITY_HORIZONTAL,
> +    POLARITY_VERTICAL,
> +    POLARITY_VERTICAL_LOW = 1,
> +    POLARITY_VERTICAL_MEDIUM,
> +    POLARITY_VERTICAL_HIGH,
> +    POLARITY_MAX,
> +};

Probably a good idea to keep the S390 prefix.
This works, but aliasing VERTICAL and VERTICAL_LOW is not
entirely straight forward.

Why not have two enum?
enum s390_topology_polarity {
	S390_POLARITY_HORIZONTAL,
	S390_POLARITY_VERTICAL,
};

enum s390_topology_entitlement {
	S390_ENTITLEMENT_LOW = 1,
	S390_ENTITLEMENT_MEDIUM,
	S390_ENTITLEMENT_HIGH,
	S390_ENTITLEMENT_MAX,
};
Maybe add an ENTITLEMENT_INVALID/NONE, if you need that, as first value.

> +#endif
> 
[...]