Re: [PATCH v21 03/20] target/s390x/cpu topology: handle STSI(15) and build the SYSIB

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

On Fri, 2023-06-30 at 11:17 +0200, Pierre Morel wrote:
> On interception of STSI(15.1.x) the System Information Block
> (SYSIB) is built from the list of pre-ordered topology entries.
> 
> Signed-off-by: Pierre Morel <pmorel@linux.ibm.com>
> ---
>  MAINTAINERS                      |   1 +
>  qapi/machine-target.json         |  14 ++
>  include/hw/s390x/cpu-topology.h  |  25 +++
>  include/hw/s390x/sclp.h          |   1 +
>  target/s390x/cpu.h               |  76 ++++++++
>  hw/s390x/cpu-topology.c          |   4 +-
>  target/s390x/kvm/kvm.c           |   5 +-
>  target/s390x/kvm/stsi-topology.c | 310 +++++++++++++++++++++++++++++++
>  target/s390x/kvm/meson.build     |   3 +-
>  9 files changed, 436 insertions(+), 3 deletions(-)
>  create mode 100644 target/s390x/kvm/stsi-topology.c
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 0b03ac5a9b..b8d3e8815c 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -1702,6 +1702,7 @@ M: Pierre Morel <pmorel@linux.ibm.com>
>  S: Supported
>  F: include/hw/s390x/cpu-topology.h
>  F: hw/s390x/cpu-topology.c
> +F: target/s390x/kvm/stsi-topology.c
>  
>  X86 Machines
>  ------------
> diff --git a/qapi/machine-target.json b/qapi/machine-target.json
> index 3362f8dc3f..8ea4834e63 100644
> --- a/qapi/machine-target.json
> +++ b/qapi/machine-target.json
> @@ -361,3 +361,17 @@
>                     'TARGET_MIPS',
>                     'TARGET_LOONGARCH64',
>                     'TARGET_RISCV' ] } }
> +
> +##
> +# @CpuS390Polarization:
> +#
> +# An enumeration of cpu polarization that can be assumed by a virtual
> +# S390 CPU
> +#
> +# Since: 8.1
> +##
> +{ 'enum': 'CpuS390Polarization',
> +  'prefix': 'S390_CPU_POLARIZATION',
> +  'data': [ 'horizontal', 'vertical' ],
> +    'if': { 'all': [ 'TARGET_S390X' , 'CONFIG_KVM' ] }
> +}
> diff --git a/include/hw/s390x/cpu-topology.h b/include/hw/s390x/cpu-topology.h
> index 9164ac00a7..193b33a2fc 100644
> --- a/include/hw/s390x/cpu-topology.h
> +++ b/include/hw/s390x/cpu-topology.h
> @@ -15,10 +15,35 @@
>  #include "hw/boards.h"
>  #include "qapi/qapi-types-machine-target.h"
>  
> +#define S390_TOPOLOGY_CPU_IFL   0x03
> +
> +typedef union s390_topology_id {
> +    uint64_t id;
> +    struct {
> +        uint8_t sentinel;
> +        uint8_t drawer;
> +        uint8_t book;
> +        uint8_t socket;
> +        uint8_t dedicated;
> +        uint8_t entitlement;
> +        uint8_t type;
> +        uint8_t origin;

The order here is not quite right according to the PoP. Type should be
higher, after socket, such that all cpus of the same type in a socket
are stored as a block.
Also entitlement and dedication need to be inverted, e.g such that
dedicated cpus are shown before non dedicated ones.

> +    };
> +} s390_topology_id;
> +

[...]

> +/**
> + * s390_topology_empty_list:
> + *
> + * Clear all entries in the S390Topology list except the sentinel.

The comment is out of date.

> + */
> +static void s390_topology_empty_list(S390TopologyList *topology_list)
> +{
> +    S390TopologyEntry *entry = NULL;
> +    S390TopologyEntry *tmp = NULL;
> +
> +    QTAILQ_FOREACH_SAFE(entry, topology_list, next, tmp) {
> +        QTAILQ_REMOVE(topology_list, entry, next);
> +        g_free(entry);
> +    }
> +}
> +
> +/**
> + * insert_stsi_15_1_x:
> + * cpu: the CPU doing the call for which we set CC
> + * sel2: the selector 2, containing the nested level
> + * addr: Guest logical address of the guest SysIB
> + * ar: the access register number
> + *
> + * Create a list head for the Topology entries and initialize it.
> + * Insert the first entry as a sentinelle.
> + *
> + * Emulate STSI 15.1.x, that is, perform all necessary checks and
> + * fill the SYSIB.
> + * In case the topology description is too long to fit into the SYSIB,
> + * set CC=3 and abort without writing the SYSIB.
> + */
> +void insert_stsi_15_1_x(S390CPU *cpu, int sel2, uint64_t addr, uint8_t ar)
> +{
> +    S390TopologyList topology_list;
> +    S390TopologyEntry *entry;
> +    SysIB sysib = {0};
> +    int length;
> +
> +    if (!s390_has_topology() || sel2 < 2 || sel2 > SCLP_READ_SCP_INFO_MNEST) {
> +        setcc(cpu, 3);
> +        return;
> +    }
> +
> +    QTAILQ_INIT(&topology_list);
> +    entry = g_malloc0(sizeof(S390TopologyEntry));
> +    entry->id.sentinel = 0xff;
> +    QTAILQ_INSERT_HEAD(&topology_list, entry, next);
> +
> +    s390_topology_fill_list_sorted(&topology_list);
> +
> +    length = setup_stsi(&topology_list, &sysib.sysib_151x, sel2);
> +
> +    if (!length) {
> +        setcc(cpu, 3);
> +        return;
> +    }
> +
> +    sysib.sysib_151x.length = cpu_to_be16(length);
> +    s390_cpu_virt_mem_write(cpu, addr, ar, &sysib, length);
> +    setcc(cpu, 0);
> +
> +    s390_topology_empty_list(&topology_list);
> +}
> diff --git a/target/s390x/kvm/meson.build b/target/s390x/kvm/meson.build
> index 37253f75bf..bcf014ba87 100644
> --- a/target/s390x/kvm/meson.build
> +++ b/target/s390x/kvm/meson.build
> @@ -1,6 +1,7 @@
>  
>  s390x_ss.add(when: 'CONFIG_KVM', if_true: files(
> -  'kvm.c'
> +  'kvm.c',
> +  'stsi-topology.c'
>  ), if_false: files(
>    'stubs.c'
>  ))