Re: [PATCH v3 4/4] s390x: topology: implementating Store Topology System Information

[Thomas Huth <thuth@redhat.com>]

On 16/09/2021 15.50, Pierre Morel wrote:
> The handling of STSI is enhanced with the interception of the
> function code 15 for storing CPU topology.
> 
> Using the objects built during the pluging of CPU, we build the
> SYSIB 15_1_x structures.
> 
> With this patch the maximum MNEST level is 2, this is also
> the only level allowed and only SYSIB 15_1_2 will be built.
> 
> Signed-off-by: Pierre Morel <pmorel@linux.ibm.com>
> ---
>   target/s390x/kvm/kvm.c | 101 +++++++++++++++++++++++++++++++++++++++++
>   1 file changed, 101 insertions(+)
> 
> diff --git a/target/s390x/kvm/kvm.c b/target/s390x/kvm/kvm.c
> index dd036961fe..0a5f2aced2 100644
> --- a/target/s390x/kvm/kvm.c
> +++ b/target/s390x/kvm/kvm.c
> @@ -52,6 +52,7 @@
>   #include "hw/s390x/s390-virtio-ccw.h"
>   #include "hw/s390x/s390-virtio-hcall.h"
>   #include "hw/s390x/pv.h"
> +#include "hw/s390x/cpu-topology.h"
>   
>   #ifndef DEBUG_KVM
>   #define DEBUG_KVM  0
> @@ -1908,6 +1909,102 @@ static void insert_stsi_3_2_2(S390CPU *cpu, __u64 addr, uint8_t ar)
>       }
>   }

Could you maybe put the new code in a separate file under target/s390x/ 
(maybe target/s390x/topology.c ?), in case we ever want to implement this 
for TCG, too?

> +static int stsi_15_cpus(void *p, S390TopologyCores *cd)
> +{
> +    SysIBTl_cpu *tle = (SysIBTl_cpu *)p;
> +
> +    tle->nl = 0;
> +    tle->dedicated = cd->dedicated;
> +    tle->polarity = cd->polarity;
> +    tle->type = cd->cputype;
> +    tle->origin = cd->origin;

If we want to use this for TCG, too, one day:

    tle->origin = be16_to_cpu(cd->origin);

> +    tle->mask = cd->mask;
> +
> +    return sizeof(*tle);
> +}
> +
> +static int set_socket(const MachineState *ms, void *p,
> +                      S390TopologySocket *socket)
> +{
> +    BusChild *kid;
> +    int l, len = 0;
> +
> +    len += stsi_15_container(p, 1, socket->socket_id);
> +    p += len;
> +
> +    QTAILQ_FOREACH_REVERSE(kid, &socket->bus->children, sibling) {
> +        l = stsi_15_cpus(p, S390_TOPOLOGY_CORES(kid->child));
> +        p += l;
> +        len += l;
> +    }
> +    return len;
> +}
> +
> +static void insert_stsi_15_1_2(const MachineState *ms, void *p)
> +{
> +    S390TopologyBook *book;
> +    SysIB_151x *sysib;
> +    BusChild *kid;
> +    int level = 2;
> +    int len, l;
> +
> +    sysib = (SysIB_151x *)p;
> +    sysib->mnest = level;
> +    sysib->mag[TOPOLOGY_NR_MAG2] = ms->smp.sockets;
> +    sysib->mag[TOPOLOGY_NR_MAG1] = ms->smp.cores;
> +
> +    book = s390_get_topology();
> +    len = sizeof(SysIB_151x);
> +    p += len;
> +
> +    QTAILQ_FOREACH_REVERSE(kid, &book->bus->children, sibling) {
> +        l = set_socket(ms, p, S390_TOPOLOGY_SOCKET(kid->child));
> +        p += l;
> +        len += l;
> +    }
> +
> +    sysib->length = len;

For TCG awareness:

     sysib->length = be16_to_cpu(len);

> +}
> +
> +static void insert_stsi_15_1_x(S390CPU *cpu, int sel2, __u64 addr, uint8_t ar)
> +{
> +    const MachineState *machine = MACHINE(qdev_get_machine());
> +    void *p;
> +    int ret, cc;
> +
> +    /*
> +     * Until the SCLP STSI Facility reporting the MNEST value is used,
> +     * a sel2 value of 2 is the only value allowed in STSI 15.1.x.
> +     */
> +    if (sel2 != 2) {
> +        setcc(cpu, 3);
> +        return;
> +    }
> +
> +    p = g_malloc0(TARGET_PAGE_SIZE);
> +
> +    insert_stsi_15_1_2(machine, p);
> +
> +    if (s390_is_pv()) {
> +        ret = s390_cpu_pv_mem_write(cpu, 0, p, TARGET_PAGE_SIZE);
> +    } else {
> +        ret = s390_cpu_virt_mem_write(cpu, addr, ar, p, TARGET_PAGE_SIZE);
> +    }
> +    cc = ret ? 3 : 0;
> +    setcc(cpu, cc);
> +    g_free(p);
> +}
> +
>   static int handle_stsi(S390CPU *cpu)
>   {
>       CPUState *cs = CPU(cpu);
> @@ -1921,6 +2018,10 @@ static int handle_stsi(S390CPU *cpu)
>           /* Only sysib 3.2.2 needs post-handling for now. */
>           insert_stsi_3_2_2(cpu, run->s390_stsi.addr, run->s390_stsi.ar);
>           return 0;
> +    case 15:
> +        insert_stsi_15_1_x(cpu, run->s390_stsi.sel2, run->s390_stsi.addr,
> +                           run->s390_stsi.ar);
> +        return 0;
>       default:
>           return 0;
>       }
> 

  Thomas