Re: [PATCH v9 05/10] s390x/cpu: reporting drawers and books topology to the guest

[Pierre Morel <pmorel@linux.ibm.com>]

On 9/7/22 12:36, Janis Schoetterl-Glausch wrote:
> On Fri, 2022-09-02 at 09:55 +0200, Pierre Morel wrote:
>> The guest can ask for a topology report on drawer's or book's
>> level.
>> Let's implement the STSI instruction's handling for the corresponding
>> selector values.
>>
>> Signed-off-by: Pierre Morel <pmorel@linux.ibm.com>
>> ---
>>   hw/s390x/cpu-topology.c         | 19 +++++++---
>>   hw/s390x/s390-virtio-ccw.c      |  2 ++
>>   include/hw/s390x/cpu-topology.h |  7 +++-
>>   target/s390x/cpu_topology.c     | 64 +++++++++++++++++++++++++++------
>>   4 files changed, 76 insertions(+), 16 deletions(-)
>>
>> diff --git a/hw/s390x/cpu-topology.c b/hw/s390x/cpu-topology.c
>> index e2fd5c7e44..bb9ae63483 100644
>> --- a/hw/s390x/cpu-topology.c
>> +++ b/hw/s390x/cpu-topology.c
>>
> [...]
> 
>> @@ -99,13 +103,20 @@ static void s390_topology_realize(DeviceState *dev, Error **errp)
>>       S390Topology *topo = S390_CPU_TOPOLOGY(dev);
>>       int n;
>>   
>> +    topo->drawers = ms->smp.drawers;
>> +    topo->books = ms->smp.books;
>> +    topo->total_books = topo->books * topo->drawers;
>>       topo->sockets = ms->smp.sockets;
>> +    topo->total_sockets = topo->sockets * topo->books * topo->drawers;
>>       topo->cores = ms->smp.cores;
>> -    topo->tles = ms->smp.max_cpus;
>>   
>> -    n = topo->sockets;
>> +    n = topo->drawers;
>> +    topo->drawer = g_malloc0(n * sizeof(S390TopoContainer));
>> +    n *= topo->books;
>> +    topo->book = g_malloc0(n * sizeof(S390TopoContainer));
>> +    n *= topo->sockets;
>>       topo->socket = g_malloc0(n * sizeof(S390TopoContainer));
>> -    topo->tle = g_malloc0(topo->tles * sizeof(S390TopoTLE));
>> +    topo->tle = g_malloc0(n * sizeof(S390TopoTLE));
> 
> Same question here about using g_new0.

yes, g_new0 is better here

>>   
>>       qemu_mutex_init(&topo->topo_mutex);
>>   }
>> diff --git a/hw/s390x/s390-virtio-ccw.c b/hw/s390x/s390-virtio-ccw.c
>> index 15cefd104b..3f28e28d47 100644
>> --- a/hw/s390x/s390-virtio-ccw.c
>> +++ b/hw/s390x/s390-virtio-ccw.c
>> @@ -626,6 +626,8 @@ static void ccw_machine_class_init(ObjectClass *oc, void *data)
>>       hc->unplug_request = s390_machine_device_unplug_request;
>>       nc->nmi_monitor_handler = s390_nmi;
>>       mc->default_ram_id = "s390.ram";
>> +    mc->smp_props.books_supported = true;
>> +    mc->smp_props.drawers_supported = true;
>>   }
>>   
>>   static inline bool machine_get_aes_key_wrap(Object *obj, Error **errp)
>> diff --git a/include/hw/s390x/cpu-topology.h b/include/hw/s390x/cpu-topology.h
>> index 0b7f3d10b2..4f8ac39ca0 100644
>> --- a/include/hw/s390x/cpu-topology.h
>> +++ b/include/hw/s390x/cpu-topology.h
>> @@ -29,9 +29,14 @@ typedef struct S390TopoTLE {
>>   
>>   struct S390Topology {
>>       SysBusDevice parent_obj;
>> +    int total_books;
>> +    int total_sockets;
> 
> What are these used for? I'm not seeing anything.
> 
>> +    int drawers;
>> +    int books;
>>       int sockets;
>>       int cores;
>> -    int tles;
> 
> You remove this in this patch and you didn't really need it before.
> As far as I can tell it was just used for calculating the number of
> tles to allocate and you could use a local variable instead.
> So I would get rid of it in the patch that introduced it.

yes


> 
>> +    S390TopoContainer *drawer;
>> +    S390TopoContainer *book;
>>       S390TopoContainer *socket;
>>       S390TopoTLE *tle;
>>       QemuMutex topo_mutex;
>> diff --git a/target/s390x/cpu_topology.c b/target/s390x/cpu_topology.c
>> index 56865dafc6..305fbb9734 100644
>> --- a/target/s390x/cpu_topology.c
>> +++ b/target/s390x/cpu_topology.c
>> @@ -37,19 +37,18 @@ static char *fill_tle_cpu(char *p, uint64_t mask, int origin)
>>       return p + sizeof(*tle);
>>   }
>>   
>> -static char *s390_top_set_level2(S390Topology *topo, char *p)
>> +static char *s390_top_set_level2(S390Topology *topo, char *p, int fs, int ns)
>>   {
> 
> I wouldn't hate more verbose names for fs and ns. start_socket,
> num_socket maybe? Same for fb, nb, but it is your call, it's not really
> hard to understand the code.

I prefer to keep the names short but I will have a second thought.

> 
>> -    int i, origin;
>> +    int socket, origin;
>> +    uint64_t mask;
>>   
>> -    for (i = 0; i < topo->sockets; i++) {
>> -        if (!topo->socket[i].active_count) {
>> +    for (socket = fs; socket < fs + ns; socket++) {
>> +        if (!topo->socket[socket].active_count) {
>>               continue;
>>           }
>> -        p = fill_container(p, 1, i);
>> +        p = fill_container(p, 1, socket);
> 
> Have you considered using an enum for the level constants?

did not but yes it would be better.

> 
>>           for (origin = 0; origin < S390_TOPOLOGY_MAX_ORIGIN; origin++) {
>> -            uint64_t mask = 0L;
>> -
>> -            mask = be64_to_cpu(topo->tle[i].mask[origin]);
>> +            mask = be64_to_cpu(topo->tle[socket].mask[origin]);
>>               if (mask) {
>>                   p = fill_tle_cpu(p, mask, origin);
>>               }
>> @@ -58,19 +57,63 @@ static char *s390_top_set_level2(S390Topology *topo, char *p)
>>       return p;
>>   }
>>   
>> +static char *s390_top_set_level3(S390Topology *topo, char *p, int fb, int nb)
>> +{
>> +    int book, fs = 0;
>> +
>> +    for (book = fb; book < fb + nb; book++, fs += topo->sockets) {
>> +        if (!topo->book[book].active_count) {
>> +            continue;
>> +        }
>> +        p = fill_container(p, 2, book);
>> +    p = s390_top_set_level2(topo, p, fs, topo->sockets);
> 
> Indent is off.

thx

> 
>> +    }
>> +    return p;
>> +}
>> +
>> +static char *s390_top_set_level4(S390Topology *topo, char *p)
>> +{
>> +    int drawer, fb = 0;
>> +
>> +    for (drawer = 0; drawer < topo->drawers; drawer++, fb += topo->books) {
>> +        if (!topo->drawer[drawer].active_count) {
>> +            continue;
>> +        }
>> +        p = fill_container(p, 3, drawer);
>> +        p = s390_top_set_level3(topo, p, fb, topo->books);
>> +    }
>> +    return p;
>> +}
>> +
>>   static int setup_stsi(SysIB_151x *sysib, int level)
>>   {
>>       S390Topology *topo = s390_get_topology();
>>       char *p = (char *)sysib->tle;
>> +    int max_containers;
>>   
>>       qemu_mutex_lock(&topo->topo_mutex);
>>   
>>       sysib->mnest = level;
>>       switch (level) {
>>       case 2:
>> +        max_containers = topo->sockets * topo->books * topo->drawers;
>> +        sysib->mag[TOPOLOGY_NR_MAG2] = max_containers;
>> +        sysib->mag[TOPOLOGY_NR_MAG1] = topo->cores;
>> +        p = s390_top_set_level2(topo, p, 0, max_containers);
> 
> Isn't this logic change already required for the patch that introduced
> stsi 15.1.2 handling?

yes, thx

> 
>> +        break;
>> +    case 3:
>> +        max_containers = topo->books * topo->drawers;
>> +        sysib->mag[TOPOLOGY_NR_MAG3] = max_containers;
>>           sysib->mag[TOPOLOGY_NR_MAG2] = topo->sockets;
>>           sysib->mag[TOPOLOGY_NR_MAG1] = topo->cores;
>> -        p = s390_top_set_level2(topo, p);
>> +        p = s390_top_set_level3(topo, p, 0, max_containers);
>> +        break;
>> +    case 4:
>> +        sysib->mag[TOPOLOGY_NR_MAG4] = topo->drawers;
>> +        sysib->mag[TOPOLOGY_NR_MAG3] = topo->books;
>> +        sysib->mag[TOPOLOGY_NR_MAG2] = topo->sockets;
>> +        sysib->mag[TOPOLOGY_NR_MAG1] = topo->cores;
>> +        p = s390_top_set_level4(topo, p);
>>           break;
>>       }
>>   
>> @@ -79,7 +122,7 @@ static int setup_stsi(SysIB_151x *sysib, int level)
>>       return p - (char *)sysib->tle;
>>   }
>>   
>> -#define S390_TOPOLOGY_MAX_MNEST 2
>> +#define S390_TOPOLOGY_MAX_MNEST 4
> 
> AFAIK you're only allowed to increase this if the maximum mnest
> facility is installed. If it isn't, only level 2 is supported.
> Which would mean that this patch doesn't do anything.

AFAIU this is model dependant but I have to rework the MNEST entry of 
the SYSIB anyway.

> 
>>   void insert_stsi_15_1_x(S390CPU *cpu, int sel2, __u64 addr, uint8_t ar)
>>   {
>>       SysIB_151x *sysib;
>> @@ -105,4 +148,3 @@ void insert_stsi_15_1_x(S390CPU *cpu, int sel2, __u64 addr, uint8_t ar)
>>   out_free:
>>       g_free(sysib);
>>   }
>> -
> 

Thanks for the comments

Regards,
Pierre

-- 
Pierre Morel
IBM Lab Boeblingen