Re: [Qemu-devel] [PATCH v3 3/7] s390x/cpumodel: Set up CPU model for AP device support

[Tony Krowiak <akrowiak@linux.vnet.ibm.com>]

On 04/06/2018 10:51 AM, Pierre Morel wrote:
> On 16/03/2018 00:24, Tony Krowiak wrote:
>> A new CPU model feature and two new CPU model facilities are
>> introduced to support AP devices for a KVM guest.
>>
>> CPU model features:
>>
>> 1. The KVM_S390_VM_CPU_FEAT_AP CPU model feature indicates that
>>     AP facilities are installed. This feature will be enabled by
>>     the kernel only if the AP facilities are installed on the linux
>>     host. This feature must be turned on from userspace to access
>>     AP devices from the KVM guest. The QEMU command line to turn
>>     this feature looks something like this:
>>
>>     qemu-system-s390x ... -cpu xxx,ap=on
>>
>> CPU model facilities:
>>
>> 1. The S390_FEAT_AP_QUERY_CONFIG_INFO feature indicates the AP Query
>>     Configuration Information (QCI) facility is installed. This feature
>>     will be enabled by the kernel only if the QCI is installed on
>>     the host.
>>
>> 2. The S390_FEAT_AP_FACILITY_TEST feature indicates that the AP
>>     Facility Test (APFT) facility is installed. This feature will
>>     be enabled by the kernel only if the APFT facility is installed
>>     on the host.
>>
>> Signed-off-by: Tony Krowiak <akrowiak@linux.vnet.ibm.com>
>> ---
>>   target/s390x/cpu_features.c     |    3 +++
>>   target/s390x/cpu_features_def.h |    3 +++
>>   target/s390x/cpu_models.c       |    2 ++
>>   target/s390x/gen-features.c     |    3 +++
>>   target/s390x/kvm.c              |    1 +
>>   5 files changed, 12 insertions(+), 0 deletions(-)
>>
>> diff --git a/target/s390x/cpu_features.c b/target/s390x/cpu_features.c
>> index a5619f2..1abe987 100644
>> --- a/target/s390x/cpu_features.c
>> +++ b/target/s390x/cpu_features.c
>> @@ -36,8 +36,10 @@ static const S390FeatDef s390_features[] = {
>>       FEAT_INIT("srs", S390_FEAT_TYPE_STFL, 9, "Sense-running-status 
>> facility"),
>>       FEAT_INIT("csske", S390_FEAT_TYPE_STFL, 10, "Conditional-SSKE 
>> facility"),
>>       FEAT_INIT("ctop", S390_FEAT_TYPE_STFL, 11, 
>> "Configuration-topology facility"),
>> +    FEAT_INIT("qci", S390_FEAT_TYPE_STFL, 12, "Query AP 
>> Configuration facility"),
>>       FEAT_INIT("ipter", S390_FEAT_TYPE_STFL, 13, "IPTE-range 
>> facility"),
>>       FEAT_INIT("nonqks", S390_FEAT_TYPE_STFL, 14, "Nonquiescing 
>> key-setting facility"),
>> +    FEAT_INIT("apft", S390_FEAT_TYPE_STFL, 15, "Adjunct Processor 
>> Facilities Test facility"),
>>       FEAT_INIT("etf2", S390_FEAT_TYPE_STFL, 16, 
>> "Extended-translation facility 2"),
>>       FEAT_INIT("msa-base", S390_FEAT_TYPE_STFL, 17, 
>> "Message-security-assist facility (excluding subfunctions)"),
>>       FEAT_INIT("ldisp", S390_FEAT_TYPE_STFL, 18, "Long-displacement 
>> facility"),
>> @@ -125,6 +127,7 @@ static const S390FeatDef s390_features[] = {
>>
>>       FEAT_INIT("dateh2", S390_FEAT_TYPE_MISC, 0, "DAT-enhancement 
>> facility 2"),
>>       FEAT_INIT("cmm", S390_FEAT_TYPE_MISC, 0, 
>> "Collaborative-memory-management facility"),
>> +    FEAT_INIT("ap", S390_FEAT_TYPE_MISC, 0, "AP facilities installed"),
>>
>>       FEAT_INIT("plo-cl", S390_FEAT_TYPE_PLO, 0, "PLO Compare and 
>> load (32 bit in general registers)"),
>>       FEAT_INIT("plo-clg", S390_FEAT_TYPE_PLO, 1, "PLO Compare and 
>> load (64 bit in parameter list)"),
>> diff --git a/target/s390x/cpu_features_def.h 
>> b/target/s390x/cpu_features_def.h
>> index 7c5915c..8998b65 100644
>> --- a/target/s390x/cpu_features_def.h
>> +++ b/target/s390x/cpu_features_def.h
>> @@ -27,8 +27,10 @@ typedef enum {
>>       S390_FEAT_SENSE_RUNNING_STATUS,
>>       S390_FEAT_CONDITIONAL_SSKE,
>>       S390_FEAT_CONFIGURATION_TOPOLOGY,
>> +    S390_FEAT_AP_QUERY_CONFIG_INFO,
>>       S390_FEAT_IPTE_RANGE,
>>       S390_FEAT_NONQ_KEY_SETTING,
>> +    S390_FEAT_AP_FACILITIES_TEST,
>>       S390_FEAT_EXTENDED_TRANSLATION_2,
>>       S390_FEAT_MSA,
>>       S390_FEAT_LONG_DISPLACEMENT,
>> @@ -118,6 +120,7 @@ typedef enum {
>>       /* Misc */
>>       S390_FEAT_DAT_ENH_2,
>>       S390_FEAT_CMM,
>> +    S390_FEAT_AP,
>>
>>       /* PLO */
>>       S390_FEAT_PLO_CL,
>> diff --git a/target/s390x/cpu_models.c b/target/s390x/cpu_models.c
>> index cf82589..7e2af09 100644
>> --- a/target/s390x/cpu_models.c
>> +++ b/target/s390x/cpu_models.c
>> @@ -769,6 +769,8 @@ static void check_consistency(const S390CPUModel 
>> *model)
>>           { S390_FEAT_PRNO_TRNG_QRTCR, S390_FEAT_MSA_EXT_5 },
>>           { S390_FEAT_PRNO_TRNG, S390_FEAT_MSA_EXT_5 },
>>           { S390_FEAT_SIE_KSS, S390_FEAT_SIE_F2 },
>> +        { S390_FEAT_AP_QUERY_CONFIG_INFO, S390_FEAT_AP },
>> +        { S390_FEAT_AP_FACILITIES_TEST, S390_FEAT_AP },
>>       };
>>       int i;
>>
>> diff --git a/target/s390x/gen-features.c b/target/s390x/gen-features.c
>> index 0cdbc15..0d5b0f7 100644
>> --- a/target/s390x/gen-features.c
>> +++ b/target/s390x/gen-features.c
>> @@ -447,6 +447,9 @@ static uint16_t full_GEN12_GA1[] = {
>>       S390_FEAT_ADAPTER_INT_SUPPRESSION,
>>       S390_FEAT_EDAT_2,
>>       S390_FEAT_SIDE_EFFECT_ACCESS_ESOP2,
>> +    S390_FEAT_AP_QUERY_CONFIG_INFO,
>
> Placing QCI feature in the full feature for z13 has for effect that:
>
> 1)  it must be on the qemu command line.
> Do we really want this?
> QCI is always available when AP is available in the real hardware
> before z13.

Are you suggesting we always set STFLE.12 for the guest whenever
AP is available and get rid of this feature? This feature maps
to what the architecture requires, i.e., that STFLE.12 indicates
whether QCI is available. I think we should keep it. This was
discussed and decided upon during v1 review.

>
>
> 2) AP exist since z10 and QCI since EC12 AFAIK

This seems to conflict with what you stated above concerning QCI
availability.

> Do we enable both only beginning with z13?

If I am not mistaken, GEN12_GA1 is EC12 .... or is that not true?
I queried the team architects and there was unanimous agreement
that AP virtualization should start with EC12 regardless of when
it was available in the real hardware.

>
>> +    S390_FEAT_AP_FACILITIES_TEST,
>> +    S390_FEAT_AP,
>>   };
>>
>>   static uint16_t full_GEN12_GA2[] = {
>> diff --git a/target/s390x/kvm.c b/target/s390x/kvm.c
>> index fbc887e..33e5ec3 100644
>> --- a/target/s390x/kvm.c
>> +++ b/target/s390x/kvm.c
>> @@ -2178,6 +2178,7 @@ static int kvm_to_feat[][2] = {
>>       { KVM_S390_VM_CPU_FEAT_PFMFI, S390_FEAT_SIE_PFMFI},
>>       { KVM_S390_VM_CPU_FEAT_SIGPIF, S390_FEAT_SIE_SIGPIF},
>>       { KVM_S390_VM_CPU_FEAT_KSS, S390_FEAT_SIE_KSS},
>> +    { KVM_S390_VM_CPU_FEAT_AP, S390_FEAT_AP},
>>   };
>>
>>   static int query_cpu_feat(S390FeatBitmap features)
>
>