Re: [kvm-unit-tests PATCH v9 2/2] s390x: topology: Checking Configuration Topology Information

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

On 6/1/23 11:38, Janosch Frank wrote:
> On 5/19/23 13:22, Pierre Morel wrote:
>> STSI with function code 15 is used to store the CPU configuration
>> topology.
>>
>> We retrieve the maximum nested level with SCLP and use the
>> topology tree provided by the drawers, books, sockets, cores
>> arguments.
>>
>> We check :
>> - if the topology stored is coherent between the QEMU -smp
>>    parameters and kernel parameters.
>> - the number of CPUs
>> - the maximum number of CPUs
>> - the number of containers of each levels for every STSI(15.1.x)
>>    instruction allowed by the machine.
>
>>   [topology]
>>   file = topology.elf
>> +# 3 CPUs on socket 0 with different CPU TLE (standard, dedicated, 
>> origin)
>> +# 1 CPU on socket 2
>> +extra_params = -smp 
>> 1,drawers=3,books=3,sockets=4,cores=4,maxcpus=144 -cpu z14,ctop=on 
>> -device z14-s390x-cpu,core-id=1,entitlement=low -device 
>> z14-s390x-cpu,core-id=2,dedicated=on -device z14-s390x-cpu,core-id=10 
>> -device z14-s390x-cpu,core-id=20 -device 
>> z14-s390x-cpu,core-id=130,socket-id=0,book-id=0,drawer-id=0 -append 
>> '-drawers 3 -books 3 -sockets 4 -cores 4'
>> +
>> +[topology-2]
>> +file = topology.elf
>> +extra_params = -smp 
>> 1,drawers=2,books=2,sockets=2,cores=30,maxcpus=240  -append '-drawers 
>> 2 -books 2 -sockets 2 -cores 30' -cpu z14,ctop=on -device 
>> z14-s390x-cpu,drawer-id=1,book-id=0,socket-id=0,core-id=2,entitlement=low 
>> -device 
>> z14-s390x-cpu,drawer-id=1,book-id=0,socket-id=0,core-id=3,entitlement=medium 
>> -device 
>> z14-s390x-cpu,drawer-id=1,book-id=0,socket-id=0,core-id=4,entitlement=high 
>> -device 
>> z14-s390x-cpu,drawer-id=1,book-id=0,socket-id=0,core-id=5,entitlement=high,dedicated=on 
>> -device 
>> z14-s390x-cpu,drawer-id=1,book-id=0,socket-id=0,core-id=65,entitlement=low 
>> -device 
>> z14-s390x-cpu,drawer-id=1,book-id=0,socket-id=0,core-id=66,entitlement=medium 
>> -device 
>> z14-s390x-cpu,drawer-id=1,book-id=0,socket-id=0,core-id=67,entitlement=high 
>> -device 
>> z14-s390x-cpu,drawer-id=1,book-id=0,socket-id=0,core-id=68,entitlement=high,dedicated=on
>
> Pardon my ignorance but I see z14 in there, will this work if we run 
> on a z13?

I think it will, we do not use anything specific to the CPU but the 
Configuration topology facility which start with z10EC
and AFAIU QEMU will accept a processor newer than the one of the host, 
at least it does on my LPAR (VM z16b > host z16a)

But we can use z13 as basis, which also covers the case where I forgot 
something.


>
> Also, will this work/fail gracefully if the test is run with a quemu 
> that doesn't know about topology or will it crash?

It will crash, QEMU will refuse the drawers and book parameters if the 
QEMU patch for topology has not been applied.

So, I should first propose a simple unittests.cfg working with both, 
which will SKIP with "Topology facility not present" without the patch.

When the patch is becoming used we can add more testings.

Thanks for the comments.

Pierre