Re: [PATCH v2 08/13] s390x: protvirt: Add new VCPU reset functions

[Janosch Frank <frankja@linux.ibm.com>]

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On 12/4/19 12:58 PM, Thomas Huth wrote:
> On 29/11/2019 10.48, Janosch Frank wrote:
>> CPU resets for protected guests need to be done via Ultravisor
>> calls. Hence we need a way to issue these calls for each reset.
>>
>> As we formerly had only one reset function and it was called for
>> initial, as well as for the clear reset, we now need a new interface.
>>
>> Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
>> ---
> [...]
>> diff --git a/target/s390x/kvm.c b/target/s390x/kvm.c
>> index b802d02ff5..5b1ed3acb4 100644
>> --- a/target/s390x/kvm.c
>> +++ b/target/s390x/kvm.c
>> @@ -154,6 +154,7 @@ static int cap_ri;
>>  static int cap_gs;
>>  static int cap_hpage_1m;
>>  static int cap_protvirt;
>> +static int cap_vcpu_resets;
>>  
>>  static int active_cmma;
>>  
>> @@ -346,6 +347,7 @@ int kvm_arch_init(MachineState *ms, KVMState *s)
>>      cap_mem_op = kvm_check_extension(s, KVM_CAP_S390_MEM_OP);
>>      cap_s390_irq = kvm_check_extension(s, KVM_CAP_S390_INJECT_IRQ);
>>      cap_protvirt = kvm_check_extension(s, KVM_CAP_S390_PROTECTED);
>> +    cap_vcpu_resets = kvm_check_extension(s, KVM_CAP_S390_VCPU_RESETS);
>>  
>>      if (!kvm_check_extension(s, KVM_CAP_S390_GMAP)
>>          || !kvm_check_extension(s, KVM_CAP_S390_COW)) {
>> @@ -407,20 +409,44 @@ int kvm_arch_destroy_vcpu(CPUState *cs)
>>      return 0;
>>  }
>>  
>> -void kvm_s390_reset_vcpu(S390CPU *cpu)
>> +static void kvm_s390_reset_vcpu(S390CPU *cpu, unsigned long type)
>>  {
>>      CPUState *cs = CPU(cpu);
>>  
>> -    /* The initial reset call is needed here to reset in-kernel
>> -     * vcpu data that we can't access directly from QEMU
>> -     * (i.e. with older kernels which don't support sync_regs/ONE_REG).
>> -     * Before this ioctl cpu_synchronize_state() is called in common kvm
>> -     * code (kvm-all) */
>> +    /*
>> +     * The reset call is needed here to reset in-kernel vcpu data that
>> +     * we can't access directly from QEMU (i.e. with older kernels
>> +     * which don't support sync_regs/ONE_REG).  Before this ioctl
>> +     * cpu_synchronize_state() is called in common kvm code
>> +     * (kvm-all).
>> +     */
>> +    if (cap_vcpu_resets) {
>> +        if (kvm_vcpu_ioctl(cs, KVM_S390_VCPU_RESET, type)) {
>> +            error_report("CPU reset type %ld failed on CPU %i",
>> +                         type, cs->cpu_index);
>> +        }
>> +        return;
>> +    }
>>      if (kvm_vcpu_ioctl(cs, KVM_S390_INITIAL_RESET, NULL)) {
>>          error_report("Initial CPU reset failed on CPU %i", cs->cpu_index);
>>      }
> 
> Don't you want to check for type != KVM_S390_VCPU_RESET_NORMAL before
> doing the INITIAL_RESET here?
> 
>>  }
>>  
>> +void kvm_s390_reset_vcpu_initial(S390CPU *cpu)
>> +{
>> +    kvm_s390_reset_vcpu(cpu, KVM_S390_VCPU_RESET_INITIAL);
>> +}
>> +
>> +void kvm_s390_reset_vcpu_clear(S390CPU *cpu)
>> +{
>> +    kvm_s390_reset_vcpu(cpu, KVM_S390_VCPU_RESET_CLEAR);
>> +}
>> +
>> +void kvm_s390_reset_vcpu_normal(S390CPU *cpu)
>> +{
>> +    kvm_s390_reset_vcpu(cpu, KVM_S390_VCPU_RESET_NORMAL);
>> +}
> 
> ... otherwise this might reset more things than expected?
> 
> Or do I miss something here?

Hey Thomas I split out this patch into the "architectural compliance"
patch series. Have a look into there, this is an old version.

> 
>  Thomas
> 



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