Re: [PATCH 2/3] s390/kvm: handle diagnose 318 instruction call

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On 09/19/2018 05:37 AM, Cornelia Huck wrote:
> On Fri, 31 Aug 2018 12:51:18 -0400
> Collin Walling <walling@xxxxxxxxxxxxx> wrote:
> 
>> The diagnose 318 instruction is a privileged instruction that must be
>> interpreted by SIE and handled via KVM.
>>
>> The control program name and version codes (CPNC and CPVC) set by this
>> instruction are saved to the kvm->arch struct. The CPNC is also set in
>> the SIE control block of all VCPUs. The new kvm_s390_set_misc interface
>> is introduced for migration.
>>
>> Signed-off-by: Collin Walling <walling@xxxxxxxxxxxxx>
>> Reviewed-by: Janosch Frank <frankja@xxxxxxxxxxxxx>
>> ---
>>  arch/s390/include/asm/kvm_host.h       |  6 ++-
>>  arch/s390/include/uapi/asm/kvm.h       |  5 ++
>>  arch/s390/kvm/diag.c                   | 16 ++++++
>>  arch/s390/kvm/kvm-s390.c               | 90 ++++++++++++++++++++++++++++++++++
>>  arch/s390/kvm/kvm-s390.h               |  1 +
>>  tools/arch/s390/include/uapi/asm/kvm.h |  1 +
>>  6 files changed, 118 insertions(+), 1 deletion(-)
>>
> 
>> @@ -2568,6 +2655,9 @@ void kvm_arch_vcpu_postcreate(struct kvm_vcpu *vcpu)
>>  	vcpu->arch.sie_block->epoch = vcpu->kvm->arch.epoch;
>>  	vcpu->arch.sie_block->epdx = vcpu->kvm->arch.epdx;
>>  	preempt_enable();
>> +
>> +	vcpu->arch.sie_block->cpnc = vcpu->kvm->arch.cpnc;
> 
> Any reason why you set this _after_ the preempt_enable()?
> 

I didn't consider setting this value as time-critical as the TOD-Clock values. I guess
it doesn't hurt to throw the cpnc in there, too?

>> +
>>  	mutex_unlock(&vcpu->kvm->lock);
>>  	if (!kvm_is_ucontrol(vcpu->kvm)) {
>>  		vcpu->arch.gmap = vcpu->kvm->arch.gmap;
> 


-- 
Respectfully,
- Collin Walling




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