Re: [RFC 21/37] KVM: S390: protvirt: Instruction emulation

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

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On 11/14/19 4:38 PM, Cornelia Huck wrote:
> On Thu, 24 Oct 2019 07:40:43 -0400
> Janosch Frank <frankja@linux.ibm.com> wrote:
> 
>> We have two new SIE exit codes 104 for a secure instruction
>> interception, on which the SIE needs hypervisor action to complete the
>> instruction.
>>
>> And 108 which is merely a notification and provides data for tracking
>> and management, like for the lowcore we set notification bits for the
>> lowcore pages.
> 
> What about the following:
> 
> "With protected virtualization, we have two new SIE exit codes:
> 
> - 104 indicates a secure instruction interception; the hypervisor needs
>   to complete emulation of the instruction.
> - 108 is merely a notification providing data for tracking and
>   management in the hypervisor; for example, we set notification bits
>   for the lowcore pages."
> 
> ?
> 
>>
>> Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
>> ---
>>  arch/s390/include/asm/kvm_host.h |  2 ++
>>  arch/s390/kvm/intercept.c        | 23 +++++++++++++++++++++++
>>  2 files changed, 25 insertions(+)
>>
>> diff --git a/arch/s390/include/asm/kvm_host.h b/arch/s390/include/asm/kvm_host.h
>> index 2a8a1e21e1c3..a42dfe98128b 100644
>> --- a/arch/s390/include/asm/kvm_host.h
>> +++ b/arch/s390/include/asm/kvm_host.h
>> @@ -212,6 +212,8 @@ struct kvm_s390_sie_block {
>>  #define ICPT_KSS	0x5c
>>  #define ICPT_PV_MCHKR	0x60
>>  #define ICPT_PV_INT_EN	0x64
>> +#define ICPT_PV_INSTR	0x68
>> +#define ICPT_PV_NOT	0x6c
> 
> Maybe ICPT_PV_NOTIF?

NOTF?

> 
>>  	__u8	icptcode;		/* 0x0050 */
>>  	__u8	icptstatus;		/* 0x0051 */
>>  	__u16	ihcpu;			/* 0x0052 */
>> diff --git a/arch/s390/kvm/intercept.c b/arch/s390/kvm/intercept.c
>> index b013a9c88d43..a1df8a43c88b 100644
>> --- a/arch/s390/kvm/intercept.c
>> +++ b/arch/s390/kvm/intercept.c
>> @@ -451,6 +451,23 @@ static int handle_operexc(struct kvm_vcpu *vcpu)
>>  	return kvm_s390_inject_program_int(vcpu, PGM_OPERATION);
>>  }
>>  
>> +static int handle_pv_spx(struct kvm_vcpu *vcpu)
>> +{
>> +	u32 pref = *(u32 *)vcpu->arch.sie_block->sidad;
>> +
>> +	kvm_s390_set_prefix(vcpu, pref);
>> +	trace_kvm_s390_handle_prefix(vcpu, 1, pref);
>> +	return 0;
>> +}
>> +
>> +static int handle_pv_not(struct kvm_vcpu *vcpu)
>> +{
>> +	if (vcpu->arch.sie_block->ipa == 0xb210)
>> +		return handle_pv_spx(vcpu);
>> +
>> +	return handle_instruction(vcpu);
> 
> Hm... if I understood it correctly, we are getting this one because the
> SIE informs us about things that it handled itself (but which we
> should be aware of). What can handle_instruction() do in this case?

There used to be an instruction which I could just pipe through normal
instruction handling. But I can't really remember what it was, too many
firmware changes in that area since then.

I'll mark it as a TODO for thinking about it with some coffee.

> 
>> +}
>> +
>>  int kvm_handle_sie_intercept(struct kvm_vcpu *vcpu)
>>  {
>>  	int rc, per_rc = 0;
>> @@ -505,6 +522,12 @@ int kvm_handle_sie_intercept(struct kvm_vcpu *vcpu)
>>  		 */
>>  		rc = 0;
>>  	break;
>> +	case ICPT_PV_INSTR:
>> +		rc = handle_instruction(vcpu);
>> +		break;
>> +	case ICPT_PV_NOT:
>> +		rc = handle_pv_not(vcpu);
>> +		break;
>>  	default:
>>  		return -EOPNOTSUPP;
>>  	}
> 



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