Re: [PATCH v2 06/13] s390x: protvirt: KVM intercept changes

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

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On 12/5/19 6:15 PM, Cornelia Huck wrote:
> On Fri, 29 Nov 2019 04:48:02 -0500
> Janosch Frank <frankja@linux.ibm.com> wrote:
> 
>> Secure guests no longer intercept with code 4 for an instruction
>> interception. Instead they have codes 104 and 108 for secure
>> instruction interception and secure instruction notification
>> respectively.
>>
>> The 104 mirrors the 4 interception.
>>
>> The 108 is a notification interception to let KVM and QEMU know that
>> something changed and we need to update tracking information or
>> perform specific tasks. It's currently taken for the following
>> instructions:
>>
>> * stpx (To inform about the changed prefix location)
>> * sclp (On incorrect SCCB values, so we can inject a IRQ)
>> * sigp (All but "stop and store status")
>> * diag308 (Subcodes 0/1)
>>
>> Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
>> ---
>>  target/s390x/kvm.c | 6 ++++++
>>  1 file changed, 6 insertions(+)
>>
>> diff --git a/target/s390x/kvm.c b/target/s390x/kvm.c
>> index ad6e38c876..3d9c44ba9d 100644
>> --- a/target/s390x/kvm.c
>> +++ b/target/s390x/kvm.c
>> @@ -115,6 +115,8 @@
>>  #define ICPT_CPU_STOP                   0x28
>>  #define ICPT_OPEREXC                    0x2c
>>  #define ICPT_IO                         0x40
>> +#define ICPT_PV_INSTR                   0x68
>> +#define ICPT_PV_INSTR_NOTIFICATION      0x6c
>>  
>>  #define NR_LOCAL_IRQS 32
>>  /*
>> @@ -151,6 +153,7 @@ static int cap_s390_irq;
>>  static int cap_ri;
>>  static int cap_gs;
>>  static int cap_hpage_1m;
>> +static int cap_protvirt;
>>  
>>  static int active_cmma;
>>  
>> @@ -342,6 +345,7 @@ int kvm_arch_init(MachineState *ms, KVMState *s)
>>      cap_async_pf = kvm_check_extension(s, KVM_CAP_ASYNC_PF);
>>      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);
>>  
>>      if (!kvm_check_extension(s, KVM_CAP_S390_GMAP)
>>          || !kvm_check_extension(s, KVM_CAP_S390_COW)) {
>> @@ -1664,6 +1668,8 @@ static int handle_intercept(S390CPU *cpu)
>>              (long)cs->kvm_run->psw_addr);
>>      switch (icpt_code) {
>>          case ICPT_INSTRUCTION:
>> +        case ICPT_PV_INSTR:
>> +        case ICPT_PV_INSTR_NOTIFICATION:
>>              r = handle_instruction(cpu, run);
> 
> I'm still a bit uneasy about going through the same path for both 104
> and 108. How does the handler figure out whether it should emulate an
> instruction, or just process a notification? Is it guaranteed that a
> given instruction is always showing up as either a 104 or a 108, so
> that the handler can check the pv state?

diag 308 subcode 0/1 are 108, but all other subcodes are defined as a
104 (if they are an exit at all)...

> 
> [Even if that works, it still feels a bit unclean to me.]
> 
>>              break;
>>          case ICPT_PROGRAM:
> 
> 



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