Re: [PATCH 1/2] docs: kvm: add documentation for KVM_CAP_S390_DIAG318

[Collin Walling <walling@linux.ibm.com>]

On 6/25/20 3:16 AM, Janosch Frank wrote:
> On 6/24/20 10:21 PM, Collin Walling wrote:
>> Documentation for the s390 DIAGNOSE 0x318 instruction handling.
>>
>> Signed-off-by: Collin Walling <walling@linux.ibm.com>
>> ---
>>  Documentation/virt/kvm/api.rst | 19 +++++++++++++++++++
>>  1 file changed, 19 insertions(+)
>>
>> diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst
>> index 426f94582b7a..056608e8f243 100644
>> --- a/Documentation/virt/kvm/api.rst
>> +++ b/Documentation/virt/kvm/api.rst
>> @@ -6150,3 +6150,22 @@ KVM can therefore start protected VMs.
>>  This capability governs the KVM_S390_PV_COMMAND ioctl and the
>>  KVM_MP_STATE_LOAD MP_STATE. KVM_SET_MP_STATE can fail for protected
>>  guests when the state change is invalid.
>> +
>> +8.24 KVM_CAP_S390_DIAG318
>> +-------------------------
>> +
>> +:Architecture: s390
>> +
>> +This capability allows for information regarding the control program that may
>> +be observed via system/firmware service events. The availability of this
> 
> I'm not sure if control program is understood universally, it's a rather
> old term to say guest kernel.
> 
> How about:
> 
> This capability allows a guest to set information about its control
> program (i.e. guest kernel type and version). The information is helpful
> on system/firmware service events, providing additional data about what
> environments are running on the machine.
> 
> 

Fair point. I'll add some clarity to this.

>> +capability indicates that KVM handling of the register synchronization, reset,
>> +and VSIE shadowing of the DIAGNOSE 0x318 related information is present.
>> +
>> +The information associated with the instruction is an 8-byte value consisting
>> +of a one-byte Control Program Name Code (CPNC), and a 7-byte Control Program
>> +Version Code (CPVC). The CPNC determines what environment the control program
>> +is running in (e.g. Linux, z/VM...), and the CPVC is used for extraneous
>> +information specific to OS (e.g. Linux version, Linux distribution...)
>> +
>> +If this capability is available, then the CPNC and CPVC can be synchronized
>> +between KVM and userspace via the sync regs mechanism (KVM_SYNC_DIAG318).
>>
> 
> 


-- 
Regards,
Collin

Stay safe and stay healthy