Re: [Xen-devel] [PATCH RFC V4 5/5] Documentation/kvm : Add documentation on Hypercalls and features used for PV spinlock

[Alexander Graf <agraf@xxxxxxx>]

On 16.01.2012, at 09:44, Raghavendra K T wrote:

> On 01/16/2012 08:53 AM, Alexander Graf wrote:
>> 
>> On 14.01.2012, at 19:27, Raghavendra K T wrote:
>> 
>>> Add Documentation on CPUID, KVM_CAP_PVLOCK_KICK, and Hypercalls supported.
>>> 
>>> KVM_HC_KICK_CPU  hypercall added to wakeup halted vcpu in
>>> paravirtual spinlock enabled guest.
>>> 
>>> KVM_FEATURE_PVLOCK_KICK enables guest to check whether pv spinlock can
>>> be enabled in guest. support in host is queried via
>>> ioctl(KVM_CHECK_EXTENSION, KVM_CAP_PVLOCK_KICK)
>>> 
>>> A minimal Documentation and template is added for hypercalls.
>>> 
>>> Signed-off-by: Raghavendra K T<raghavendra.kt@xxxxxxxxxxxxxxxxxx>
>>> Signed-off-by: Srivatsa Vaddagiri<vatsa@xxxxxxxxxxxxxxxxxx>
>>> ---
> [...]
>>> diff --git a/Documentation/virtual/kvm/hypercalls.txt 
>>> b/Documentation/virtual/kvm/hypercalls.txt
>>> new file mode 100644
>>> index 0000000..7872da5
>>> --- /dev/null
>>> +++ b/Documentation/virtual/kvm/hypercalls.txt
>>> @@ -0,0 +1,54 @@
>>> +KVM Hypercalls Documentation
>>> +===========================
> 
>>> +2. KVM_HC_MMU_OP
>>> +------------------------
>>> +value: 2
>>> +Architecture: x86
>>> +Purpose: Support MMU operations such as writing to PTE,
>>> +flushing TLB, release PT.
>> 
>> This one is deprecated, no? Should probably be mentioned here.
> 
> Ok, then may be adding state = deprecated/obsolete/in use (active) may
> be good idea.
> 
>> 
>>> +
>>> +3. KVM_HC_FEATURES
>>> +------------------------
>>> +value: 3
>>> +Architecture: PPC
>>> +Purpose:
>> 
>> Expose hypercall availability to the guest. On x86 you use cpuid to 
>> enumerate which hypercalls are available. The natural fit on ppc would be 
>> device tree based lookup (which is also what EPAPR dictates), but we also 
>> have a second enumeration mechanism that's KVM specific - which is this 
>> hypercall.
>> 
> 
> Thanks, will add this. I hope you are OK if I add Signed-off-by: you.

I don't think you need a signed-off-by from me for this very simple 
documentation addition :). You should probably also reword it. I didn't quite 
write it as a paragraph that should go into the file.


Alex


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