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

[Raghavendra K T <raghavendra.kt@xxxxxxxxxxxxxxxxxx>]

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.

> > +
> > +4. KVM_HC_PPC_MAP_MAGIC_PAGE
> > +------------------------
> > +value: 4
> > +Architecture: PPC
> > +Purpose: To enable communication between the hypervisor and guest there is a
> > +new
> It's not new anymore :)
>
> > shared page that contains parts of supervisor visible register state.
> > +The guest can map this shared page using this hypercall.
> ... to access its supervisor register through memory.
Will update accordingly.

- Raghu


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