[PATCH v4 3/3] KVM: PPC: epapr: install ev_idle hcall for e500 guest

[Alexander Graf]

On 16.02.2012, at 18:36, Scott Wood wrote:

> On 02/16/2012 11:30 AM, Alexander Graf wrote:
>> 
>> On 16.02.2012, at 18:28, Scott Wood wrote:
>> 
>>> On 02/16/2012 11:18 AM, Alexander Graf wrote:
>>>> Hrm. But we can clobber ctr, right? So how about we make the generic version do a bctr and then just do a small C wrapper that takes lr, moves it to ctr and branches to the generic one?
>>> 
>>> If it's just for this, I would say don't mess with the normal hcall path
>>> for the sake of idle.  If using CTR would let us get away without
>>> creating a stack frame in call sites, maybe that would be worthwhile,
>>> depending on what sort of hcalls we end up having.
>>> 
>>>> Then we don't have to replicate the hypercall code all over again for every invocation.
>>> 
>>> We shouldn't need to do it for every invocation.  Idle is special due to
>>> the TLF_NAPPING hack.
>> 
>> Famous last words. If it's the only case, duplication should be ok. Let's hope there are no others.
> 
> Actually, we can't use CTR -- it's volatile in the ePAPR hypercall ABI.

Ugh. Alrighty, let's duplicate the hc code then.


Alex