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

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

On 02/16/2012 11:30 AM, Alexander Graf wrote:

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On 16.02.2012, at 18:28, Scott Wood wrote:
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On 02/16/2012 11:18 AM, Alexander Graf wrote:

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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?

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If it's just for this, I would say don't mess with the normal hcall =

path

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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,

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depending on what sort of hcalls we end up having.
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Then we don't have to replicate the hypercall code all over again =

for every invocation.

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We shouldn't need to do it for every invocation.  Idle is special =

due to

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the TLF_NAPPING hack.

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Famous last words. If it's the only case, duplication should be ok. =

Let's hope there are no others.

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Actually, we can't use CTR -- it's volatile in the ePAPR hypercall =

ABI.

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


Alex