On Thu, 31 Mar 2011 12:11:48 +0200
Alexander Graf <[email protected]> wrote:

> >>>>>>> On 31.03.2011, at 05:21, Liu Yu-B13201 wrote:
> >>>>>>> 
> >>>>>>>> 
> >>>>>>>> I think the patch miss the bit to handle the case that
> >>>>>>>> if guest clear the MSR_SPE.

Doh.

> >>>> So that MSR[SPE] should always be traped.
> >>> 
> >>> It doesn't have to be trapped - we can enable it lazily on 
> >>> SPE_UNAVAIL :). Of course we should also explicitly enable it 
> >>> on set_msr.

I don't see any benefit to doing this, if we're going to take a trap one
way or another.  Since we need to trap on clearing it anyway, might as well
just keep things simple and have SPE always be a trapworthy MSR bit.

> Scott, to verify that I don't completely screw up the lazy FPU work back when 
> I did it, I wrote some small test program that would just initialize an fpu 
> register with a value and then constantly loop to verify if it's still the 
> same. I ran that program with different values on the host and guest sides. 
> That exposed quite a lot of glitches.
> 
> It would be nice if you could provide something similar for the SPE patches, 
> so we have some more faith in it :).

OK.

-Scott

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