On 07/03/2013 12:07:30 PM, Alexander Graf wrote:
On 03.07.2013, at 18:49, Caraman Mihai Claudiu-B02008 wrote:
>>>> Do we need to do this even when the guest doesn't use Altivec?
Can't
>> we
>>>> just load it on demand then once we fault? This code path really
>> should
>>>> only be a prefetch enable when MSR_VEC is already set in guest
>> context.
>>>
>>> No we can't, read 6/6.
>>
>> So we have to make sure we're completely unlazy when it comes to a
KVM
>> guest. Are we?
>
> Yes, because MSR[SPV] is under its control.
Oh, sure, KVM wants it unlazy. That part is obvious. But does the
kernel always give us unlazyness? The way I read the code, process.c
goes lazy when !CONFIG_SMP.
So the big question is why we're manually enforcing FPU giveup, but
not Altivec giveup? One of the 2 probably is wrong :).
Why do you think we're not enforcing it for Altivec? Is there some
specific piece of code you're referring to that is different in this
regard?
-Scott
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