Re: [Xen-devel] fpu_taskswitch adjustment proposal

[Keir Fraser <keir@xxxxxxx>]

On 18/06/2012 13:45, "Jan Beulich" <JBeulich@xxxxxxxx> wrote:

>> Wouldn't it be hidden entirely behind pv_ops hooks and within Xen-specific
>> SSE save/restore code? I suppose you'd need to statically allocate the
>> per-cpu space for tracking the CR0.TS state... But overall it seems it will
>> be of little/no concern to other kernel maintainers?
> 
> The #NM handler part wouldn't afaict. Everything else indeed
> ought to be restricted to the functions backing paravirt.h's clts()
> and write_cr0().

Yes, the #NM handler might need extra treatment. Perhaps we could install
our own #NM wrapper around the kernel's generic handler, which first clears
the saved CR0.TS flag. Then on clts() in the generic handler, our paravirt
clts() would see the flag is already clear and do no hypercall.

 -- Keir



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