Re: [PATCH 2/4] mm: introduce new VM_NOZEROPAGE flag

[Paolo Bonzini]

On 10/18/2014 06:28 PM, Dave Hansen wrote:
> > Currently it is an all or nothing thing, but for a future change we might want to just
> > tag the guest memory instead of the complete user address space.
>
> I think it's a bad idea to reserve a flag for potential future use.  If
> you_need_  it in the future, let's have the discussion then.  For now, I
> think it should probably just be stored in the mm somewhere.

I agree with Dave (I thought I disagreed, but I changed my mind while 
writing down my thoughts).  Just define mm_forbids_zeropage in 
arch/s390/include/asm, and make it return mm->context.use_skey---with a 
comment explaining how this is only for processes that use KVM, and then 
only for guests that use storage keys.

Paolo (who was just taught what storage keys really are)
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