Re: [RFC PATCH 18/32] KVM: PPC: Book3S HV: Use kvmppc_unmap_pte() in kvm_unmap_radix()

[David Gibson <david@gibson.dropbear.id.au>]

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On Wed, Sep 26, 2018 at 09:18:56PM +1000, Paul Mackerras wrote:
> On Wed, Sep 26, 2018 at 02:30:02PM +1000, David Gibson wrote:
> > On Wed, Sep 26, 2018 at 02:08:37PM +1000, David Gibson wrote:
> > > >  static void kvmppc_unmap_pte(struct kvm *kvm, pte_t *pte,
> > > > -			     unsigned long gpa, unsigned int shift)
> > > > +			     unsigned long gpa, unsigned int shift,
> > > > +			     struct kvm_memory_slot *memslot)
> > > >  
> > > >  {
> > > > -	unsigned long page_size = 1ul << shift;
> > > >  	unsigned long old;
> > > >  
> > > >  	old = kvmppc_radix_update_pte(kvm, pte, ~0UL, 0, gpa, shift);
> > > >  	kvmppc_radix_tlbie_page(kvm, gpa, shift);
> > > >  	if (old & _PAGE_DIRTY) {
> > > >  		unsigned long gfn = gpa >> PAGE_SHIFT;
> > > > -		struct kvm_memory_slot *memslot;
> > > > +		unsigned long page_size = PAGE_SIZE;
> > > >  
> > > > -		memslot = gfn_to_memslot(kvm, gfn);
> > > > -		if (memslot && memslot->dirty_bitmap)
> > > > +		if (shift)
> > > > +			page_size = 1ul << shift;
> > > > +		if (!memslot)
> > > > +			memslot = gfn_to_memslot(kvm, gfn);
> > 
> > ..it might be nicer to avoid the explicit test on memslot by maping a
> > __kvmppc_unmap_pte() which must have memslot passed in, and a wrapper
> > which computes it from the gfn.
> 
> Then we would be looking up the memslot even when we aren't going to
> use it.  In a subsequent patch this function gets used on shadow page
> tables and in that case we never need the memslot.

Ah, good point.

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

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