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Subject: Re: [PATCH 07/13] powerpc: Preemptible mmu_gather
From: Peter Zijlstra <peterz@infradead.org>
To: Nick Piggin <npiggin@suse.de>
Cc: Andrea Arcangeli <aarcange@redhat.com>, Avi Kivity <avi@redhat.com>,
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Date: Fri, 09 Apr 2010 11:22:06 +0200
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On Fri, 2010-04-09 at 18:46 +1000, Nick Piggin wrote:
> > struct mmu_page {
> >   struct page *page;
> > #ifdef HAVE_ARCH_TLB_VADDR
> >   unsigned long vaddr;
> > #endif
> > };
> 
> Well you could also have a per-arch struct for this, which they can
> fill in their own info with (I think powerpc takes the pte as well)

Ah, right you are.

Maybe something like:

#ifndef tlb_fill_page
struct mmu_page {
	struct page *page;
};

#define tlb_fill_page(tlb, pte, addr) do { } while (0)
#endif

Which can be used from the tlb_remove_tlb_entry() implementation to
gather both the pte and addr. The only complication seems to be that
tlb_remove_tlb_entry() and tlb_remove_page() aren't always matched.

Also, it looks like both power and sparc drive the pte/vaddr flush from
the pte_update/set_pte_at like functions. Which means its not synced to
the mmu_gather at all.

So I'm not at all sure its feasible to link these, but I'll keep it in
mind.