On Fri, Feb 07, 2014 at 04:04:56AM +0000, Christoffer Dall wrote:
> On Thu, Feb 06, 2014 at 10:43:28AM +0000, Catalin Marinas wrote:
> > On Wed, Feb 05, 2014 at 07:55:45PM +0000, Marc Zyngier wrote:
> > > The default pmd_addr_end macro uses an unsigned long to represent
> > > the VA. When used with KVM and stage-2 translation, the VA is
> > > actually an IPA, which is up to 40 bits. This also affect the
> > > SMMU driver, which also deals with stage-2 translation.
> > >
> > > Instead, provide an implementation that can cope with larger VAs
> > > by using a u64 instead. This version will overload the default
> > > one provided in include/asm-generic/pgtable.h.
> > >
> > > Signed-off-by: Marc Zyngier <marc.zyngier@xxxxxxx>
> > > ---
> > > arch/arm/include/asm/pgtable-3level.h | 5 +++++
> > > 1 file changed, 5 insertions(+)
> > >
> > > diff --git a/arch/arm/include/asm/pgtable-3level.h b/arch/arm/include/asm/pgtable-3level.h
> > > index 03243f7..594867b 100644
> > > --- a/arch/arm/include/asm/pgtable-3level.h
> > > +++ b/arch/arm/include/asm/pgtable-3level.h
> > > @@ -262,6 +262,11 @@ static inline int has_transparent_hugepage(void)
> > > return 1;
> > > }
> > >
> > > +#define pmd_addr_end(addr, end) \
> > > +({ u64 __boundary = ((addr) + PMD_SIZE) & PMD_MASK; \
> > > + (__boundary - 1 < (end) - 1)? __boundary: (end); \
> > > +})
> >
> > I see why you need this but it affects all the other uses of
> > pmd_addr_end() with 32-bit VA. It would be slight performance, I don't
> > think it's noticeable.
> >
> > A different approach could be something like (untested):
> >
> > #define pmd_addr_end(addr, end) \
> > ({ __typeof__(addr) __boundary = ...
> > ...
> > })
> >
> > What about the pgd_addr_end(), do we need this or it's not used by KVM?
> >
>
> What about pud_addr_end(), is that defined as a noop on LPAE, or?
>
> I would be in favor of introducing them all using your approach to avoid
> somebody being inspired by the KVM code when dealing with IPAs and
> breaking things unknowingly.
I had a brief chat with Marc yesterday around this and it may be safer
to simply introduce kvm_p*d_addr_end() macros. You already do this for
pgd_addr_end() since it cannot be overridden in the generic headers.
--
Catalin
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