From mboxrd@z Thu Jan  1 00:00:00 1970
From: Catalin Marinas <catalin.marinas@arm.com>
Subject: Re: [PATCH v3 05/11] ARM: LPAE: provide an IPA capable pmd_addr_end
Date: Thu, 6 Feb 2014 10:43:28 +0000
Message-ID: <20140206104328.GB29446@arm.com>
References: <1391630151-7875-1-git-send-email-marc.zyngier@arm.com>
 <1391630151-7875-6-git-send-email-marc.zyngier@arm.com>
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	Christoffer Dall <christoffer.dall@linaro.org>
To: Marc Zyngier <marc.zyngier@arm.com>
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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@arm.com>
> ---
>  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?

-- 
Catalin