From mboxrd@z Thu Jan  1 00:00:00 1970
From: Will Deacon <will.deacon@arm.com>
Subject: Re: [PATCH 01/15] ARM: add mem_type prot_pte accessor
Date: Tue, 18 Sep 2012 13:23:08 +0100
Message-ID: <20120918122308.GJ32204@mudshark.cambridge.arm.com>
References: <20120915153359.21241.86002.stgit@ubuntu>
 <20120915153436.21241.95691.stgit@ubuntu>
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To: Christoffer Dall <c.dall@virtualopensystems.com>
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On Sat, Sep 15, 2012 at 04:34:36PM +0100, Christoffer Dall wrote:
> From: Marc Zyngier <marc.zyngier@arm.com>
> 
> The KVM hypervisor mmu code requires access to the mem_type prot_pte
> field when setting up page tables pointing to a device. Unfortunately,
> the mem_type structure is opaque.
> 
> Add an accessor (get_mem_type_prot_pte()) to retrieve the prot_pte
> value.
> 
> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
> Signed-off-by: Christoffer Dall <c.dall@virtualopensystems.com>
> ---
>  arch/arm/include/asm/mach/map.h |    1 +
>  arch/arm/mm/mmu.c               |    6 ++++++
>  2 files changed, 7 insertions(+)
> 
> diff --git a/arch/arm/include/asm/mach/map.h b/arch/arm/include/asm/mach/map.h
> index a6efcdd..3787c9f 100644
> --- a/arch/arm/include/asm/mach/map.h
> +++ b/arch/arm/include/asm/mach/map.h
> @@ -37,6 +37,7 @@ extern void iotable_init(struct map_desc *, int);
>  
>  struct mem_type;
>  extern const struct mem_type *get_mem_type(unsigned int type);
> +extern pteval_t get_mem_type_prot_pte(unsigned int type);
>  /*
>   * external interface to remap single page with appropriate type
>   */
> diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c
> index 4c2d045..76bf4f5 100644
> --- a/arch/arm/mm/mmu.c
> +++ b/arch/arm/mm/mmu.c
> @@ -301,6 +301,12 @@ const struct mem_type *get_mem_type(unsigned int type)
>  }
>  EXPORT_SYMBOL(get_mem_type);
>  
> +pteval_t get_mem_type_prot_pte(unsigned int type)
> +{
> +	return get_mem_type(type)->prot_pte;
> +}
> +EXPORT_SYMBOL(get_mem_type_prot_pte);
> +

get_mem_type can return NULL, so you should probably pass the error through
rather than dereferencing it.

Will