Re: [PATCH 1/6] xen/arm: introduce map_phys_range

[Tim Deegan <tim@xen.org>]

At 18:19 +0000 on 05 Dec (1354731583), Stefano Stabellini wrote:
> Introduce a function to map a physical memory into virtual memory.
> It is going to be used later to map the videoram.
> 
> Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
> ---
>  xen/arch/arm/mm.c        |   23 +++++++++++++++++++++++
>  xen/include/asm-arm/mm.h |    3 +++
>  2 files changed, 26 insertions(+), 0 deletions(-)
> 
> diff --git a/xen/arch/arm/mm.c b/xen/arch/arm/mm.c
> index 68ee9da..418a414 100644
> --- a/xen/arch/arm/mm.c
> +++ b/xen/arch/arm/mm.c
> @@ -376,6 +376,29 @@ void __init setup_frametable_mappings(paddr_t ps, paddr_t pe)
>      frametable_virt_end = FRAMETABLE_VIRT_START + (nr_pages * sizeof(struct page_info));
>  }
>  
> +/* Map the physical memory range start -  end at the virtual address
> + * virt_start in 2MB chunks. start and virt_start have to be 2MB
> + * aligned.
> + */
> +void map_phys_range(paddr_t start, paddr_t end,
> +        unsigned long virt_start, unsigned attributes)
> +{
> +    ASSERT(!(start & ((1 << 21) - 1)));
> +    ASSERT(!(virt_start & ((1 << 21) - 1)));

Please use SECOND_SHIFT rather than 21, and maybe even add a SECOND_MASK
&c to page.h rather than open-coding the <<s here.

Also, can you add some assertions that the VAs here are in some
well-defined region (with annotations in config.h)?

> +    while ( start < end )
> +    {
> +        lpae_t e = mfn_to_xen_entry(start >> PAGE_SHIFT);
> +        e.pt.ai = attributes;
> +        write_pte(xen_second + second_table_offset(virt_start), e);
> +        
> +        start += (1<<21);
> +        virt_start += (1<<21);

Maybe add SECOND_SIZE &c too?

> +    }
> +
> +    flush_xen_data_tlb();

What's this for?

Cheers,

Tim.

> +}
> +
>  enum mg { mg_clear, mg_ro, mg_rw, mg_rx };
>  static void set_pte_flags_on_range(const char *p, unsigned long l, enum mg mg)
>  {
> diff --git a/xen/include/asm-arm/mm.h b/xen/include/asm-arm/mm.h
> index 3549c83..a11f20b 100644
> --- a/xen/include/asm-arm/mm.h
> +++ b/xen/include/asm-arm/mm.h
> @@ -152,6 +152,9 @@ extern void setup_frametable_mappings(paddr_t ps, paddr_t pe);
>  extern void set_fixmap(unsigned map, unsigned long mfn, unsigned attributes);
>  /* Remove a mapping from a fixmap entry */
>  extern void clear_fixmap(unsigned map);
> +/* map a 2MB aligned physical range in virtual memory. */
> +extern void map_phys_range(paddr_t start, paddr_t end,
> +		unsigned long virt_start, unsigned attributes);
>  
>  
>  #define mfn_valid(mfn)        ({                                              \
> -- 
> 1.7.2.5
> 
> 
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