Re: [Xen-devel] [PATCH 06/14] arm: make p2m operations NOPs

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

On Thu, 4 Oct 2012, Ian Campbell wrote:
> This makes common code less ifdef-y and is consistent with PVHVM on
> x86.
> 
> Also note that phys_to_machine_mapping_valid should take a pfn
> argument and make it do so.
> 
> Add __set_phys_to_machine, make set_phys_to_machine a simple wrapper
> (on systems with non-nop implementations the outer one can allocate
> new p2m pages).
> 
> Make __set_phys_to_machine check for identity mapping or invalid only.
> 
> Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>


Acked-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>

>  arch/arm/include/asm/xen/page.h |   13 ++++++++++---
>  drivers/xen/balloon.c           |    2 +-
>  2 files changed, 11 insertions(+), 4 deletions(-)
> 
> diff --git a/arch/arm/include/asm/xen/page.h b/arch/arm/include/asm/xen/page.h
> index 1742023..c6b9096 100644
> --- a/arch/arm/include/asm/xen/page.h
> +++ b/arch/arm/include/asm/xen/page.h
> @@ -10,7 +10,7 @@
>  #include <xen/interface/grant_table.h>
>  
>  #define pfn_to_mfn(pfn)                      (pfn)
> -#define phys_to_machine_mapping_valid        (1)
> +#define phys_to_machine_mapping_valid(pfn) (1)
>  #define mfn_to_pfn(mfn)                      (mfn)
>  #define mfn_to_virt(m)                       (__va(mfn_to_pfn(m) << 
> PAGE_SHIFT))
>  
> @@ -30,6 +30,8 @@ typedef struct xpaddr {
>  #define XMADDR(x)    ((xmaddr_t) { .maddr = (x) })
>  #define XPADDR(x)    ((xpaddr_t) { .paddr = (x) })
>  
> +#define INVALID_P2M_ENTRY      (~0UL)
> +
>  static inline xmaddr_t phys_to_machine(xpaddr_t phys)
>  {
>       unsigned offset = phys.paddr & ~PAGE_MASK;
> @@ -74,9 +76,14 @@ static inline int m2p_remove_override(struct page *page, 
> bool clear_pte)
>       return 0;
>  }
>  
> +static inline bool __set_phys_to_machine(unsigned long pfn, unsigned long 
> mfn)
> +{
> +     BUG_ON(pfn != mfn && mfn != INVALID_P2M_ENTRY);
> +     return true;
> +}
> +
>  static inline bool set_phys_to_machine(unsigned long pfn, unsigned long mfn)
>  {
> -     BUG();
> -     return false;
> +     return __set_phys_to_machine(pfn, mfn);
>  }
>  #endif /* _ASM_ARM_XEN_PAGE_H */
> diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c
> index 4625560..7885a19 100644
> --- a/drivers/xen/balloon.c
> +++ b/drivers/xen/balloon.c
> @@ -452,7 +452,7 @@ static enum bp_state decrease_reservation(unsigned long 
> nr_pages, gfp_t gfp)
>       /* No more mappings: invalidate P2M and add to balloon. */
>       for (i = 0; i < nr_pages; i++) {
>               pfn = mfn_to_pfn(frame_list[i]);
> -             /* PVH note: following will noop for auto translated */
> +             /* The following is a noop for auto translated */
>               __set_phys_to_machine(pfn, INVALID_P2M_ENTRY);
>               balloon_append(pfn_to_page(pfn));
>       }
> -- 
> 1.7.2.5
> 

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