Re: [Xen-devel] [PATCH 03 of 11] arm: Implement get_page_from_gfn()

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Thu, 2012-05-10 at 15:59 +0100, Tim Deegan wrote:
> # HG changeset patch
> # User Tim Deegan <tim@xxxxxxx>
> # Date 1336661656 -3600
> # Node ID d774bb5c6326d1a7e88a3bfadc546d154a2ad895
> # Parent  e03806b10f0026590e7775008f24d2a96051552e
> arm: Implement get_page_from_gfn()
> 
> We will be calling this from common code, so add a basic
> implementation to arch/arm.
> 
> After 4.2 we should reshuffle some of the p2m interface out of
> arch/x86 into common headers; for now duplicate a little bit of it.
> 
> Signed-off-by: Tim Deegan <tim@xxxxxxx>

Acked-by: Ian Campbell <ian.campbell@xxxxxxxxxx>

Feel free to commit along with the rest of the series.

Ian.

> 
> diff -r e03806b10f00 -r d774bb5c6326 xen/include/asm-arm/p2m.h
> --- a/xen/include/asm-arm/p2m.h       Thu May 10 15:54:16 2012 +0100
> +++ b/xen/include/asm-arm/p2m.h       Thu May 10 15:54:16 2012 +0100
> @@ -53,6 +53,28 @@ p2m_pod_decrease_reservation(struct doma
>                               xen_pfn_t gpfn,
>                               unsigned int order);
>  
> +/* Look up a GFN and take a reference count on the backing page. */
> +typedef int p2m_type_t;
> +typedef unsigned int p2m_query_t;
> +#define P2M_ALLOC    (1u<<0)   /* Populate PoD and paged-out entries */
> +#define P2M_UNSHARE  (1u<<1)   /* Break CoW sharing */
> +
> +static inline struct page_info *get_page_from_gfn(
> +    struct domain *d, unsigned long gfn, p2m_type_t *t, p2m_query_t q)
> +{
> +    struct page_info *page;
> +    unsigned long mfn = gmfn_to_mfn(d, gfn);
> +
> +    ASSERT(t == NULL);
> +
> +    if (!mfn_valid(mfn))
> +        return NULL;
> +    page = mfn_to_page(mfn);
> +    if ( !get_page(page, d) )
> +        return NULL;
> +    return page;
> +}
> +
>  /* Compatibility function exporting the old untyped interface */
>  static inline unsigned long get_gfn_untyped(struct domain *d, unsigned long 
> gpfn)
>  {
> 
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