Ian.Campbell at citrix
May 10, 2012, 8:21 AM
Post #2 of 2
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Re: [PATCH 03 of 11] arm: Implement get_page_from_gfn()
[In reply to]
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On Thu, 2012-05-10 at 15:59 +0100, Tim Deegan wrote:
> # HG changeset patch
> # User Tim Deegan <tim [at] xen>
> # 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 [at] xen>
Acked-by: Ian Campbell <ian.campbell [at] citrix>
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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