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Commit f73314b2 authored by Julien Grall's avatar Julien Grall Committed by David Vrabel
Browse files

xen/grant-table: Add an helper to iterate over a specific number of grants 



With the 64KB page granularity support on ARM64, a Linux page may be
split accross multiple grant.

Currently we have the helper gnttab_foreach_grant_in_grant to break a
Linux page based on an offset and a len, but it doesn't fit when we only
have a number of grants in hand.

Introduce a new helper which take an array of Linux page and a number of
grant and will figure out the address of each grant.

Signed-off-by: default avatarJulien Grall <julien.grall@citrix.com>
Signed-off-by: default avatarDavid Vrabel <david.vrabel@citrix.com>
parent 9cce2914

drivers/xen/grant-table.c

+22 −0
Original line number Diff line number Diff line
@@ -802,6 +802,28 @@ void gnttab_foreach_grant_in_range(struct page *page, 
}

EXPORT_SYMBOL_GPL(gnttab_foreach_grant_in_range);



void gnttab_foreach_grant(struct page **pages,

			  unsigned int nr_grefs,

			  xen_grant_fn_t fn,

			  void *data)

{

	unsigned int goffset = 0;

	unsigned long xen_pfn = 0;

	unsigned int i;



	for (i = 0; i < nr_grefs; i++) {

		if ((i % XEN_PFN_PER_PAGE) == 0) {

			xen_pfn = page_to_xen_pfn(pages[i / XEN_PFN_PER_PAGE]);

			goffset = 0;

		}



		fn(pfn_to_gfn(xen_pfn), goffset, XEN_PAGE_SIZE, data);



		goffset += XEN_PAGE_SIZE;

		xen_pfn++;

	}

}



int gnttab_map_refs(struct gnttab_map_grant_ref *map_ops,

		    struct gnttab_map_grant_ref *kmap_ops,

		    struct page **pages, unsigned int count)

include/xen/grant_table.h

+6 −0
Original line number Diff line number Diff line
@@ -264,6 +264,12 @@ static inline void gnttab_for_one_grant(struct page *page, unsigned int offset, 
	gnttab_foreach_grant_in_range(page, offset, len, fn, data);

}



/* Get @nr_grefs grants from an array of page and call fn for each grant */

void gnttab_foreach_grant(struct page **pages,

			  unsigned int nr_grefs,

			  xen_grant_fn_t fn,

			  void *data);



/* Get the number of grant in a specified region

 *

 * start: Offset from the beginning of the first page