From 008c320a96d218712043f8db0111d5472697785c Mon Sep 17 00:00:00 2001 From: Julien Grall Date: Fri, 19 Jun 2015 17:49:03 +0100 Subject: xen/grant: Introduce helpers to split a page into grant Currently, a grant is always based on the Xen page granularity (i.e 4KB). When Linux is using a different page granularity, a single page will be split between multiple grants. The new helpers will be in charge of splitting the Linux page into grants and call a function given by the caller on each grant. Also provide an helper to count the number of grants within a given contiguous region. Note that the x86/include/asm/xen/page.h is now including xen/interface/grant_table.h rather than xen/grant_table.h. It's necessary because xen/grant_table.h depends on asm/xen/page.h and will break the compilation. Furthermore, only definition in interface/grant_table.h is required. Signed-off-by: Julien Grall Reviewed-by: David Vrabel Reviewed-by: Stefano Stabellini Signed-off-by: David Vrabel --- drivers/xen/grant-table.c | 26 ++++++++++++++++++++++++++ 1 file changed, 26 insertions(+) (limited to 'drivers/xen') diff --git a/drivers/xen/grant-table.c b/drivers/xen/grant-table.c index a4b702c9ac68..dbeaa67dec47 100644 --- a/drivers/xen/grant-table.c +++ b/drivers/xen/grant-table.c @@ -776,6 +776,32 @@ void gnttab_batch_copy(struct gnttab_copy *batch, unsigned count) } EXPORT_SYMBOL_GPL(gnttab_batch_copy); +void gnttab_foreach_grant_in_range(struct page *page, + unsigned int offset, + unsigned int len, + xen_grant_fn_t fn, + void *data) +{ + unsigned int goffset; + unsigned int glen; + unsigned long xen_pfn; + + len = min_t(unsigned int, PAGE_SIZE - offset, len); + goffset = xen_offset_in_page(offset); + + xen_pfn = page_to_xen_pfn(page) + XEN_PFN_DOWN(offset); + + while (len) { + glen = min_t(unsigned int, XEN_PAGE_SIZE - goffset, len); + fn(pfn_to_gfn(xen_pfn), goffset, glen, data); + + goffset = 0; + xen_pfn++; + len -= glen; + } +} +EXPORT_SYMBOL_GPL(gnttab_foreach_grant_in_range); + int gnttab_map_refs(struct gnttab_map_grant_ref *map_ops, struct gnttab_map_grant_ref *kmap_ops, struct page **pages, unsigned int count) -- cgit v1.2.3-59-g8ed1b