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authorJulien Grall <julien.grall@citrix.com>2015-06-19 17:49:03 +0100
committerDavid Vrabel <david.vrabel@citrix.com>2015-10-23 14:20:33 +0100
commit008c320a96d218712043f8db0111d5472697785c (patch)
treead1140a3a51567e5bb14b71fe002ba40db3bf681 /drivers/xen/grant-table.c
parent1084b1988d22dc165c9dbbc2b0e057f9248ac4db (diff)
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 <julien.grall@citrix.com> Reviewed-by: David Vrabel <david.vrabel@citrix.com> Reviewed-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com> Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Diffstat (limited to 'drivers/xen/grant-table.c')
-rw-r--r--drivers/xen/grant-table.c26
1 files changed, 26 insertions, 0 deletions
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)

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