summaryrefslogtreecommitdiff
diff options
context:
space:
mode:
authorJulien Grall <julien.grall@citrix.com>2015-06-19 19:49:03 +0300
committerDavid Vrabel <david.vrabel@citrix.com>2015-10-23 16:20:33 +0300
commit008c320a96d218712043f8db0111d5472697785c (patch)
treead1140a3a51567e5bb14b71fe002ba40db3bf681
parent1084b1988d22dc165c9dbbc2b0e057f9248ac4db (diff)
downloadlinux-008c320a96d218712043f8db0111d5472697785c.tar.xz
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>
-rw-r--r--arch/x86/include/asm/xen/page.h2
-rw-r--r--drivers/xen/grant-table.c26
-rw-r--r--include/xen/grant_table.h42
3 files changed, 69 insertions, 1 deletions
diff --git a/arch/x86/include/asm/xen/page.h b/arch/x86/include/asm/xen/page.h
index b922fa4bb4a1..fe58e3a935de 100644
--- a/arch/x86/include/asm/xen/page.h
+++ b/arch/x86/include/asm/xen/page.h
@@ -12,7 +12,7 @@
#include <asm/pgtable.h>
#include <xen/interface/xen.h>
-#include <xen/grant_table.h>
+#include <xen/interface/grant_table.h>
#include <xen/features.h>
/* Xen machine address */
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)
diff --git a/include/xen/grant_table.h b/include/xen/grant_table.h
index 4478f4b4aae2..05b5b08c2afc 100644
--- a/include/xen/grant_table.h
+++ b/include/xen/grant_table.h
@@ -45,8 +45,10 @@
#include <asm/xen/hypervisor.h>
#include <xen/features.h>
+#include <xen/page.h>
#include <linux/mm_types.h>
#include <linux/page-flags.h>
+#include <linux/kernel.h>
#define GNTTAB_RESERVED_XENSTORE 1
@@ -224,4 +226,44 @@ static inline struct xen_page_foreign *xen_page_foreign(struct page *page)
#endif
}
+/* Split Linux page in chunk of the size of the grant and call fn
+ *
+ * Parameters of fn:
+ * gfn: guest frame number
+ * offset: offset in the grant
+ * len: length of the data in the grant.
+ * data: internal information
+ */
+typedef void (*xen_grant_fn_t)(unsigned long gfn, unsigned int offset,
+ unsigned int len, void *data);
+
+void gnttab_foreach_grant_in_range(struct page *page,
+ unsigned int offset,
+ unsigned int len,
+ xen_grant_fn_t fn,
+ void *data);
+
+/* Helper to get to call fn only on the first "grant chunk" */
+static inline void gnttab_for_one_grant(struct page *page, unsigned int offset,
+ unsigned len, xen_grant_fn_t fn,
+ void *data)
+{
+ /* The first request is limited to the size of one grant */
+ len = min_t(unsigned int, XEN_PAGE_SIZE - (offset & ~XEN_PAGE_MASK),
+ len);
+
+ gnttab_foreach_grant_in_range(page, offset, len, fn, data);
+}
+
+/* Get the number of grant in a specified region
+ *
+ * start: Offset from the beginning of the first page
+ * len: total length of data (can cross multiple page)
+ */
+static inline unsigned int gnttab_count_grant(unsigned int start,
+ unsigned int len)
+{
+ return XEN_PFN_UP(xen_offset_in_page(start) + len);
+}
+
#endif /* __ASM_GNTTAB_H__ */