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.gr...@citrix.com>
Reviewed-by: David Vrabel <david.vra...@citrix.com>
Reviewed-by: Stefano Stabellini <stefano.stabell...@eu.citrix.com>
---
Cc: Konrad Rzeszutek Wilk <konrad.w...@oracle.com>
Cc: Boris Ostrovsky <boris.ostrov...@oracle.com>
Cc: Thomas Gleixner <t...@linutronix.de>
Cc: Ingo Molnar <mi...@redhat.com>
Cc: "H. Peter Anvin" <h...@zytor.com>
Cc: x...@kernel.org
Changes in v4:
- Typoes
- Rename gnttab_one_grant into gnttab_for_one_grant
- Add Stefano and David's reviewed-by
- s/xen_page_to_pfn/page_to_xen_pfn/ based on the new naming
Changes in v3:
- Fix error reported by checkpatch.pl
- Typoes
- s/pfn/xen_pfn/ in gnttab_foreach_grant
- Drop the possibility to use less data. The complexity is moved
in netback which is the only user
- Rename gnttab_foreach_grant into gnttab_foreach_grant_in_range
- s/offset/start/ in gnttab_count_grant and update the
description of the parameter
- s/mfn/gfn base on the new terminologies
- Add EXPORT_SYMBOL_GPL for gnttab_foreach_grant_in_range
- Use xen_offset_in_page and XEN_PFN_DOWN whenever it's possible
- Fix compilation on x86.
Changes in v2:
- Patch added
---
arch/x86/include/asm/xen/page.h | 2 +-
drivers/xen/grant-table.c | 26 +++++++++++++++++++++++++
include/xen/grant_table.h | 42 +++++++++++++++++++++++++++++++++++++++++
3 files changed, 69 insertions(+), 1 deletion(-)
diff --git a/arch/x86/include/asm/xen/page.h b/arch/x86/include/asm/xen/page.h
index 0b762f6..501479e 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 62f591f..7b4e1cf 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 4478f4b..05b5b08 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__ */
--
2.1.4
--
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