xen/granttable: Grant tables V2 implementation

Receiver-side copying of packets is based on this implementation, it gives
better performance and better CPU accounting. It totally supports three types:
full-page, sub-page and transitive grants.

However this patch does not cover sub-page and transitive grants, it mainly
focus on Full-page part and implements grant table V2 interfaces corresponding
to what already exists in grant table V1, such as: grant table V2
initialization, mapping, releasing and exported interfaces.

Each guest can only supports one type of grant table type, every entry in grant
table should be the same version. It is necessary to set V1 or V2 version before
initializing the grant table.

Grant table exported interfaces of V2 are same with those of V1, Xen is
responsible to judge what grant table version guests are using in every grant
operation.

V2 fulfills the same role of V1, and it is totally backwards compitable with V1.
If dom0 support grant table V2, the guests runing on it can run with either V1
or V2.

Acked-by: Ian Campbell <ian.campbell@citrix.com>
Signed-off-by: Annie Li <annie.li@oracle.com>
[v1: Modified alloc_vm_area call (new parameters), indentation, and cleanpatch
     warnings]
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

1 files changed, 38 insertions, 1 deletions

diff --git a/arch/x86/xen/grant-table.c b/arch/x86/xen/grant-table.c
index c6ab2e7..65160a8 100644
--- a/arch/x86/xen/grant-table.c
+++ b/arch/x86/xen/grant-table.c
@@ -54,6 +54,20 @@ static int map_pte_fn(pte_t *pte, struct page *pmd_page,
 	return 0;
 }
 
+/*
+ * This function is used to map shared frames to store grant status. It is
+ * different from map_pte_fn above, the frames type here is uint64_t.
+ */
+static int map_pte_fn_status(pte_t *pte, struct page *pmd_page,
+			     unsigned long addr, void *data)
+{
+	uint64_t **frames = (uint64_t **)data;
+
+	set_pte_at(&init_mm, addr, pte, mfn_pte((*frames)[0], PAGE_KERNEL));
+	(*frames)++;
+	return 0;
+}
+
 static int unmap_pte_fn(pte_t *pte, struct page *pmd_page,
 			unsigned long addr, void *data)
 {
@@ -83,7 +97,30 @@ int arch_gnttab_map_shared(unsigned long *frames, unsigned long nr_gframes,
 	return rc;
 }
 
-void arch_gnttab_unmap_shared(void *shared, unsigned long nr_gframes)
+int arch_gnttab_map_status(uint64_t *frames, unsigned long nr_gframes,
+			   unsigned long max_nr_gframes,
+			   grant_status_t **__shared)
+{
+	int rc;
+	grant_status_t *shared = *__shared;
+
+	if (shared == NULL) {
+		/* No need to pass in PTE as we are going to do it
+		 * in apply_to_page_range anyhow. */
+		struct vm_struct *area =
+			alloc_vm_area(PAGE_SIZE * max_nr_gframes, NULL);
+		BUG_ON(area == NULL);
+		shared = area->addr;
+		*__shared = shared;
+	}
+
+	rc = apply_to_page_range(&init_mm, (unsigned long)shared,
+				 PAGE_SIZE * nr_gframes,
+				 map_pte_fn_status, &frames);
+	return rc;
+}
+
+void arch_gnttab_unmap(void *shared, unsigned long nr_gframes)
 {
 	apply_to_page_range(&init_mm, (unsigned long)shared,
 			    PAGE_SIZE * nr_gframes, unmap_pte_fn, NULL);