[LINUX] Kexec: Ensure that pages allocated for kexec have MFNs which are within

the required limits.

Previously we were lucky since most dom0 pages would be low enough but now Xen
is more aggressive in giving out higher MFNs when it can.

Signed-off-by: Ian Campbell <ian.campbell@xensource.com>

linux-2.6-xen-sparse/kernel/kexec.c

@@ -330,13 +330,27 @@ static int kimage_is_destination_range(struct kimage *image,
 	return 0;
 }
 
-static struct page *kimage_alloc_pages(gfp_t gfp_mask, unsigned int order)
+static struct page *kimage_alloc_pages(gfp_t gfp_mask, unsigned int order, unsigned long limit)
 {
 	struct page *pages;
 
 	pages = alloc_pages(gfp_mask, order);
 	if (pages) {
 		unsigned int count, i;
+#ifdef CONFIG_XEN
+		int address_bits;
+
+		if (limit == ~0UL)
+			address_bits = BITS_PER_LONG;
+		else
+			address_bits = long_log2(limit);
+
+		if (xen_create_contiguous_region((unsigned long)page_address(pages),
+						 order, address_bits) < 0) {
+			__free_pages(pages, order);
+			return NULL;
+		}
+#endif
 		pages->mapping = NULL;
 		set_page_private(pages, order);
 		count = 1 << order;
@@ -355,6 +369,9 @@ static void kimage_free_pages(struct page *page)
 	count = 1 << order;
 	for (i = 0; i < count; i++)
 		ClearPageReserved(page + i);
+#ifdef CONFIG_XEN
+	xen_destroy_contiguous_region((unsigned long)page_address(page), order);
+#endif
 	__free_pages(page, order);
 }
 
@@ -400,7 +417,7 @@ static struct page *kimage_alloc_normal_control_pages(struct kimage *image,
 	do {
 		unsigned long pfn, epfn, addr, eaddr;
 
-		pages = kimage_alloc_pages(GFP_KERNEL, order);
+		pages = kimage_alloc_pages(GFP_KERNEL, order, KEXEC_CONTROL_MEMORY_LIMIT);
 		if (!pages)
 			break;
 		pfn   = kexec_page_to_pfn(pages);
@@ -709,7 +726,7 @@ static struct page *kimage_alloc_page(struct kimage *image,
 		kimage_entry_t *old;
 
 		/* Allocate a page, if we run out of memory give up */
-		page = kimage_alloc_pages(gfp_mask, 0);
+		page = kimage_alloc_pages(gfp_mask, 0, KEXEC_SOURCE_MEMORY_LIMIT);
 		if (!page)
 			return NULL;
 		/* If the page cannot be used file it away */