tee: make tee_shm_register_kernel_buf vmalloc supported

In some low-memory devices, it's hard to aquire large-orders pages,
this patch allowed user using scatter pages to register shm.
Signed-off-by: NPhil Chang <phil.chang@mediatek.com>
Reviewed-by: NSumit Garg <sumit.garg@linaro.org>
Signed-off-by: NJens Wiklander <jens.wiklander@linaro.org>

drivers/tee/optee/call.c

@@ -362,7 +362,7 @@ int optee_check_mem_type(unsigned long start, size_t num_pages)
 	 * Allow kernel address to register with OP-TEE as kernel
 	 * pages are configured as normal memory only.
 	 */
-	if (virt_addr_valid(start))
+	if (virt_addr_valid(start) || is_vmalloc_addr((void *)start))
 		return 0;
 
 	mmap_read_lock(mm);

drivers/tee/tee_shm.c

@@ -23,10 +23,24 @@ static void shm_put_kernel_pages(struct page **pages, size_t page_count)
 static int shm_get_kernel_pages(unsigned long start, size_t page_count,
 				struct page **pages)
 {
-	struct kvec *kiov;
 	size_t n;
 	int rc;
 
+	if (is_vmalloc_addr((void *)start)) {
+		struct page *page;
+
+		for (n = 0; n < page_count; n++) {
+			page = vmalloc_to_page((void *)(start + PAGE_SIZE * n));
+			if (!page)
+				return -ENOMEM;
+
+			get_page(page);
+			pages[n] = page;
+		}
+		rc = page_count;
+	} else {
+		struct kvec *kiov;
+
 		kiov = kcalloc(page_count, sizeof(*kiov), GFP_KERNEL);
 		if (!kiov)
 			return -ENOMEM;
@@ -38,6 +52,7 @@ static int shm_get_kernel_pages(unsigned long start, size_t page_count,
 
 		rc = get_kernel_pages(kiov, page_count, 0, pages);
 		kfree(kiov);
+	}
 
 	return rc;
 }