resource: Consolidate resource walking code

The walk_iomem_res_desc(), walk_system_ram_res() and walk_system_ram_range()
functions each have much of the same code.

Create a new function that consolidates the common code from these
functions in one place to reduce the amount of duplicated code.

Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Borislav Petkov <bp@suse.de>
Tested-by: Borislav Petkov <bp@suse.de>
Cc: kvm@vger.kernel.org
Cc: Borislav Petkov <bp@alien8.de>
Link: https://lkml.kernel.org/r/20171020143059.3291-9-brijesh.singh@amd.com

kernel/resource.c

@@ -400,6 +400,26 @@ static int find_next_iomem_res(struct resource *res, unsigned long desc,
 	return 0;
 }
 
+static int __walk_iomem_res_desc(struct resource *res, unsigned long desc,
+				 bool first_level_children_only,
+				 void *arg, int (*func)(u64, u64, void *))
+{
+	u64 orig_end = res->end;
+	int ret = -1;
+
+	while ((res->start < res->end) &&
+	       !find_next_iomem_res(res, desc, first_level_children_only)) {
+		ret = (*func)(res->start, res->end, arg);
+		if (ret)
+			break;
+
+		res->start = res->end + 1;
+		res->end = orig_end;
+	}
+
+	return ret;
+}
+
 /*
  * Walks through iomem resources and calls func() with matching resource
  * ranges. This walks through whole tree and not just first level children.
@@ -418,26 +438,12 @@ int walk_iomem_res_desc(unsigned long desc, unsigned long flags, u64 start,
 		u64 end, void *arg, int (*func)(u64, u64, void *))
 {
 	struct resource res;
-	u64 orig_end;
-	int ret = -1;
 
 	res.start = start;
 	res.end = end;
 	res.flags = flags;
-	orig_end = res.end;
 
-	while ((res.start < res.end) &&
-		(!find_next_iomem_res(&res, desc, false))) {
-
-		ret = (*func)(res.start, res.end, arg);
-		if (ret)
-			break;
-
-		res.start = res.end + 1;
-		res.end = orig_end;
-	}
-
-	return ret;
+	return __walk_iomem_res_desc(&res, desc, false, arg, func);
 }
 
 /*
@@ -451,22 +457,13 @@ int walk_system_ram_res(u64 start, u64 end, void *arg,
 				int (*func)(u64, u64, void *))
 {
 	struct resource res;
-	u64 orig_end;
-	int ret = -1;
 
 	res.start = start;
 	res.end = end;
 	res.flags = IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY;
-	orig_end = res.end;
-	while ((res.start < res.end) &&
-		(!find_next_iomem_res(&res, IORES_DESC_NONE, true))) {
-		ret = (*func)(res.start, res.end, arg);
-		if (ret)
-			break;
-		res.start = res.end + 1;
-		res.end = orig_end;
-	}
-	return ret;
+
+	return __walk_iomem_res_desc(&res, IORES_DESC_NONE, true,
+				     arg, func);
 }
 
 #if !defined(CONFIG_ARCH_HAS_WALK_MEMORY)
@@ -508,6 +505,7 @@ static int __is_ram(unsigned long pfn, unsigned long nr_pages, void *arg)
 {
 	return 1;
 }
+
 /*
  * This generic page_is_ram() returns true if specified address is
  * registered as System RAM in iomem_resource list.