1 files changed, 68 insertions, 24 deletions

diff --git a/drivers/base/memory.c b/drivers/base/memory.c
index 8f3a41d9bfaa..ed3e69dc785c 100644
--- a/drivers/base/memory.c
+++ b/drivers/base/memory.c
@@ -110,6 +110,57 @@ static void memory_block_release(struct device *dev)
 	kfree(mem);
 }
 
+
+/* Max block size to be set by memory_block_advise_max_size */
+static unsigned long memory_block_advised_size;
+static bool memory_block_advised_size_queried;
+
+/**
+ * memory_block_advise_max_size() - advise memory hotplug on the max suggested
+ *				    block size, usually for alignment.
+ * @size: suggestion for maximum block size. must be aligned on power of 2.
+ *
+ * Early boot software (pre-allocator init) may advise archs on the max block
+ * size. This value can only decrease after initialization, as the intent is
+ * to identify the largest supported alignment for all sources.
+ *
+ * Use of this value is arch-defined, as is min/max block size.
+ *
+ * Return: 0 on success
+ *	   -EINVAL if size is 0 or not pow2 aligned
+ *	   -EBUSY if value has already been probed
+ */
+int __init memory_block_advise_max_size(unsigned long size)
+{
+	if (!size || !is_power_of_2(size))
+		return -EINVAL;
+
+	if (memory_block_advised_size_queried)
+		return -EBUSY;
+
+	if (memory_block_advised_size)
+		memory_block_advised_size = min(memory_block_advised_size, size);
+	else
+		memory_block_advised_size = size;
+
+	return 0;
+}
+
+/**
+ * memory_block_advised_max_size() - query advised max hotplug block size.
+ *
+ * After the first call, the value can never change. Callers looking for the
+ * actual block size should use memory_block_size_bytes. This interface is
+ * intended for use by arch-init when initializing the hotplug block size.
+ *
+ * Return: advised size in bytes, or 0 if never set.
+ */
+unsigned long memory_block_advised_max_size(void)
+{
+	memory_block_advised_size_queried = true;
+	return memory_block_advised_size;
+}
+
 unsigned long __weak memory_block_size_bytes(void)
 {
 	return MIN_MEMORY_BLOCK_SIZE;
@@ -816,21 +867,6 @@ static int add_memory_block(unsigned long block_id, unsigned long state,
 	return 0;
 }
 
-static int __init add_boot_memory_block(unsigned long base_section_nr)
-{
-	unsigned long nr;
-
-	for_each_present_section_nr(base_section_nr, nr) {
-		if (nr >= (base_section_nr + sections_per_block))
-			break;
-
-		return add_memory_block(memory_block_id(base_section_nr),
-					MEM_ONLINE, NULL, NULL);
-	}
-
-	return 0;
-}
-
 static int add_hotplug_memory_block(unsigned long block_id,
 				    struct vmem_altmap *altmap,
 				    struct memory_group *group)
@@ -957,7 +993,7 @@ static const struct attribute_group *memory_root_attr_groups[] = {
 void __init memory_dev_init(void)
 {
 	int ret;
-	unsigned long block_sz, nr;
+	unsigned long block_sz, block_id, nr;
 
 	/* Validate the configured memory block size */
 	block_sz = memory_block_size_bytes();
@@ -970,15 +1006,23 @@ void __init memory_dev_init(void)
 		panic("%s() failed to register subsystem: %d\n", __func__, ret);
 
 	/*
-	 * Create entries for memory sections that were found
-	 * during boot and have been initialized
+	 * Create entries for memory sections that were found during boot
+	 * and have been initialized. Use @block_id to track the last
+	 * handled block and initialize it to an invalid value (ULONG_MAX)
+	 * to bypass the block ID matching check for the first present
+	 * block so that it can be covered.
 	 */
-	for (nr = 0; nr <= __highest_present_section_nr;
-	     nr += sections_per_block) {
-		ret = add_boot_memory_block(nr);
-		if (ret)
-			panic("%s() failed to add memory block: %d\n", __func__,
-			      ret);
+	block_id = ULONG_MAX;
+	for_each_present_section_nr(0, nr) {
+		if (block_id != ULONG_MAX && memory_block_id(nr) == block_id)
+			continue;
+
+		block_id = memory_block_id(nr);
+		ret = add_memory_block(block_id, MEM_ONLINE, NULL, NULL);
+		if (ret) {
+			panic("%s() failed to add memory block: %d\n",
+			      __func__, ret);
+		}
 	}
 }